Phytophthora Root Rot and Aerial Blight Management

Derived from the Greek word “Plant Destroyer” the genus Phytophthora affects crops worldwide causing economic losses. Thriving in wet conditions, it is a very fast moving pathogen to susceptible crops. Phytophthora is being classified as a water mold and more related to algae then fungi. Overwintering as chlamydospores, oospores or sporangia that can persist and survive in the soil for years. The chlamydospores are produced asexually and can directly produce sporangia which release zoospores that swim through water to reinfect plants with ease.  The thick walled oospores also produce sporangia which release swimming zoospores that enable spread under idea temperatures and moist, wet conditions. Spores are disseminated by water, rain, irrigation runoff, by humans and even wildlife such as snails. In greenhouses, shorefly and fungus gnat larvae can carry chlamydospores.

There are more than 60 recognized Phytophthora species; at least 10 have been reported on potted plants. Many Phytophthora species are specific to common plant genera: azalea, bacopa, calibrachoa, dogwood, gerbera, lavender, pansy, petunia, poinsettia, rhododendron, vinca, and many herbaceous perennials and vegetable crops, particularly tomato.

Phytophthora on Rhododendron, APS net

The four key pathogen species: P. cryptogea, P. infestans, P. parasitica and P. ramorum, are each capable of causing mortality over a wide range of host plants. P. cryptogea has been associated with tomato, petunia, begonia, cineraria, gerbera and other hosts. Optimum temperatures for growth are 72-78˚F but sporangia can form as low as 40˚F. P. infestans is the pathogen that caused the potato famine and impacts tomatoes causing the destructive late blight, preferring cool spring/fall weather (60-70˚ F days, 50-60˚ F nights). P. parasitica which is more common in potted plants prefers temperatures of 78-90˚F but can colonize in the absence of symptoms at lower temperatures. P. ramorum is associated with foliar blights and dieback of nursery host plants particularly causing the Sudden Oak Death of several oak tree species. 

Bring Down the Intensity this Spring with Shade

Plan to shade your crops and spare them, and yourself, the pain of sunburned foliage. Greenhouse operations can get tense in early spring as the intensity of the workload, space crunches, and insect populations all start to build. The increasing intensity of the sunlight can also be anticipated.  Each spring GGSPro sees examples of sunburned crops during this early spring transition. Below are some tips to help you avoid the setbacks and costs of a sunburned crop.

Timing the Shade

In the early spring light levels increase rapidly. The more northern the location, the more rapidly the daylength increases over the spring months. At the same time as the duration is increasing, the intensity of the light is also increasing. The cumulative effect is calculated in the Daily Light Integral (DLI).  Mapping DLI data by month shows the seasonal progression, as illustrated below from the work of Dr. Jim Faust’s lab at Clemson University.

These data can be used as simple guides for shading decisions, even if over simplified.  Deep shade plants and many ferns are best shaded at DLIs in the 30-35 range (Kelly green).  Shading should be applied over sun-sensitive and light shade loving crops when your location falls into the range of 35-40 DLI (lime green) in the maps. Most sun-loving plants will benefit from 30% shade at DLIs of 40 and above (yellow to orange shades). Remove the shade when the DLI falls below the trigger level you used in putting it on.  These guides are perhaps over-simplified but provide a starting point for planning and scheduling. Note that the light level in the maps can be, and normally are, significantly reduced inside the greenhouse by the glazing, settled dust and pollen, and overhead infrastructure.

Printable version

An Aphid BCA Guide for Dummies

Available in every bookstore or on the internet are the famous “For Dummies” reference books, helping readers with non-intimidating instructions on various topics. Discussed in this article today is the GGSPro version of “An Aphid BCA for Dummies.” BCA stands for Biological Control Agents. Successful pest control with predatory insects is possible, but sometimes, when aphids will not yield to BCAs alone, compatible pesticides can be used without crashing an entire BCA program. 

Before starting BCAs for aphid control, stop pesticide applications not designated as compatible 8-weeks prior to releasing unless you are using compatible pesticides (see below). Make sure you ask your supplier for pesticide records for all incoming plant material.

Next, follow these four principles:

    1.Commit time to scouting weekly with trained personnel that can correlate pest identification and risks.

    2. Place BCA orders to begin releases at the beginning of production based on desired sq ft.

    3. Check viability of BCAs upon arrival and release on a predetermined schedule (release frequency and rates may need to be modified depending on pest pressure development)

    4. Follow up with routing scouting and evaluations and keep records. 

Aphidius wasp, aphid mummy, Aphidoletes and lacewing larvae (left to right). Photo credit: GGSPro and Cornell IPM

The most reliable aphid parasitoids belong to the Aphidius genus. Aphidius colemani is released for smaller aphids like the green and melon aphids, while Aphidius ervi is used for larger aphids like foxglove and potato aphid. The Aphelinus abdominalis, also an aphid parasitoid species, targets larger second and third instar aphid nymphs. Both parasitoid species lay their eggs inside the aphid where it then hatches and the larvae consumes the body. The Aphidius forms a tan colored aphid mummy while the Aphelinus produces a distinctive black mummy. Releases are done on a biweekly basis until the first sighting of an aphid. Then, plan on three weekly releases before going back to biweekly releases. Ideal temperatures are 65-85oF and 70% relative humidity. Lower or higher temperatures outside this range will delay parasitoid development. 

The predatory midge, Aphidoletes or the Chrysoperla carnae/rufilabris (common name - lacewing), are used for hot spot areas along with the continued parasitoid wasp releases. Both will prey on all species of aphids. Additionally, both require warm temperatures of 70-80oF and 80-90% relative humidity. Aphidoletes will enter diapause under cool temperatures and low light condition. Releases are biweekly to weekly for Chrysoperla and weekly for Aphidoletes for 3-4 weeks or as needed to clean up an infestation. 

When our biological enemies do not provide adequate control, careful choices and timing of low toxicity pesticides will provide a back up to biological control. This should allow a reduction of pest reproduction so that within 1-2 weeks, a return to BCA releases is possible. The GGSPro department can provide tailored compatibility charts to reduce harmful effects on your BCA program from pesticide applications.. 

The safest choices typically include biological insecticides like Ancora, BotaniGard WP, Velifer, or Venerate. These can be tank-mixed with an Azadirachtin IGR (Insect Growth Regulator) like AzaGuard, Azatin O, or Molt-X. Insecticides with short residual toxicity include: Suffoil-X/Ultra-Pure Oil, Kopa/M-pede, Endeavor (spray/drench), Kontos (spray/drench), and PyGanic. Avoid tank mixing insecticides with fungicides when using BCAs because less information is available for fungicides. Try to always spray before new BCA releases rather than after. Omit use of surfactants when possible as these can have a negative impact on BCA populations.

Product Name	MOA	Size	Comments	Item Number
Apheline	NA	250	Mummies/adults	SB0202-01, 30AD25
Aphidoline BioAphidoletes		1K 2K	Pupae	SB0151-01, BB-0006, 30AA2
APHIDIUSforce C BioAphidoletes		500	Mummies/adults	30AC5, BB-0005,
Apheline APHIDIUSforce C		1K	Mummies/adults	SB0102-04, 30AC10

Other sizes and packaging of Aphidius mixes are available. Contact GGSPro

Product Name	MOA	Size	Comments	Item Number
CHRYSOforce R		1K	Larvae	SB0301-04, 30LWB
CHRYSOforce R		1K	Eggs on cards	30LWE

Other sizes and packaging of Chrysoperla larvae and eggs are available. Contact GGSPro

Product Name	MOA	Size	Comments	Item Number
Ancora	UNF	1 lb	Spray	70-1166
BotaniGard WP	UNF	1 lb	Spray	70-12521
Endeavor	9B	15 oz	Spray or Drench	70-1655
Kopa	UN	2.5 gal	Spray	70-1970
Kontos	23	8.45 oz	Spray or Drench	70-19601
M-Pede	UN	2.5 gal	Spray	75-10262
PyGanic 5.0	3A	1 qt	Spray	70-2687
Velifer	UNF	1 qt	Spray	70-9540
Venerate	UNB	1 qt	Spray	70-9461
Azatin O	UN	1 qt	IGR, Spray	70-12301
AzaGuard	UN	1 qt	IGR, Spray	70-1224
Molt-X	UN	1 qt	IGR, Spray	70-2400
Suffoil-X	UNE	2.5 gal	Spray	70-4040
Ultra-Pure Oil	UNE	2.5 gal	Spray	70-21401

This information is intended to help reduce aphid outbreaks that may occur during implementation of BCA programs. It is the responsibility of the applicator to read and follow all label directions. Labels do change without notice. Pesticides other than those listed may be safe, legal and effective.

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Preventing Disease In Propagation

Many growers start crops from unrooted cuttings. High humidity and warm temperatures in propagation promote rooting but can also promote disease. Disease progression in propagation can be swift, so it is important to recognize and treat problems quickly and consider preventative treatments.

Product Name	Description	Item Number
Affirm	FungicideFungicide	71-1131
Badge SC	Bactericide, FungicideBactericide, Fungicide	71-1205
Broadform	FungicideFungicide	71-1290
Camelot O	Bactericide, FungicideBactericide, Fungicide	70-21202
CapSil	SurfactantSurfactant	74-1541
Cease	FungicideFungicide	71-13301
Empress Intrinsic	FungicideFungicide	70-1510
Fascination	PGRPGR	73-1910
Fenstop	FungicideFungicide	71-14801
Fosphite	FungicideFungicide	71-1520
Grotto	Bactericide, FungicideBactericide, Fungicide	71-2030
Kleengrow	Bactericide, Fungicide, SanitizerBactericide, Fungicide, Sanitizer	74-21101
Mural	FungicideFungicide	71-1690
Pageant Intrinsic	FungicideFungicide	71-26801
Palladium	FungicideFungicide	71-2685
Phostrol	FungicideFungicide	71-2725
Phyton 35	Bactericide, FungicideBactericide, Fungicide	71-2732
Protect DF	Bactericide, FungicideBactericide, Fungicide	71-2748
SaniDate 5.0	SanitizerSanitizer	71-35001
Segovis	FungicideFungicide	71-3100
Segway O	FungicideFungicide	71-31102
Stargus	Bactericide, FungicideBactericide, Fungicide	71-2950
Strip-it Pro	CleanerCleaner	74-2124
Triathlon BA	Bactericide, FungicideBactericide, Fungicide	71-3040
Zerotol 2.0	Bactericide, Fungicide, SanitizerBactericide, Fungicide, Sanitizer	71-35501

Printable version

The Relationship Between Water Quality and Fertilizer Programs

The Importance of Water Testing

Testing your irrigation water can help determine an appropriate fertilizer program that sufficiently meets nutritional requirements while managing optimal substrate media pH. There are many labs available that offer water quality testing; regardless of the lab you choose, make sure some specific horticultural parameters are measured. These include pH, alkalinity, electrical conductivity (EC), primary (nitrogen, phosphorus, potassium) and secondary (calcium, magnesium, sulfur) plant macronutrients, as well as micronutrients such as iron. Sodium and chloride, which can be negative to plant growth in large quantities, are also valuable to measure. The quality of your “clear water” or water directly from your main irrigation source (wells, ponds, city water, etc.) without any additional inputs (fertilizer, acids, bases) should be determined year to year as  water quality can change over time. At a minimum, it is a good idea to have your water tested annually.

Alkalinity and Substrate pH 

Alkalinity is a measure of the dissolved bicarbonates and carbonates (calcium, magnesium, and sodium) in water. More simply put, alkalinity can be seen as a fertilizer salt that is not taken up by the plant that makes a critical difference in the availability of other plant essential nutrients by altering the pH of the growing media. These carbonate species create a basic environment in the media, the higher the alkalinity, the greater the increase in media pH over time. Alkalinity can also be described as buffering capacity, or resistance to pH change. Low alkalinity water offers little or no resistance to pH changes coming from acids (sulfuric acid) and fertilizers. High alkalinity water overwhelms the effects of the acids and bases and becomes the controlling factor of media pH.

Fertilizer Rotation 

Fertilizers can have a significant impact on raising or lowering substrate pH. The relative “acid forming” or “basic forming” ability of a given fertilizer is primarily determined by the percentage of ammonium to nitrate in the fertilizer. For example, fertilizers with high amounts of ammonium forms of nitrogen (21-7-7) are considered acid forming fertilizers, whereas fertilizers containing predominately nitrate forms of nitrogen (15-0-15) are considered basic forming. The relative acid/basic forming ability of a fertilizer can typically be found on most fertilizer labels below the guaranteed analysis (Figure 1). Please reference Table 1 for examples of acid and basic forming fertilizers. 

Figure 1: Example fertilizer label for Jack's 20-10-20

Figure 2: Iron deficiency due to high soil pH in calibrachoa

Figure 3: Iron and manganese toxicity due to low soil pH in geranium

Bringing alkalinity back into the conversation, we can now combine our understanding of how both alkalinity and fertilizer choice influence substrate pH. Each plant species has an optimal substrate pH to be grown at for all the macro and micronutrients required to be available for plant uptake. Poinsettias for example have an optimal substrate pH of 6.0 to 6.5. If we go below or above this range, micronutrients can become in toxic or deficient in the plant, respectively. We can manage substrate pH by rotating between acid and basic forming fertilizers in an appropriate schedule based on the alkalinity of the irrigation water. As shown in Table 2, a poinsettia grower with an alkalinity level of source of 100 ppm CaCO3 would irrigate their crop twice with an acid forming fertilizer and then use a basic forming fertilizer on the third irrigation. 

Adjusting Substrate pH with Acid

For water with alkalinity greater than 150 ppm CaCO3, injection of technical grade sulfuric acid is recommended to neutralize alkalinity and help keep media pH within the optimum range. Sulfuric acid may be added to most acid forming fertilizers (20-10-20 or 21-5-20) but is not compatible with any fertilizer containing calcium (15-0-15, 15-0-0), which are typically basic forming as well. Reference Table 3 for rates of continuous sulfuric acid injection based on alkalinity level. Please contact GGSPro for recommended rates when using other types of acids (phosphoric, citric), suggestions on where to have your water tested, or if you have any questions on fertilizer rotation programs.

Item Description		Item Number(s)
20-10-20 (25lb bag)		333614, 31-140200, 67-2316
15-0-15 (25lb bag)		33626, 31-140100, 67-2340
21-5-20 (25lb bag)		33602, 31-140306, 67-2308
Sulfuric Acid (1 gal)		75-5030
Jack's Potassium Bicarbonate (1lb, 25lb)		91-2190, 91-2191
BioSafe CalOx (2.5 gal)		75-0525

Printable version

Poinsettias - Tips for End of Season Success

This is the time of year where poinsettia growth has come to a crawl, and bract develop is in full swing. Bract development and overall poinsettia health during the late season can be managed through a combination of cultural and chemical practices. This article will outline some techniques and considerations for ensuring end of season poinsettia quality. 

Bract Development and Temperature 

Temperature has a direct effect on bract expansion, color, maturity, and durability. Night temperatures are critical for bract expansion, with 65-68°F being ideal for most varieties. Higher night temperatures can encourage weak bracts, dull color, bract edge problems, and foliar diseases. Night temperatures that are too cool can cause bracts not to size up properly. White flowering varieties can also look green or yellow if night temperatures are too cool. Day temperatures should be kept relatively cool to reduce stretch and increase stem strength. 

Average daily temperature (ADT) has the largest impact on the rate of bract expansion and saleable color date. The stage of bract development is the best indicator of when to change temperature requirements (Table 1). Stage 3 should begin when bracts are ~75% of finished size. Stage 4 represents the time when bracts are nearly fully expanded or at saleable quality. For example, early flowering varieties may enter stages 3 and 4 up to 2 weeks earlier than Table 1 indicates. Temperatures below 60°F in stage 4 can increase the risk of Botrytis on bracts. Maintaining dry air during the last stage when the coolest temperatures occur may be difficult with reduced heat. Cooler air temperatures increase the relative humidity in the plant canopy, which in turn makes condensation more likely. Free moisture on plant surfaces favors Botrytis development.

Average daily temperature (ADT) has the largest impact on the rate of bract expansion and saleable color date. The stage of bract development is the best indicator of when to change temperature requirements (Table 1). Stage 3 should begin when bracts are ~75% of finished size. Stage 4 represents the time when bracts are nearly fully expanded or at saleable quality. For example, early flowering varieties may enter stages 3 and 4 up to 2 weeks earlier than Table 1 indicates. Temperatures below 60°F in stage 4 can increase the risk of Botrytis on bracts. Maintaining dry air during the last stage when the coolest temperatures occur may be difficult with reduced heat. Cooler air temperatures increase the relative humidity in the plant canopy, which in turn makes condensation more likely. Free moisture on plant surfaces favors Botrytis development.

Maintaining Bract Health

Figure 1. Bract edge burn

During the end of the season, healthy bract development is key to a quality product and long-term shelf-life. The biggest issues to look out for is Botrytis and bract edge burn, which can go hand in hand. Botrytis is a quickly spreading fungal pathogen that can propagate in damaged material caused by bract edge burn. Bract edge burn is caused by a calcium deficiency. Both of these issues can be prevented by using foliar applications of calcium and fungicides. We recommend weekly sprays with calcium chloride dihydrate rather than calcium nitrate, because calcium nitrate can occasionally cause additional bract damage. Weekly foliar sprays of calcium chloride dihydrate at 0.5 oz per 3 gal or 16 oz per 100 gal should be applied at onset of bract color. Affirm WDG, Astun, Medallion WDG, Palladium, or Spirato GHN are all effective, bract safe options for preventing and controlling Botrytis. All of these

Figure 2. Poinsettia bract with Botrytis

applications should be used in conjunction with a surfactant such as CapSil (¼ tsp per gal or 4 oz per 100 gal) to reduce any potential for residues. CapSil should not be applied more than once per week during bract development.

Increasing Bract Size with Fascination

Inadequate bract expansion can be caused by a number of reasons including but not limited to: a

Figure 3. Spikey bract effect with Fascination spray

lower than ideal ADT (Average Daily Temperature) and excessive or late applications of PGRs. Foliar sprays of Fascination can be successful in increasing bract expansion but carries certain risks with it. Over-applications of Fascination at this stage of development can lead to weakened petioles, overly large floppy bracts, a change in bract color, and accelerated cyathia abscission. Consider these to be rescue treatments for when the risk of unsaleable plants due to small bracts outweighs the potential risks. Conduct trials on a small number of plants before widespread applications. Bracts sometimes have a “spikey” appearance soon after the treatment, but they usually flatten out within a few days. Fascination can be sprayed at 3ppm from first color to mid-November. Concentrations should decrease to 1-2 ppm during mid-November to December 1st. It is important to wait at least 5 days to evaluate changes in growth before reapplying if needed. 

Nutrition

Once poinsettias have essentially stopped vegetative growth and put their efforts in flowering, their overall nutrient requirements should be cut in half. Applying too much fertilizer during the bract development stage can lead to off colored bracts, salt stress, and disease issues such as Botrytis and Pythium. Please refer to Table 2 for general recommended feed rates based on dates during the late season. 

*All of these recommendations are based on top irrigation. For sub-irrigation, typically ½ as much fertilizer is used. Early cultivars go to clear water ~7-10 days earlier. The recommended schedule will need to adjusted if black clothing plants.

Nutrient deficiencies that do occur during the later portion of the season need to be corrected immediately to prevent a decrease in plant quality. Most of these issues can be prevented by making sure your crop is appropriately fed and soil pH is in the correct range leading into flower. We recommend testing your tissue and soil prior to first color in order to correct any issues before bracts begin developing. The most common deficiencies typically fall under the category of molybdenum (Mo), manganese (Mn), magnesium (Mg), iron (Fe), and calcium (Ca). Mn, Mg, and Fe will increase in availability to the plant as soil pH goes down, while Mo and Ca will decrease in solubility. Utilizing a micronutrient package such as S.T.E.M. or M.O.S.T. in combination with adjusting soil pH within 6.0 to 6.5 can help correct all of these deficiencies except Ca. Calcium deficiencies can be corrected by using a calcium containing fertilizer such

Figure 4. Pythium root rot causing plant wilting

as 15-0-15 and foliar sprays of calcium chloride dihydrate as described previously. 

Late Season Pythium 

There are various Pythium species that can cause root rot issues throughout the season. Most often, we can prevent root rot by supplying the appropriate concentration of fertilizer based on the stage of growth as described above and maintaining an appropriate irrigation frequency. Applying high amounts of fertilizer can lead to salt stress and damaged root systems. These conditions are ideal for Pythium to colonize and overtake the plant. Pythium can also be prevented with scheduled fungicidal drenches. Table 3 shows a recommended drench program for preventing root rot issues throughout the season. 

Product Name		Item Number
Affirm WDG		71-1129
Astun		71-1190
Medallion WDG		71-16502
Palladium		71-2685
Spirato GHN		71-2948
Banrot 40 WP		71-1210
Fenstop		71-14801
Segway O		71-31101
Subdue Maxx		71-2979
Terrazole L		71-3025
Terrazole WP		3183862
Truban 25 EC		71-3070
Fascination		73-1910
CapSil		74-1541
Jack's 15-0-15		33627
Peters ICL 15-0-15		67-2340
Plantex 15-0-15		31-140100
S.T.E.M.		67-2344
M.O.I.S.T.		33633
Calcium chloride dihygrate		35315

Printable version

Heat Stress in Plants

All good things are best when used in moderation, as the saying goes. That is certainly true of heat in the summer, as we can all attest. As the temperatures soar plants can take a turn for the worse, a condition generally termed ‘heat stress’. Several common crops cultivated over the summer season provide well-known examples of the effects of non-lethal heat stress. Tomato crops set fruit less efficiently, poinsettias

Heat distortion of chrysanthemum foliage.

and chrysanthemums can develop strappy foliage and experience delayed flowering. These effects occur when the local temperature the plant is experiencing is higher that the inherent stability of the plant’s cellular DNA, protein enzymes, and membrane structures.The process of photosynthesis is the first to be affected as temperatures rise. The enzymes involved in photosynthesis, are heat-sensitive and denature, or unfold, easily. Plants try to protect themselves physically by changing leaf orientation and size, and plant morphology under prolonged stress. Furthermore, plants change their biochemistry in order to preserve their normal cellular functions. Plants express heat-shock proteins to stabilize the enzymes of photosynthesis and other processes, they produce enzymes to deactivate oxidizing molecules, and shore up cell membranes with more saturated and less fluid lipids to mitigate damage. (Think of lard or shortening versus vegetable oil.) Printable version

Fall Pansies - Fighting Black Root Rot and Phytophthora

Pansy, Cercospora

Fungicide	MOA	Comments	Item Number
Thielaviopsis
Affirm	19	Chemigation label approved	71-1129
Cleary’s 3336 EG	1	Max label rate, re-apply in 3 weeks	71-2550
Cleary’s 3336 F	1	Max label rate, re-apply in 3 weeks	71-2575
Medallion	12	2 oz per 100 gals rate	71-16502
Mural	7 & 11	Broad-spectrum control	71-1690
OHP 6672 F	1	Max label rate, re-apply in 3 weeks	71-2670
OHP 6672 WSP	1	Max label rate, re-apply in 3 weeks	71-2672
Orkestra Intrinsic	7 & 11	Broad-spectrum control	71-2200
Rootshield Plus G	UN	Pre-incorporation	71-27911
Rootshield Plus WP	UN	Best applied at time of transplant	71-27951
Spirato GHN	12	Formerly called Emblem	71-1570

Fungicide	MOA	P= Pythium Ph= Phytophthora	Comments	Item Number
Actinovate SP	NC	P	Best applied at the time of transplant	71-1118
Adorn	43	Ph	Foliar spray or drench	71-1130
Areca	33	Ph	Foliar spray, avoid open bloom	71-1180
Aliette	33	Ph	Foliar spray, avoid open bloom	71-11352
Banrot	1 & 14	P, Ph	Soil drench, use max label rate	71-1210
Broadform	7 & 11	Ph	Foliar spray aerial Phytophthora only	72-1290
Fenstop	11	P,Ph	Foliar spray or drench	71-14801
Fosphite	33	Ph	Foliar spray or drench	71-1520
Heritage	11	Ph	Foliar spray or drench, preventative	71-1400
Kleengrow	NC	P,Ph	Do not combine with fertilizer	74-21151
Micora	40	Ph	Foliar spray or drench	71-1655
Orkestra Intrinsic	7 & 11	Ph	New product, trial for plant safety	71-2200
Orvego	40 & 45	Ph	Foliar spray or drench	71-2300
Phostrol	33	Ph	Foliar spray or drench	71-1520
Rootshield G	NC	P	Pre-incorporation	0
Rootshield WP	NC	P	Best applied at the time of transplant	71-27901
Rootshield Plus G	NC	P, Ph	Pre-incorporation	71-27911
Rootshield Plus WP	NC	P, Ph	Best applied at the time of transplant	71-27951
Segovis	U15	Ph	Foliar spray or drench	71-3100
Segway	21	P, Ph	Foliar spray or drench	71-31101
Stature SC	40	Ph	Foliar spray or drench	71-14652
Subdue MAXX	4	P, Ph	Some resistance reported	71-2978
Terrazole L	14	P, Ph	Stronger vs Pythium	71-3025
Truban EC	14	P, Ph	Stronger vs Pythium, no tank mixing	71-3070
Truban WP	14	P, Ph	Stronger vs Pythium	71-3065

Products for Common Pansies Foliar Diseases

Read and follow all label directions. The label is the law! Products other than those mentioned may also be safe and effective. Some pesticides may be restricted-use or unregistered in certain states.

Printable version

Insect Pest Control Roulette

Common Name	Life Cycle*	Damage	Chemical Control	Item Number
Aphids	I	Piercing/sucking mouthpart; Curling, deformed, yellowing leaves	Altus Pradia Tristar	70-1161 (64 oz)  70-2630 (qt)  70-85221 (qt)
Beetles	C	Chewing mouthpart; Holes or skeletonized leaves; bark beetles bore holes into bark, look for frass and/or sap	Discus LMainspring Sarisa	70-14091 (gal) 70-2331 (pt) 70-2975 (64 oz)
Grasshoppers	I	Chewing mouthparts; holes in foliage and flowers; worse in dry weather	Acephate Pycana Tristar	71-1105 (lb) 70-2655 (gal) 70-85221 (qt)
Moths	C	Chewing mouthparts; eat leaves, roots, and can bore into stems; wider host range than caterpillars	DiPel Pro Pycana Venerate CG	70-1450 (lb) 70-2655 (gal) 70-9461 (qt)
Plant Bugs	I	Piercing/sucking mouthpart; stipple foliage, distorted foliage	Altus Pradia Pycana	70-1161 (64 oz) 70-2630 (qt)  70-2655 (gal)
Plant Hoppers  (including leafhoppers)	I	Piercing/sucking mouthpart; may have waxy coating; jump when disturbed	Discus L Flagship 25WGTristar	70-14091 (gal) 70-1700 (8 oz) 70-85221 (qt)
Sawflies	C	Chewing mouthparts; larvae consume needles/leaves quickly one branch at a time	Conserve Pycana Sarisa	70-1365 (qt) 70-2655 (gal) 70-2975 (64 oz)
Spider Mites	I	Piercing/sucking mouthpart; Chlorotic spots, whitish stippling; bronzed appearance	Shuttle O Sultan Suffoil-X	70-30151 (pt) 70-3045 (16 oz) 70-4040 (2.5 gal)
Stink Bugs	I	Piercing/sucking mouthpart; causes distortion, sunken areas, scarring	Azera Pro PyGanic 5.0 Sarisa	70-1232 (qt) 70-2687 (qt) 70-2975 (64 oz)
Thrips	C	Piercing/sucking/thrashing mouthpart; whitish/silvery stippling or streaking; the presence of fecal spots	Mainspring Pradia Pycana	70-2331 (pt) 70-2630 (qt) 70-2655 (gal)
Weevils	C	Chewing mouthpart; chew distinctive notches along leaf margins; grubs injury roots/crowns	Flagship 25WGMainspring Sarisa	70-1700 (8 oz) 70-2331 (pt) 70-2975 (64 oz)
Whiteflies	C	Piercing/sucking mouthparts; yellowing, chlorotic spots on upper leaf surfaces, honeydew/sooty mold	Ancora Pradia Tristar	70-1166 (lb) 70-2630 (qt) 70-85221 (qt)

Printable version

Extending Shelf Life and Marketability of Spring Plants

·       Argyranthemum
Putting crops out early is not without its risks. One grower shared this picture after an April snowstorm and freeze. Despite the icy appearance, the entire outdoor crop pulled through with minimal damage.
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The ABCs of BCAs

Figure 1. A parasitic wasp (Eretmocerus eremicus)  laying eggs under whitefly pupae

Target Pest	Type of BCA
Aphids	Parasitic wasps, lacewing, and larvae (bulk release)
Black Vine Weevil & White Grubs	Nematodes
Fungus Gnats	Nematodes, predatory beetles, and mites
Leafminers	Parasitic wasps
Mealybugs	Predatory beetles and larvae
Spider Mites	Predatory mites
Thrips	Nematodes, predatory beetles, and mites
Whiteflies	Predatory bugs, beetles, parasitic wasps, and mites

Figure 2. Sachets on sticks containing predatory mites used for annual young plant pest management	Figure 3. Bulk release bottle of Aphidius ervi, a predatory wasp used for aphid control
Figure 4. Bulk release material containing  predatory mites for whitefly and thrips control	Figure 5. Beneficial nematodes used for  fungus gnat and thrips control

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Plant Lighting – Introduction into Supplemental and Sole-Source Lighting

Introducing Lighting Units

The previous lighting article focused on photoperiodic lighting. This article will focus on supplemental and sole-source lighting strategies. Utilizing these lighting techniques requires thorough understanding of what light is and how it is quantified. There are some standardized terms and units that are used in today’s industry, which can help you maximize the benefits of plant lighting (Table 1). 

Fig1. Photosynthetic  Active Radiation (PAR) Spectrum (400-700nm) Photo provided by Dr. Erik Runkle, MSU

Light is a form of energy measured in photons. Photons can travel in different wavelengths and these wavelengths are measured in nanometers (nm). The wavelength that light travels in can be broadly described as light quality. Humans can visibly see photons traveling in wavelengths ranging from 380-770 nm (i.e. the visible light spectrum). Within this range, plants utilize photons within 400-700 nm (light qualities of blue to far-red) for photosynthesis (Fig. 1). We call light within this range photosynthetic active radiation (PAR).

It is important for growers to know how much light plants receive for a given area, so light intensity measurements are typically reported as a density (amount of light given off every second per square meter of growing space). We call this photosynthetic photon flux density (PPFD).

Fig 2. Supplemental lighting during winter months for young plant production

Supplemental Lighting and Sole-Source Lighting

Supplemental lighting is the use of artificial light to supplement PPFD provided by sunlight. The purpose of supplemental lighting is to add additional light at intensities high enough to increase photosynthesis and improve plant quality in situations where sunlight is limited. During periods where light levels are minimal such as the winter (due to a lower photoperiod) or cloudy days, supplemental lighting can provide additional PPFD to plants to carry on with adequate rates of development.

Fig 3. Indoor vertical farm with sole-source lighting

Sole-source lighting is the use of artificial light without additional PPFD from sunlight to produce any or all stages of a crop. This form of lighting application has been utilized in environmental controlled settings such as factory farms, indoor grow operations, and vertical farms. This is the most expensive plant lighting application. These costs are attributed to high capital and installation costs of the light modules themselves and electrical costs required to operate the lights on a daily basis. For supplemental and sole-source lighting applications, achieving a target DLI is very important. The target DLI a grower should strive for is crop and crop stage specific (Table 2). DLI is essentially the total amount of PAR light one square meter of growing space receives over a single day (mol∙m-2∙d-1).



Griffin offers a wide range of lighting products and services to meet all your photoperiodic, supplemental, and sole-source lighting needs. Please reach out to GGSPro or the Griffin CEA division with any questions or inquiries you may have regarding plant lighting.

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Plant Lighting - Introduction into Photoperiodic Lighting

Overview

Light is an essential input for driving plant growth and producing a high-quality product. The major light sources for growing plants include sunlight and plant lighting technology. Growers can use plant lighting in three major ways:

• Photoperiodic Lighting - manipulating vegetative and reproductive stages of plant development through day/night length control
• Supplemental Lighting - adding additional light to increase total crop photosynthesis and quality 
• Sole-Source Lighting - growing plants in completely artificial light 

This article will focus on photoperiodic lighting and how it is utilized in plant production. There will be a follow-up article on utilizing supplemental and sole-source lighting over the coming year. 

Photoperiodic Lighting

Fig 1. Photoperiodic lighting to keep young plants vegetative

Photoperiod can be defined as the number of hours of light a plant perceives on any given day. The number of hours of light/darkness a plant receives per day can directly influence flowering response, stem elongation, and dormancy. Typically, photoperiod is naturally controlled by the most common light source for plants, the sun. Depending on where your operation is located geographically, your photoperiod can vary by several hours throughout the year and even growing season.

A majority of plants we grow are separated into three photoperiodic requirement categories: plants requiring daylengths less than a given amount of time are short-day (SD), plants requiring daylengths more than a given amount of time are long-day (LD), and plants that do not require a given daylength to show a response are day-neutral (DN). A majority of LD plants require greater than 12 hours of daylength to initiate flowering while most SD plants require less than 12 hours to initiate flowering. Photoperiod requirements can be species specific and even vary between varieties. 





Examples of Photoperiodic Control in Production

Fig 2. Black cloth used to force SD plants into flower

Running lights from 10pm to 2am will keep SD plants vegetative. This practice is commonly used to extend the vegetative phase and prevent plants from flowering or going dormant. Keeping plants vegetative provides more time for plants to increase in size as well as allows precise control on when plants flower. Extending photoperiod is also useful for propagation during the fall and winter months. It is important to keep young plants vegetative to encourage adequate rooting and development. The most common light sources used for extending photoperiod include incandescent, high pressure sodium (HPS) Beamflicker, metal halide, and fluorescent bulbs.

Scheduling plants is vital to meet consumer needs. There are times when the natural photoperiod is greater than 12 hours and growers need to force SD plants into flower. Growers can decrease natural photoperiod by pulling black cloth over the crop in the morning and evening hours on a daily basis. This will extend the “nighttime” period and force SD plants into flower. 


Griffin offers a wide range of lighting products and services to meet all your photoperiodic, supplemental, and sole-source lighting needs. Please reach out to GGSPro or the Griffin CEA division with any questions or inquiries you may have regarding plant lighting.

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New Products from the Softer Side of Pest Control

The trend in new pesticide introductions for commercial greenhouse and nursery operations is towards “softer” pesticides, many of which are approved for organic production. Many consumers and producers are asking for these types of products and the market has responded to this demand in a significant way. A few notable introductions into this category of pesticides are discussed below.

Sil-Matrix is based on a liquid concentrate of potassium silicate. It is an EPA registered fungicide, insecticide and miticide. Silicon research is being conducted in a number of places and as a result many plant health benefits have been described. Sil-Matrix is applied as a foliar spray for the control of aphids, spider mites and whiteflies as well as important foliar diseases such as Botrytis and powdery mildew. It is labeled for use on ornamentals and many edible crops including certain vegetables, berries, vines and fruit trees. The addition of a high quality surfactant such as CapSil improves coverage and reduces visible residue on plant surfaces. Sil-Matrix is OMRI listed and benefits from a 4 hr REI and can be used up to the day of harvest.

Item 71-2940 Size 2.5 gal

Spider mite, 5 days after Velifer treatment - Photo credit BASF

Velifer is a new microbial insecticide and miticide based on Beauveria bassiana strain PPRI 5339. The formulation is described as an oil dispersion, with the oil being plant based. Velifer is labeled for greenhouse use only, for the control of aphids, mealybugs, mites, thrips and whiteflies. It can be used on ornamentals, fruits, vegetables, herbs and spices. GGSPro recommends a program for Velifer that includes tank mixing it with an azadirachtin based IGR such as: AzaGuard, Azatin O or Molt-X to further enhance performance. Contact GGSPro for more tips on maximizing the effectiveness of microbial insecticides such as Velifer.  BASF has produced a list of pesticides that are compatible with Velifer. Velifer has a 12 hr REI and can be used up to the day of harvest.

Item: 70-9540 Size: quart

FireWorxx is a fast acting, non-selective broadleaf weed, grass, algae and moss killer. On a warm sunny day results can be seen in a few hours, but never longer than 2 days. It can be used in and around ornamentals and edible crops, so long as all contact with desirable foliage is avoided. FireWorxx can also be added at a 1% rate to improve the performance of other herbicides such as glyphosate, (Round-Up, etc) and glufosinate, (Cheetah Pro, Finale). FireWorxx is an OMRI listed product with a 12 hr REI.

Item: 72-1608 Size: gal

Dahlia, Powdery Mildew

EcoSwing is a botanical extract from Swinglea glutinosa.  If that is a new plant name for you, you are in good company! Swinglea is a type of citrus. EcoSwing acts as a contact desiccant and cell wall disruptor to fungal hyphae. EcoSwing is primarily a preventative fungicide with some curative activity versus Botrytis, downy mildew of basil, powdery mildew and brown rot. EcoSwing can be used on ornamental and food crops in greenhouses, nurseries and landscapes. It is OMRI listed with a 4 hr REI and it can be used up to the day of harvest.

Item: 71-1455 Size: quart
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Algae Is A Slippery Slope

Algae on a walkway

Algae on a floor or walkway is a known slipping hazard –it ranks right up there with cartoon banana peels! That is no laughing matter in your production areas. On the soil surface in pots, algae can interfere with water penetration and drying of the soil. Its’ growth robs the plant of nutrients, and decreases the soil oxygen levels. Algae can also grow on the foliage, blocking light for photosynthesis. As if interfering with growth is not enough, algae also provides a hatchery and a food source for both fungus gnat and shorefly larvae wherever it exists. In hydroponic production, algae can have an even more interesting effect. The unwanted growth can cause extreme pH swings in recirculated hydroponic systems. The pH swings occur with the light and dark cycles as photosynthesis is carried out by the algae.  How can this green pest be prevented and, once present, how can it be controlled?

Preventing establishment of algae is the best practice, after it takes up residence, a grower is sliding down that metaphorical slippery slope. It can be hard to reign in the green slime.  Prevention begins when the system or structure is recently cleaned and sanitized, or is new in the case of soil-less media or rockwool cubes. Algae reproduces by sporulation and by simple cell division. Spores can be airborne and can cling to greenhouse surfaces, including the greenhouse plastic, leading to recurring issues. Thorough cleaning using an acid or chlorine-based product, followed by a disinfecting sanitizer is necessary to eliminate the spores on surfaces. Request the GGSPro bulletin: Hard Surface Sanitation Practices for more information. 

Algae on a basil float bed

Algae in the water system the leading cause of algae on the soil surface and provides a continual source of algal inoculum for hydroponic systems, drip irrigation systems, walkways and other greenhouse surfaces. Water systems are best cleaned when no plants are on the line or in the greenhouse. To break down the algae, biofilms, and mineral deposits that build up even when ‘clean’ water is used, strong cleaners are required. An empty production area is also best for cleaning surfaces, floors and bench supports. For some growers seasonal breaks provide the perfect opportunity for cleaning and sanitation. For growers in perpetual production, it is worth the effort to make a day, or even part of a day to clean the irrigation system and production area surfaces.

Product	Rate	Use Notes	Item Number
Cleaners
GreenClean Acid Cleaner	2.5 oz/gal (1:50 direct injection)	Soak up to 8 hrs	74-2040
SaniDate 12.0 OMRI listed	12.8 oz/100 gal (1:1000 dilution)	Soak 12-48 hrs. Does not remove mineral scale	71-35351
Strip-It Pro	2.5 oz/gal (1:50 direct injection)	Soak overnight	74-2125

Treat water system, irrigation lines, drop tubing and emitters (no lead emitters). All products are allowed in food packaging areas. Rinse the products through opn flush valves to prevent clogging. For GreenClean and Strip-It Pro acid cleaners, rinse further until the water has neutral pH at the last outlet on the line.

Product	Rate	Use Notes	Item Number
Cleaners
GreenClean Acid Cleaner	3-8 oz/gal	Use as spray or foam. Contact time 10-15 min. Avoid soft metals and painted surfaces	74-2040
GreenClean Alkaline Cleaner	4-8 oz/gal	Use as spray or foam. Allow a contact time 10-15min.	74-2045
GreenClean Pro OMRI listed	Granular Use: 0.5-2lb/1k sq ft Liquid or Foam Use: 0.5 lb/gal	Use as granular control on floors; spray or foam with a foam agent for vertical surfaces. Break up thick clumps of algae as cleaning occurs. No use on painted surfaces.	74-20521
Horti-Klor	2.5-7.5 oz/gal	Use as spray, foam or dip. Rate based on soil level.	74-2105
Strip-It Pro	2.5-8 oz/gal	Use as spray, foam or brush application. 5-30 min contact time.	74-2125

Treat floors, hydroponic troughs of channels, sidewalls, benches, and supports. Rinse copper or aluminum, which are soft metals as soon as possible. These are strong cleaners, obey all label precautions and personal protection equipment requirements.

Once algae has been dealt a deadly blow, a sanitizer should be used to finish the job by disinfecting the cleaned system or surface, see chart below.  


When algae control is needed in and around crops, many of these same products are used for preventative maintenance against algae, either periodically, or by continuous injection in the water.  Furthermore, SaniDate12.0 or ZeroTol 2.0 can be used to clean irrigation lines while ‘in use’. After soaking with one of these oxidizers, the bulk of the algae and sanitizer is flushed through an opened drain valve before irrigation, since it will not be fully broken down. 

Product	Rate	Use Notes	Item Number
Cleaners
Eco-Clean	0.25 oz/100 gal	Water treatment only, not a sanitizer. Vegetable extract inhibits biofilm and algae adhesion to maintain water system by continuous injection in clean system. Safe for all plants including food crops.	74-2040
Kleengrow	Mist Propagation 1-2 time/week: 6 oz/100 gal or .06 oz/gal Soil surface sprench Weekly: 0.06 oz/gal Biweekly: 0.12 oz/gal Drip or Flood irrigation systems Weekly 12.5 oz/100 gal or 0.12 oz/gal	Sanitizer for surfaces, irrigation lines, crops. No direct contact with or irrigation of food crops. Use low rate for continuous water injection or propagation mist. Use high rate for weekly or biweekly spray applications to control algae on soil surface. Test crops for phytotoxicity. Do not mix with fertilizer if contacting foliage.	74-2045
SaniDate 5.0 OMRI listed	Surfaces: 0.5-2.2 oz/gal Irrigation water: Periodic or continuous 0.58-4.65 oz/100 gal Evaporative Coolers: Weekly: 0.16 oz/gal	Sanitizer for surfaces, irrigation lines, water treatment, continuous injection. Add foaming agent for vertical surfaces. Consult BioSafe for rates based on water quality and additives for continuous water injection. Not labeled for direct crop use.	74-20521
SaniDate 12.0 OMRI listed	Non porous surfaces: 0.21 oz/gal Hydroponic systems: 0.26-0.64 oz/100 Cleaning irrigation lines: 0.64 oz/100 gal Irrigation water: Periodic: 0.32-12.8 oz/100 gal Continuous (starting point): 0.13 oz/100 Evaporative Coolers: Shock at 0.2 oz/gal Maintain at .03 to 0.06 oz/gal	Sanitizer for surfaces, irrigation lines, hydroponic and irrigation water treatment, continuous injection. Add foaming agent for vertical surfaces. When cleaning irrigation lines, flush though drain valve before irrigating crops. Consult BioSafe for rates based on water quality and fertilizers used for continuous use. Not labeled for direct crop use.	74-2105
ZeroTol 2.0 OMRI listed	Surfaces: 1.25 oz/gal Foliar/ Soil Surface Spray: 0.5-1.25 oz/gal Cleaning Irrigation lines: 1.25-2.5 oz/gal (direct inject @ 1:100-1:50, respectively) Irrigation water Clean water: 1.25 oz/100 gal Contaminated: up to 25 oz/100 gal Evaporative Coolers: Shock at 1.25 oz/gal Maintain at 0.25 – 0.66 oz/gal	Sanitizer for use over plants, surfaces, irrigation lines, water treatment, continuous injection. Add foaming agent for vertical surfaces. When cleaning irrigation lines, flush though drain valve before irrigating crops. Consult BioSafe for rates based on water quality and additives for continuous water injection.	74-2125

All rates are the final concentration, per gallon or per 100 gallons.

Cyclamen Production - Plan Now to Succeed

Product Name		Item Number
14-5-38		JP14538
15-0-15		33627
21-5-20		33602
Affirm		71-1131
Astun		71-1190
Broadform		71-1290
Cease		71-13301
Camelot O		70-21202
Cleary's 3336		71-2575
Empress Intrinsic		70-1510
Heritage		71-1400
Kalmor		71-2050
Medallion		71-16502
Mural		71-1690
Nordox		71-1700
Orkestra Intrinsic		71-2200
Pageant Intrinsic		71-26801
Palladium		71-2685
Phyton 35		71-2732
Spirato GHN		71-2948
Triathlon BA		71-3040

Garden Mum Disease, Insect, and Mite Control Options

Chrysanthemum White Rust

Bacterial Leaf Spot

Pythium Root Rot

Aerial Rhizoctonia Web Blight

Not all products are registered in all states. Some pesticides are restricted use in some state or regions and not others. It is the responsibility of the applicator to read and follow all label directions.

Product Name	Mode of Action (MOA)	Item Number
Disease Control Options
Affirm	19	71-1131
Banrot 40 WP	1&14	71-1210
Broadform	7&11	71-1290
Cease	44	71-13301
Daconil Weather-stik	M5	71-1420
Eagle 20 EW	M3	71-1435
Fame SC	11	71-1505
Heritage	11	71-1400
Kalmor	M1	71-2050
Medallion	9	71-16502
Mural	7&11	71-1690
Nordox 75 WG	M1	71-1700
Orkestra Intrinsic	7&11	71-2200
Pageant Intrinsic WG	7&11	71-26801
Palladium WDG	9&12	71-2685
Phyton 35	M1	71-2732
PreFence	NC	71-2771
Protect DF	M3	71-2748
Rootshield Plus G	NC	71-27921
Rootshield Plus WP	NC	71-27961
Segway	21	71-31101
Spirato GHN	9	71-2948
Terrazole L	14	71-3025
Triathlon BA	44	71-3040
Truban 25 EC	14	71-3070
Truban 30 WP	14	71-3065
Insect and Pest Control Options
Altus	4D	70-1161
Akari	21A	70-1160
Aria WDG	29	70-3399
Avalon Golf & Nursery	3A	70-1210
Avid 0.15 EC	6	70-1185
AzaGuard EC	UN	70-1224
Azatin O	UN	70-12301
Citation WSP	17	70-13501
Conserve SC	5	70-1365
DiPel Pro DF	11A	70-1450
Endeavor WDG	9B	70-1660
Hachi-Hachi SC	21A	70-1795
Kontos	23	70-19601
Mainspring GNL	28	70-2331
Mesurol 75 WP	1A	70-2325
Minx 2	6	70-2398
Molt-X	UN	70-2400
Pedestal SC	15	70-2950
Sanmite SC	21A	70-2915
Savate	23	70-2980
Shuttle O	20B	70-30151
Sultan	25	70-3045
Tristar 8.5 SL	4A	70-85221
Ventigra	9D	70-9550
Surfactant
Capsil	N/A	74-1541

Defense Against Fusarium Wilt in Chrysanthemum

Symptoms of Fusarium Wilting in Chrythsanthemum

Vascular Streaking within Stems

1 Advance Fusarium revealing White Mold on Stems

Product	Size	Item Number
Cleary’s 3336 F	1 qt, 2.5 gal	71-2575, 71-2585
Cleary’s 3336 EG	5 lb	71-2550
Empress Intrinsic	24 oz	70-1501
Fame G	25 lb	71-1500
Fame SC	16 oz	71-1505
Heritage	4 oz, 1 lb	71-1404, 71-1400
Medallion WDG	8 oz	71-16502
Mural WG	1 lb	71-1690
OHP 6672 L	2.5 gal	71-2670
OHP 6672 WSP	2 lb	71-2672
Orkestra Intrinsic	16 oz	71-2200
Pageant Intrinsic	1 lb, 12 lb	71-26801, 71-26821
Terraguard SC	1 qt	71-3018
Spirato GHN	1 pt	71-1570
RootShield Plus G	10 lb, 40 lb	71-27911, 71-27921
RootShield Plus WP	1 lb, 3 lb	71-27951, 71-27971
PreFence	5 gm, 25 gm	71-2770, 71-2771
PVent	0.5 lb, 1 lb	71-2775, 71-2776
Greenshield II	1 gal, 30 gal	74-36601, 74-36611
KleenGrow	5 gal, 30 gal	74-21151, 74-21301
Strip-It Pro	5 gal, 30 gal	74-2125, 74-21230

It is applicator’s responsibility to read and follow all pesticide label instructions. Labels can and do change without notice. Not all of the products mentioned in this bulletin are registered for use in all states. Some pesticides are restricted-use in some states or regions and not others. Contact GGSPro or your state’s Department of Agriculture to verify registration status. Pesticides other than those mentioned may be safe and effective.

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Beautiful Disaster: How to Defend Against Spotted Lanternfly

SLF nymphs, first instar

Many insects hatch and emerge at this time of year. The early nymphal stages of the spotted lanternfly (SLF) are easily recognizable. These wingless planthoppers are small, black and white. As they grow in size to the fourth instar by July/September, they develop a red pattern that covers most of their body. During these instar stages, they range in size from 1/10” to 5/8” and will crawl or jump on many of our favorite woody and edible crops. From the USDA’s perspective, the SLF is not a welcome indication of spring.

SLF nymph, fourth instar Photo credit: UMass Extension

SLF are native to China and Vietnam and feed on more than 70 plant species as phloem feeders. They’re known to move 3-4 miles a year, mostly by being excellent hitchhikers. Therein lies the challenge: how to quarantine a pest that’s now detected in seven states (Pennsylvania, Virginia, New Jersey, Delaware, New York, Maryland and Connecticut) since its first detection in Pennsylvania in September 2014.

Adults emerge by mid-July and are exquisitely beautiful. The wings are gray with black spots at the front and speckled bands on the last 1/3 of the wings. When wings are spread, the base of the hind wings is scarlet with white spots in the front, and white with black bars at the rear. The abdomen is yellow with black bars.
Major plants at risk to SLF damage include 
tree of heaven, maples, grapes, apples, hops, 

SLF adult Photo credit: Penn. Dept. of Agriculture

ornamentals, Christmas trees and species relevant to the lumber industry. Unfortunately, SLF adults can impact quality of life in quarantined areas. As the adults feed via a piercing-sucking mouthpart similar to a straw, they excrete copious amounts of honeydew that drip onto plants, cars and hard surfaces. This byproduct can attract ants, bees, hornets and wasps to feed on the sap. Extensive feeding can result in wounds, wilting and death of branches on young trees. Honeydew on leaves can also reduce the overall quality and limit photosynthesis.
Insects that resemble SLF include green stink bug nymphs and ticks. If you suspect you may have detected SFL, take a photo and send it to your state department of agriculture for verification. Keep the insect in a sealed bag and put it into the freezer.

Green stink bug nymphs

To limit the spread of SLF, actionable quarantine and shipping restrictions have been implemented. For details on regulatory articles, see the www.northeastipm.org or visit www.agriculture.pa.gov for information on the permit process for businesses operating within a regulated area.

Learn to identify the tree-of-heaven (Ailanthus altissima), which is used as a monitoring host tree. The SLF prefers to feed and mate on this specific tree species. To establish a trap crop for SLF, land owners should leave in place male trees that are at least 10” in trunk diameter, and clear all other male and female trees. This facilitates the use of systemic chemicals to limit the exposure of non-target organisms, as few other pests feed on these trees. Application must be repeated annually until no SFL adults are detected on a property.

Removal of trees-of-heaven is a mechanical option to eliminate breeding sites for SLF. Chemical options include spraying targeted plants mid-May through August. Systemic insecticide drenches (e.g., dinotefuran, imidacloprid) are most effective when applied in spring and early summer, before adults build up their populations. The most effective option in controlling SLF are foliar-applied chemicals that contain bifenthrin, carbaryl, dinotefuran or imidacloprid. Basal bark treatments and stump treatments with approved herbicides are among the methods available to remove unwanted trees. Contact GGSPro for more details.
It’s the responsibility of the applicator to check labels and state laws for regulated application sites. Some products may be restricted use. Always read and follow all label directions. The label is the law! Products other than those mentioned may also be safe and effective. Some pesticides may be restricted-use or unregistered in certain states.

Products for Control of SLF Adults (Apply as soil drenches)

Product	MOA	Description	Item Number
Mallet 2F T &O	4A	1 gal	70-2340
Marathon 1% G	4A	5 lbs	70-23752
Safari 20SG	4A	3 lbs	70-29951

Products for SLF Nymphs (Apply as foliar sprays)

Product	MOA	Description	Item Number
Avalon Golf & Nursery Insecticide	3A	1 gal	70-1210
Mallet 2F T &O	4A	1 gal	70-2340
Marathon II	4A	250 ml	70-23712
Safari 20SG	4A	3 lb	70-29951
Sevin SL	1A	2.5 gal	70-3002
Talstar Pro	3A	1 qt	70-34052

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Good to the Last Raindrop: How to Protect Crops Through Prolonged Wet Weather

In many parts of the country, last spring was so wet that you had to laugh to keep despair from setting in: “Some growers only had two rain storms last season. The first one lasted for 52 days and the second one only lasted for 40 days.”

We kid but, of course, we know soggy spring weather is no joke. A greenhouse filled to capacity with pot-to-pot mature plants in full bloom is not a good place to ride out a long spell of cool, damp weather. Such persistent conditions can provide a launchpad for Botrytis and aerial Rhizoctonia.

There’s no time like the present to prepare for soaking spring rains. Since we can’t control the weather, the best we can do is limit the associated risks. When cloudy, wet weather sets in, disease scouting and control become top priorities.

Botrytis on marigold

Understanding Botrytis and aerial Rhizoctonia

Botrytis and aerial Rhizoctonia share two favorite things. The first is full greenhouses, where air movement is limited or, at worst, inadequate. The second is free moisture on leaf surfaces.

Botrytis symptoms can vary in appearance due to several factors including where on the plant it occurs and the current environmental conditions. Symptoms can occur on leaves, stems, fruit, buds and blooms. Expanding brown lesions of decaying plant material are sometimes covered with white/grey spores when environmental conditions are favorable for disease development.

Aerial Rhizoctonia on Vinca minor

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Into the Great Wide Open: Tips to Transition Spring Crops from Greenhouse to Outdoors

As the greenhouse fills with new plantings and partially finished crops are screaming to be spaced, moving finished product outside can open up valuable heated space. However, moving plants outdoors early in the season comes with risks as well as potential rewards.

The primary risk is, of course, cold damage due to frost or freeze. Rewards include heated space available for younger plants, better holding ability among the finished plants and stronger weather-acclimated performance for the final customer. Through careful selection of cold-tolerant plants, active management and emergency actions as needed, the risks are diminished and the rewards become a win-win for both the grower and end user.

Hardening off involves physical changes in the plant that can be seen and felt as the plant begins to acclimate to lower temperatures. These changes typically require a minimum of 7-14 days with temperatures above freezing and below 50˚F.

Every plant grown in a warm greenhouse over the winter -- whether an annual, a hardy perennial or woody plant -- must be “hardened off” before exposure to the realities of early spring frosts and possible freezing temperatures. Hardening off involves physical changes in the plant that can be seen and felt as the plant begins to acclimate to lower temperatures. New leaves thicken and darken in color, and stems of new tips mature and stiffen. These changes typically require a minimum of 7-14 days with temperatures above freezing and below 50˚F. More on that below.

Freeze damage on calibrachoa

The most important factor for success is choosing which crops to transition outside and when. The most cold-tolerant crops should be the first to move outside. Woodies and hardy perennials are easy choices, but annuals fall into many categories of cold tolerance. The most tolerant include alyssum/lobularia, annual phlox, antirrhinum (snapdragon), bidens, calibrachoa, diascia, dracaena spikes, dusty miller, lobelia, mimulus, nemesia, osteospermum, pansy, petunia, verbena and viola.

Cold-tough annuals and hardy perennials can be transitioned much the same way. To maintain the foliage in good condition, prevent frost exposure and frozen rootballs during the hardening time. When temperatures are mild (38-45˚F nights) plants can move directly outdoors. For temperatures of 33-37˚F, when frost is likely if the wind is calm, cover crops with row cover or frost cloth, or provide other overhead protection to prevent potential frost formation on the foliage. A cold frame also works well for this purpose.

When light freezing temperatures are expected (28-32˚F), a closed cold frame will provide a few precious degrees of warmth to plants on the ground. Frost cloth or a winter blanket, spread in mid-afternoon to trap radiant heat, will generally maintain overnight temperatures at the foliage of 3-6 degrees higher than the surrounding air, depending on the weight of the cloth. Be sure to support heavier cloth off the top of the plant canopy to reduce damage.

When repeat or hard freezes are expected, hardening can be carried out in a greenhouse maintained at 40-45˚F. When an occasional unexpected or brief freeze pops up in the forecast, growers may need to resort to emergency measures.

When repeat or hard freezes are expected, hardening can be carried out in a greenhouse maintained at 40-45˚F nights. However, when the occasional unexpected and brief freeze pops up in the forecast, sometimes the protections above can’t be employed.

In this case, the grower may resort to emergency measures. The traditional action is to use overhead sprinklers to prevent freeze damage. This works because, as the water begins to freeze on the leaf, it releases a small amount of heat. As long as a thin layer of water is present, the plant will be protected from freezing, whether the water is landing directly on the foliage or on the outer layer of ice that will form over the plant. The constant freezing of water throughout the night will maintain the plants above the critical temperature.

When using the sprinkler method, continue applying water until the protective ice melts in the morning.

The sprinkler method only works when the water application is started before frost begins to form, and is continued until all ice has melted off in the morning. Once frost or ice has formed on plants, it’s too late to turn the water on. Evaporating water causes cooling and actually causes the tissue temperatures to plunge further, making damage more severe. With the sprinkler method, growers must also manage the risk of plants breaking under the weight of the ice.

Another emergency measure that can be employed is a foliar application of a strobilurin fungicide such as Pageant or Mural (MOA 7 +11). When sprayed within 24 hours of a freeze event, these fungicides effect physiological processes in the plant, such as slowing water transpiration. This tactic can impart several degrees of cold tolerance, in addition to disease protection. Spray Pageant at 12 oz/100 gallons (3/4 tsp per gallon) or Mural at 6-8 oz/100 gallons (3/8 to 1/2 tsp per gallon).

The hardening process should be actively managed according to the weather forecast, closing and venting cold frames, or covering and uncovering as necessary to protect the plants during periods of low temperatures.

Well-hydrated plants will withstand the cold better. Desiccation is often a major contributor to cold damage. Make sure outdoor plants are well watered and the foliage is dry before temperatures drop. Once the plants are thoroughly hardened, they’ll survive exposure to cold temperatures down to the limit of their genetic tolerance. Light overhead protection during cold snaps will still produce the best foliage and quickest flowering.

Product Name	Description	Item Number
Pageant Intrinsic	1 lb	71-26801
Mural	1 lb	71-1690
Winter protection fabric*	15' x 150', 6 oz per sq yard	81-730400
Heavy frost cloth*	15' x 300', 1.25 oz per sq yard	78-2045

*Additional sizes available. Contact your Griffin sales representative for details.


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Geraniums: A Crop Culture Tune-Up

Well-branched, uniform geraniums ready for retail sale

We can all agree: Geraniums have created quite a legacy for themselves. Our industry has seen a tremendous number of new plant species over the years, and gardening trends certainly come and go. Through it all, the venerable geranium – including zonal, ivy and hybrid types – maintains its status as a staple of the garden center.

Producing top-quality geraniums requires close attention to detail. Not everyone can do it well! But for the growers who do, their attentiveness is rewarded. Let’s review some of the finer points of geranium culture. Are there details you haven’t considered lately? Is there an opportunity to fine-tune production of your next crop?

Soil mix and pH

Soil mixes should be well drained and be maintained at a soil pH in the range of 6.6. pH control is crucial because geraniums are very susceptible to iron/manganese toxicity at a soil pH of 5.8 or lower. Monitor soil pH weekly to prevent problems before they occur.

Temperature

The most economical geranium production takes place at average daily temperatures in the range of 65-70° F. Typically, this means night temperatures between 62-65° F and day temperatures in the range of 68-70° F. Crop timing for a 4.5” pot is 6-8 weeks.

Although geraniums can be grown much cooler, doing so comes with some risk: The lower temperatures significantly increase crop time and raise the risk for Botrytis.

Fertilizer

Geraniums are moderate feeders. Maintain 200 ppm CLF, reducing that to 125-150 ppm as the crop approaches marketable size. This practice improves shelf life and eases the transition to be planted outdoors. Fine-tuning your geranium fertilizer program through water testing is recommended.

Height control via PGRs

Florel on geranium

While smaller pots (e.g., 4.5”) can be grown without it, geraniums often benefit from a soft hand pinch to improve branching. For 6” and larger pots, a soft pinch should be made 2-3 weeks after transplant. In the interest of efficiency, a Florel application can be used in place of a pinch. Zonal geraniums require foliar sprays of Florel at 500ppm, while 350ppn is more common among ivy geraniums and ivy/zonal hybrids such as Calliope and Caliente. Florel can be re-applied two weeks later, as long as the crop is six or more weeks until full bloom is needed.

Cycocel has long been used to control height and leaf size on geraniums. Zonals generally receive 1500 ppm, while Calliope and most ivy geraniums are treated at 1000 ppm. To avoid yellowing or distorted foliage, spray Cycocel only to glisten. This approach can be used on a bi-weekly basis. Cycocel metabolizes quickly in the warmer temperatures that we often experience in late spring and summer. More frequent sprays, up to once a week, may be required.

This trial compares the effects of Bonzi and Cycocel on geranium

Bonzi is another PGR option for zonal and ivy geraniums. Bonzi can be applied as a foliar spray at 1-5 ppm on compact or ivy varieties, and up to 10 ppm on more vigorous varieties when the plants are 75% of finished size. Bonzi is only absorbed through the stems and roots, rather than the foliage. For tightly spaced plants, drenching Bonzi might be a better option. Rates vary based on plant vigor, ranging from 0.25-0.5 ppm in most cases.

Height control without PGRs

To control geranium height without PGRs, the Morning Temperature Dip technique can be quite effective. Most plant stretch occurs during the first three hours of daylight. Beginning at first light in the greenhouse and continuing for the first three hours of the day, drop the air temperature to 5° F below the night set point. After three hours, return temperatures to their normal setting. This simple practice can greatly reduce the need for PGRs, limiting stem elongation without significantly decreasing the average daily temperature.


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A Greenhouse Game Changer: Introducing the Bluelab 3-in-1 Pulse Meter

Pulse meter with depth gauge Photo credit: Bluelab Corporation

Technology is coming to the aid of growers once again, this time in the form of a versatile direct-stick meter. The Pulse multimedia meter from Bluelab measures EC (electrical conductivity, a.k.a. soluble salts), soil moisture and temperature in a wide variety of growing media.

Peat, coir, composted pine bark, rockwool and mineral soils can all be tested with nearly instant results. For the greatest amount of precision, the Pulse meter offers different settings for each type of soil mix. Settings can be quickly and easily changed to efficiently test multiple media mixes.

The Pulse meter can also be used to test solutions, saving the need for an additional meter. Test results can be transferred to a Bluetooth-enabled smartphone with the help of the free Pulse mobile app. Test data is stored by the app, so growers can easily review and analyze data. The Pulse app is currently available for Android devices; support for iPhones is expected to follow sometime in 2019.

The Pulse mobile app is currently available for Android devices. Photo credit: Bluelab Corporation

Compared to making slurries and performing the 2:1 test, the Pulse meter is a bona fide timesaver. Testing is so fast that a large number of samples can be taken in order to get the most representative picture of what’s going on in the crop.

Calibration and cleanup are fast and easy, too. The probes are 8 inches long and come with a built-in depth gauge to ensure consistent measurements. (Note: The Pulse meter can accurately test pots 4 inches deep or deeper.) Just like the other meters from Bluelab, the Pulse meter is reliable and is backed by excellent technical support.

Bluelab Pulse Multimedia Meter
Item number: 83-2778

Blinded by the Blight: What to Do When Your Foliar Disease is Actually a Soil-Borne Pathogen

Plants are subject to an array of foliar diseases: blights, root and stem rots, bacterial infections, wilts, viruses and nematode diseases. Symptoms that appear on afflicted plants are clues, but unless a telltale sign of the causal organism is present, identification can be challenging without microscopic examination. The same goes for pathogens affecting roots.

While symptoms may be visible above ground, the actual cause could be a soil-borne fungus. Let’s explore two root-root pathogens – Rhizoctonia and Phytophthora -- with the unique ability to infect plant foliage as an aerial blight, and how to tell the difference.

Real talk about Rhizoctonia

Rhizoctonia web blight on dianthus

Aerial Rhizoctonia web blight (RWB) outbreaks occur when weather is sunny, humidity is high and foliage remains wet for hours. Ideal conditions are 70-90° F with humidity above 65%. The Rhizoctonia pathogen can cause root and crown rot, as well as stem cankers. It’s one of the two primary causes of seedling death (damping off).

Rhizoctonia doesn’t produce spores, but it can produce a survival structure known as sclerotia and it can survive in plant debris and in soil for years.
Rhizoctonia affects many plants including aster, begonia, chrysanthemum, dianthus, ferns, gerbera, impatiens, petunia, vinca and zinnia. Many herbaceous perennials and landscape plants are prone to infection, too.

Rhizoctonia web blight on aster

Typical infections occur when the crop canopy is dense. Often, a plant can look great from the outside but, using your hands to gently separate foliage, you may see rotted foliage within. In other cases, symptoms are very visible. Hyphae grow into a spider web-like mat known as mycelium. This can be seen with the naked eye, growing along the soil surface or up stems onto foliage.

When in doubt, take a sample from the diseased plant material; place foliage and stems between two layers of wet, brown paper towel or moist, dark-colored newspaper. In both cases, the dark color enhances visibility of the mycelia, which is white. Seal the sample in a zip-top bag or salad container and store at room temperature for 36-48 hours. Examine for webbing.

All about aerial Phytophthora

Aerial Phytophthora sporulation on tomato

Phytophthora is a common root and crown pathogen of many ornamental and edible crops. Phytophthora root rot appears darker in color with less sloughing off of roots than Pythium. Stunting and wilting often occur, and crowns may break off easily at the soil line. There are more than 60 recognized Phytophthora species; at least 10 have been reported on potted plants.

Many Phytophthora species are specific to common plant genera: azalea, bacopa, calibrachoa, dogwood, gerbera, lavender, pansy, petunia, poinsettia, rhododendron, vinca, and many herbaceous perennials and vegetable crops, particularly tomato.

Phytophthora canker on poinsettia

There are three key pathogen species: P. infestans, P. ramorum and P. parasitica. P. infestans prefers cool spring/fall weather (60-70° F days, 50-60° F nights), while the others are considered hot-weather diseases.

When above-ground infections occur, known as aerial Phytophthora, plants often exhibit a rapid wilt with a characteristic bleaching of leaves starting at the leaf base. Leaf spotting, leaf drop, dull-colored isolated branches/stems or stem lesions are other pathogen indicators. On some plants (e.g., tomato), whitish sporulation can be observed under high infections, though this is somewhat uncommon.

Phytophthora belongs to the class Oomycetes, which also includes Pythium and downy mildew. The pathogen is spread by splashing water where zoospores swim to infect roots, foliage and stems. Oospores produced are the resting/survival equipment of the pathogen; they’re responsible for the random reoccurrences under certain conditions. Sanitation is the link that breaks the chain of the reinfection process.

Control options

Management of both aerial pathogens, Rhizoctonia web blight and aerial Phytophthora, includes practices to reduce humidity within the canopies of susceptible crops. Allow for adequate spacing and facilitate good air flow. Avoid late-day irrigation and saturated conditions that leave wet foliage going into the night. Both fungi are soil-borne and rely on movement through splashing and running water to spread.

While some fungicides may control both pathogens, it’s important to note that products for Phytophthora must be carefully chosen and rotated, due to reported resistance to mefenoxam (Subdue) among some Phytophthora species. To reduce further resistance, rotation with other MOA products will improve performance. For foliar aerial Rhizoctonia and aerial Phytophthora, foliar sprays are recommended. While the tables below are provided as a summary, growers must read and follow the entire pesticide label. Products other than those mentioned may be safe, legal and effective. Not all products may registered for use in all states. Contact GGSPro as needed for further guidance.

Aerial Rhizoctonia web blight control options

Product Name	MOA	Size	Comments	Item Number
Affirm	19	0.5 lb	4-hour REI	71-1129
Broadform	7 & 11	12 oz	Not for edibles, not labeled in all states, not compatible with CapSil	71-1290
Banner Maxx II	3	1 gal	Outdoor use only, not for edibles	71-2972
Cease	44	1 gal	Microbial fungicide, preventative only	71-13301
Chipco 26019 Flo	2	2.5 gal	RUP NY, not for edibles	71-1350
Chipco N/G	2	2 lbs	RUP NY, not for edibles	71-13501
Cleary’s 3336 EG	1	5 lbs	RUP NY, limited edibles	71-2550
Cleary’s 3336 -F	1	1 qt	RUP CT & NY, not for edibles	71-2575
Companion	44	1 gal	Microbial fungicide, preventative only	71-1375
Concert II	3/M5	2.5 gal	Outdoor use only; may damage bud/bloom, not for edibles, not registered in all states	71-1365
Daconil Ultrex	M5	5 lbs	RUP MA & RI, will burn open blooms, not for edibles, not compatible with CapSil	71-1420
Daconil Weather-stik	M5	2.5 gal	RUP MA, will burn open blooms,not for edibles, not compatible with CapSil	3117025
Fame SC	11	16 oz	Do not use with CapSil, not for edibles, RUP NY, not for use Suffolk & Nassau counties NY	71-1505
Heritage	11	1 lb	RUP VT, some edibles, not compatible with CapSil	71-1400
Medallion WDG	12	8 oz	Not for edibles, restrictions in Suffolk & Nassau counties NY	71-16502
Mural WG	7 & 11	1 lb	Do not use with CapSil, some edibles, RUP NY	71-1690
OHP 6672 4.5 L	1	2.5 gal	RUP CT & NY, not for edibles	71-2670
OHP 6672 50 WSP	1	2 lbs	RUP CT & NY, not for edibles	71-2672
Orkestra Intrinsic	7 & 11	16 oz	RUP CT & NY, no Long Island NY use, not compatible with CapSil, not for edibles	71-2200
Pageant Intrinsic WG	7 & 11	1 lb	RUP NY, not compatible with CapSil, limited edibles	71-26801
Palladium WDG	9 & 12	2 lbs	Not for edibles	71-2685
Protect DF	M3	6 lbs	Preventative, limited edibles	71-2745
Spirato GHN	12	1 pt	Formerly called Emblem, for use with many edibles	71-2948
Terraguard SC	3	1 qt	RUP NY, restrictions in Suffolk & Nassau counties NY, edible use not for RWB, see label precautions	71-3018
Triathlon BA	44	1 gal	Microbial fungicide, preventative only	71-3040

Aerial Phytophthora control options

Product Name	MOA	Size	Comments	Item Number
Adorn	43	1 qt	Must be tank-mixed with another MOA, RUP NY, not for edibles	71-1130
Aliette WDG	33	5 lbs	Not for edibles; do not use within 14 days of copper sprays	71-11352
Alude	33	2.5 gal	Edibles, do not use within 20 days of copper sprays	71-27601
Areca	33	5 lbs	Not for edibles, do not use within 14 days of copper sprays	71-1180
Broadform	7 & 11	12 oz	Not for edibles, not registered in all states, not compatible with CapSil	71-1290
Fenstop	11	1 qt	Not for edibles, not registered in NY	71-14801
Fosphite	33	1 gal	Edibles, do not apply within 20 days of copper sprays	71-1520
Micora	40	1 qt	Some edibles, RUP NY, not compatible with CapSil	71-1655
Orvego	45 & 40	28 oz	RUP NY, no edibles	71-2300
Pageant Intrinsic	7 & 11	1 lb	RUP NY, tomato transplants only, not compatible with CapSil	71-26801
Segovis	49	1 pt	Some edible transplants	71-3100
Segway O	21	16 oz	RUP NY, not for edibles, some bloom risk	71-31101
Stature SC	40	25 oz	Not for edibles	71-14652
Subdue Maxx	4	1 qt	Edible transplants	71-2979

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The Nightmare Before Christmas: How to Stop Pest and Disease Carryover

Fall crops have wrapped up across the country. If they haven’t already, growers will soon say, “Goodbye and good riddance!” to the problems of last season. Hopefully – unless the problem was a pest or pathogen with the potential to overwinter. Whether you’re a continuous or seasonal grower, don’t let your nightmare before Christmas come back to bite on St. Patrick’s Day or Easter.

Recurring disease nightmares

Thielaviopsis, Fusarium and Sclerotinia are some of the most insidious diseases, due to their ability to carry over, at some level, from season to season, year to year. Each has a mechanism that allows spores to survive through even harsh environmental conditions.

Sclerotinia sclerotiorum on lettuce