Plastic mulch, usually used with trickle irrigation, has many horticultural benefits for summer vegetable crops, and black plastic controls most annual weeds. Mulch does not solve all the weed problems in the field, and creates new challenges for the grower.
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July 8, 2022 Thierry Besancon
Recommendations for Under Plastic Mulch Weed Control
July 8, 2022 Thierry Besancon
Update on Status of Dacthal Herbicide
DCPA (dimethyl tetrachloroterephthalate) is a selective preemergence herbicide used for control of annual grasses (foxtail, crabgrass, barnyardgrass, goosegrass, fall panicum) and some broadleaved weeds (purslane, common lambsquarters, pigweeds) in vegetable crops and ornamental turf. Commercial formulations of DCPA include Dacthal® Flowable herbicide. Dacthal® Flowable is labelled for use on the following vegetable and fruiting crop groups: cole leafy vegetables, seeded melons (cantaloupe, honeydew, watermelon), collards and mustard greens, horseradish and radish, onions, sweet potatoes, tomatoes and eggplants, strawberries.
- What is happening with DCPA, the technical ingredient in Dacthal® Flowable herbicide from AMVAC?
On April 27th the U.S. Environmental Protection Agency (EPA) published a notice of intent to suspend (NOITS) DCPA technical registration in the U.S. The basis for this action was that AMVAC had not provided multiple studies required during the registration review. - How did AMVAC and key grower stakeholders respond to this action by the EPA?
According to FIFRA (Federal Insecticide, Fungicide, and Rodenticide Act), AMVAC and impacted stakeholders had the opportunity to
appeal the NOITS within 30 days, which they did on May 27th. The purpose of the appeal was to obtain a hearing that would allow
evidence from each side to be presented in front of an Administrative Law Judge (ALJ) appointed by EPA. - Did AMVAC and the grower stakeholders have the opportunity for a hearing?
No. The assigned EPA administrative law judge (ALJ) ruled on Friday July 1st that the NOITS was upheld without requiring a hearing. - How will that impact end use formulated products like Dacthal Flowable herbicide?
This decision does not impact formulated products (i.e., Dacthal Flowable). AMVAC’s customers can continue to sell, distribute, and
apply Dacthal Flowable. - What happens now in this process concerning DCPA?
The July 1st decision granted EPA the ability to suspend DCPA technical without requiring a hearing to examine AMVAC and
EPA testimony. AMVAC will appeal this decision to the Environmental Appeals Board. - Is the registration of the end-use product Dacthal Flowable herbicide impacted by the NOITS?
If you have used or plan to use end-use products containing DCPA, there are no consequences from that use or downstream
consequence for the crop you applied it to, now or in the future, from NOITS activities. Applications of Dacthal Flowable end-use
products remain legal and the established United States tolerances remain in place. - What are the next steps in this process? How will it impact the availability of Dacthal Flowable?
AMVAC can continue to manufacture, sell, and distribute end-use products until notification of the appeal process has been completed. AMVAC’s customers can continue to sell, distribute, and apply Dacthal Flowable. AMVAC is commitment to continuing to exhaust all options to defend DCPA. Outside of any legal proceedings, AMVAC continues to generate and submit to EPA the data necessary to fulfill the Data Call-In (DCI) Notices required to complete registration review for DCPA, regardless of the suspension status.
July 6, 2022 Andy Wyenandt
Diagnosing Southern blight and White mold in tomato and pepper
There have been a few reports of Southern blight (Sclerotinia rolfsii) and White mold (Sclerotinia sclerotiorum) on tomato and pepper in New Jersey. Southern blight is much more common in vegetable areas south of the state where summer temperatures remain hotter (above 90°F) for longer periods of time. Like white mold, it can survive in the soil for many years. Symptoms of Southern blight include infection at the base of the stem at the soil line. The resulting infection will girdle the plant causing wilt and death. The fungus will produce white, cottony mycelium and very small, spherical sclerotia which are often have a tannish, brown color.
White mold is more common than Southern blight in New Jersey, and like Southern blight, once introduced into a field or high tunnel it can very difficult to control. The pathogen produces large black sclerotia on the surface and inside infected stems. If sclerotia of either pathogen make their way back into the soil, both can survive for years causing significant problems.
All infected plants need to be removed immediately and disposed of properly to help reduce the chances of sclerotia returning to the soil.
For more information on chemical control please see the 2022/2023 mid-Atlantic Commercial Vegetable Production Recommendations Guide.
Symptoms of Southern blight on infected pepper plant. Note the numerous, small white to tan colored sclerotia on the stem.
White mold of tomato. Note the large black sclerotia developing inside the brittle stems.
July 1, 2022 Andy Wyenandt
Identifying white mold in tomato production
White mold, or timber rot, is caused by the soil-borne fungal pathogen, Sclerotinia sclerotiorum.
High tunnel tomato plant with main stem infected by white mold.
The photo on right shows a high tunnel tomato plant with main stem infected by white mold. Over time the entire plant will slowly collapse looking similar to a wilt or root rot pathogen as the water supply is cut off to the plant.
White mold is common and once introduced into a field or high tunnel it can very difficult to control. The pathogen produces black sclerotia on the surface and inside infected stems. Sclerotia, if they make their way back into the soil, can survive for years causing significant problems.
Infected stems will turn a light brown color and dry up becoming brittle. If the main stem is infected the entire plant will collapse looking like a wilt or root rot issue.
Under hot, humid conditions white fungal growth will develop on the surface of the stems and in some cases sclerotia will develop on the outside of the stem. Breaking open the stem will reveal numerous black sclerotia.
All infected plants and or plant material need to be removed immediately and disposed of properly. Preventative protectant fungicide programs beginning at flowering will help control white mold. Cool, wet weather and poor air circulation favors disease development.
There are a number of control options for conventional and organic growers listed in Table E-11 in the 2022/2023 mid-Atlantic Commercial Vegetable Production Recommendations Guide.
Tomato stem infected by white hold. Note the fungal growth on the surface of the stem.
White mold of tomato. Note the black sclerotia developing inside the brittle stems.
April 27, 2022 Kris Holmstrom
Allium leaf miner update: 04/27/22
Allium Leaf Miner (ALM)
Allium leaf miner (ALM) adults (flies) continue to be captured on yellow sticky cards in chive plantings in Hunterdon and Mercer counties. Numbers have declined somewhat this week (Milford, Hunterdon County 21, Princeton, Mercer County 13) relative to the week prior (Milford 27, Princeton 45), but it is still too soon to stay whether the first flight has peaked. We will report the captures over the next two weeks, with hopes for signs that the flight is ending.
Growers should consider maintaining the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks. Look for neat rows of white spots descending from the upper tips of allium leaves (photo at left). Initial injury often occurs on the tallest leaves. Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adult at lower right).
Floating row covers, kept on until this flight ends will help minimize access to plants. Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, 
Warrior), neonicotinoids (Scorpion, Venom), the diamide Exirel (section 2ee recommendation) and the insect growth regulator Trigard are labeled for miner control.
April 4, 2022 Kris Holmstrom
Allium leaf miner update: 04/05/22
Allium Leaf Miner (ALM)
Allium leaf miner (ALM) feeding/egg laying scars have been detected in Cape May County as of 4/3/22 (see photo at left). It is likely that this pest is active, and depositing eggs in alliums throughout south Jersey at this time. Many weather stations in southern and central counties exceeded 250 growing degree days (GDD) base 39˚F over a week ago, with northern counties surpassing this threshold more recently. 39˚F is close to the lower developmental temperature (38.3˚ F) which our colleagues at Penn State recommend for predicting the first emergence of ALM adults. Last year, initial feeding/egg laying scars were detected within a few days of local weather stations recording the 250 GDD threshold.
Growers should consider initiating the control method of their choice at this time. Affected crops include chives, scallions, garlic, onions and leeks. Look for neat rows of white spots descending from the upper tips of allium leaves. Initial injury often occurs on the tallest leaves. Under warmer, less breezy conditions, adults may be seen near the tips of leaves (see photo of adult at lower right).
Floating row covers, kept on until this flight ends will help minimize access to plants. Insecticide applications targeting adults may be helpful as well, although frequency of applications is uncertain. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom), the diamide Exirel (section 2ee recommendation) and the insect growth regulator Trigard are labeled for miner control.
Adult activity and observations of feeding will be reported on in the IPM Update as they occur. At this time, all growers should prepare to respond to the first adult generation. We will deploy yellow sticky cards and attempt to identify the end of the first flight so that growers know when the risk of infestation has abated.
