Now is a good time to start thinking about ways to help mitigate cucurbit downy mildew pressure later in the production season. All cucurbit fields, especially cucumber and other summer squash fields should be destroyed immediately after the last harvest to help limit potential inoculum sources for cucurbit downy mildew. For a review of CDM control please click here. To track the progress of CDM on your phone or PC please visit the CDM forecasting website.
Vegetable Crops Edition
Seasonal updates and alerts on insects, diseases, and weeds impacting vegetable crops. New Jersey Commercial Vegetable Production Recommendations updates between annual publication issues are included.
Subscriptions are available via EMAIL and RSS.
Quick Links:
NJ Commercial Vegetable Production Recommendations
Rutgers Weather Forecasting - Meteorological Information important to commercial agriculture.
Destroying cucurbit plantings after harvesting is a must to help mitigate downy mildew
Diagnosing important diseases in Cucurbit crops – Reference Guide
The following images consist of important diseases in cucurbit crops. These images can be used as a quick reference for diagnosing important fungal and bacterial pathogens. For best results, please turn your device (i.e., cell phone) sideways. For information on commercial control recommendations, please visit the cucurbit sections of the 2022/2023 Mid-Atlantic Commercial Vegetable Production Guide.
Cucurbit powdery mildew (CPM) | Cucurbit powdery mildew | CPM on infected pumpkin stem |
Cucurbit downy mildew (CDM) | CDM sporulating on underside of infected cucumber leaf | CDM sporulating on underside of infected cucumber leaf with 10x hand |
Anthracnose on cucumber | Anthracnose lesion on infected leaf vein | Anthracnose-infected cucumber fruit |
Plectosporium blight on infected stem | Plectosporium lesions on infected vines | Plectosporium lesions on infected pumpkin fruit |
Phytophthora blight symptoms | Phytophthora-infected squash | Phytophthora-infected watermelon field |
Phytophthora-infected pumpkin | Phytophthora-infected squash fruit | Phytophthora-infected watermelon fruit |
Mosaic virus symptoms on leaves of infected pumpkin plant | Pumpkin fruit infected with mosaic virus | Virus infected squash fruit |
Fusarium fruit rot of pumpkin | White mold on infected fruit | Gummy stem blight |
Choanephora-infected fruit | Choanephora spores in infected pumpkin fruit | Choanephora infecting giant pumpkin fruit |
Bacterial wilt infected plant | Symptoms of bacterial canker infected stem | Damage done by cucumber beetle feeding |
Angular leaf spot | Shot holes in pumpkin leaves caused by Angular leaf spot in pumpkin | Mature pumpkin fruit with sunscald injury due to the loss of plant canopy |
Andy Wyenandt and Kris Holmstrom
Controlling basil downy mildew in the field in 2022
For over a decade, basil downy mildew (BDM) has caused significant losses in basil grown in organic and conventional field and greenhouse production across the United States. At the time of its introduction, there were very few fungicides labeled for its control making it nearly impossible to grow a successful crop in many areas of the country. [Read more…]
Vegetable Disease Update: 07-02-22
- Powdery mildew has been reported in cucurbit crops. For more information on the control of CPM please click here.
- Cucurbit downy mildew has been reported on cucumber in southern New Jersey and Eastern PA. For more information on CDM control please click here.
- Bacterial leaf spot has been reported in pepper. More more information on BLS control please click here.
- Bacterial canker has been reported in tomato. For more information on diagnosing important tomato diseases please click here.
- Early blight has been reported on potato.
- Phytophthora blight has been reported on pepper. For more information please click here.
- Dickeya dianthicola has been reported in potato in Virginia and Massachusetts.
- The 2022/2023 Commercial Vegetable Production Recommendations Guide is available for free online or for sale in hardcopy form at many County offices.
- For a quick review on managing fungicide resistance development using tank mixes and fungicide rotations, and information on FRAC group 4, FRAC group 7, and FRAC group 3 and FRAC group 11 fungicides please click on hyperlinks.
Crop progress and sicklebarring palmer greenstalks
Salem County: Two plus inches of June precipitation on the 9th and 12th carried non-irrigated corn and soybean through the month with only trace amounts of precipitation until the 24th when some areas received another half inch.
In exceptionally wet fields, climbing humidity levels on the 13th, 14th, and 15th were high enough to allow for foliar disease development in beans. But the following week of low humidity was less than conducive for disease proliferation until the 22nd through the 25th when humidity levels briefly rose and remained in the high 80’s and 90’s for three days, before dropping nicely to the mid 60’s the last two days of June. However, wind speeds of 15 to 25 mph from June 13th to June 19th wicked moisture out of corn and soybeans leaving the crops in a moisture deficit.
This is confirmed in ‘The Evaporative Demand Drought Index’ (EDDI) monitoring tool for South-Jersey. This tool created by the NOAA Physical Science Laboratory is an indicator of both rapidly evolving “flash” droughts and sustained droughts. “EDDI can offer early warning of agricultural drought, hydrologic drought, and fire-weather risk.”
Pest pressure: Producers should monitor beans for Japanese beetle, green stink bug and grasshopper feeding going into July and be alert to excessive damage from flea beetles on crops stressed from wind evaporation. Palmer amaranth is exceptionally tolerant to droughty conditions and thrives under stresses that wilt other pigweed species. Shattercane and johnsongrass are both warm-season grasses that also thrive under these weather conditions.
Mechanical options: In addition to chemical control options, if droughty evaporative weather persists, producers should consider manually removing seedhead stalks to protect maximum yield projections in soybeans. The ideal mechanical tool to do this would be a front mounted sickle bar mower. Do-it-yourself fabricators maybe interested in this attachment created specifically to deal with palmer amaranth by a Kansas farmer. (A cooperative build, purchase, may be a good investment for combine and spray rig operators in the County). https://www.rowshaver.com/
Forecast: Going into this weekend, the 24-hour precipitation forecast for
New Jersey anticipates a tenth of an inch to half inch of rainfall for most of Salem County through July 3 and much-needed swath probable for the northern counties where drought conditions the last seven days are 51% to 75% below normal.
Identifying white mold in tomato production
White mold, or timber rot, is caused by the soil-borne fungal pathogen, Sclerotinia sclerotiorum.
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.