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.
 
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October 1, 2014

Vegetable Disease Update – 10/1/14

  • Cole Crops
  • Pumpkin
  • Spinach

Cole Crops

Downy mildew and Alternaria – Symptoms of downy mildew include purple to yellowish-brown spots on upper leaf surfaces. A grayish-white spore mass will develop and cover the underside of leaves under ideal temperatures (night temperatures of 46 to 61°F and day temperatures below 75°F). Downy mildew can kill young plants. Heavily infected leaves may drop providing entry points for bacterial infections (i.e., black rot and soft rot).

Symptoms of Alternaria on infected leaves include small, expanding circular lesions with concentric rings that may have a ‘shot-hole’ appearance as lesions age.  Heavily infected seedlings may result in damping-off.

Control of Downy mildew and Alternaria begin with preventative fungicide applications. Use one of the following at the first sign of disease and continue every 7 to 10 days (Please refer to the pesticide table on page F31 of the 2014 NJ Commercial Vegetable Production Recommendations to determine which fungicide is labeled for each specific crop.
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Filed Under: Vegetable Crops
October 1, 2014

Vegetable Disease Briefs – 10/1/14

Basil downy mildew remains active. The weather this time of year is ideal for downy mildew development across many crops. Growers should remain diligent going into the fall with regular scouting and preventative fungicide applications.

Cucurbit downy and powdery mildew remain active. Growers holding mature pumpkins in the field for the next few weeks should do their best to maintain the foliage for as long as possible to prevent potential sunscald injury. Late-season fungicide applications will also help keep powdery mildew off of the stems extending the pumpkin’s post-harvest longevity. Stems infected with powdery mildew will turn brown and dry out much quicker than healthier stems. Additionally, powdery mildew and downy mildew fungicide programs for all fall cucurbit crops should continue as along as harvesting continues.

There have been no new reports of Late blight this past week.  Growers with late-season tomato plantings should be diligent and scout on a regular basis. The cooler weather and prolonged dew periods are ideal conditions for Late blight development. All old plantings should be sprayed with gramoxone to burn the foliage down or mowed/disced under as soon as possible after the last harvest.

Filed Under: Vegetable Crops
October 1, 2014

Cold Injury in Cucumber

The effects of a cold night a few weeks ago are showing up in some varieties of cucumber around New Jersey. Symptoms on maturing fruit appear as brownish-tan areas on the epidermis of fruit. The fruit will also show cracking as if it has a dry rot. The effects are physiological where areas of young developing fruit got chilled by the cold night time temperatures.

Cuke_cold injury

Cold injury on cucumber fruit. The initial damage was done a few weeks ago while the fruit was very young.

Filed Under: Vegetable Crops Tagged With: ,
October 1, 2014

Veg IPM Update: Week Ending 10/1/14

Note: The backlight network is now being dismantled. Some traps will remain in operation for the next few weeks as crops continue. No maps will be produced for the remainder of the season, but pertinent pest information will be reported in subsequent weekly updates.

Topics for the Week

  • Sweet Corn
  • Tomatoes
  • Pumpkins and Winter Squash
  • Cole Crops

Maps for the Week
–Corn Earworm Moth Blacklight Trap Map
–Corn Earworm Moth Pheromone Trap Map

Vegetable IPM Report 10-1-14 – Click to View | Download | Print

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Filed Under: Vegetable Crops
September 29, 2014

Managing Cercospora in Beet

Cercospora leaf spot can significant losses in beet if not controlled properly.

Cercospora on beet.

Cercospora leaf spot on beet. Note the round tan leaf spots with dark red margins.

The fungus overwinters in soils and be a continual problem in fields with short crop rotations. It has developed resistance to important fungicides in beet production areas in the US and abroad. Resistance has been detected in the Benzimidazole fungicides (FRCA code 1); the DMI fungicides (Tilt, tebuconazole; FRAC code 3) and the strobilurin fungicides (Quadris, Cabrio, Headline; FRAC code 11). Beet growers in NJ who have relied heavily on, and are not obtaining adequate control of Cercospora with either DMI or strobilurin fungicide applications in their weekly programs should discontinue their use. These growers should switch to fungicides with different modes of action such as Fontelis (penthiopyrad, 7) at 16.0 to 30.0 fl oz/A (3 day PHI) and Merivon (fluxapyroxad + pyraclostrobin, 7 + 11) at 5.5 fl oz/A (7 day PHI). Growers who are still obtaining adequate control with either the DMI or strobilurin fungicides can continue their use, but should make efforts to incorporate the use of the mentioned fungicides above to help reduce the chances for resistance development.

Merivon Supplemental Label

Filed Under: Vegetable Crops Tagged With: ,
September 26, 2014

Late blight Found in Cherry Tomato in Cumberland County – 9/26/14

Late blight has been found in small cherry tomato field near Roadstown, NJ today where 100% of the field is affected. This is the third report of Late blight in New Jersey this year and the first since 9/8.

Cool day and night temperatures with prolonged dews are ideal for Late blight development, especially in fields where no protectant fungicides have been applied in recent weeks.

All growers who are still in tomato production should continue to scout on a regular basis and apply protectant fungicides. Abandoned commercial fields, need to be disked under or  sprayed with gramoxone to kill all living tissue. All abandoned organic fields should be disked under or plants should be pulled and discarded.

Filed Under: Vegetable Crops Tagged With: ,