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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 13, 2014 Andy Wyenandt
Late Blight Still Active on Tomato
Late blight was confirmed in a homeowner garden today near Clementon, NJ (Camden County) and here at the Rutgers research station near Bridgeton, NJ (Cumberland County). This is a good reminder that as long as weather conditions are conducive, the threat of late blight in the state and region will continue until the first killing frost.
All abandoned tomato fields need to be destroyed either by mowing, discing under, or sprayed with a herbicide such as gramoxone to kill all living foliage. This is especially important if protectant fungicide programs have been discontinued. Homeowners can simply pull plants and put in their compost pile or discard in the trash.
October 13, 2014 Andy Wyenandt
Internal Fruit Rot in Tomato
A fresh market tomato from a home owner garden was dropped off the other day with some strange internal rot. The internal rot (photo 1) was most likely caused by water accumulating in areas immediately around the stem and as the fruit developed growth cracks (photo 2). This allowed for opportunistic fungi and bacteria into infect the fruit causing the internal rot. As it turned out the home owner was using sprinklers to water their garden.
As the season continues into the late fall, it might be worthwhile to slice up one or more of your tomato varieties that are prone to growth cracks around the stem just to check if this is happening in your operation – especially with heavy dews and the wet weather we have had recently.
Photo 1: Internal Fruit Rot
Photo 2: Growth Cracks
October 9, 2014 Meredith Melendez
New Jersey Soils and Copper Fungicide Use
During my field visits to Mercer County organic farms, growers often express concerns about negative soil health impacts from copper based fungicides. In an effort to evaluate soil copper use and the resulting soil copper levels, soil was sampled at fifteen farms throughout the state.
Soils sampled for copper levels.
Both conventional and organic farms participated in this study which was funded by The Phillip Alampi Fund. Two composite samples were taken from each farm, one where copper fungicides had been applied and one where copper fungicides had never been used. Total and soluble copper levels were higher on copper applied soils compared to the non-copper applied soils. Even though copper levels were higher in these soils, the levels were not high enough to cause plant toxicity symptoms, reduce plant growth, nor were the soils showing signs of reduced microbial activity.
Best management practices developed for copper based fungicides use:
October 3, 2014 Andy Wyenandt
Leaf blight in Dill
Leaf blight in Dill as shown up in the past week in some areas of southern New Jersey.
Leaflets on plants will appear wilted, often on the lower portion of the plant first. Up close, irregular lesions will appear scattered over the leaflets, girdling them, causing them to look wilted.
There have been a couple fungal pathogens associated with causing dill leaf blight. Options for controlling foliar pathogens in dill are extremely limited. Growers can apply Quadris (azoxystrobin, 11) at 15.5 fl. oz/A (O day PHI) alone or tank mixed with fixed copper on a 7 day schedule. Conventional growers can also apply a disinfestant, such as Oxidate, after overhead irrigation. Organic growers can apply OMRI-approved copper products. Other OMRI-approved products for leaf blight control may help suppress the pathogen.
Only overhead irrigate on sunny days in the in AM or early afternoon so planting can dry out.
October 1, 2014 Andy Wyenandt
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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