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. [Read more…]
September 21, 2013 Andy Wyenandt
Late Blight Reported: S.NJ Greenhouse Tomato – 9/21/13
An isolated case of Late blight has been confirmed in Southern New Jersey on a farm that was growing both field-grown and greenhouse-grown tomatoes. The pathogen originated in an old tomato planting that had been unsprayed since the last pick over 6 weeks ago. Left unscouted, the field developed Late blight and the pathogen moved into the greenhouse operation within days of an otherwise healthy-looking greenhouse tomato crop.
As a reminder any crop, conventional or organic, left standing in a field after last harvest will only act to serve as a source of potential incoculum for many diseases. As with tomatoes and other crops, all should be disced down, tilled, and/or mowed down as soon as possible after harvest. Conventionally, applying the herbicide, gramoxone, is also an easy way to achieve this. Organic growers need to be just as diligent and disc down, till, or pull old plantings soon after use.
For more on the control of Late blight in tomato please see the 2013 Commercial Vegetable Production Recommendations Guide.
 Late blight in Greenhouse Tomato |
Late blight lesions developing on a greenhouse grown tomato plant. Under dryer, less humid conditions the lesions may not have the characterstic dark, greasy appearance. |
 Late blight in GH Tomato |
Late blight sporulating on the underside of an infected tomato leaf. Note the pure white sporangia (spores) on the underside of the leaf. |
September 20, 2013 Andy Wyenandt
Vegetable Disease Briefs – 9/20/13
Late blight has been reported in tomato on an organic farm near Long Valley in Morris County, New Jersey. The cooler weather along with longer periods of leaf wetness lasting into the morning hours this time of year makes conditions ideal for potential Late blight development. As a reminder, once fields or blocks of tomatoes are finished, care should be taken to burn down, remove, or disc down the foliage. Fields left un kept can act as a source of inoculum. Tomato fields should be scouted on a regular basis. Regular protectant fungicide programs should continue as long as fields or blocks are in production. Organic tomato growers can apply an OMRI-approved copper fungicides to help suppress late blight development.
September 20, 2013 Andy Wyenandt
Vegetable Disease Update – 9/20/13
Carrots – Leaf blights – Powdery mildew, Alternaria and Cercospora. Alternaria and Cercospora are two soil-borne fungal pathogens that may cause early defoliation in carrots reducing yields and making harvest difficult. Both pathogens produce distinct symptoms on carrots. [Read more…]
September 12, 2013 Andy Wyenandt
Vegetable Diseases of the Week – 9/13/13
Septoria Leaf Spot
on Sunflower Leaf
Black Rot on butternut squash.
Note the distinctive lesion pattern.
Downy mildew on turnip leaves.
Note non-descript chlorotic lesions developing on top side of infected leaves. Under ideal conditions tufts on white sporangia will develop on underside.
September 12, 2013 Andy Wyenandt
Vegetable Disease Briefs – 9/13/13
There have been no new reports of Late blight.
Downy mildew has been found in turnip greens this past week. The expected rainfall and cooler temperatures to follow in the upcoming week make conditions favorable for downy mildew development across many crops.
Asparagus – Summer foliar diseases in Asparagus have been reported. With the cooler weather and all the rain we’ve have been experiencing on and off all summer disease pressure in asparagus is higher than normal. See article from 9/4/13 for more information.
Basil downy mildew remains active – All basil growers should scout on a daily basis and should add a labeled downy mildew specific fungicide to their weekly fungicide program. Phosphite fungicides (FRAC code 33), such as Prophyt, K-Phite, and Rampart have shown the best efficacy in trials at RAREC. Actinovate (OMRI- approved) is also labeled for downy mildew control. Please remember, all abandoned basil fields should be worked under immediately after last harvest to kill the foliage! Abandoned fields left unattended after use will only serve as a source of inoculum for other fields.
Cucurbit downy mildew and powdery mildew remains active in New Jersey.
