Rutgers Cooperative Extension
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.
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.
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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. Powdery mildew causes characteristic white, powdery lesions on foliage. Symptoms of Alternaria include irregular, dark brown to black spots which typically show up on older leaves first. Cercospora leaf spots are round, grayish-brown and are more prevalent on younger foliage. Both leaf blights typically start at the margins of leaflets and as more spots develop leaflets begin to wither and die. Symptoms similar to leaf infections can develop on stems and petioles.
Control of both diseases begins with regular scouting and preventative fungicide applications on susceptible varieties. Apply Quadris (azoxystrobin, 11) at 9.0 to 15.5 fl. oz 2.08F/A, or Cabrio 20EG (pyraclostrobin, 11) at 8.0 to 12.0 oz/A, or Pristine (pyraclostrobin + boscalid, 11 +7) at 8.0 to 10.5 oz 38WG/A tank-mixed or alternated with chlorothalonil (M5) at 1.5 to 2 pt/A. For Alternaria only: Apply a tank mix of 1.5 to 2.0 pt/A chlorothalonil plus Endura (boscalid, 70 at 4.5 oz 70W/A, or Switch (cyprodinil + fludioxonil, 9 +12) at 11.0 to 14.0 oz 62.5WG/A, or iprodione at 1.0 to 2.0 pt 50WP/A. For more information on tolerant varieties and control please the 2013 New Jersey Commercial Vegetable Production Recommendations. [Read more…]
There have been no new reports of Late blight.
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). [Read more…]
Asparagus growers should consider scouting their fields for foliar disease development. Important pathogens growers need to scout for on a regular basis are Purple spot, Cercospora, and Rust. [Read more…]
White speck on vine and stem of infected pumpkin plant. Note the numerous small, white diamond shaped lesions.
White speck lesions covering the surface of immature and mature pumpkin fruit. White speck will only cause cosmetic injury to fruit.
