Rutgers University | New Jersey Agricultural Experiment Station | Pesticide User Responsibility

September 12, 2013

Vegetable Disease Update – 9/13/13

  • Carrots
  • Cole Crops
  • Cucurbits
  • Leeks
  • Lettuce
  • Parsley
  • Peppers
  • Tomato
  • Sunflower
  • Pumpkin
  • Spinach

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. 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…]

Filed Under: Vegetable Crops Tagged With: , , , , ,
August 16, 2013

Vegetable Disease of the Week – 8/16/13

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.

Filed Under: Vegetable Crops Tagged With: ,
August 6, 2013

Cucurbit downy mildew confirmed on pumpkin in Morris County – 8/6/13

Cucurbit downy mildew has been reported on pumpkin in Morris County. This is the first report of downy mildew on pumpkin this growing season. Cucurbit downy mildew has also been showing up on cucurbit crops (other than cucumber) in other states this past week. All cucurbit crops in New Jersey are at risk for downy mildew. Downy mildew specific fungicides should now be a part of all weekly fungicide maintenance programs if not already initiated. For current 2013 Cucurbit Downy and Powdery Mildew Management Guidelines please see post from 6/7/13. If you suspect downy mildew on any cucurbit crop please contact your county agent. Please visit http://cdm.ipmpipe.org/ to track the progress of downy mildew throughout the US.

Filed Under: Vegetable Crops Tagged With: ,