Potato Disease Advisory #17 – July 22, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Disease Severity Value (DSV) Accumulation as of July 21, 2010 is as follows:
Location: Art and Keith Wicks Farm, Rt 9, Little Creek, Kent County
Green row: May 6

  LATE BLIGHT EARLY BLIGHT
Date Daily DSV Total DSV Spray Recs Accumulated
P- days*
6/26- 6/27 0 42 10-days 391
6/28 – 6/30 0 42 10-days 408
7/1 – 7/5 0 42 10-days 444
7/6 -7/7 0 42 10-days 449
7/8 1 43 10-days 454
7/9 8 51 7-days 462
7/10 0 51 7-days 471
7/11- 7/12 0 51 7-days 484
7-12 -7/13 3 54 7-days 490
7/13 – 7/14 10 64 7-days 499
7/15 -7/16 1 65 7-days 508
7/17- 7/20 0 65 10-days 526
7/20- 7/21 1 66 10- days 530

 

Late blight was found in a commercial potato field north of Bridgeton, NJ. Potatoes and tomatoes in the region could be at risk. It is important to keep scouting and maintaining fungicide applications at this time. Potato harvest has begun here in DE and there are still some fields with green tissue that could become infected. The hot weather forecasted for the rest of the week and the weekend will not be favorable for late blight infection and development but be aware of the presence of the disease in the region.

For specific fungicide recommendations, see the 2010 Delaware Commercial Vegetable Production Recommendations Book.