Potato Disease Advisory #15 – July 7, 2011

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

Location: Art and Keith Wicks Farm, Rt 9, Little Creek, Kent County.
Greenrow: May 3

Date Late Blight Early Blight Spray Interval Recommendation
DSV Total DSV Accumulated P-days*
6/16 1 67 328 7-days
6/17 0 67 336 7-days
6/18-6/19 0 67 352 10-days
6/20-6/22 1 68 377 10-days
6/23 1 69 383 10-days
6/24-6/26 0 69 407 10-days
6/27 1 70 416 10-days
6/28 1 71 424 10-days
6/29 0 71 432 10-days
6/29-7/2 0 71 456 10-days
7/3 1 72 462 10-days
7/4 0 72 468 10-days
7/5 1 73 474 10- days
7/6 0 73 481 10-days

Continue to scout fields for symptoms of late blight. Conditions will continue to favor early blight. Continued dry weather will not favor the spread of late blight.

Late Blight was reported last week in DE, on the eastern shore VA, and Long Island, New York. There have been no further reports of late blight in DE or VA but late blight has been reported on the North Fork on Long Island, NY in addition to the earlier find on the South Fork.

For specific fungicide recommendations, see the 2011 Delaware Commercial Vegetable Production Recommendations Book.