Potato Disease Advisory #2 – May 23, 2014

Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu

Date DSV Total DSV Accumulated P-Days Spray Interval Recommendation
5/12-5/21 19 19 81 5-days
5/21-5/23 2 21 100 10-days

Location: Leipsic, Kent Count, Delaware

Green row: May 12, 2013

Late Blight
The threshold of 18 DSVs has been exceeded. Protective fungicides are recommended. Twenty-one (21) DSVs have accumulated so far for any potatoes that established green row (approximately 50% emergence) prior to and since May 12.

Any suspect samples can be sent to the UD Plant Diagnostic Lab or dropped off at your local extension office. See the 2014 Commercial Vegetable Production Recommendations-Delaware for recommended fungicides: http://extension.udel.edu/ag/vegetable-fruit-resources/commercial-vegetable-production-recommendations/

The website USABlight tracks tomato and potato late blight across the nation and can be found here: http://usablight.org/. Information on scouting, symptomology, and management can also be found on this website.

Early Blight
One-hundred (100) P-days have accumulated. No fungicides for early blight control are recommended. Commercial fungicide recommendations can be found in the 2014 Commercial Vegetable Production Recommendations-Delaware: http://extension.udel.edu/ag/vegetable-fruit-resources/commercial-vegetable-production-recommendations/