Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu; @Delmarplantdoc
Late blight was reported 5/29 near the North Carolina and Virginia border. Weather has been conducive for disease. A protective fungicide application for late blight protection is recommended. I have included Early Blight P values as well. A P value of 300 is the threshold for early blight fungicide application.
Greenrow – May 1, 2017
| Frederica | |||
| Date | DSV | Total DSV | P Value |
| 5/30-6/1 | 5 | 22 | 244 |
| 5/25-5/30 | 3 | 17 | 225 |
| 5/23-5/25 | 4 | 14 | 179 |
| 5/15-5/23 | 7 | 10 | 161 |
| 5/4-5/15 | 3 | 3 | 104 |
| 5/1-5/4 | 0 | 0 | 30 |
Notes: Season severity of 18 severity values indicates the need for the first fungicide application. An accumulated severity of 7 after fungicide application identifies the need for a subsequent fungicide application. You can personalize your late blight forecasts for specific fields, sign up for email or text alerts, and enter in management information at http://blight.eas.cornell.edu/blight/.
Real time fungicide application timing tables for locations within Delaware can be accessed at http://blight.eas.cornell.edu/blight/DE
See the 2016 Commercial Vegetable Production Recommendations-Delaware for recommended fungicides: http://extension.udel.edu/ag/vegetable-fruit-resources/commercial-vegetable-production-recommendations/
Any suspect samples can be sent to the Plant Diagnostic Clinic or dropped off at your local Extension office. Dr. Nathan Kleczewski can also be contacted at nkleczew@udel.edu or 302-300-6962.
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.