Potato Disease Advisory #12 – July 19, 2013

July 19, 2013 in Vegetable Crops

Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu and Phillip Sylvester, Kent Co. Ag Agent; phillip@udel.edu

Location: Art and Keith Wicks Farm, Rt 9, Leipsic, Kent County
Greenrow: May 5

Date

DSV

Total DSV

Accumulated

P-Days

Spray Interval Recommendation

5/23 – 5/27

5

39

5-days

5/27 – 5/30

0

39

10-days

5/30 – 6/6

2

41

251

10-days

6/6 – 6/7

10

51

261

5-days

6/7 – 6/9

10

61

280

5-days

6/9 – 6-13

4

65

314

7-days

6/16 – 6/20

13

78

377

7-days

6/20 – 6/27

6

84

420

7-days

6/28 – 7/4

24

108

477

5-days

7/5 – 7/11

4

112

516

10-days

7/12 – 7/18

11

125

552

10-days

Late Blight
The threshold of 18 DSVs has been exceeded. One hundred and twenty five (125) DSVs have accumulated so far for any potatoes that established green row (approximately 50% emergence) prior to and since May 5. Growers should continue to scout their potato fields and consider applying fungicides preventatively. Any suspect samples can be sent to the UD Plant Diagnostic Lab or dropped off at your local extension office. See the 2013 Commercial Vegetable Production Recommendations-Delaware for recommended fungicides: http://extension.udel.edu/ag/files/2012/03/Potatoes.pdf. 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
The threshold of 300 P-Days has been exceeded. Five hundred and fifty-two (552) P-days have accumulated. A fungicide for early blight control is recommended. Commercial fungicide recommendations can be found in the 2013 Delaware Commercial Vegetable Recommendations Guide at http://extension.udel.edu/ag/files/2012/03/Potatoes.pdf