Potato Disease Advisory #10 – June 7, 2012

Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu

Late blight Advisory
Location: Art and Keith Wicks Farm, Rt 9, Leipsic, Kent County, Delaware
Greenrow: April 20

Date

DSV

Total DSV

Accumulated
P-Days

Spray Interval Recommendation

5/20-5/22

11

55

229

5-days

5/22-5/23

2

57

238

5-days

5/24-5/28

8

65

279

5-days

5/28-5/30

3

68

294

5-days

5/31-6/3

3

71

331

7-days

6/4-6/6

0

71

355

10-days

 

The spray interval recommendation is now 10 days. The forecast is predicting warm and dry weather which should reduce the threat. Late blight has been reported in Virginia and Pennsylvania over the past seven days. The map below shows confirmed reports of late blight. The red shaded areas indicate the report was made in the past seven days while the blue shaded areas indicate an older report (more than seven days ago). You can visit this map at http://www.usablight.org/. There have been no reports of late blight in Delaware this year.

Continue to scout for late blight symptoms in local potato fields. Please notify and submit samples with symptoms to your local county extension office (Kent: 302-730-4000 Sussex: 302-856-7303) or contact the UD Plant Diagnostic clinic (302-831-1390) to have the sample confirmed. You may also email Nancy Gregory at ngregory@udel.edu or Phillip Sylvester at phillip@udel.edu if you have a sample to submit.

Early Blight
A total of 355 P-days have accumulated at this site as of Wednesday, June 6. Protectant fungicide applications targeted at early blight are recommended at this time. Commercial fungicide recommendations can be found in the 2012 Delaware Commercial Vegetable Recommendations Guide at http://ag.udel.edu/extension/vegprogram/pdf/potatoes.pdf.

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