Potato Disease Advisory #12 – June 15, 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

6/7-6/11

0

71

395

10-days

6/11-6/14

8

79

424

7-days

 

The spray interval recommendation has been lowered to 7 days. Rainfall and high humidity earlier in the week made conditions for late blight more favorable. The forecast is predicting sunny and dry weather, which should make conditions less favorable.  There are no reports of late blight in Delaware.

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.

Late blight has been found in the region. You can monitor where late blight is showing up by visiting the USA blight website at: http://www.usablight.org/?q=map. Confirmations of late blight on potato and tomato are tracked and added to the map as they are reported.

Early Blight
A total of 424 P-days have accumulated at this site as of Thursday, June 14. 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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