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The UVM Apple Team

Dr. Lorraine Berkett,  Terence Bradshaw,  Sarah Kingsley-Richards, Morgan Cromwell

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The UVM Apple Program:

Extension and Research for the commercial tree fruit grower in Vermont and beyond...

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Vermont Apple IPM Focus

  L.P.Berkett, IPM Specialist


2009 Degree Day Accumulation for Apple Scab Ascospore Maturity

2009  Estimated Degree-Day Accumulation (Base 32F, from McIntosh Green Tip) for Selected Sites

UVM HRC

South Burlington Chittenden Co.

Elev. 71 M

    Shoreham

Addison Co.

Elev. 107 M

South Hero

Grand Isle Co.

Elev. 54M

Dummerston

Windham Co.

Elev. 171 M

East Dorset
Bennington Co.

Elev. 408 M

Date 4/18: 4/19 4/18 4/13 4/18
4/18 17 - 17 77 18
4/25 133 119 132 202 123
5/02 315 305 310 404 304
5/09 482 472 477 573 457
5/16 631 630 625 740 606
5/24 832 837 822 957 804
5/31 983 990 976 1118 948

Date for 900 dd

5/28 5/28 5/28 5/23 5/29

Degree Day and other weather information received from Skybit E-Weather Service: http://www.skybit.com/

 

Please use the following chart to Estimate Ascospore Maturity

Cumulative Percentage of Ascospores Matured at Various Degree Day Accumulations (Base=32 F)1

 

Degree Days (2)

Cumulative

Ascospores

Matured (%)

90%

Confidence Interval

for Estimate (3)

35

1

0-7

110

3

0-14

145

5

1-19

215

12

2-32

325

25

7-55

450

50

21-80

575

75

46-94

685

90

69-98

740

95

79-99

790

97

86-100

865

99

93-100

1-Table from 2009 New England Tree Fruit Management Guide

2- DD should be recorded from the date when 50% McIntosh fruit buds are between silver tip and green tip. The base temperature = 32F. Data of Gadoury and MacHardy, 1982.

3-The width of the 90% confidence interval is a statistical measure of the precision of estimated maturity. It is the range within which the estimate should fall 90% of the time.


Please send comments and suggestions tolorraine.berkett@uvm.edu

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