2010 DD Accumulation for Plum Curculio

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The UVM Apple Team

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

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Beginning at petal fall, cumulative heat units are recorded using a base temperature of 50°F. Daily heat units can be calculated as (Max+Min)/2-50 where Max and Min are maximum and minimum temperatures. If this quantity is less than zero, no heat units are accumulated. Daily heat units are summed beginning at petal fall and no further insecticide applications are required provided the last insecticide was applied no later than 10 to 14 days prior to the date when summed units reach 308. Note that thisdegree day threshold is different than the recommended value in the past. Entomologists at Cornell have revised this value to reflect a correction in the metric to SAE conversions used (http://www.nysaes.cornell.edu/ent/scaffolds/2005/050516.html).

2010 Estimated Degree-Day Accumulation (Base 50F, from 95% McIntosh Petal Fall Date) for Selected Sites
Date	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 Rutland Co. Elev. 408 M
95% McIntosh Petal Fall Date	5/10	5/04	5/10	5/06	5/08
5/08	-	39	-	24	3
5/15	21	59	20	45	19
5/22	93	132	93	114	79
6/01	277	313	277	299	242
Date of 308 DD threshold reached	6/6	6/1	6/8	6/4	6/5

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