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Updated: August 8, 2017
The model was run about 1:30 PM this Monday. Warm weather on Friday and then sunny conditions on Sunday caused a few more stations to come into full bloom. Across the state most stations suggested normal rates of chemical thinners during the weekend. However, beginning today the model suggests that chemical rates be decreased over the next 4 days due to predicted weather. Sunday morning at Rock Springs we had a two hour period of low temperatures at 31 degrees F. Potentially there could be some damage on the valley floor. All stations predict temperatures to be in the mid to upper 70s by Friday. Where fruit size is small, suggested materials are carbaryl and possibly NAA or NAD. Remember that based on fruit size chemical thinners are more effective beginning at 10 mm.
For more information on the carbohydrate thinning model, visit Carbohydrate Thinning Model. For more details on factors that affect plant growth regulator performance and chemical thinner rates, visit Growth Regulators in Apple and Pear Production.
Table 1. Decision rules for using the output of the Carbohydrate model to adjust chemical thinning rate
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