Carbohydrate Thinning Model Updates for Central Virginia- April 18

In my latest blog entry, I highlighted that this week, particularly on Wednesday and Thursday, presents an optimal window for fruit thinning treatments, especially for Gala, Pink Lady, and possibly Fuji. Taking into account the green tip and full bloom dates of March 6th and March 29th respectively for Gala apples in Central Virginia and data from the Crozet weather station, the model forecasts a moderate to severe shortfall in daily carbohydrate levels over the next three days, impacting the 6-day weighted average. As such, it is crucial to apply thinning treatments judiciously, with a focus on 6-BA and NAA. However, over-thinning may occur if high rates are used. Therefore, the model suggests reducing thinning material rates by 15% for applications scheduled on Wednesday, April 19th. This recommendation may extend to Thursday and Friday, based on current forecasts. In practical terms, if your standard application rate for Gala consists of 64 fl oz of Maxcel, 1 qt of Sevin, and 1 pt of Regulaid per 100 gal/acre, a 15% reduction corresponds to 54 fl oz of Maxcel and 27 fl oz of Sevin. No adjustments to the surfactant are needed.

I encourage you to utilize the model with the weather station nearest to your location, inputting accurate green tip and bloom dates for your orchard. If the degree days (DD) column displays values under 200, but your king fruits measure over 7mm in size (averaging around 15-20 fruitlets), I still advise proceeding with thinning treatments this week, rather than postponing to the following week and potentially encountering difficulty in finding an appropriate temperature window for application. To access the model, use the following link:

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