The MaluSim carbohydrate model was run on May 13 for both Winchester and Central Virginia.
In Central Virginia, many later blooming cultivars are around 10 mm fruitlet size and can still be chemically thinned. From applications made over the past weekend, growers can expect average responses to chemical thinners. As we move through the week, greater and greater carbohydrate deficits are predicted, which will increase the potency of chemical thinners.
For Winchester, the model is predicting mild carbohydrate deficits early in the week, and much more severe deficits towards the end of the week and over the weekend. Applications made this past weekend through the middle of the week will likely have an average to slightly aggressive response. However, applications make towards the end of the week may result in very aggressive thinning activity. If the weather forecasts hold up, growers should consider reducing rates for applications made towards the end of the week.
I will run the model again on Thursday, May 16.
Fruitlet sizes from the Winchester AREC:
- Honeycrisp: 8.8 mm
- York: 8.0 mm
- Fuji: 8.6 mm
- Suncrisp: 8.4 mm
- Pink Lady: 9.2 mm
- Empire: 11.8 mm
One more note, there are widespread frost/freeze predictions for most of Virginia for Tuesday morning. If a significant frost/freeze event occurs, growers should be cautious with their thinning applications until they can assess if damage has occurred. However, the forecast for Winchester predicts the temperature will only go to 32F, which will not be cold enough to cause significant damage. The forecast for fruit growing regions to the south of Winchester appears to be in the mid-30s to low 40s.
To see more information, click on the linked pdf files below: