Output from the Carbon Balance Model for four sites in western NC (Apple Wedge, Flat Rock, Sugarloaf, and Moravian Falls) and two sites in North Georgia (Blue Ridge and Ellijay) is below (click figures to enlarge).

If you have access to NEWA, I'd recommend calculating the carbon balance for your own site. Predicted weather data is used in these estimates and the forecast can change throughout the course of a day. If you’d like to run the model on your own, the link at the NEWA site is on the drop-down menu under “Crop Management”. Choose a site nearest your orchard location and enter your Green Tip and Full Bloom date. Then hit the green Calculate button.

• North Carolina sites: Thinning responses are predicted to be normal to slightly aggressive. Most NC growers are in the middle of a good thinning window if the weather forecast is correct.
• Georgia sites: Thinning responses are predicted to be aggressive and/or excessive. This is due to the combination of forecasted warm temperatures and cloudy weather over the next few days. Please use caution!

Notes on Using Output from the Carbon Balance Model

A positive carbohydrate balance makes it more difficult to thin whereas increasing carbohydrate deficits are predicted to increase the response to chemical thinning sprays. For example, you might respond to a predicted carbohydrate surplus or mild deficit by either adopting a more aggressive approach to chemical thinning or by waiting until more ideal conditions for thinning develop. Alternatively, if the model is predicting a severe carbohydrate deficit then you might consider reducing the rate of chemical thinner or perhaps not applying a thinner at that time for risk of over-thinning.