Figure 1. Delicious fruit size on June 4, 2018 at Rock Springs, PA. Photo: Rob Crassweller, Penn State
The model will automatically cease making a thinning recommendation at this point due to the unreliability of further carbohydrate production predictions. Additionally, most apples are also at or beyond the size at which they may readily respond to chemical thinners (Figure 1).
The more northern parts of the state may still have a few cultivars that are still within the size range that they may respond to thinners; however, that window is rapidly closing. I have added the predictions based upon the table in the Information section of the model discussion for your interest. All the sites in the state had very low sunlight levels yesterday due to cloudy, rainy weather. I measured slightly over 3 inches of rainfall at home from Saturday night into Monday morning.
Reports from the southern portions of the state indicate that growers are seeing considerable fruit dropping either from thinner applications or just natural weather conditions this spring. Some growers are worried that the drop is more than normal. However, being the optimist, I think that come August many growers may be wondering how all the apples appeared.
Apple Carbohydrate Thinning Models for Pennsylvania Counties
How to Use the Carbohydrate Model
Where to Find Penn State's Recommendations on Chemical Thinning Materials