Effects of preharvest precipitation, air temperature, and humidity on the occurrence of soft scald in 'Honeycrisp' apples.

The relationship of soft scald incidence (SSI) with precipitation, temperature, and fruit maturity indicators in 'Honeycrisp' apples was examined using 7 years of data in Maine and 6 years in Ontario, Canada. Relative humidity was also examined in Maine. Soft scald incidence was highly variable from year to year ranging from 1% to 85% in Maine and from 0% to 76% in Ontario. In Ontario, SSI was negatively related to soluble solids at harvest (partial r(2) = 0.50; P = 0.0041) and negatively related to precipitation during 90 to 120 days from bloom (DFB; partial r(2) = 0.28; P = 0.0344). In Maine, SSI was most strongly related to precipitation in the 90 to 120 DFB (partial r(2) = 0.53; P = 0.0001), maximum air temperature 60 to 90 DFB (partial r(2) = 0.21; P = 0.0001), and number of hours when relative humidity was greater than 85% (partial r(2) = 0.11; P = 0.0001).