Peel Maturity Only Correlates with Soft Scald in a Highly Susceptible Orchard of Ambrosia™ Apple

The relationship of peel or flesh maturity of apples and susceptibility to soft scald has been suggested in the existing literature. In British Columbia, the new apple cultivar Ambrosia™ has been documented to have significant susceptibility, especially in certain orchards that appear to have consistently more occurrence of soft scald than others. Two orchards in the Cawston area of British Columbia (Similkameen Valley) were selected for their close proximity to each other and because they have historically had significant differences in incidence and severity of soft scald. The two orchards are across the road from each other, the first having a northwest by north row orientation and the second having a northeast by east row orientation. In the first orchard the incidence of soft scald reached a maximum of 16% of the fruit being affected and only having slight severity rating. In the second orchard incidence ranged from 23% to 55% of the fruit being affected, and severity ratings approached moderate on a relative scale. Maturity of the apples was determined with a DA meter, which can be used to measure peel maturity. In the first orchard, incidence and severity of soft scald were not correlated with DA meter values (R² = 0.0031 and 0.026, respectively), while in the second orchard, the incidence and severity were strongly correlated (R² = 0.86 and 0.77, respectively) with DA meter values. These results suggest that apple maturity is only associated with soft scald incidence and severity for orchards that have a higher susceptibility to soft scald. Clearly the factors affecting soft scald susceptibility and severity are complex in nature and dependence on maturity sorting for segregating potentially susceptible fruit may not be warranted for all orchards, at least for Ambrosia™ apples.