The effects of collar rot (Phytophthora cactorum) on ‘Cox’s Orange Pippin’ fruit quality

The effects of collar rot (Phytophthora cactorum) of ‘Cox’s Orange Pippin’ apple trees on fruit maturity and quality at harvest and after storage have been investigated. Fruit were harvested from trees in five orchards in Nelson, New Zealand. Trees were either without signs of collar rot (control), or were girdled by collar rot lesions, but all were producing fruit which might be commercially harvested. At harvest, fruit from diseased trees had higher starch pattern indices, flesh firmness, soluble solids content, percentage blush, lower titratable acidity levels, and were more yellow than control fruit. Internal ethylene concentrations of fruit were at preclimacteric levels at harvest and were not influenced by collar rot. Magnesium and potassium concentrations were lower in fruit from diseased than from control trees, but calcium concentrations were not different. After storage, fruit from diseased trees were slightly firmer than fruit from control trees but there was no effect of collar rot on backgrou...