FRUIT FIRMNESS, CALYX AND NECK RATINGS CORRELATED WITH FIELD FRUIT ROT REACTIONS OF 9 STRAWBERRY CULTIVARS

Fruit calyxes and necks were rated, and fruit epidermis toughness and flesh firmness were measured, for nine strawberry (Fragaria x ananassa) cultivars on four harvest dates during 1991. These data were correlated with percent of fruit with each of several rot diseases at harvest in 1991 and 1992. The cultivars differed significantly for all traits. 'Earliglow' and 'Tristar' had the most reflexed calyxes, and 'Earliglow' and 'Cardinal' had the most raised necks. 'Cardinal' and 'Allstar' had the greatest fruit flesh firmness and epidermis toughness. Greater fruit epidermis toughness did not correlate well with reduced levels of any fruit rot. Greater fruit flesh firmness correlated significantly, although not highly (r = 0.26 to 0.37), with reduced anthracnose fruit rot (caused by Colletotrichum gloeosporioides (Penz.) Penz. and Sacc.), leather rot (incited by Phytophthora cactorum (Leb. and Cohn) Schrot.), and total rots during both years, but not with reduced gray mold (caused by Botrytis cinerea Pers.: Fr). Mid-season calyx ratings correlated significantly (r = 0.39 to 0.50) with reduced leather rot, anthracnose and total rots during one year each. Both mid-season neck ratings, and the mean of mid-season calyx and neck ratings, correlated significantly (r = 0.37 to 0.62) with reduced levels of all rots during both years, except for leather rot in 1992. Overall, the mid-season calyx-neck mean predicted rot levels the best of the fruit traits studied.