Abscission and Kernel Quality of Almond Fruit Inoculated with the Shot Hole Pathogen Wilsonomyces carpophilus

Fruit of almond cultivar Mission were aerosol-spray inoculated with aqueous suspensions containing 10³, 10⁴, or 10⁵ conidia/ml of Wilsonomyces carpophilus beginning when fruit emerged from the hypanthium and continuing at approximately weekly intervals until they reached full size and embryo development had begun. There was a linear increase in percent fruit abscission (P = 0.001) and average number lesions per fruit (P = 0.007) with increasing inoculum concentration. Percent fruit abscission decreased with increasing fruit length (maturity) at inoculation (P = 0.001). Lesions were most abundant when mid-size fruit were inoculated. The kernel quality of infected and healthy fruit of cultivar Carmel were compared in 1994 and 1995. Mid- to full-size fruit were inoculated one or three times with 10⁵ conidia/ml of W. carpophilus. Kernels from inoculated fruit were shorter than those from uninoculated fruit (P = 0.007), but kernel weight did not differ. Fewer than 2.5% of kernels in 1994 and none in 1995 were covered with gum deposits or incompletely filled.