BACTERIAL-BLIGHT OF KIWIFRUIT IN CALIFORNIA

Flower bud rot, blossom blight, and leaf spot of kiwifruit (Actinidia deliciosa) have been observed in numerous commercial orchards in California since 1986. As the diseased flower buds develop, petals become yellow-orange, then brown, and the entire bud falls from the vine. Fruit may be small, misshapen, or fail to set. The bacterial pathogens Pseudomonas syringae and P. viridiflava, in addition to the saprophyte P. fluorescens, consistently have been isolated from both symptomatic and asymptomatic vines throughout the spring. In pathogenicity tests, P. viridiflava caused significantly more flower bud rot and blossom blight, but not leaf spot, than P. syringae. P. fluorescens was not pathogenic.