Perennation and control of Pseudomonas tomato in Victoria

Abstract

Seed of tomato fruit affected by bacterial speck was examined for Pseudomonas tomato. The bacterium was isolated from seed taken directly from fruit, but not from seed extracted by the fermentation process. Acid and fermentation extraction processes appeared to eliminate P. tomato. Pulp containing natural and/or added populations of the bacterium was non-infective at 1 hr and 48 hr after commencement of the acid and fermentation processes respectively. Studies on the perennation of P. tomato showed that the bacterium survived in plant debris either on or 2 cm below the soil surface for the test period of 30 weeks; it also survived on Nylon mesh in soil for 25 weeks. The incidence of bacterial speck in seedlings was reduced significantly (P = 0.01) by cupric hydroxide sprays, two sprays per week being more effective (P = 0.05) than one. No heat-tolerant strain of P. tomato was detected, and thermal death points for isolates from green and ripe fruit were 48 and 49°C respectively.