EPIDEMIOLOGY AND MANAGEMENT OF SYRINGAE LEAF SPOT INCITED BY PSEUDOMONAS SYRINGAE PV. SYRINGAE ON TOMATO

Leaf spot of tomato, incited by Pseudomonas syringae pv. syringae has been recently reported in Italy on grafted and non grafted tomato plants (scion ‘Cuore di Bue’, rootstock Solanum lycopersicum × Solanum hirsutum ‘Beaufort’). A first set of trials were carried out in growth chambers, in order to understand the effect of the number of hours of incubation at high relative humidity (RH) and temperature (10, 15, 20, 25 and 30°C) as well as the consequence of the presence of wounds at infection time on the development of syringae leaf spot.
A second set of trials were carried out under greenhouse condition in order to test the efficacy of spray programmes, based on the use of several copper based compounds, acibenzolar-S-methyl, fosetyl Al and two biological control agents, Bacillus subtilis strain QST 713 and Pseudomonas chlororaphis MA 342, against Pseudomonas syringae pv. syringae on tomato.
The results showed that the development of leaf spot was mostly favoured by wounds and by temperatures ranging from 15 to 20°C. The severity of the disease was lower at 10 and 25°C, being very low at 30°C. Under the most favourable temperature conditions, the presence of wounds was sufficient to allow the development of the pathogen without incubation at high RH. Results showed that among the tested copper-based fungicides, copper oxychloride provided the best and most consistent results.
The best syringae leaf spot control was obtained with the alternation of copper oxychloride, used alone or in mixture with acibenzolar-S-methyl, with acibenzolar-S-methyl, applied for a total of two sprays.
Acibenzolar-S-methyl applied alone was also effective.

III International Symposium on Tomato Diseases

G. Gilardi, M.L. Gullino, A. Garibaldi

bacterial leaf spot, Solanum lycopersicum, integrated disease management

https://doi.org/10.17660/ActaHortic.2011.914.64