Biological Control of Foliar Diseases of Tomato Grown in Soilless Culture

News source: MARDI, Malaysia, 2001-03-01

Fungus Diseases of Tomato Foliage

Foliar diseases are important in tomato production under rain shelters in the Cameron Highlands of Malaysia. The rainshelter or greenhouse environment is very conducive to several diseases, particularly powdery mildews caused by Leveillula taurica, grey mold caused by Botrytis cinerea, and late blight caused by Phythopthora infestans. Biocontrol represents an attractive alternative for the future because of widespread consumers concerns over pesticide residues.

Control by Bacterial Isolates

Recent in-vitro studies of the effect of bacteria on these foliar diseases indicated five promising isolates which showed high antagonistic activity against late blight and grey mold. The isolates are SC96, CT1, LT2, KTTW2 and T5. They were identified as Bacillus sp., Enterobacter agglomerans, Enterobacter gergoviae, Comamonas acidovorans and Bacillus amiloliquesaciens, respectively. The performance of the isolates was tested, in terms of their ability to control the three foliar diseases under farm conditions. The bacterial isolate which was most active against powdery mildew was SC96. The incidence on stem and calyx was 20%, and less than 30% on the leaves. The other isolates were not very effective in controlling powdery mildew. The isolate SC96 also gave good control of late blight. Various frequencies of application and mixtures of antagonists were tested. The results showed that weekly applications of SC96, and a mixture of SC96 and T5, were effective in controlling powdery mildew and late blight.

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