Fruit rot of guava caused by Botryosphaeria sp.

W. H. Lim

Abstract

A previously unidentified fruit rot disease of guava( var. Kampuchea) caused by a Botryosphaeria sp. similar to Botryosphaeria ribis (identified by CMI, England), was observed in several orchards in Peninsular Malaysia. The disease was characterized by brown rot on the skin; the infected flesh or mesocarp appeared water-soaked and tinged with areas of purple. The cultural and morphological characteristics of the fungus are described. Inoculation studies confirmed its pathogenicity on guava; only the ripe fruits approaching maturity were attacked. Infection was obtained on both wounded and unwounded fruits in laboratory and field trials. In vitro evaluation of fungicides showed benomyl and prochloraz to be highly effective against the fungus. For benomyl the ED 50 and MIC values (for radial growth) were0 .6 and 11 ug/mL- respectively, while for prochloraz, the values were 0.4 and 28 ug/mL respectively. Possible field control measures involving sanitation and chemical sprays are discussed.

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