Effect of calcium sulfate and organic matter applying on the incidence of brown rot of guava (Psidium guajava']java L.)

The brown rot in guava fruits caused by the fungus Dothiorella sp., is a widely distributed disease, producing 62% of damage in guava orchards in Venezuela. Calcium sulfate and organic matter effects on the brown rot incidence in guava fruit were determined in an experimental orchard of guava at Centro Fruticola del Zulia (CENFRUZU-CORPOZULIA) (10 degrees 49'47", 31914 LN, 71 degrees 46'28", 44742 LW), which has 204 guava trees of 12 years. 32 guava trees were selected by uniformed morphological characteristics for this essay. The evaluated treatments were: 20 kg.plant(-1) of organic matter (OM), 6 kg.plant-1 calcium sulfate per plant, calcium sulfate and OM at mentioned doses and a control without OM and calcium sulfate application. The studied variables were: fruit production, brown rot incidence (BRI), fruit mineral content (N, P, K, Ca, Mg and Na) and fruit texture. The studied treatments did not affect the production and BRI, there was a difference between BRI and sampling time, the higher value of BRI was in September 2006, three months after a rain pick. The infected fruit showed higher the content of P, K, and the lower contents of N, Ca, and Mg, in contrast with healthy fruit. The Na content and fruit texture didnot shown differences.