The epidemiology, control and cause of sooty blotch of carambola, Averrhoa carambola L., in South Florida.

摘要

Carambola, Averrhoa carambola, produces a fruit that is an important commodity in South Florida (USA). A newly recognized disease in South Florida, sooty blotch, caused by the epiphytic growth of fungi, results in fruit cosmetic damage. Disease incidence and severity were monitored in seven commercial groves from 1994 to 1996 to examine the influence of grove attributes, fruit size/maturity and season on sooty blotch development. Various fungicides were evaluated for control of the disease on calendar (1 and 3 weeks) and rainfall-driven application schedules. To identify the causal fungi, fungal colonies on fruit (thalli) and in culture were compared with those that have been reported on apple. Disease incidence and severity were significantly greater in groves with older vs. younger trees, N-S vs. E-W row orientations, and wind screens vs. no wind protection. The disease developed predominantly on mid- to late-stage fruit, and continued to increase as fruit matured. Moderate, but significant, control was obtained with certain fungicides. Based on the morphology of thalli on affected fruit, the anatomical and morphological characteristics of the fungi in culture, and their response to fungicides, the disease appears to be a disease complex similar to sooty blotch on apple. The most common agent on carambola resembles, but is distinct from, Peltaster fructicola. In the absence of a formal description, we call the fungus Peltaster sp. carambola. This is the first report on the epidemiology, control and cause of the sooty blotch disease on carambola in South Florida. Previous reports indicating that the disease was either sooty mold or was caused by Leptothyrium sp. or Gloeodes pomigena are incorrect.