Influence of environmental factors on the development of the anthracnose diseases of <i>Stylosanthes</i> spp

Abstract

The influence of temperature, period of leaf wetness after inoculation, and relative humidity on the development of the type A and type B diseases of Stylosanthes spp. caused by Colletotrichum gloeosporioides was studied in controlled environment cabinets. Severe disease of both types developed in plants incubated at temperatures of 20-30¦C, and given 24 h of leaf wetness after inoculation. Provided these conditions were imposed, high levels of disease developed following the leaf wetness period, irrespective of the relative humidity (40-50% or &amp;gt;95%). High levels of disease developed for both the type A and type B combinations at temperatures in the range 20-3OoC, but only the type A disease developed at &amp;gt;34¦C. Neither disease developed at constant temperatures of 15 or 37¦C. The use of these results in the development of a model to predict field infection is discussed.