Effect of Nutrition and Soil Function on Pathogens of Tropical Tree Crops

Abstract

Crops grown in the tropics are subject to different kinds of disease pressure from those produced in temperate regions. The greater biodiversity found in the tropics, including diversity of fungi, is reflected by the larger number of pathogen species in tropical regions (see Ploetz, 2007; Wellman, 1968, 1972). Perennial crops, and tropical perennials in particular, have features in common that may predispose them to pathogen infections. Pathogen inocula, such as microsclerotia, may build up from year to year in perennial crops (Pennypacker, 1989). Also, tropical conditions are usually suitable for the year-round survival and propagation of pathogen species, unlike temperate climates which have a cooler season when pathogen populations die off or are reduced. Tropical perennial crops often include susceptible genotypes on the farm and the presence of susceptible host material encourages the production of inoculum and the initiation of new infections (Ploetz, 2007). Ploetz (2007) remarks that the presence of susceptible hosts is a particularly important barrier to disease control in tropical perennials.