Forage Diseases
 Plant
diseases are important constraints to forage production and seed health. Tropical forages
are diverse, comprising both legumes and grasses. Numerous pathogens infect these forages.
Unlike crop diseases, the study of many of these diseases has been limited to
identification and documentation.
We have selected some economically important diseases of key forage legumes and
grasses for detailed research work. One is anthracnose of Stylosanthes and Arachis,
caused by the fungus Colletotrichum gloeosporioides. South America is the center
of origin of Stylosanthes, and thus also the presumed center of genetic diversity
of its pathogen. Isolates of the fungus so far found in this region are highly variable
and complex, complicating breeding.
Another significant fungal pathogen is Rhizoctonia solani, which causes
Rhizoctonia foliar blight disease. It can produce substantial foliar damage on susceptible
genotypes of numerous plant species, including Brachiaria spp. and various
tropical and subtropical crops. The fungus can survive for long periods in the soil or on
plant debris as hardy sclerotia, which form the primary source of inocula
For such diseases, we are searching for resistant cultivars, which, when
available, comprise the cheapest, most effective, and most environmentally friendly method
for combating diseases. We are also studying other disease management strategies.
Endophytic Fungi
 Endophytic
fungi have highly complex associations with their plant hosts, resulting in physiological
responses of applied value in terms of plant vigor, water ratios, nutrient acquisition and
use, and protection from pathogens and insects. Although considerable information on
temperate grass/endophyte associations is available, little is known about tropical
grasses and their endophytes. Our work shows that endophytic fungi inhabit several
tropical grasses native to Colombia, as well as introduced grasses such as Brachiaria
spp.
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