Greenhouse controlled experiments and field trials, under natural infestation, were carried out in order to verify the transmissibility and the reaction of cotton genotypes to a presumed new virus disease affecting cotton crops, mainly in Mato Grosso State, Brazil. The tests revealed that the disease, which is being tentatively named "atypical vein mosaic", has as a vector the cotton aphid (Aphys gossypii Glover). Cotton genotypes, comprising cultivars and advanced lineages available in Brazil, differed considerably with respect to reaction to the pathogen; they were put in graded groups of resistance/susceptibility. The lack of positive correlation between the genotypes' response to this disease, and to the vein mosaic viruses ("blue disease") currently present in this region, indicated that different pathogens could be responsible for these two diseases.
Gossypium spp; viruses; plant disease resistance
