Cotton yield losses due to a new adversity of unknown cause, refered by the authors as "reddish wilting", were evaluated under field conditions at State of Sao Paulo, Brazil. Excepting those already dried or dead, affected plants, with about 100 days of age, were marked, according to three degrees of symptoms severity, in order to compare their average yield to that of apparently normal plants. Highly significant differences were verified among the groups and based on a linear regression analysis (r² = 0.996) expected losses of 16, 33 and 49% were estimated, respectively, for the increasing symptoms intensity classes of affected plants. Although foliage restauration was observed, the results indicated that this can not be considered, from the cotton production viewpoint, as an effective recuperation of the affected plants. Otherwise, the data suggest stability of potential damage, at plant level - once the problem is manifested - in each one of de symptom categories analysed.
cotton; "reddish wilting"; yield losses