High mite infestations were observed during two consecutive years (1999 and 2000) in peanut fields of cultivar IAC-Caiapó, at the Adamantina Experiment Station of Instituto Agronômico de Campinas (IAC). The mites were identified as Tetranychus ogmophallos Ferreira & Flechtmann, and the symptoms consisted of an initial silver-like chlorosis on leaves, progressing to formation of a great ammount of web structures covering the plants. For a preliminary evaluation of the damage, two 1.000 m² plots were marked during the 1998/99 field growing. One was not treated with pesticide and the other was chemically sprayed for mite control. In both plots, pod harvesting was done at three intervals, and pod yield within each plot was estimated as the average of harvesting intervals. Comparison between treated and untreated plots indicated a 76,5% yield reduction due to mite infestation. T. ogmophallos has been previously known from Arachis pintoi, a wild peanut species, but no report of its occurrence on cultivated peanut (Arachis hipogaea) was known.
Arachis hypogaea; phytophagous mite