Azobenzene Dusts to Control Red Spiders on Some Greenhouse Plants12

Abstract

Use of azobenzene as a fumigant in greenhouses is limited to houses where steam heat is available for its volatilization. Expts. presented show that very good kill of all stages of the 2-spotted spider mite, Tetranychus telarius, the southern red mite, Paratetranychus ilicis, a sp. of Brevi-palpus and the broad mite, Hemitarsonemus latus were ob-tained with dusts containing azobenzene. Dusts containing 75, 50, 35 and 25% of azobenzene were tested. Satisfactory control was obtained with the dusts containing 25% azobenzene, although dusts containing higher percentages may be desirable where excessive inert material is objectionable. The azobenzene dusts were tested on a number of greenhouse plants with no bleaching of foliage and very little bleaching of bloom. The common violet and the African violet or Saintpaulia plants were severely injured by azobenzene dusts.