Control of Phytoparasitic Nematodes Attacking Sorghum (Sorghum bicolor (L.) Moench) in Puerto Rico

Abstract

Under laboratory conditions, Fensulfothion (20 lb/acre), D-D (40 gal/acre), and Vorlex (40 gal/acre) increased dry weights of sorghum roots over those of the controls, two other nematicides, and two fungicides. Under field conditions methyl bromide (1 lb/100 ft²) was highly effective in one experiment but not in a second one. Preplant soil treatments with methyl bromide, Fensulfothion (30 lb/acre and D-D (40 gal/acre) increased plant top dry weights 132, 106, and 66%, respectively, over the control plants. Vorlex (40 gal/acre), D-D (40 gal/acre) and Fensulfothion (20 lb/acre) significantly increased plant top dry weight over nontreated plants and the Oxamyl and Phenamiphos treatments. Of three different dosages evaluated, 20 lb/acre of Fensulfothion and 60 gal of D-D/acre significantly increased sorghum plant tops dry weight by 44% over the controls. Both under field and greenhouse conditions, soil fungicides and insecticides failed to produce significant increases. Nematode population levels and pH were lower in plants showing symptoms of abnormal growth with purple leaves and reddish rootlets than in healthy-looking plants free of the symptoms; Al concentration was higher in soil around stunted plants.