Control of Citrus Nematode with Ditera WDG, a Biological Nematicide, Applied through Minisprinkler Irrigation

Abstract

The objectives of the study were to measure the effectiveness of Ditera WDG, a biological nematicide derived from the fermentation of a nematode-parasitic isolate of the Myrothecium species, in controlling citrus nematode numbers and the effects on tree growth, fruit yield, and fruit size as applied through minisprinkler irrigation. Nematode-infested trees utilized for the study included three different blocks of sweet oranges: 1) 20-year-old `Valencia' orange trees on Troyer citrange rootstock; 2) 15-year-old Washington navel orange trees on Troyer citrange rootstock; and 3) 8-year-old Washington navel orange trees on three citrange rootstocks (Troyer, Carizzo, and C-35). Three treatments were utilized within each orchard block: 1) 28.01 kg of active ingredient per hectare (25 lb per acre); 2) 56.02 kg of active ingredient per hectare (50 lb per acre); and 3) an untreated control. Treatments 1 and 2 were split into early spring and early fall applications for three seasons. Chemical was injected through minisprinkler irrigation in a 3.41 m (11.2 ft.) diameter under each tree. There was a positive trend toward reduction of nematode numbers for the high rate of Ditera in all three treatment blocks and for the low rate in one block. Effects on tree growth, fruit yield, and fruit size will also be presented.