Effects of Alternative Control Methods Against Meloidogyne incognita in Organic Tomato Production

Abstract

The effects of some alternative control methods consisting of biofumigation, intercropping with attractive plants, grafting, solarization or biological nematicides against Meloidogyne incognita in organic tomato production were evaluated in two successive short growing cycles (2007 autumn and 2008 spring) in unheated greenhouse conditions. Eight treatments were investigated in both growing seasons while four treatments were the same in each year, two were different. Soil solarization was applied for 6 weeks with a covering of 110 μm thickness of clear polyethylene sheets. For the biofumigation treatments, all the plant parts of the broccoli (Brassica olerace var. italica) (14 t ha -1 ) or the leaves and fruits of the castor oil plant (Ricinus communis) (2.5 t ha -1 ) were added to the soil one week before planting the tomatoes. The American Marigold plant (Tagetes erecta) seedlings were transplanted to the plots one week before planting as an intercrop with the tomato plants. As a biological nematicide, BioAct® [Paecilomyces lilacinus, strain 251: 62.5 g kg-1, 1010 cfu g-1 LD 50>5000 mg kg-1 cfu mL-1 (Boyut Foreign Trade Ltd, Turkey)] was applied three times at the firm's recommended rates. Organic manure, acting as a biological nematicide namely Netisin® (BioGlobal Company, Turkey), was applied at a rate of 10 kg ha -1 using a drip irrigation system to the soil twice. In both seasons root galling caused by M. incognita was lower (1.90 in autumn and 2.95 in spring) in the grafted tomato plants on the rootstock Beaufort than the other treatments. In terms of yield, among the tested treatments, grafting (0.922 kg plant-1 in autumn and 1.785 kg plant -1 in spring) and biofumigation with R. communis in autumn (0.924 kg plant-1) and biofumigation with broccoli in the spring (2.315 kg plant-1) gave higher yields. The overall results showed that biofumigation with broccoli and