High tunnels and grafting for disease management in organic tomato production

High tunnels are gaining popularity for organic and conventional tomato growers as they may provide season extension, reduced foliar disease incidence (particularly against early blight and Septoria), and increased fruit quality. However, crop rotation is often compromised, and soilborne disease can be prevalent in these systems. A research program was initiated to evaluate commercially-available tomato rootstocks capable of reducing soilborne disease incidence and increasing yield under tunnel and field conditions. Soilborne diseases such as bacterial wilt, root-knot nematode, and southern stem blight were effectively managed utilizing various rootstocks in infested field and tunnel soils (P < 0.05). An experiment was established at the Center for Environmental Farming Systems (Goldsboro, NC) to compare grafted and non-grafted plants within field and high tunnel production. The systems comparison showed that total fruit yield was higher in the tunnels (P = 0.01). Insect damage and tomato spotted wilt virus incidence was higher in the field (P < 0.05). In contrast, fruit cracking and catfacing incidence was higher in the tunnel system (P < 0.05). The main effect of grafting showed that yields were increased when 'Maxifort' rootstock was used, even under little disease pressure from soilborne pathogens (P < 0.01). High tunnels and grafting with resistant rootstock offer complementary roles in an integrated pest management approach for tomato.