Manejo orgânico do tomateiro

Abstract

Tomato is one of the main vegetables grown in Brazil in a conventional system. Due to the damages caused by the use of pesticides the society has been demanding for food produced in organic systems. The objective of the present work was to evaluate the control of tomato early blight (Alternaria solani) with plant extracts, the performance of tomato cultivars in the organic system and to verify the nutrient content in biofertilizer formulated for the crop. Aqueous extracts of garlic (Allium sativum), ginger (Zingiber officinale), neem (Azadirachta indica) and jurema (Mimosa tenuiflora) at concentrations of 2.5%; 5%; 7.5%, 10%, 12.5% and 15% were evaluated for fungitoxicity to the pathogen in vitro conditions. In tomato (IPA 6) cultivated in pots the extract of garlic (15%) was pulverized with or without adjuvants (oil, milk and kaolin) for the control of the early blight. The performance of eight tomato cultivars (Giulianna, Débora Max, Carinaty, Débora Pto, Débora Victory, Tyna, Carina Golden, Carina Star (Sakata Seed America) and IPA (Feltrin Sementes)) was evaluated in semiarid conditions (Picuí, Microregion of the Eastern Seridó paraibano) in organic system of production. The nutrient content of the biofertilizer was verified at 0, 15, 30, 45 and 60 days after preparation. Aqueous extracts of garlic, neem, jurema and ginger are fungitoxic to A. solani. Aqueous extract of garlic (15% v/v) plus sunflower oil has the potential to be used in the control of the black spot. The cultivar Giuliana (Sakata Seed America) had higher productivity (67.75 kg.ha^-1) among the cultivars evaluated, being higher in 2.4 times than the average productivity of the state of Paraíba. On the plants occurred spider mites, which caused leaf spot and necrosis. Greater presence of leaf spot was verified for the cultivars Giuliana, Carina Star and Carina Golden. Leaf necrosis was more frequent in the cultivar Débora Victory; and the cultivars with the lowest number of necrotic leaves were IPA 6, Giuliana and Débora Pto. The cultivars that had the highest incidence of apical rot were Débora Victory, Débora Max and Débora Pto. The content of macro and micronutrients contained in the biofertilizer oscillates over time. According to the d ata obtained it is concluded that there is potentiality in the organic cultivation of the tomato in semiarid conditions.