Plant-parasitic nematodes associated with vegetables in Northern Minas Gerais, Brazil / Fitonematoides associados a hortaliças no Norte de Minas Gerais, Brasil

Plant-parasitic nematodes are frequently associated with vegetables causing yield losses. There is little information on the occurrence of these pathogens in the state of Minas Gerais, Brazil. The objective of this work was to identify plant-parasitic nematodes associated with vegetable crops, focusing on the detection of Meloidogyne spp. in commercial production areas located in the municipality of Montes Claros, Northern Minas Gerais, Brazil. Soil and roots samples were collected from 15 farms including 19 vegetable crops. Nematodes were extracted from soil and identified to genus level, and the roots were assessed for gall index. In soil samples, the genera Meloidogyne spp., Helicotylenchus spp., Rotylenchulus spp., Criconemoides spp., Pratylenchus spp. and Tylenchus spp. were observed in a percentage of 46.1; 31.8; 11.8; 7.4; 6.4 and 3.6%, respectively. The average gall index in vegetable crops were: squash (4.5), lettuce (2.2), eggplant (9.3), beetroot (2.4), broccoli (1.9), carrot (0.3), coriander (2.6), cabagge (0.3), cauliflower (1.2), spinach (2.0), beans (2.8), scarlet eggplant (3.3), gherkin (1.9), cucumber (3.0), pepper (3.3), okra (2.3), arugula (0.7), parsley (3.7) and tomato (3.3)

Antagonistic effect of Trichoderma isolates and its metabolites against Fusarium solani and F. oxysporum in chickpea / Efeito antagonista de isolados de Trichoderma e seus metabólitos contra Fusarium solani e F. oxysporum em grão-de-bico

The aim of this work was to study and select Trichoderma sp. strains with biocontrol potential against Fusarium solani and F. oxysporum, the causal agents of root rot and wilt in chickpea. Antagonism against pathogenic isolates of F. solani and F. oxysporum of twenty-one isolates of Trichoderma sp. obtained from the rhizosphere of chickpea plants were evaluated in vitro through competition in dual culture tests as well as the production of volatile and non-volatile organic compounds exhibiting fungicidal and/or fungistatic activity. In the in vivo experiment, four isolates of Trichoderma sp. were selected and their antagonism was evaluated separately and combined with a commercial product based on T. asperellum under greenhouse conditions. Trichoderma sp. isolates were efficient competitors and produced metabolites capable of inhibiting mycelial growth of both species of Fusarium. Our results show the great versatility of the mechanisms of action from Trichoderma isolates, mainly associated with the production of volatile organic compounds. Despite the antagonistic effect of Trichoderma isolates observed in vitro, these isolates did not control Fusarium neither promote chickpea growth in in vivo conditions.