Maize (Zea mays L.) is one crop of major relevance in Brazil; however, nematodes are limiting factors in maize growth and productivity due to the difficulty to control them. Studies point out that arbuscular mycorrhizal fungi (AMF) increase plant tolerance to nematodes. Thus, the aim of this study was to assess the association between AMFs and Pratylenchus brachyurus in maize growth. Six AMF species (Rhizophagus clarus, Claroideoglomus etunicatum, Gigaspora rosea, G. margarita, Scutellospora calospora, S. heterogama), as well as a control treatment free of mycorrhizae, were assessed under two different nematode inoculum conditions (presence and absence). Plants were collected and analyzed 60 d after inoculation. The nematode population was higher in the treatments inoculated with AMFs. On the other hand, just the plants inoculated with R. clarus did not present improved development in comparison to the control. Nematodes increased AMF spore density, but despite the fact that AMFs have presented different root colonization capacity (ranging from 2.3% to 95.0%), such capacity was not affected by the nematodes.

Root-knot nematodes are responsible for significant tomato production losses and require taking integrated control measures. The aim of the current study is to evaluate the association between biological control and organic matter sources to Meloidogyne javanica control in tomato. In order to do so, two experiments were carried out under greenhouse conditions, in two different periods. Tomato plants were transplanted to pots and inoculated with 2,000 M. javanica eggs. Plants were treated with either Nem-Out™ or Compost-Aid ® biological control products, which were individually applied or in association with organic wastes such as poultry litter, filter cake, rice hull and coffee hull. Nematological and vegetative parameters were evaluated 60 days later. The treatments, except for Nem-Out™ + poultry litter and Compost-Aid ® + poultry litter, were efficient in reducing the number of galls. Treatment with Nem-Out™ + filter cake presented 83% gall reduction, whereas Compost-Aid ® + filter cake presented 98.5% reduction. The associations between Nem-Out™ + poultry litter and Compost-Aid ® + poultry litter did reduce the number of nematodes g -1 of root. Reduction in this parameter were observed for all others treatments, mainly when there was association between biological control (both, Nem-Out™ and Compost-Aid ® ) and organic wastes; the treatment with Nem-Out™ + coffee hull reduced by 96% the number of nematodes g -1 of root, whereas the one with Compost-Aid ® + filter cake reduced it by 97%. Most of the treatments have positively influenced the vegetative variables in comparison to the inoculated control.

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Summary Nematodes of the genus Meloidogyne are one of the major limiting factors in tomato production and a challenging problem in organic systems. This study aimed to investigate the effect of agro-industrial wastes, their forms of application and doses on tomato plants inoculated with Meloidogyne javanica. First, nematodes were multiplied on tomato under glasshouse conditions to simulate a naturally infested environment. At 60 days after inoculation, plant shoots were removed, new seedlings were transplanted into the pots, and the soil was amended with agro-industrial wastes. Treatments were as follows: rice husk, common bean hull, soybean hull, orange bagasse, poultry litter and waste mixture (wastes mixed in equal proportions) applied in three different forms (raw, powdered and biodigester effluent). A non-treated control and a composted waste mixture were also assessed. At 60 days after transplanting, plants were evaluated for nematode parameters. Powdered bean hulls, soybean hulls, orange bagasse and waste mixture provided the best results and were selected for dose-response investigations. A second experiment was conducted in two periods using, in addition to the selected wastes, a mixture of powdered bean hulls, soybean hulls and orange bagasse. Wastes were applied at doses of 0 (control), 2, 4, 6 and 8 t ha−1. Powdered bean hulls, soybean hulls, orange bagasse and waste mixtures at 5 t ha−1 gave the best nematode control, with reductions of 55-100%. The optimal doses for vegetative growth were 4 t ha−1 in the first period and 5 t ha−1 in the second period.

Crambe is an oilseed, which pressing for oil extraction results in the waste called crambe cake. The aforementioned waste may present potential to control nematodes, since it derives from brassica species. The aim of the current study is to assess the best crambe cake application to control Meloidogyne javanica in lettuce plants. Five experiments were carried out in a greenhouse by adopting different crambe cake application procedures; each experiment comprised five treatments (0 (control), 5; 10; 15; 20 g crambe cake per 1 L soil). Lettuce seedlings were cultivated in soil treated with crambe cake, and inoculated with 5,000 nematode eggs and occasional juveniles (J2). Nematological and vegetative parameters were assessed 45 days after inoculation. Nematode reduction was observed in the experiment that applied doses close to 15 g crambe cake to the soil surface; nematode control recorded 83 and 68% for eggs and J2 total and per root gram, respectively. The same parameters showed up to 82 and 93% reduction when the cake was incorporated to the first 8 cm deep into the soil. The number of eggs and J2 per root system reduced by 93% when the cake was incorporated to the total soil volume. Overall, the crambe cake did not increase plant development; in some cases, phytotoxicity was observed at the highest doses.