Integrated management strategies of Meloidogyne incognita and Pseudopyrenochaeta lycopersici on tomato using a Bacillus firmus-based product and two synthetic nematicides in two consecutive crop cycles in greenhouse

Abstract

Because of the restrictions on chemical pesticide use and their negative effects on the environment, as well as on human and animal health, alternative strategies for plant pest and pathogen managements are highly desirable. The objective of this work was to evaluate the suitability of a commercial formulation of Bacillus firmus strain 1-1582, applied either alone or in combination with oxamyl or fosthiazate, to control the southern root-knot nematode Meloidogyne incognita and the fungal plant pathogen Pseudopyrenochaeta lycopersici under greenhouse conditions during two tomato crop cycles. Application of B. firmus suppressed nematode population levels during the second crop cycle and when the treatments were repeated on soil previously amended with organic matter. In contrast, fungal infection was reduced during both crop cycles regardless of the application of organic matter. The combinations of the bioformulation and chemicals induced the lowest Root Galling Index compared to all other treatments in both crop cycles. The suppression of nematode populations levels and infection rate of the fungus induced by B. firmus alone or in combination with the chemicals was more pronounced during the second tomato crop cycle than the first crop cycle, also because the temperatures during the second crop cycle were unfavorable to the nematode development. The greatest increase in tomato yield induced by the combined treatments was observed during the second crop cycle, and it was up 50% compared to the untreated control. The applications of the bionematocide and two chemicals used in this study did not result in dramatic suppression of nematode and fungal populations. However, the application of these products alone or in combination, supplemented by organic amendment increases the yield of tomato plants compared to that of the untreated control, although the plants were infected by the pest and the pathogen. These results indicate that early spring/early fall application of B. firmus is an effective biopesticide treatment for management of the southern root-knot nematode and P. lycopersici on tomato crops growing in the integrated pest management system of this experiment and in the environmental conditions of southern Italy.