The purpose of this work was to evaluate the yield performance of Bt maize hybrids under field conditions with damage of the Spodoptera frugiperda in a completely randomized blocks design, under a factorial scheme, with four replications. Six treatments (five Bt maize hybrids and one non-Bt hybrid) were evaluated, with and without control of the S. frugiperda. In the evaluations of number of larvae and average damage scores on maize plants there was a lower incidence and lower damage of larvae on the genotypes containing Leptra® and Viptera 3® technologies and for the productive parameters there was no significant difference between the studied genotypes, even with and without chemical control of the pest. It was concluded that there are genotypes of corn resistant to S. frugiperda, however, there was no significant difference in the yield performance of the different hybrids when comparing the difference between lack of control and chemical control in the infestation conditions found in this study. This suggests that the levels of economic damage of S. frugiperda on corn crop are higher than the levels of infestation occurred in the study.

Beans (Phaseolus vulgaris) are one of the most important crops in human food, but the occurrence of disease can greatly reduce their productivity. The objective of this work was to evaluate the use of biotic and abiotic products to control angular spot (Pseudocercosporagriseola) in bean crop. Hight Roots ® treatments; V6 ® ; Wert Plus ® , potassium phosphite; manganese phosphite; Copper phosphite, manganese, fungicide (fentin hydroxide), Ascophyllum nodosum, Bacillus subtilis and Bacillus thuringiensis, acibenzolar-S-methylic (ASM) and Trichoderma asperallum were used in greenhouse and field experiments with IPR Uirapuru cultivar. Biotic to abiotic products controlled angular leaf spot in bean plants. In greenhouse, the lowest values of Area Under the Disease Progress Curve (AUDPC) were obtained with fungicide application, A. nodosum, T. asperellum and copper phosphite, B. subtillis, acibenzolar-S-methyl, potassium phosphite, Hight Roots ® , V6 ® and Wert Plus ® . In field, in the first sowing season the treatments with fungicide, A. nodosum, B. thuringiensis and manganese resulted in lower AUDPC in relation to the other products. In the second sowing season, the tested products did not reduce the severity of the angular spot, since the productivity was higher for fungicide treatment. In the health quality of seeds, potentially pathogenic fungi such as Fusarium sp., Colletotrichum truncatum and Phomopsis sp., as well as the saprophytic fungus Aspergillus sp.

BACKGROUND: Corn intercropped with ruzigrass is common in Brazil, and it can improve the physicochemical features of soils, increase water retention, and suppress the emergence of resistant weeds and soil nematodes. As both corn and ruzigrass are hosts to Spodoptera frugiperda (the main corn pest in South America), the cultivation of both these plants in the same place at one time motivates investigation into the pest population dynamics. We hypothesize that the intercropping system influences S. frugiperda pressure and leaf injury in corn. Considering that if corn hybrids with high dose toxin expression are used, ruzigrass may be a potential host to susceptible S. frugiperda larvae, consequently an alternative refuge and be included as a tool for the resistant management of Bt corn. To test these hypotheses about the use of ruzigrass as an alternative host of S. frugiperda in an intercropping system with corn, we conducted field trials in three seasons to verify S. frugiperda population dynamics and leaf injury to crop systems. In addition to phenotypic evaluation, we also characterized molecularly S. frugiperda strains collected in corn and ruzigrass to identify strain differences.RESULTS: The insects collected in both corn and ruzigrass were identified as corn strains. Ruzigrass was used as a S. frugiperda host during all crop cycles. The intercropped system did not increase the S. frugiperda population or leaf injury on Bt corn. CONCLUSION:The results suggest that the intercropped system is not prejudicial to Bt corn cultivation since high dose concept applies to all larvae instars. The results also suggest that ruzigrass may be used as a promising alternative refuge in Bt corn agroecosystems, if compliance with management strategies is followed.

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