Corn yield response to weed and fall armyworm controls

Abstract

-The interference imposed the by weeds on corn decreases practically all vegetative characteristics. As consequence, the green ear and grain yield are also reduced. Losses due to the fall armyworm (Spodoptera frugiperda) attack can reduce corn grain yield up to 34%. In general, weed and insect control issues are addressed separately in research papers. Nevertheless, interaction between weeds and insects may exist. This study aimed to evaluate green ear and corn grain yield response to weed and fall armyworm control. A completely randomized block design with split-plots and five replicates was adopted. Corn cultivar AG 1051 was grown under weedy conditions or with control by hand hoeings performed at 20 and 40 days after planting. Fall armyworm control (applied to subplots) was performed with sprays of water (control), deltamethrin (5g active ingredient ha -1 ); neem oil, at 0.5% (diluted in water), and neem leaf extract at 5%. Each product was sprayed three times, at seven-day intervals, starting at the 7 th day after planting, using 150 L ha -1 of the tank solution. Dry mass of the above-ground part, internode diameter, leaf length, leaf width, leaf area, green ear yield and grain yield of corn were reduced due to the lack of weed control. Fall armyworm control in the weeded plots did not influence green ear yield and grain yield, except green mass of marketable, husked ears, which was reduced when the caterpillar was not controlled. Without weed control, neem extracts and deltamethrin sprays provided highest yields of number and total weight of green ears with husks, number and weight of marketable ears with husks and number of marketable ears without husks. The best results for husked ear mass and for grain yield were obtained with neem extract and deltamethrin, respectively.Keywords: Zea mays, Spodoptera frugiperda, Azadirachta indica, weed-pest interaction.RESUMO -A interferência imposta pelas plantas daninhas ao milho reduz praticamente todas as características vegetativas. Em conseqüência, os rendimentos de espigas verdes e degrãos são reduzidos. Perdas devidas ao ataque da lagarta-do-cartucho (Spodoptera frugiperda) podem reduzir o rendimento de grãos em até 34%. Em geral, os efeitos dos controles das plantas daninhas e das pragas são estudados separadamente. Apesar disso a interação entre interferência de plantas daninhas e ataque de pragas pode existir. O objetivo deste trabalho foi avaliar os rendimentos de espigas verdes e de grãos de milho em resposta ao controle das plantas daninhas e da lagarta-docartucho. Utilizou-se o delineamento de blocos completos casualizados com parcelas subdivididas e cinco repetições. O milho cultivar AG 1051 foi cultivado no mato ou com controle de plantas daninhas por capinas manuais aplicadas aos 20 e 40 dias após a semeadura. Para avaliar o controle do inseto (aplicado às subparcelas) foram feitas pulverizações com: água (testemunha); deltamethrin (5 g do ingrediente ativo ha -1 ); óleo de nim, obtido comercialmente, à base de 0,5% (com diluição em água); e e...

Soil organisms associated to the weed suppressant Crotalaria juncea (fabaceae) and its importance as a refuge for natural enemies

“…Doru luteipes was found in C. juncea and superficially on the soil of crop plants without cartridge, where they feed on different prey (Fenoglio & Trumper, 2006). This predator is common in maize and sorghum where it lay eggs and preys on the main pests, Diatraea saccharalis (Lepidoptera: Crambidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae) (Figueiredo et al, 2006;Wyckhuys & O'Neil, 2007;Lima et al, 2010). However, the higher abundance of natural enemies in organic agriculture is also due to lower levels of chemical application in these areas (Birkhofer et al, 2008;Tavares et al, 2009).…”

EFICÁCIA DE TECNOLOGIAS DE MILHO Bt NO MANEJO DE LEPIDÓPTEROS-PRAGAS

“…Em termos de injúrias e danos, na ausência de manejo, a praga chega a destruir completamente o cartucho (Gallo et al, 2002), atacando espigas e colmos, acarretando perdas no rendimento de grãos na ordem de 15% a 34% (Lima et al, 2010). Outra praga de importância na cultura do milho é a lagarta Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae), que ataca colmos abrindo galerias, dificultando a translocação de fotoassimilados e predispondo as plantas ao tombamento por ação do vento, podendo causar perdas na produção de até 39% (Pinto et al, 2004).…”

Development of a simple and accurate molecular tool for Spodoptera frugiperda species identification using LAMP

“…At high densities, S. frugiperda larvae can completely defoliate their host plants and can cause severe yield losses in many economically important crops. In Brazil, attacks from S. frugiperda can reduce the corn grain yield up to 34%, causing losses of 400 million US dollars annually (Lima et al, 2010).…”