Addition of mancozeb to the fungicide mixtures DMI + QoI and SDHI + QoI on the control of wheat leaf blights

AUTOR(ES)
FONTE

Summa phytopathol.

DATA DE PUBLICAÇÃO

2019-03

RESUMO

RESUMO As manchas foliares do trigo causadas por Drechslera siccans e, principalmente, D. tritici-repentis são de difícil controle pelas misturas de fungicidas sítio específicos. Devido ao desenvolvimento da resistência, o uso das misturas duplas de sítio específicos apresenta controle inferior a 50%. Em experimento conduzido no campo com a cultivar de trigo Jadeíte 11, parcelas de 3 x 6 m, com quatro repetições, avaliou-se o efeito da adição de fungicida multi sítio às misturas de fungicidas no controle das manchas foliares. Foi avaliado o efeito das misturas picoxistrobina + ciproconazol, cresoxim metílico + epoxiconazol, azoxistrobina + ciproconazol, piraclostrobina + epoxiconazol, piraclostrobina + fluxapiroxada, trifloxistrobina + protioconazol e azoxistrobina + propiconazol adicionadas de cinco doses de mancozebe, 0; 1,5; 2,0; 2,5 e 3,0 kg/ha. A primeira aplicação foi feita após o afilhamento com 30% de incidência foliar e as outras duas com intervalos de 15 a 18 dias. Os fungicidas foram aplicados com pulverizador costal e pressão gerada por CO2 e vazão de 180 L/ha. Foi quantificada a severidade foliar das manchas, calculado o controle, determinado o percentual de clorofila nas folhas-bandeiras e o rendimento de grãos. A média do controle das manchas foliares pelas misturas sem adição do fungicida multi sítio foi de 44%. A severidade da doença foi reduzida em função da adição de doses do mancozebe em todos os tratamentos. Controle superior a 80% foi obtido com as misturas de cresoxim metílico + epoxiconazol e piraclostrobina + epoxiconazol, ambas adicionadas de no mínimo 2,0 kg/ha de mancozebe. Houve reflexo positivo no aumento do rendimento de grãos do trigo em função do controle, variando de 3005 kg/ha no melhor tratamento e 2026 kg/ha na testemunha.ABSTRACT Wheat leaf blights caused by Drechslera siccans, D. tritici-repentis, especially D. tritici-repentis, are difficult to be controlled by site-specific fungicide mixtures. Due to development of resistance, the use of double site-specific mixtures has shown control inferior to 50%. In an experiment conducted in the field with the wheat cultivar Jadeite 11, in 3 x 6 m plots and four replicates, the effect of a muli-site fungicide added to fungicide mixtures on the control of leaf blights was evaluated. The effect of the following mixtures was evaluated: picoxystrobin + cyproconazole, kresoxim-methyl + epoxiconazole, azoxystrobin + cyproconazole, pyraclostrobin + epoxiconazole, pyraclostrobin + fluxapyroxad, trifloxystrobin + prothioconazole and azoxystrobin + propiconazole, added of five mancozeb levels, 0; 1.5; 2.0; 2.5 and 3.0 kg/ha. The first application occurred after 30% leaf incidence, and the remaining two occurred at 15 and 18-day intervals. The fungicides were applied with a backpack sprayer pressurized by CO2, delivering 180 L/ha. Leaf blights severity was quantified, control was calculated, the percentage of chlorophyll in flag leaves was determined, and grain yield was assessed. The mean control of leaf blights by the mixtures without addition of the multi-site fungicide was 44%. The disease severity reduced as a function of the addition of mancozeb levels for all treatments. Control superior to 80% was obtained with the mixtures kresoxim methyl + epoxiconazole and pyraclostrobin + epoxiconazole, both added at least 2.0 kg/ha mancozeb. There was a positive reflex on the increase in wheat grain yield as a function of control, varying from 3005 kg/ha for the best treatment to 2026 kg/ha for control.

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