Sowing date reduces the incidence of wheat blast disease

Abstract

-The objective of this work was to assess the effect of sowing date on the intensity of wheat blast disease, as well as the yield losses caused by this disease in different wheat (Triticum aestivum) genotypes. The experiments were conducted in 2013 at the Sertãozinho experimental station of Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig), in the municipality of Patos de Minas, in the state of Minas Gerais, Brazil. Fourteen wheat genotypes and two sowing dates were evaluated. The experimental design was a randomized complete block with three replicates. The evaluated variables were: incidence, severity, thousand grain weight (TGW), grain yield, and yield losses. A disease index (DI) was calculated, based both on the incidence and the severity of the disease, to measure blast intensity in wheat. The sowing date significantly affected DI, TGW, and grain yield. Significant linear correlations were observed between DI and yield losses (0.89), between losses and TGW (-0.85), and between losses and grain yield (-0.93). For wheat blast, DIs greater than or equal to 0.5 indicate potential yield losses equal to or greater than 70%. The EP063030 line and the MGS Brilhante and BRS 264 cultivars are the most tolerant to blast, when exposed to high disease pressure.Index terms: Magnaporthe oryzae, Pyricularia oryzae, Triticum aestivum, disease index, severity, tolerance. Época de semeadura reduz a incidência da brusone do trigoResumo -O objetivo deste trabalho foi avaliar o efeito da época de semeadura sobre a intensidade da brusone, bem como as perdas na produtividade causada por essa doença em genótipos de trigo (Triticum aestivum). Os experimentos foram conduzidos, em 2013, na Fazenda Experimental de Sertãozinho da Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig), em Patos de Minas, MG. Catorze genótipos de trigo e duas datas de semeadura foram avaliados. Utilizou-se o delineamento experimental de blocos ao acaso com três repetições. As variáveis avaliadas foram: incidência, severidade, peso de mil grãos (PMG), rendimento de grãos e perdas de produtividade. Calculou-se o índice da doença (ID), com base tanto na incidência quanto na severidade, para medir a intensidade da brusone em trigo. A data de semeadura afetou significativamente ID, PMG e rendimento de grãos. Houve forte correlação linear entre ID e danos (0,89), entre danos e PMG (-0,85) e entre danos e rendimento (-0,93). Para a brusone do trigo, IDs iguais ou maiores que 0,5 indicam potencial de danos de rendimento iguais ou superiores a 70%. A linhagem EP063030 e as cultivares MGS Brilhante e BRS 264 são as mais tolerantes à brusone quando expostas à alta intensidade da doença.Termos para indexação: Magnaporthe oryzae, Pyricularia oryzae, Triticum aestivum, índice da doença, severidade, tolerância.

Genome-wide association mapping for wheat blast resistance in CIMMYT’s international screening nurseries evaluated in Bolivia and Bangladesh

“…In this study, 1,106 lines in the IBWSNs and SAWSNs were evaluated for wheat blast in Bolivia and Bangladesh, and we observed a high level of resistance, with 83.7% of them having mean blast indices less than 10. In the environments considered in this study, the planting time did not significantly affect the disease indices except in one dataset, in contrast to a previous observation 29 . In addition, traits like days to heading and height had low correlations with disease index which can be partly attributed to the low variability in the blast indices.…”

“…Management of wheat blast using fungicides is possible, but has been reported to be elusive, because of the inefficiency of fungicides in offering complete control under high disease pressure, the resistance in MoT populations to some classes of fungicides, and the high cost of the fungicides that cannot be afforded by resource-poor farmers 4 , 6 , 9 , 26 – 28 . While other potential blast control measures including altering the sowing time 5 , 29 , suspending the cultivation of wheat in disease-prone areas and declaring a ‘wheat holiday’ will help to mitigate the disease spread to some extent, the development and deployment of wheat varieties with genetic resistance to blast has been resorted to as the most sustainable and farmer-friendly approach 4 , 30 , 31 .…”

Quantitative trait loci conferring blast resistance in hexaploid wheat at adult plant stage

“…Other studies also showed that blast disease negatively affects the variables linked to wheat physiology and, consequently, grain yield, particularly during early grain filling (Rios et al, 2017). Under field conditions, significant correlations were observed between disease index and yield losses (Coelho et al, 2016). In Argentina, four commonly used wheat cultivars were evaluated after inoculation of eight M .…”

Wheat blast: from its origins in South America to its emergence as a global threat

“…In South‐East Asia, jute ( Corchorus olitorius ) cultivation could be an option for crop rotation (Government of India, ). Altering the sowing date to prevent an overlap between flowering or grain filling stages and blast‐conducive periods characterized by high temperatures, rain and high relative humidity is an effective cultural practice to manage wheat blast in South America (Coelho et al ., ; Mehta, ; Mehta et al ., ). Field experiments designed to dissect the epidemiology of wheat blast will be needed to determine which of these strategies will have the greatest impact.…”