Weather requirements and rain forecast to time fungicide application for Fusarium head blight control in wheat

Abstract

RESUMOPalavras-chave adicionais: Triticum aestivum, Gibberella zeae, Fusarium graminearum, fusariose, previsão da doença.O objetivo deste trabalho foi determinar as condições mínimas de duração do molhamento em função da temperatura requeridas para a infecção de giberela em trigo. O modelo climático desenvolvido por Zoldan (2008) foi testado em experimentos de campo com duas cultivares de trigo cultivadas em 2005 (cinco épocas de semeadura) e 2006 (seis épocas de semeadura) em parcelas de 10 m 2 com três repetições. A doença foi avaliada pela incidência em espigas (IE), incidência em espiguetas (Ie) e pela interação desses dois métodos e considerado como severidade. A partir do início da antese, a temperatura do ar e a duração do molhamento das espigas foram monitorados diariamente com uma estação meteorológica automática. Com a combinação desses dois fatores, foi Brustolin, R.; Zoldan, S. M.; Reis, E. M.; Zanatta, T.; Carmona, M. Requerimentos ambientais e previsão de chuva como indicador do momento para aplicação de fungicidas no controle da Giberela em trigo. Summa Phytopathologica, v.39, n.4, p.248-251, 2013. elaborada uma tabela de favorabilidade do ambiente para ocorrência da doença. A partir do dia do início da floração (1-5% anteras completamente expostas) a soma dos valores diários para favorabilidade para a infecção (SVDFI) foi calculada com um programa de computador, de acordo com a tabela de Zoldan (2008). Os sintomas iniciais da doença foram observados com uma incidência em espigas de 3,7% e correspondendo 2,6 de SVDFI. A infecção do trigo ocorre em função de chuvas que resultam no molhamento das espigas > 61.4 h de duração. A previsão da ocorrência de chuvas pode auxiliar na indicação do momento indicador da aplicação de fungicidas visando ao controle da giberela. Propõem-se o nome do sistema de aviso de UPF-scab-alert.The aim of this study was to determine the minimum conditions of wetness duration and mean temperature required for Fusarium head blight infection in wheat. The weather model developed by Zoldan (2008) was tested in field experiments for two wheat cultivars grown in 2005 (five sowing dates) and 2006 (six sowing dates) in 10 m 2 plots with three replicates. The disease was assessed according to head incidence (HI), spikelet incidence (SI), and the interaction between these two methods was called head blight severity (HBS). Starting at the beginning of anthesis, air temperature and head wetness duration were daily recorded with an automatic weather station. With Brustolin, R; Zoldan, S. M.; Reis, E. M.; Zanatta, T.; Carmona, M. Weather requirements and rain forecast to time fungicide application for Fusarium head blight control in wheat. Summa Phytopathologica, v.39, n.4, p.248-251, 2013. Additional keywords: Triticum aestivum, Gibberella zeae, Fusarium graminearum, scab, disease forecasting.ABSTRACT the combination of these two factors, a weather favorability table was built for the disease occurrence. Starting on the day of flowering beginning (1 -5% fully exserted anthers), the s...

Infection conditions of Fusarium graminearum in barley are variety specific and different from those in wheat

“…Despite the more favourable infection conditions due to higher precipitation during anthesis (Hooker et al 2002;Brustolin et al 2013), only few FG colonies were noted during anthesis compared with the occurrence before anthesis. This suggests that potentially ejected ascospores were washed down by the higher precipitation or that water covering the perithecia inhibited ejection as assumed by Paulitz (1996).…”

“…In addition, data about the most susceptible growth stages and favourable climatic conditions, which were shown to affect the infection with FG, are necessary to predict the occurrence in a particular field (Cowger et al 2009;Brustolin et al 2013). Since FHB epidemics are strongly dependent on the effective weather conditions, a control with fungicides is not always required (McMullen et al 1997;Brustolin et al 2013). Hence, a forecasting system can avoid unnecessary fungicide applications (Wegulo et al 2015).…”

Relationship Between Efficacy of Fusarium Head Blight Chemical Control and Deoxynivalenol Contamination on Wheat Kernels

“…However, in the 22 to 27 o C thermal range and with 45 hours of continuous wetting resulted in 60% infected spikelets. This long head wetting period showed that the disease depends on post-anthesis rains and not dew (Brustolin et al, 2013). Moreover, the longer the post-infection wetting period, the greater the DON contamination (Cowger et al, 2009).…”

“…Gibberella zeae infective period, and its reflection on the FHB intensity, considering that inoculum is always available, is direct related to anthers continuous wetting period duration (Andersen, 1948;Brustolin et al, 2013;. Thus, the predisposition period extends from the anthesis beginning (GS 60) to ripening (GS 87) (26).…”

“…Without sufficient duration of wetting period there is no infection. Therefore, the best indicator to time the first fungicide spraying aiming at the FHB control is the rainfall forecast (Brustolin et al, 2013;Reis et al, 2013).…”