Fungicidas associados ou não a fosfitos no controle da mancha foliar de glomerela em macieira

Abstract

RESUMOEste trabalho objetivou avaliar fungicidas em associação ou não com fosfito de potássio na redução da mancha foliar de glomerela (MFG) e desfolha da planta e selecionar modelo de crescimento para o progresso temporal da doença em plantas não tratadas, entre novembro e abril, safras 2004/05 e 2005/06. O delineamento foi em blocos ao acaso, quatro repetições, e as pulverizações a cada 10 dias. Avaliações de incidência, severidade e desfolha, foram quinzenais em dois ramos/tratamento. Avaliaram-se: mancozebe, clorotalonil, tiofanato metílico, e fosfito de potássio (00-20-20). Procedeu-se à análise de variância e comparação de médias entre tratamentos e se ajustaram modelos para descrever a epidemia, comparados pelo critério de informação de Akaike (AIC). O tiofanato metílico mostrou-se eficiente na redução da desfolha precoce mas não diminuiu a área abaixo da curva de progresso (AACP) da incidência e da severidade. A associação de fosfito com tiofanato metílico reduziu a AACP da incidência e da severidade. Na safra 2005/06 clorothalonil foi superior ao padrão mancozebe reduzindo a AACP da incidência e severidade. Os ajustes dos modelos foram semelhantes (R 2 >85% e valores próximos de AIC); o modelo logístico foi escolhido por melhor descrever a epidemia. Palavras-chave: Colletotrichum spp, epidemiologia, progresso temporalFungicides associated or not with phosphite for controlling glomerella leaf spot on apple ABSTRACTThe aim of study was to test fungicides and their association with potassium phosphite in reduction of glomerella leaf spot (GLS) and plant defoliation and select a grown model of the temporal progress of GLS in untreated plants during November and April, 2004/05 and 2005/06 seasons. The experimental design was random blocks with four replications and the applications at intervals of 10 days. Evaluations of incidence, severity and defoliation took place every 15 days (two branches per treatment). The fungicides evaluated were: mancozeb, chlorothalonil, methyl tiophanate, and potassium phosphite (00-20-20). Analysis of variance was performed and mean comparison between treatments, and models were adjusted to describe the epidemic, compared themselves through Akaike information criteria (AIC). Methyl tiophanate showed efficient in defoliation reduction, but it did not reduce the area under progress curve (AUPC) for incidence and severity. Association of phosphite with methyl tiophanate reduced the AUPC of incidence and severity. During 2005/06 season the fungicide chlorothalonil was better than standard mancozeb, reducing the AUPC of incidence and severity. Adjustments of models are similar (R 2 >0.85 and similar values of AIC); the logistic model had the better epidemic adjustment.

Survival of pathogens after dormancy in apple tree twigs indicates potential risk as source of inoculum

“…There was a drastic reduction in the incidence of the genus Colletotrichum at all collection orchards between dormancy and vegetative growth collections. The importance of the diseases caused by this genus in apple trees results from its wide distribution (Boneti, Ribeiro, & Katsurayama, 1999;Hamada, Nesi, Alves, & De Mio, 2012;Sutton et al, 2014;Moreira, Peres, & De Mio, 2019) and its caused damage, which can vary from 50 to 75% and the large amount of fungicide sprays required for its control (Ceresine, Leite, & Tsuneta,1992;Hamada et al, 2012). Crusius et al (2002) reported that the survival of Colletotrichum spp.…”