Avaliação de extrato de algas no progresso temporal da mancha de Mycosphaerella em cultivares de morangueiro

Abstract

Evaluation of seaweed extract on temporal progress of Mycosphaerella leaf spot in strawberry cultivarsLeaf spot, caused by Mycosphaerella fragariae, is a common foliar disease infectious to a broad variety of strawberry cultivars. In a search for alternative control methods, seaweed extract from Ascophyllum nodosum was applied to strawberry cultivars and evaluated for its effect on Mycosphaerella leaf spot symptoms: growth-curve models were fitted for the progress of disease incidence and severity over time. A 29% seaweed extract was sprayed on soil, on plants or on both at the dose of 2 L ha -1 . Disease incidence and severity were measured biweekly on the cultivars Dover, Toyonoka, Albion, Camarosa, Ventana, Campinas, Tudla and Camino Real. We used a completely randomized split plot design with three replicates. Disease incidence and severity were calculated as the area under Avaliação de extrato de algas no progresso temporal da mancha de mycosphaerella em cultivares de morangueiroEm morangueiros, a mancha das folhas, causada por Mycosphaerella fragariae, é uma das doenças mais comuns na cultura, o que torna importantes os estudos de controle alternativo e de cultivares, sobre o progresso da epidemia. Em busca de práticas alternativas para seu controle, avaliou-se o efeito de cultivares de morangueiro e do extrato da alga Ascophyllum nodosum, na expressão dos sintomas de mycosphaerella, além de avaliar o ajuste de modelos de crescimento para o progresso temporal da incidência e severidade da doença. Utilizou-se o extrato de algas a 29%, na dose de 2 L ha -1 , aplicado no solo, na folha e em ambos. As cultivares Dover, Toyonoka, Albion, Camarosa, Ventana, Campinas, Tudla e Camino Real foram avaliadas, quinzenalmente, quanto a incidência e severidade da doença. Utilizouse o delineamento inteiramente casualizado, com parcelas subdivididas e três repetições. Com os dados de incidência e severidade, calculou-se a área abaixo da curva de progresso da doença e utilizou-se a análise de variância para avaliar o efeito de cultivares e do extrato de algas. Aos dados do progresso temporal da incidência e da severidade, em cada cultivar, foram ajustados os modelos monomolecular, logístico e de Gompertz. O extrato de algas não apresentou efeito ou interação com cultivares, no controle da mycosphaerella. Houve efeito de cultivar com menor intensidade da doença, em Albion e Ventana, devido, principalmente, ao atraso na epidemia, pela redução do inóculo inicial efetivo. Aos dados de progresso temporal da incidência e da severidade ajustaram-se, respectivamente, os modelos logístico e monomolecular, para todas as cultivares. Palavras-chave:Mycosphaerella fragariae, Ascophyllum nodosum, modelagem.

Evaluation of advanced selections of strawberry in southern Brazil

“…These averages were also lower than those obtained by Mazaro et al (2013), which evaluated the effectiveness of treatments with products authorized for organic cultivation in the control of strawberry leaf spot in plants of the Camarosa cultivar, and very smaller than the values found by Heling et al (2015). However, the means found in the present work were very higher than those obtained by Nesi et al (2013), which evaluated the incidence and severity of this disease in eight cultivars.…”

Leaf spot and leaflet removal in day-neutral strawberry cultivars under different cultivation conditions, in organic management

“…The cultivars did not differ significantly in incidence AUDPC (Figure 1). Nesi et al (2013) reported differences in incidence and severity of leaf spot in eight strawberry cultivars, none evaluated in this work. The less susceptible cultivars delayed the beginning of the epidemic due to the lower effective initial inoculum.…”

“…Genetic resistance is the most desired control strategy. However, available cultivars are in majority susceptible to M. fragariae (Nesi et al, 2013). Furthermore there are several strains of M. fragariae occurring in different regions, what can modify the resistance/susceptibility response.…”