Yield loss caused by huanglongbing in different sweet orange cultivars in São Paulo, Brazil

Abstract

Citrus huanglongbing (HLB) reduces an affected orchard's economic life. This work aimed to characterize yield loss due to HLB for different sweet orange cultivars and determine the relationship between disease severity and yield. Disease severity and yield were assessed on 949 individual trees distributed in 11 different blocks from sweet orange cultivars Hamlin, Westin, Pera and Valencia. In each block, plants showing a range of HLB severity levels and asymptomatic plants were selected. Total yield (weight of harvested fruit), mean weight of asymptomatic and symptomatic fruit, relative yield (symptomatic tree yield/mean yield of asymptomatic trees from the same block) and relative number of fruits (fruit number from symptomatic tree/mean number of fruits from asymptomatic trees from the same block) were determined. The weight of symptomatic fruit was lower than the weight of asymptomatic fruit, but the weights of asymptomatic and symptomatic fruit were not correlated with disease severity, indicating that the effects of HLB were restricted to symptomatic branches. The relationship of the relative yield with HLB severity can be satisfactorily described by a negative exponential model. The rates of yield decrease as a function of disease severity were similar for all assessed cultivars. A relative yield (up to 19%) was observed even for trees where disease severity was 100%. The strong linear relationship between relative number of fruits per tree and the relative yield per tree suggested that the yield reduction was due primarily to early fruit drop or lack of fruit set on affected branches.

Computational Modelling and Predicting Spread of Arboreal Epidemic

“…Due to its advantage over other examination methods such models offer inferences from several interconnected obnubilated processes. Although there is withal a high need to incorporate the seasonal factors and the age of the host for epidemic dynamics [11][12][13]. These are a few extra challenges in assessing the key epidemiological parameters for a formerly obscure, elevating pathogen (Fig.…”

Activation of systemic acquired resistance in citrus to control huanglongbing disease

“…Fruits of HLB diseased trees are not suitable for both, the juice industry and the fresh fruit market (DAGULO et al, 2010). Diseased citrus trees become economically unproductive a few years after showing the first symptoms of the disease (BASSANEZI et al, 2011).…”

Estimativa dos impactos econômicos decorrentes de eventual introdução do huanglongbing (HLB) no estado da Bahia

“…Segundo Bassanezi et al (2010a), as epidemias de HLB são rápidas, tendo como consequência imediata a redução na produção, principalmente pela queda precoce de frutos em ramos sintomáticos. Estimativas para o Estado de São Paulo revelaram que a incidência do HLB pode atingir mais de 50% das plantas em apenas três a cinco anos após o plantio, em propriedades próximas a fontes de inóculo, onde não se realiza o controle do D. citri e a supressão das plantas sintomáticas (BASSANEZI et al, 2010a).…”

“…Segundo Bassanezi et al (2010a), as epidemias de HLB são rápidas, tendo como consequência imediata a redução na produção, principalmente pela queda precoce de frutos em ramos sintomáticos. Estimativas para o Estado de São Paulo revelaram que a incidência do HLB pode atingir mais de 50% das plantas em apenas três a cinco anos após o plantio, em propriedades próximas a fontes de inóculo, onde não se realiza o controle do D. citri e a supressão das plantas sintomáticas (BASSANEZI et al, 2010a). De acordo com (Bassanezi (2011(Bassanezi ( ), de 2005, ano em que teve início o controle oficial do HLB por meio da erradicação de plantas infectadas, até julho de 2011, só no Estado de São Paulo, mais de 12 milhões de árvores de laranja foram erradicadas com sintomas da doença.…”