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Open Access Publications from the University of California

Incidence of Huanglongbing in commercial orchards in northwest Paraná, Brazil


In the Parana state, Brazil, Huanglongbing has been advancing on the most important production areas. In this study the objective was monitoring the disease incidence in sweet orange varieties Pera, Valencia and Folha Murcha (leaf wilt) in commercial orchards in the northwest of the Parana state. The plants were grouped by age and management of the insect vector, Diaphorina citri, in 35 commercial orchards. Every three months a full assessment of the orchard was performed, totaling six evaluations in each orchard. This monitoring consisted of the walk in the street, or with platform, throughout the orchard, observing and noting the plants symptomatic for the disease. Orchards of Pera variety had a higher incidence of the disease when the plants were aged 0-5 years and in orchards over the age of 11 years and chemical management of psyllid was made only when their presence was detected. Pera orchards of ages 6 to 10 years and above 11 years, when the chemical management of insect occurred only by new shoots and without assessing the presence of the insect, also showed a higher incidence. The Folha Murcha was the variety with the lowest disease incidence, except when chemical management occurred without assessing the presence of the psyllid in orchards aged 6 to 10 years and above 11 years, and when insecticide applications were made every 20 days, without any evaluation of the presence of the vector.

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