Abstract
ABSTRACT Rainfalls may affect the efficiency of pesticides due to a decreased deposit of active ingredient on plants. This should be considered in spraying with acaricides, the main strategy used for the management of citrus leprosis, the main viral disease of the Brazilian citrus culture. Citrus leprosis disease is transmitted by Brevipalpus mites, mainly B. yothersi. The objective of this study was to evaluate the effects of artificial rains on the efficiency of the acaricide propargite in combination or not with adjuvants for the control of the mite B. yothersi. The experiment was conducted using orange plants grown in pots kept under greenhouse conditions. The acaricide propargite was evaluated isolated and with addition of the adjuvants polydimethylsiloxane (20mL cp/100 L of water) and a mixture of phosphatidylcholine (lecithin) and propionic acid (500 mL cp/100 L of water). After the application of the acaricide with and without the adjuvants, the plants were subjected to a 10-mm artificial rainfall at different time intervals: 5 minutes, and 1 and 12 hours after application. Thereafter, B. yothersi mites were transferred to plants for survival evaluation. The artificial rainfall affected negatively the efficiency of propargite isolated and in mixture. The addition of the adjuvant phosphatidylcholine and propionic acid impaired the efficiency of propargite due to an increased runoff of the broth and a decrease in the deposit of active ingredients on plants. We conclude that the acaricide propargite should not be used in combination with the adjuvants polydimethylsiloxane and mixture of phosphatidylcholine and propionic acid in rainy conditions.
Highlights
Citrus leprosis disease is the major virus disease in citrus culture in Brazil, the largest producer and exporter of orange juice in the world (LARANJEIRA et al, 2015)
By using microscopy and molecular biology techniques, it was verified that the main vector of citrus leprosis in Brazil is Brevipalpus yothersi Baker (Acari: Tenuipalpidae), a species confused with B. phoenicis for several decades in Brazil (BEARD et al, 2015, ROY et al, 2015)
The objective of this study is to evaluate the influence of artificial rains on the efficiency of the acaricide propargite with and without the addition of adjuvants for the control of B. yothersi
Summary
Citrus leprosis disease is the major virus disease in citrus culture in Brazil, the largest producer and exporter of orange juice in the world (LARANJEIRA et al, 2015). The virus causing the disease (CiLV- Citrus leprosis virus) is transmitted by mites of the genus Brevipalpus (BASTIANEL et al, 2010; RODRIGUES and CHILDERS, 2013). The symptoms of citrus leprosis appear in leaves, branches and fruits (BASTIANEL et al, 2010). Symptomatic branches dry gradually, leading to plant death; in fruits, the symptom is characterized by concentric maroon spots usually surrounded by a yellowish halo, resulting in premature fruit drop (BASTIANEL et al, 2010; LARANJEIRA et al, 2015). Until 2015, Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) was mentioned as the only vector species of citrus leprosis in Brazil. By using microscopy and molecular biology techniques, it was verified that the main vector of citrus leprosis in Brazil is Brevipalpus yothersi Baker (Acari: Tenuipalpidae), a species confused with B. phoenicis for several decades in Brazil (BEARD et al, 2015, ROY et al, 2015). By using microscopy and molecular biology techniques, it was verified that the main vector of citrus leprosis in Brazil is Brevipalpus yothersi Baker (Acari: Tenuipalpidae), a species confused with B. phoenicis for several decades in Brazil (BEARD et al, 2015, ROY et al, 2015). Mineiro et al (2015) stated that B. yothersi is the predominant species in commercial citrus orchards in the state of São Paulo
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