Controle do bolor verde em citros com produtos alternativos aos agroquímicos

• Autor(a) principal: Maro, Luana Aparecida Castilho
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4526
• topic: Citrus spp.; Penicillium digitatum; Doenças pós-colheita; Óleos vegetais; Quitosana; Citrus spp.; Penicillium digitatum; Postharvest disease; Vegetable oil; Chitosan; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The green mold, caused by Penicillium digitatum, is a major disease in the postharvest of citrus fruit. In this work the effects of alternatives to agrochemicals in the control of green mold in 'Ponkan' tangerines and 'Valencia' oranges were tested. Physiologically mature fruits were superficially wounded in the equatorial region with a tube of 9 mm in diameter filled with needles and inoculated with a conidial suspension of P. digitatum at a concentration of 1x106 conidia/mL. After air drying, they were sprayed to full wetting with distilled water (control), distilled water + 8 mL/L Tween 20, imazalil (200 mL EC/100 Magnate ® 500 L of water), thiabendazole (103 mL Tecto ® SC/100 L of water), methyl thiophanate (70 g Cercobin® 700 WP/100 L of water), chitosan 10 mL/L of water or essential oils of garlic 10 mL/L of water, clove 5 mL/L water, neem 10 mL/L of water, long pepper 5 mL/L of water and citric biomass 10 mL/L of water. To the essential oils and chitosan were added 8 mL/L Tween 20. Then the fruits were packed in groups of three in polystyrene trays and kept at 21 ± 1 º C and 85-90% RH for 8 ('Ponkan' tangerine) or 7 days ('Valencia' orange). The fruits were analyzed for incidence and severity of illness, incubation period and latent period of the fungus, loss of fresh weight and CO2 production. In the case of 'Ponkan' tangerine, citric biomass was able to reduce the incidence of 76.3% compared to the control, in the third day, and also reduce the severity in 44%, in the fourth day. For the incubation period, except for fruits treated with garlic oil, there is formation of distinct groups of averages between the control and those treated with alternative products, indicating capacity to delay the onset of symptoms. Citric biomass stood out, showing similar results to the fungicide methyl thiophanate, delaying the incubation period in a day in relation to the water. The same was observed for the latent period, in which the fruits treated with alternative products, except garlic oil, stood in a group other than the control. Although the fruits of all treatments overcome the control, imazalil was able to better maintain the turgidity of the fruit, showing the lower values of loss of fresh weight on the eighth day of evaluation (5.2%). The mass loss and CO2 production correlated positively with the incidence and severity, in other words, the largest mass losses and higher respiratory rates result from high values of incidence and severity. In the case of 'Valencia' orange, citric biomass and chitosan reduced the incidence and severity during the entire experimental period. On the seventh day after inoculation, the incidence was reduced by 73.7% and 67.4% by citric biomass and chitosan, respectively, in comparison to control water, while the severity was reduced by 59.6% and 62%, respectively. On the other hand, neem oil, long pepper oil and garlic oil were ineffective in controlling the pathogen. Imazalil and methyl thiophanate totally controlled the disease during the evaluation period. The loss of fresh weight was increasing over time, however, fruits of all treatments had acceptable values for the marketing, located in the range 3 until 5%. As for CO2 production, fungicides maintained the respiratory rate low, followed in ascending order by chitosan and subsequently by other products. Thus, the citric biomass has good potential for control of green mold on 'Ponkan', while citric biomass and chitosan are capable of controlling the disease in 'Valencia' orange.