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Pre- and post-infection activity of new fungicides against Botrytis cinerea and other fungi causing decay of table grapes.

2007; Pontifical Catholic University of Chile; Volume: 34; Issue: 3 Linguagem: Inglês

10.7764/rcia.v34i3.400

0718-3267

Ricardo A Serey, René Torres, B. A. Latorre,

Mycotoxins in Agriculture and Food

Pre- and post-harvest diseases restrict table grape production and exports ( Vitis vinifera L.) in Chile, with the most important disease being grey mold ( Botrytis cinerea ). In addition, rot due to Aspergillus niger , Cladosporium herbarum , Penicillium expansum , and Rhizopus stolonifer frequently occurs. The pre- and post-infection activity of fungicides against these pathogens was studied on Thompson Seedless table grapes. Detached, mature, berries were used, and inoculations were performed with 20 µL of a 10 6 spores·mL -1 suspension placed on three punctures aseptically made at the calyx end of each berry. Fungicides used (per liter) were boscalid (600 mg), boscalid (200 mg) + pyraclostrobin (100 mg), boscalid (200 mg) + kresoxim methyl (100 mg), cyprodinil (60 mg) + fludioxonil (40 mg), BAS 600 KBF (100 mg) + metrafenone (150 mg), BAS 600 KBF (200 mg) + boscalid (300 mg), BAS 600 KBF (100 mg) + pyraclostrobin (100 mg), and captan (400 mg). Each fungicide was applied either by drop (12 µL·berry -1 ) placed on three punctures made with a sterile hypodermic needle or by 60 s immersion. Berries were then incubated in humid chambers at 20oC. The pre-infection (protection) activity of the fungicides varied considerably among the pathogens tested and was found to be significant (p < 0.001) and, with one exception ( A . niger ), it was significantly (p < 0.002) affected by the application method. The interaction between fungicide and application method was only significant (p < 0.001) for R. stolonifer at 48 h post treatment. In general, pre-infection activity gave 0 to 4 days protection after drop applications and 0 to 21 days after immersion treatments. The post-infection (curative) activity varied among pathogens and fungicide treatments. However, it was always below 24 h. Las enfermedades de pre y postcosecha limitan la produccion y exportacion de uva de mesa ( Vitis vinifera L.) en Chile. Especialmente importante es la pudricion gris ( Botrytis cinerea ). Ademas, son frecuentes las pudriciones causadas por Aspergillus niger , Cladosporium herbarum , Penicillium expansum y Rhizopus stolonifer . Este trabajo tuvo el proposito de estudiar, en bayas de uvas Thompson Seedless, la actividad de pre y post-infeccion de nuevos fungicidas. Con este proposito se empleo bayas maduras (<16% solidos solubles) con pedicelos intactos. Cada baya se inoculo en el extremo calicinal, depositando 20 µL de una suspension de 10 6 esporas·mL -1 sobre tres heridas practicadas asepticamente con una aguja hipodermica esteril. Los productos y concentraciones empleadas por litro fueron: boscalid (600 mg), boscalid (200 mg) + pyraclostrobin (100 mg), boscalid (200 mg) + kresoxim metil (100 mg), cyprodinil (60 mg) + fludioxonil (40 mg), BAS 600 KBF (100 mg) + metrafenone (150 mg), BAS 600 KBF (200 mg) + boscalid (300 mg), BAS 600 KBF (100 mg) + pyraclostrobin (100 mg), y captan (400 mg). Cada fungicida se aplico via gota (12 µL·baya -1 ) depositada sobre tres heridas practicadas en cada baya con una aguja hipodermica esteril o por inmersion durante 60 s. Luego las bayas se incubaron en camaras humedas a 20oC. La actividad de pre-infeccion vario considerablemente entre patogeno y dependio significativamente (p < 0.001) del fungicida usado y con solo una excepcion ( A. niger ), el metodo de aplicacion tuvo un efecto significativo (p < 0.002). La relacion entre fungicida y metodo de aplicacion, determinado a las 48 h post-tratamiento, fue significativo (p < 0.001) solo para R. stolonifer . En general, la actividad de pre-infeccion otorgo una proteccion entre 0 y 4 dias al aplicar cada producto en gota y entre 0 y 21 dias luego de aplicaciones por inmersion. La actividad de post-infeccion (accion curativa) vario entre patogenos y dependio del fungicida aplicado. Sin embargo, esta fue siempre inferior a 24 h.