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

Abstract

R.A. Serey, R. Torres, and B.A. Latorre. 2007. Pre- and post-infection activity of new fungicides against Botrytis cinerea and other fungi causing decay of table grapes. Cien. Inv. Agr. 34(3):215-224. 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 r 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) + fl udioxonil (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 signifi cant (p < 0.001) and, with one exception (A. niger), it was signifi cantly (p < 0.002) affected by the application method. The interaction between fungicide and application method was only signifi cant (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.