Influence of fruit temperature and application time on the effectiveness of fungicides in controlling citrus green mould, Penicillium digitatum

Abstract

The effects of fruit temperatures (10, 15, 20 and 25¦C) on eradicant activities of 5 different fungicides against Penicilliurn digitatum on Washington Navel were studied. With the fungicide guazatine, applied as a 30 s dip at a concentration of 500 µg/mL, a decrease in fruit temperature did not significantly reduce the time permitted between harvest and treatment if complete control was to be achieved. Benomyl at fruit temperatures of 15 and 10°C gave mould control until 30.5 ± 9.7 and 25.5 ± 7.9 h (mean ± s.e.) after inoculation respectively. At 10°C fruit could be left for 42.3 ± 6.5 h before treatment with etaconazole and mould control could still be achieved. The fungicide imazalil had the most eradicant activity, with mould control being achieved 30 ± 2.9, 28.4 ± 4.2, 44.6 ± 9.2 and 73.2 ± 4.3 h after inoculation at fruit temperatures of 25, 20, 15 and 10°C respectively. At no time was complete mould control achieved with prochloraz, which suggests that a concentration higher than 500 µg/mL should be recommended.