Apple scab (Venturia inaequalis (Cke.) Wint.) is one of the most serious diseases of this fruit tree in Chile having epiphitic development in some apple zones in the south of the country, as Los Angeles, Angol and others. In such districts, due to the sandy texture of soils, winter plowing that buries old leaves is not recommended, these constituting an abundant source of the pathogen's primary inoculum for tha next Spring.
To test the efficacy of a combined apple-scab treatment using an eradicant applied to the soil and foliage protectants a trial was performed in 1951 in a 30-year old Yellow Newton orchard near Linares.
The fifty trees used were divided in two blocks of which one, at "green-tip stage" in Spring, received a ground spraying of 0.5 per cent Elgetol applied at arate of 3500 liters per hectare, the other remaining untreated.
Foliage protectants were applied to both blocks on three ocasions at the begining of vegetative growth at petal-fall stage and after blossomihg. The fungicides tested were Basi-Cup at 2.5%, Cuproxen at 2%, Fermate at 2% and lime sulphur at 0.89 Baumé using five trees per treatment in each block, including the untreated check.
Statistical analysis of data proved the efficacy of Elgetol used as eradicant and its combination with foliage protectants. Basi-Cup, Cuproxen and Fermate resulted better than lime sulphur, without significant differences among them. The soil treatment alone reduced from 43.75 to 9.41 the percentage of scabbed fruits. The combined use of the erradicant plus the better fungicides .tested lowered this percentage to 1.98 to 2.73 per cent.
These promising results reaffirm the convenienece of more extensive trials considering other localities and the new fungicides recommended against this disease. |
ChileanJAR
