Abstract:
The total hectarage of mango in Peninsular Malaysia is about 7200 ha, and most of this is found in the states of Perak, Perlis, and Kedah.
In February-March, and September-November, 1988, many orchards ;in these states were afflicted by a new bacterial disease which inflicted the fruits and foliage.
More than 50% of crop losses were reported in some orchards.
The bacterium was isolated on sucrose peptone agar and SX media, and identified as Xanthomonas campestris pv. manqiferaeindicae through a series of 15 confirmatory physiological tests, and a pathogenicity test on the fruits and leaves of MA 162, a highly susceptible cultivar.
Based on the assessment of a disease severity index, the cultivars were categorised into various susceptibility classes:
- highly susceptible - MA 162, MA 165, MA 152 (Kent), MA 151 (Keitt), MA 150 (Irwin), and MA 146 (Haden);
- moderately susceptible - MA 128 (Harumanis), MA 173 (Alphonso), and MA 203 (Bombay Green);
- tolerant - MA 125 (Siam Panjang), MA 217 (Karutha Kolumban), MA 200 (Apple mango), and Intan Safinas.
Based on a preliminary fungicide trial in September-November, 1988, a wettable formulation of copper oxychloride was found to be more efficacious than similar and micronised formulations of other copper fungicides.
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