Rubber leaves infected with Oidium heveae have an ashy coating, curl, crinkle, shrivel, turn flaccid, and edges roll inward.
V. R. PrakashValiyaveedu, Cherukunnam, Anayadi P.O., Pathanamthitta Dist., Kerala, IndiaEmail: email@example.com
Host: Rubber (Hevea brasiliensis) Disease name: Powdery mildew disease Pathogen name: Oidium heveae Steinm.
The fungus infect leaves at various stage of maturity. Predominantly noticed on newly formed tender flush during the refoliation period. The powdery mass of fungus may cover the whole upper and lower surfaces or appear in patches only. The affected leaves leaving the petioles attached to the twigs giving a broom-stick appearance. After a few days, the petioles also fall. Die-back of twigs follows. On older leaves, white patches later causing necrotic spots reduce photosynthetic efficiency. Infected flowers and tender fruits are shed, affecting seed production. Late wintered trees suffer more. Persistence of disease is more in nurseries and partially wintered trees. Cloudy days with light rains and or misty nights with dew formation during refoliation favour serious disease outbreak. Under shaded conditions and in high elevation, the disease persists the year round. The conidial stage of the fungus is known to occur. Dusting sulphur at periodical intervals, when infection is severe, is the only method for managing the disease.
APS publication number: IW000094
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