Sample Surveys of Pests and Diseases of Tea in North-East India

Abstract

Crinkle-leaf is an abnormal condition of the leaf of coffee in Kenya, the cause of which is unknown. Preliminary observations showed that its symptoms are suppressed by spraying with captan and experiments were carried out to investigate whether this material would provide an economic coi jjtrol. Spraying at the rate of 4 lb per acre, when symptoms of the condition first appeared, gave good control but lower quantities were less effective. Means of predicting the severity of the condition have not yet been evolved and the spray programme must therefore be adjusted each season to meet the local conditions. The spraying of nurseries and young suckers is recommended as soon as early symptoms are noted, since the cost is low, whereas the spraying of large areas of mature coffee requires a careful assessment of the possible economic advantages. Susceptibility to (B-inkle-leaf was found to differ between cultivars.