Plant Diseases in South Africa

Abstract

DR. VINCENT A. WAGER has published, from the Botanical Station, Durban, several brief articles dealing with crop diseases in "Farming in South Africa". Rerpint No. 28, May 1946, deals with blossom end not of tomatoes, and mentions the beneficient effect of surface mulching. The egg-plant yarieties Kopek and Matale are resistant to bacterial will (Reprint No. 37, June 1946). Further work includes crosses of these resistant varieties with a third variety, Terong Gowok, which is practically immune, but has small, round, useless fruits. It is suggested in Reprint No. 73 (Oct. 1947) that spores of the rust fungus Kuehneola albida should be sprayed on the American bramble, Bubus fruticosus var. Bergii, in order to destroy the host, which is an aggressive weed. The fibre-plant Phormium tenax, is badly attacked by a wilt disease in- South Africa. Reprint No. 75 (Nov. 1947) describes this malady, which is caused by Fusarium oxysporum, forma Phormii. It appears to owe its severity to excessive soil water. Reprint No. 80 (given as 30) (June 1948) describes the serious black spot disease of citrus fruits, caused by the fungus Phoma citricarpa. Infection takes place when the fruits are very small, but develops quickly after they are picked, especially when the temperature is high. Several control measures are mentioned briefly, and it is recom mended that no fruit be exported from affected orchards, unless cold-storage facilities are immediately available.