Proceedings of the South & East African combined agricultural, cotton, entomological and mycological conference held at Nairobi, August, 1926

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Monograph

Identifikator:: 1738588467

URN:: urn:nbn:de:zbw-retromon-115043

Document type:: Monograph

Title:: Proceedings of the South & East African combined agricultural, cotton, entomological and mycological conference held at Nairobi, August, 1926

Place of publication:: Nairobi

Publisher:: East African Standard

Year of publication:: 1926

Scope:: VI, 337 Seiten; Ill.

Digitisation:: 2020

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Part IV. Etomology & Mycology

Collection:: Economics Books

PART IV. 1 Mr. HARGREAVES suggested that humidity was the controlling factor, but Mr. Ritchie was of the opinion that extremes of any sort, e.g., over-shading, insufficient shade, excess of humidity, ete., induced the disease. Mr. WILKINSON, from experience in Kenya and Uganda, thought that temperature was the controlling factor. Trees which had over-cropped were more severely affected but the disease was capable of attacking a healthy tree. Miss WELSFORD said that there were insufficient trees in Zanzibar to justify any conclusion. The few trees, that are there, crop heavily, although Hemileia is present. The trees were not cared for but were fairly well shaded. MerHops oF CoMBATTING COFFEE LEAF Disease (Hemileia vastatriz). Mr. McDONALD made the following statement : The methods advocated in Kenya are preventive, not curative. When the leaf disease fungus has successfully invaded a coffee leaf there is no method of destroying the parasite without also killing the leaf. Chief importance is attached to measures designed to promote the general vigour of the coffee bush and, consequently, its resistance to disease. To this end plantations should be kept well cultivated and should not be allowed to become over-run with weeds. Excessive humidity must be avoided by attention to ventilation: this includes proper pruning and the regulation of shade and wind-breaks to allow free access of air. Diseased leaves are sources of infection, and must not be allowed to remain on the ground; they should either be burned or buried. The latter is the better method as it does not result in loss of valuable humus. Branches which hang down close to the ground should be removed, as they are particularly liable to become infected from fungus spores splashed up from the soil in drops of rain. Liberal dressings of farmyard manure are valuable in assisting coffee bushes to recover from any special strain, such as over-bearing, to which they may have been subjected: this assistance helps them to resist attack by leaf disease. Finally, in Kenya the disease may be considerably checked by spraying with $9, Bordeaux or Carbide mixture. In most parts of the country quicklime, which is necessary for the proper manufacture of the former spray, is not available and this fact has led to the adoption of Calcium Carbide in place of the lime. The formula for the 39% Carbide mixture is as follows: — 2 lbs. Copper Sulphate (Bluestone). 12 ozs. Caleium Carbide. 40 gallons water. To make the spray, the Bluestone is first dissolved in the water in a wooden barrel, and the Carbide is then added. a little at a time, out of doors. In districts where leaf disease is prevalent, two sprayings are recommended, the first to be completed before the advent of the main rainy season, and the second to be carried out as weather conditions permit, about two months later. The special obijeet of the second 20)

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