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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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part IV. Etomology & Mycology

Collection:: Economics Books

i ENCLOSURE TO PART IV. concerned and percentage of parasitism. It has been found that bollworm parasites often attack species of leaf-feeders as well, e.g., Cosmophila aurigoides. The mortality of pupae in the soil is often very high, but how much is due to enemies or parasitism has not yet been determined. EvimiNaTioN oF Foop-PLANTS. Control by this means has not been attempted. It would be impossible for the American bollworm since this species’ food-plants are multitudinous and would be difficult for the spiny boll-worm, since wild malvaceous plants are so numerous and so widespread in South Africa. As for the Sudan bollworm, it would be impracticable to attempt elimination of its food-plants until we know with more certainty what these are. To my. mind, it is questionable whether complete elimination of all food-plants of the Sudan bollworm would solve the problem. We have not yet found an effective remedy for this pest in the cotton fields; and until one is found these fields act as reservoirs, which are as dangerous as the reservoirs in nature. IMPLEMENTAL CULTIVATION. No data is, at present, available as to exactly how effective this method of control is, as it is extremely difficult to check up accurately the results of any given cultural method. It is my opinion that a careful study of this method of control should be made, if a satisfactory way of checking up results can be found. It certainly does not seem to be impossible to find a method of cultural operations, perhaps combined with a close season and rotations, which would help to check the bollworm pest. RoTATIONS. I have no statement to make on this method of control. However, I think it a very important factor in bollworm control, especially in conjunction with implemental cultivation and a close season. SPRAYING AND DUSTING. Both sprayings and dustings with lead arsenate, calcium arsenate, Paris green, calcium cyanide, sodium fluosilicate, and Bordeaux mixture have been tried very extensively at various times during the past seven years: and all, except Bordeaux mixture, have given negative results. Last season’s experiments with calcium arsenate dust gave absolutely negative results; in nearly every instance the controls gave more seed-cotton per acre than the treated plots, in application ranging from one to six. Also, the cost of treatment was considerable, in many cases absolutely prohibitive. = With Bordeaux mixture, more promising results were obtained, but not promising enough to warrant recommendation. Increases in yield ranging from 30 to 250 lbs. of seed cotton per acre were obtained. It is certain that spraying and dusting, as it is done at present, is not a success. At present, it appears that our only hope for success lies with Bordeaux mixture, but much more must be learned first about method of application and effect on bollworm and other pests and on diseases. It is not yet clear exactly what effect Bordeaux mixture has on the bollworms alone. My several years experience with spraying and dusting for bollworm control has made me very doubtful that it will prove to be an effective remedy. Basing my statement on the data at present available, I can say most emphatically that I am not 796

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