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

PART IV. SUDAN BOLI: WORM (Diparopsis castanea)$ _ The CHAIRMAN (Mr. Fuller) read the following note by Mr. Haines: — Both sprayings and dustings by 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 applications 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 lbs. to 250 lbs. of seed cotton per acre, were obtained. It 1s certain that spraying and dusting, as it is done at present, is not a success. At present it appears that our only hope of success lies with Bordeaux mixture, but much more must be learned first about method of application and effect on boll worm and other pests, and on diseases. It is not yet clear exactly what effect Bordeaux mixture has on the boll worms alone. My several years’ experience with spraying and dusting for boll worm 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 prepared to recommend this method of control; as a whole, the results obtained have been most discouraging. I might add that our laboratory experiments on the effect of calcium arsenate on the larvae of the Sudan Boll worm seem to indicate that this poison has no effect, in that the larvae reject the poisoned rind of the cotton boll. Mr. MILLIGAN did not think that it was satisfactory to base results on yields alone in the spraying with Bordeaux mixture: such experiments can only give rough indications. He would like to see the organisation of spraying experiments with Bordeaux mixture carried out on broader lines. He further said that he was strongly of opinion that no stone should be left unturned in an attempt to combat this pest on cotton. As to spraying and dusting, as methods of control, they did not seem to have any definite figures: spraying would be difficult, especially in South Africa and in places where there is a scarcity of water. Experiments, however ,should be continued, and he was anxious to know whether any results had been obtained by means of trap crops. His Section had had no information on the subject. Mr. SMEE had conducted one experiment on these lines but had got no results, as he could not get the Sudan Boll worm to feed on any other crop. Cotton as a trap crop had not been tried. Mr. King was working on these lines but his report had not been received Mr. HARDENBERG had known of a case in Portuguese Bast Africa where a planter took the trouble to hand-pick the first infested bolls; and the planter was of the opinion that hand-picking, in that Y See also page 177. 189

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