Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-28T05:17:42.009Z Has data issue: false hasContentIssue false
  • English
  • Français

Studies of Crop Loss following Insect Attack on Cotton in East Africa

II.—Further Experiments in Uganda

Published online by Cambridge University Press:  10 July 2009

T. H. Coaker
T. H. Coaker
Affiliation:
Empire Cotton Growing Corporation, Cotton Research Station, Namulonge, Uganda.
Get access Rights & Permissions [Opens in a new window]

Extract

The study of crop loss following insect attack on cotton in Uganda, described in Part I of this work, was continued for two further seasons (1954–56), using the same experimental procedure, except that half the DDT in the spray formulation was replaced by toxaphene, only three periods of protective treatment were used for each date of sowing, and the late-season ones were continued until boll-opening was complete, so as to give maximum control of boll worm.

Methods are described of estimating an index of leaf damage caused by Lygus spp., based on comparisons with standard grades. At Serere (Eastern Province), the index of leaf damage was closely related to Lygus populations in the crop, and at Namulonge (Buganda) it was markedly reduced on plots protected from Lygus attack, but in the 1954–56 experiments no relationship could be found between the mean seasonal index and the loss of fruiting bodies attributable to Lygus attack, or the final yield.

Analysis of the cause and incidence of shedding of developing fruit bodies (flower buds or young bolls, the latter predominating among those recovered) showed that the total amount of shedding was roughly the same whatever the treatment, that due to insect damage tending to be balanced by that due to other causes, which were probably physiological in nature. There was thus some over-riding factor, other than pest attack, that governed the crop finally held by the plant.

Damage caused by insects to older bolls, which do not shed, constitutes a real loss that is reflected in the final harvest. The proportion of clean seed cotton was higher in the treated plots, particularly in the early-sown cotton, in which analysis of the harvested locules showed that the damage was predominantly due to bollworm, but there were no significant differences in yield between the various treatments in either date of sowing or in either season.

It is concluded that under such conditions as those experienced at the Research Station in the three seasons of the experiments, insect damage to cotton is small in relation to other environmental factors governing crop production.

Type
Original Articles
Information
Bulletin of Entomological Research , Volume 48 , Issue 4 , December 1957 , pp. 851 - 866
Copyright
Copyright © Cambridge University Press 1957

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Coaker, T. H. (1955). Entomology.—Progr. Rep. Exp. Stas Emp. Cott, Gr. Corp., Namulonge, 1954–55, pp. 24–30.Google Scholar
Coaker, T. H. (1956). Entomology.—Progr. Rep. Exp. Stas Emp. Cott, Gr. Corp., Namulonge, 1955–56, pp. 24–29.Google Scholar
Farbrother, H. G. (1953). Plant physiology.—Progr. Rep. Exp. Stas Emp. Cott. Gr. Corp., Namulonge, 1952–53, pp. 15–22.Google Scholar
Farbrother, H. G. (1954). Plant physiology.—Progr. Rep. Exp. Stas Emp. Cott. Gr. Corp., Namulonge, 1953–54, pp. 15–21.Google Scholar
Farbrother, H. G. (1955). Plant physiology.—Progr. Rep. Exp. Stas Emp. Cott. Gr. Corp., Namulonge, 1954–55, pp. 16–21.Google Scholar
Goodman, A. (1956). The effects of leaf, bud and fruit pruning upon X1730A cotton at Tokar, Sudan.—Emp. Cott. Gr. Rev., 33, pp. 24–34.Google Scholar
Gwynn, A. M. (1936). Report of Assistant Entomologist.—Rep. Dep. Agric. Uganda, 1935–36, 2, pp. 12–18.Google Scholar
Hancock, G. L. R. (1935). Notes on Lygus simonyi, Reut. (Capsidae), a cotton pest in Uganda.—Bull. ent. Res., 26, pp. 429–438.Google Scholar
McKinlay, K. S. (1953). Use of repellents to simplify insecticide field trials.—Nature, Lond., 171, p. 658.Google Scholar
Mckinlay, K. S. & Geering, Q. A. (1957). Studies of crop loss following insect attack on cotton in East Africa. I.—Experiments in Uganda and Tanganyika.—Bull. ent. Res., 48, pp. 833–849.Google Scholar
Manning, H. L. (1950). Report of the Senior Botanist, Kawanda area.—Rep. Dep. Agric. Uganda, 1947–48, 2, pp. 12–27.Google Scholar
Manning, H. L. & Farbrother, H. G. (1955). Climatology.—Progr. Rep. Exp. Stas Emp. Cott. Gr. Corp., Namulonge, 1954–55, pp. 5–9.Google Scholar
Taylor, T. H. C. (1945). Lygus simonyi, Reut., as a cotton pest in Uganda.—Bull. ent. Res., 36, pp. 121–148.Google Scholar