Pest Management Strategies for Cotton in North Ghana
ABSTRACT: Aspects of component research to formulate rationale ecological and economical pest management strategies for cotton production were conducted with emphasis on reassessing the economic importance of members of the pest complex. Studies also included planting date and trap cropping effects as mechanisms for ameliorating pest incidence and timing pyrethroid application for managing cotton bollworms. The results indicate that GUILD II pests – principally bollworms – were the most economically significant. Yield of cotton obtained when these pests were controlled were Dot significantly (p = 0.01) different from the treatment involving complete control of all pests. This trend was similar in all three locations. Cotton sown in early and mid-June were most susceptible to infestation by early season sucking pests such as leafhoppers Jacobiella facialis. Cotton planted in July on the other hand appeared to escape significant populations of these pests. The highest yield was obtained on crops sown in early June for all varieties. This was consistent with the trend of bollworm attack where early sown crops were the least affected by bollworms. Cotton sown in mid-June recorded significantly lower yields compared to the early sown crop. Mid-June crops were however significantly superior to late crops. Some degree of attraction of Helicoverpa, and particularly Cryptophlebia, was obtained but differences
were not statistically significant to draw any conclusions on the effectivity of maize as a trap crop for these pests. The results of yield loss due to bollworms from pyrethroid timing studies indicated that loss levels were similar for all timings; hence there appeared to be no risk in obtaining a higher bollworm damage when pyrethroid application commenced much later in the season. These results indicated that early spraying for bollworms may not be entirely needed in all cotton growing zones and underlined the possibility for optimizing bollworm rnauag-.nent while still conserving natural enemies.