My protegé, Daniel Rukazambuga, was funded under the Project Agreement to take an MSc in Crop Protection at Imperial College, UK. Following the end of the Agristudio participation in the Project, he continued my programme but without serious financial backing. Fortunately, he was able to particpate in an IITA and Rockefeller Foundation funded research programme in Uganda. This enable him to do a doctorate research study into banana weevils. Without pre-empting his own publication of that study, comments on aspects which evaluated my ideas can be made.

Crop Vigour studies

A single banana cultivar, Atwalira, was grown at Kawanda Research Station, north of Kampala, Uganda, in a relatively low area (1300 m asl), with more seasonal (peaking in February-March and September-October) and somewhat lighter rain (1250 mm) than Bukoba.

Two trials were planted. The first examined the effect of host vigour on banana weevil populations and plant damage. Four levels of plant vigour - highly stressed (no manure and intercropping with finger millet); moderate stress (no amendment); low stress (manured); and, vigorous (manure plus mulching). The second had varying levels of initial weevil populations - plants being artificially infested with 0, 10, 20 or 40 weevils per plant.

The overall results resembled those we obtained in Kagera Region, showing as one might expect that better nutrition gave better vigour, measured as growth rate, plant size, bunch weights, etc.. As time passed the more vigorous plants gradually gained higher weevil populations. The key factor ultimately appeared to be the mulching. In effect what happened was that the mulch had the dual benefits for weevils of maintaining higher ground humidity both directly (the mulch layer retaining moisture) and indirectly (the greater plant growth giving a denser leaf canopy).

Weevil Damage Assessment

Rukazambuga used a somewhat modified gauge following my ideas for design but his report includes a statement that "GOLD et al. (1994) have suggested that damage to the central cylinder (internal damage)....might be the most critical measurement".

My concept, of course, predates that of Gold and his colleagues by several years. Rukazambuga found that there was a negative linear relationship between the bunch size and internal damage, thus, showing that my thinking was correct.

The actual level of attack, in terms of % damage to the corm, was similar whatever the plant vigour. The depth of corm damage also was similar. The bigger corms of the vigorous bananas attracted more weevils and, thus, had larger amounts of corm tissue consumed by weevil larvae. This had a negative effect on crop production by way of the larger plants being more prone to toppling and stem snapping. Interestingly, however, his work also showed that peripheral cortex damage had an important effect in reducing the stool capacity for sucker production. In the vigourous plants more suckers were produced attracting more weevils. It was concluded that early attention to weevil infestations was called for as a part of a package of good husbandry, because of the propensity of the vigourous plants to provide a better habitat for weevils.

href="\bananas2000\postscript.htm"