The Bananas of Upland East Africa - FIELD TRIALS PROGRESS AND RESULTS UP TO MAY 1990 |
| I | Germination of stools. |
| II | Loss of plants which germinated but did not attain maturity. |
| III | Plant height, taken from the ground to the junction of the two leaf petioles below the youngest unfurled leaf or below the flower stalk. |
| IV | Plant girth, or circumference, measured at 50 cm above ground. |
| V | Number of suckers, including the first plant to grow from the initial planting material, be it a sword sucker or a pared corm. |
| VI | Flowering date, to the nearest week after planting, for each plant. |
| VII | Local varietal name of each plant. With most of the varieties grown in Kagera Region, the task of identification, or, perhaps more correctly, of applying local names, generally cannot be done until the fruit is almost mature. In the present trials, the field staff, assisted by farmers, used the overall bunch appearance and finger shape to assign local variety names. The names were noted down with the spelling according to local usage; it should be noted that the letters "l" and "r" are interchangeable in Kihaya, and (in the Region) in Kiswahili. |
| VIII | Bunch weight, number of hands, and number of fingers at harvest. |
| IX | Weevil damage at the junction of pseudostem and corm on the day of harvest, assessed using the Gauge described earlier. |
| X | Nematode damage to roots, measured on the day of harvest, as discolouration seen on longitudinally splitting five root samples per plant. |
During the process of site selection for the factorial trials, the incidence and apparent damage caused by root nematodes and weevils was evaluated at three locations near Bukoba. A good number of stools were dug up, the roots were examined by splitting them longitudinally and the pseudostems were cut transversely at the stem-corm junction (by using the gauge described earlier). At the first location, Kitendaguro, which was not used for a trial, 13 stools were examined; 89.4% of roots were severely discoloured or dried out; only 6 of 20 stems had any weevil larva tunnels and only two had a 100% damage score using the gauge. Eight stools were examined at Kibeta; all of 11 corms had severe root damage but no tunnelling by weevil larvae was found. Ten stools were examined at Nyakato; all of 18 corms had severe root damage but only one stool had any damage from weevil larvae and that amounted to a score of only 18.8%.
During the many survey visits, only one example of stem snapping was seen by the author. In that instance, a coincidence of three larval tunnels, which converged towards the centre of the pseudostem just above the stem-corm junction, had led to the snapping of a bunch-bearing stem. Although it was quite common for larval tunnelling to be found in stems from which the bunch had been harvested the extent of tunnelling always was greatest in those stems which had been harvested the longest. If immature pseudostems were available for examination, for example when pruning or thinning had taken place, the amount of larval tunnelling usually was nil or else not at all considerable.
By contrast, the sight of completely uprooted stools, bearing moderate to good sized bunches but with the roots nematode damaged or dried up, was a common feature of farm visits, especially in the littoral "Crisis Zone" of Bukoba and Muleba Districts. It should be noted, however, that, unless propped, mature, healthy plants are prone to toppling by heavy wind and rain, this was seen, for instance at Kayanga, Bukoba District, in early 1989.
In the latter "Category A" areas severely stunted stools with minute bunches also were common. These tended not to topple but usually they could very easily be pushed over with the whole corm coming out of the soil.
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| ©1999 - Brian Taylor CBiol FIBiol
FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. Visiting Academic in the Department of Life Science, University of Nottingham |
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