Sprays of malathion and fenitrothion were used for the control of antestia bugs (Antestiopsis spp.), from 1961-74, in order to assess the effect of these insects on the yield and quality of smallholder arabica coffee in Bugisu district Uganda. Insecticide application nearly always gave economically worthwhile increases in yield of coffee cherry but these were not usually significant, except when the mean population of antestia was about two per tree or higher. Spraying also reduced the percentage of badly damaged beans and improved the yield from coffee cherry of good dry beans. Two or three sprays of fenitrothion 50% e.c. at 1.1 l/ha were no more effective than a single spray in February but antestia populations were low in these particular trials. There was a significant linear regression relationship between the percentage loss of crop through not spraying and the logarithm of the mean antestia number per 100 trees for the year October-September. This was y = 50.6 log x - 65.5, which indicated yield losses of 20, 36 and 51% at mean populations of 0.5, 1 and 2 antestia per tree, respectively. Within the year the percentage losses in yield were most closely related to antestia populations in the January-March period, when the flowers were setting, and from April-June, when the fruits grew rapidly, but the relationship was poor for the pre-harvest time of July-September. There was no insecticide applied during the peak harvest time of October-December, so it is not known if spraying then would protect the following season's crop. The overall yield of coffee cherry for each season was affected by the antestia population and it seemed that more than one insect per tree could cause a sufficient reduction in crop to justify spraying. It is recommended that arabica coffee be sprayed first of all about February, provided that the antestia population exceeds one per tree at that time. The approved insecticide is fenitrothion 50% e.c. at 1.0 l/ha, which can be applied either by motorised knapsack sprayers in 220 l/ha of spray mixture or at higher volumes with hydraulic knapsack sprayers. The coffee should be sampled again in May and August and sprayed then if there are more than two antestia per tree. Yields of coffee were greatly increased following a yearly schedule of four sprays of cuprous oxide (50% Cu), each of 8.5 kg/ha. The main effect was to retard leaf-fall and the treatment, although expensive, was economically worthwhile. The resulting more productive trees supported higher antestia populations but these could be reduced by adding insecticide to the copper fungicide spray. Fentin hydroxide and dithianon sprays did not appear to be as beneficial as those of cuprous oxide. Calcium ammonium nitrate (26% N) fertilizer, when applied twice yearly at 270 kg/ha, also increased yields in the years following the first treatment.
Tijdschrift beschrijving