Within-Canopy Distribution of Incidence and Damage of Pests and Diseases of Robusta Coffee, Coffea Canephora and Implications for their Management

Abstract

Due to its perennial and robust vegetative growth nature, the Robusta coffee harbors a diversity of pests and diseases that are not necessarily evenly distributed within the coffee canopy and this has management implications. We thus, conducted a study in a Kaweri Coffee Plantation Limited in central Uganda to determine the distribution of incidence and damage caused by the pests and diseases within the Robusta coffee canopy. In each of the four section of plantation (Kitagweta, Kyamutuma Luwunga and Nonve), a plot measuring 100 x 100 m was demarcated and 20 Robusta coffee trees were systematically selected along two diagonals in each of the plots. All the stems on each of the selected coffee tree were assessed for pest and disease incidence and damage on the leaves, berry clusters and berries. The coffee canopy was divided into three sections (lower, middle and upper) and incidence and damage of the pests and diseases were determined on coffee leaves, berry clusters and berries. Results showed that the pests and diseases were not evenly distributed within the canopy. On the leaves, the incidence and damage caused by Leucoptera coffeella, Leucoplema dohertyi and Hemilleia vastatrix varied significantly (p≤0.05) across the canopy sections, with the highest levels (23.1, 36.1 and 30.5%) being recorded in the lower section. On the other hand, though the damage caused by Epicampoptera andersoni and the leaf eating beetles was not significantly (p≥0.05) different within the canopy, the highest infestation was recorded in the upper (26.9%) and middle (19.3%) sections, respectively. For the berry cluster, only damage caused by Planococcus spp. varied significantly (p=0.0188) across the canopy, with the highest infestation (18.6%) being recorded in lower section. However, incidence and damage caused by Prophantis smaragdina and Cercospora coffeicola were not significantly (p≥0.05) different within the canopy but, the highest levels were recorded in the upper section of the canopy (15.8 and 24.4%, respectively). On the coffee berries, the incidence and damage of both Hypothenemus hampei and Cercospora coffeicola did not significantly (p≥0.05) across the canopy sections but the highest levels were recorded in the lower (28.5%) and upper (20.7%), respectively. Our findings enlightened the understanding of the vertical distribution of the incidence and damage of pest and disease within the Robusta coffee canopy. This information will contribute to developing and implementing monitoring techniques and regimes as well as ecologically-informed management strategies for these pests and diseases.