Incidence of pests and diseases in tree nurseries and plantations in Kimondi forest, Nandi county, Kenya

Abstract

Increasing demand for wood is putting pressure on forest resources that are equally under threat from insect pests and diseases. Reported average annual forest loss stands at 0.2% globally, 0.8% in Africa, and 1.6% in Kenya. To meet the increasing demand for forest products in Kenya, the government and private sector have established plantations of non-native tree species dominated by Eucalyptus species, Cupressus lusitanica, and Pinus patula. To ensure successful forest plantation establishment and management schemes, there is a need for sufficient knowledge and understanding of tree growth conditions and threats including pests and diseases. This study aimed at determining the incidence of plantation and tree nurseries in Kimondi Forest, Kenya. Tree plantations were mapped into 2.5 Ha rectangular portion transects parallel to the forest roads. In randomly selected portions, observations were carried out for disease and pest signs and symptoms on various tree parts (leaves, stem, roots, fruits, and twigs). In the tree nurseries, 3 m × 1 m rectangular quadrants were placed on seedling beds and similar observations were made. Collected data indicated a high incidence of nursery seedling pests (5.3 % leaves and 5.1% stems) on Eucalyptus species and least on P. patula (2.4% leaves and 3% stems). Higher incidence of plantation pests (35.0% leaves of Eucalyptus sps.) and least on P. patula stems (1.2%) were recorded. On the other hand, twelve (12.0%) of C. lusitanica and (1.8%) Eucalyptus species plantation twigs were infested by pests. A high incidence of nursery seedling disease (9.8%) was observed on C. lusitanica leaves and least on P. patula stems (3.6%). A higher incidence of plantation diseases (32 %) on leaves of Eucalyptus sps. and least on C. lusitanica stem (1.4%) was recorded. In both tree nurseries and plantations, roots and fruits remained free from pests and disease. Major tree pests and diseases identified in Kimondi forests include (Human, wildlife, livestock, Cinara cupressi, Gonipterus scutellatus, Pinus pini, and Leptocybe invasa) and (damping-off, Fusarium wilt, Botryosphaeria canker, cypress canker, and Mycosphaerella spp.) respectively. These results suggest a need for regular monitoring and intervention measures to control pest and disease infestation in the Kimondi forest.