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.
