Impact of Pine Woolly Aphid, Pineus Pini (Homoptera/ Adelgidae) on Cone Development and Seed Production of Pinus pinaster in the Southern Cape

1989

S. 1-6

3 Abb., 4 Tab., 19 Lit. Ang.

Unselbständiges Werk

200028764

Cones of Pinus pinaster that were heavily infested by Pineus pini showed deformation, cracks and resinous outflow. On average 31,8% of the collected cones in a sample from a seed orchard were affected. Mean mass, volume, length and width of the cones were reduced by 50,3%, 38,3%, 22,5% and 15,3% respectively, when compared with unaffected cones. The total number of seeds obtained from affected cones was reduced by 71,7%. Germination of stratified seeds extracted from unaffected and affected cones did not differ significantly. In general, seed production was reduced by 23% in mature cones, considering the percentage of affected cones and the reduced number of seed extracted from them. This affect is additional to a probable reduction in the number of cones reaching maturity.