Trees may be killed in severe and prolonged infestations, but this is not common. Normally, the loss or retardation of height, growth, and the deformation of the main stem are the most important aesthetic and economic injuries. Where tree vigor is poor, deformations such as stem crooking and forking may also occur. In seed orchards, cone and seed production may be reduced through destruction of shoots containing flower buds or conelets. Most severe damage occurs on susceptible species of pines that are less than 15 feet tall and growing in open areas.
Larger trees are less susceptible to attack but are sometimes heavily damaged.
Shaded trees are often not as heavily damaged as those growing in open areas. Prevention Certain cultural practices will often help reduce tip moth damage. Maintenance of high tree vigor by fertilization and irrigation is an effective method of reducing damage. This also promotes rapid growth through the first six to eight years, when the tree is most susceptible to injury. Highly susceptible pine species should be planted only on sites to which they are well adapted.