Situation of forest pests in North America in 1994
The 1994 situation of forest pests in North America was reviewed during the annual meeting (Winnipeg, CA, 1994-10-04/06) of the Insect and Disease Study Group of the North American Forestry Commission and can be summarized as follow.
- Canada
In eastern Canada, the most serious pests were: Choristoneura fumiferana, Malacosoma disstria and Lymantria dispar. However, there were significant decreases in areas defoliated by Malacosoma disstria, Lymantria dispar and C. fumiferana, significant increases of Choristoneura pinus and decreases of Lambdina fiscellaria in Newfoundland and in other areas.
In western Canada: Dendroctonus ponderosae, Choristoneura occidentalis and C. fumiferana were the most important pests.
Forest diseases of concern were: Elytroderma deformans and Lophodermella concolor (pine needle diseases), Gremmeniella abietina and maple decline (unknown etiology). Dwarf mistletoes (Arceuthobium spp.), root and stem rots continued to be a forest management problem. Bursaphelenchus xylophilus has also been reported but is not considered to be a significant forest pest according to this report.
- United States
In eastern US, Lymantria dispar and Dendroctonus frontalis were the most serious pests. Defoliation by C. fumiferana was extremely low, area defoliated by L. dispar decreased to only 360.000 ha, the Asian form of L. dispar has been again introduced from Germany; southern pine beetle (Dendroctonus frontalis) epidemic continued in parts of the South; the area infested by Tomicus piniperda continued to increase.
In western US, C. occidentalis defoliation and mountain pine beetle (Dendroctonus ponderosae) were at historically low levels.
Forest diseases of concern were: Cronartium quercuum, C. fusiforme, root and stem decays, tree decline (especially on ash, oak, fir, larch, maple, and red spruce), Arceuthobium spp., Scleroderris canker, Lachnellula wilkommii (European larch canker), and B. xylophilus. Pine pitch canker (Fusarium subglutinans) a disease common in the Southeastern United States, is now found in 11 counties in California.
- Mexico
In 1994, 14,800 ha were affected by pests, mainly in temperate forests. The main problem is due to bark beetles (Dendroctonus spp.) of conifers which affected an area of 2,600 ha in central and southern Mexico. Arceuthobium spp. and other parasitic plants (Psittacanthus) affected 9,700 ha.
Some serious insects and diseases exist in conifer and urban areas, i.e. pine pitch canker (Fusarium subglutinans), oak decline (unknown agent), Heterobasidion annosum and Paranthrene dolli (poplar borer).
Sources
Anonymous (1995) North America's forest pest conditions
NAPPO Newsletter 15 (1), pp 6 & 9.