Common Tree Pests

TARA

Planting trees in an urban environment is extremely helpful because it reduces the heat island effect, it provides shade, habits, cuts down on CO2, and they are relaxing. Although they are beneficial they endure a lot of things in order to grow in the city including: water, weather, and insect stresses.

 One of the invasive insects that trees have to deal with is the Asian longhorned beetle. It is known to cause considerable ecological damages in urban, recreational, and forested landscapes of eastern North America (Thompson, Mar 2008). SEE Figure 1. They become a problem when the “early instar larvae of the beetle destroy cambial tissue of trees by feeding under the bark, and later instar larvae cause further damage by tunneling and feeding in sapwood and hardwood” (Thompson, Mar 2008). It is complicated to combat the Asian longhorned beetle because they are most damaging during the phloem-feeding larvae phase where they burrow under the bark and can not be controlled by normal topical and foliar insecticides (Thompson, Mar 2008). A chloro-neonicotinyl insecticide has been effective in combating the Asian longhorned beetle by blocking the nicotinergic neuronal pathway for the insects (Thompson, Mar 2008). It is inserted into the trees through stem or soil injections (Thompson, Mar 2008).

There are a couple categories of tree pests: Defoliators, Leafminers, Borers, Root feeders, and Galls (Meeks, April 2002). Tent caterpillars are examples of Defoliators which feed upon foliage and leafminers feed upon foliage also but within (Meeks, April 2002). Tent caterpillars are a problem because when they populate they lay about  150 to 300 eggs ( Meeks, April 2002).  “Galls result when certain insects- some adelgids for example- convey compounds into the host plant, which alter its growth pattern in a localized area, such as in an oak or maple leaf” (Meeks, April 2002). Root feeders like black vine weevils cause declines in host plants and are hard to tell because they are underground (Meeks, April 2002). The first step in protecting trees from pests is by proper watering, fertilization, and smart planning of the placement (Meeks, April 2002).In order to protect trees in urban environments there must also be diversity in order to prevent wiping out the whole section of trees in the city (Santamour, 2002). Planting trees of different species is important because there are native insects that prey on certain trees and if the majority of trees are the same and an insect infects a tree it will spread quickly.  Insects like borers take advantage of trees that are weakened by other circumstances like by drought and trimmer damage (Meeks, April 2002). When a tree is infected by insects they can be saved but it is very difficult depending on the host and insect and how long they have been there (Meeks, April 2002). Special tools to help get rid of these pests can be predatory nematodes, horticultural oils, and chemical sprays and systemic insecticides (Meeks, April 2002).

Urban greening is an important part of cultivating the city but without proper care pests can ruin a tree’s life. There are several types of pests that need different kinds of treatment in order to try to save it. The only way to ensure an insect from infecting a tree is from prevention but with early detection a tree can be saved through different chemical treatments. In the greater good of things having trees in the city is very important and with proper management it can be beneficial for the whole city. 

Figure 1: 

Asian Longhorned Beetle

Bibliography: 

Meeks, P. 2002. Insects of urban trees: Pests, the trees they impact, and methods of control. A  Arbor Age 22(4):30.

Chartrand, D., Scarr, T. and D. Thompson. 2008. Are Leaves that Fall from Imidacloprid-Treated Maple Trees to Control Asian Longhorned Beetles Toxic to Non-target Decomposer Organisms? J  Environment Quality 37(2): 639-646.

Santamour F (1990) Trees for urban planting: Diversity, uniformity and common sense. Proceedings, Metro Tree Improvement Alliance. METRIA 7: 57–65.