Spring Tips for Healthy Trees and Shrubs
With spring upon us it is time to start thinking about our landscapes again. Of particular concern are our shrubs and trees, which are very susceptible to insects and fungal infections as they transition from dormancy to their most active growth stage. In the Eagle Valley there are three very common issues that are found in our trees including White Pine Weevil on spruces, and Black spot and Marssonina Blight on aspens and cottonwoods. These issues can be effectively managed by making preventative spray applications in the early spring. These applications will not only prevent attack and infection of vulnerable trees, but also promote their future health and vigor, especially when combined with deep root feeding.
White Pine Weevil
Even though the name suggests that pine trees are the target for this tree pest, the main host plant in Colorado is the spruce tree. This species of weevil affects the terminal leader (top) of the tree. Adult Females spend the winter on the ground in protective areas under trees. In the spring, the pregnant female seeks out spruce trees then crawls to their tops to feed and lay eggs in the feeding cavities. When eggs hatch the young larvae tunnel underneath the bark of the tree’s leader and start feeding. The damage from the feeding begins to show in early summer when the top growth of the tree starts to wilt and then die back. Fortunately, a lower lateral branch will usually become next year’s leader. However, if leaders are impacted in successive years, the spruce tree will lose its classic pyramid shape and look more like a shrub. Early season preventive sprays will prevent weevil damage on spruce trees and help them remain healthy.
Marssonina Blight and Black Spot
Even though Marssonina blight and Black spot are different by nature, they have similar effects on aspens, cottonwood and other poplar trees. Both affect the leaves by causing blotches, early leaf drop, and lackluster fall colors. These fungi overwinter on old effected leaves that have fallen to the ground. In the spring the fungal spores are transported by wind and rain to infect developing foliage on trees. Secondary infections happen later in the season when wind blows the spores from the fruiting bodies to adjacent leaves and other trees. Effective management requires at least two fungicide spray applications; the first to occur when the new leaf buds begin to open and the second one several weeks later.
The Valley supports a beautiful community forest that will require vigilance from both H.O.A.s and homeowners to maintain its health and vigor for future generations. Preventative spray applications is a vital tool in combating insect pests and fungal infections to trees. An International Society of Arboriculture certified arborist can help manage any issue with your trees and has the knowledge and credentials to help you support your trees and forest.