With fall coming right around the corner, many things are going on in our landscapes. There are many weed species creeping their way through our trees and lawns. We are also having a great deal of problems with many nuisance insect pests in our trees. The following are the horticultural pests I have had the most calls on over the past couple of weeks that I feel the majority of the public is trying to deal with.
We are seeing wild cucumber covering up trees in our windbreaks. This weed is very similar to cucumber vine that you grow in your vegetable garden and it grows up and over our trees, especially through windbreaks. If left on the tree, most often the tree will survive, but in some cases, this vine can smother the tree from sunlight and cause death. It is very easily pulled and can be treated with general herbicides, such as 2,4-D, but only as a stump treatment or carefully painted on the leaves.
Another problem that many people are facing this year is the issue with high populations of crabgrass in lawns. With all of the spring rains we had this year, many weeds are taking over our lawns. Crabgrass is a warm season annual so it germinates early in the spring and dies with the first frost of the year. What is in your yard now, does not need to be controlled as it will die in the next couple of weeks. Just remember to apply a crabgrass pre-emergent herbicide in the spring next year.
I have had numerous calls lately on small branches on the ground all around large trees. This is most likely due to a couple of beetle insects, the twig girdler or the twig pruner. These are two very similar insects that cause similar damage to trees. These insects will chew small branches of trees causing them to fall out of the tree on windy days. The twig pruner causes branches to have a jagged edge where it tears from the tree after the inside is chewed. Twig girdler causes branches to have a very smooth cut on the outside of the branch, like it was pruned off with a pair of pruning shears. Both of these insects cause minimal damage, it is mainly an aesthetic nuisance to the tree. Chemical treatments are not necessary or recommended for treating twig girdler or twig pruner.
One thing that we all see as we drive around Nebraska right now, is fall webworm. Fall webworm is the immature form of a medium-sized white moth. The caterpillars form webbing at the ends of branches of many deciduous trees in the fall. This webbing entangles and kills the leaves within it, and causes no further harm to the tree. They are not necessary to control with chemicals and it is not effective to get chemicals through the webbing. If they are not wanted in your tree, for aesthetic reasons, they can be pulled out with a broom and put into a burn barrel (where permitted) or a bucket of soapy water.