Fall Insects & Weeds

fall landscapeWith 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.

2015-07-30 17.00.35We 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.

Damage from Twig Girdler

Damage from Twig Girdler

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.

Fall Webworm photo by G. Keith Douce, University of Georgia, Bugwood.org

Fall Webworm photo by G. Keith Douce, University of Georgia, Bugwood.org

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.

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Coldframes & Fall Gardening

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This year, gardening has been difficult. We have faced a great deal of challenges. Our early spring gardens didn’t do as well due to flooding. And our summer gardens were late to get planted in many locations because of rainy weather and water soaked soils. Then, the rainy, cool weather shut off and we were faced with hot conditions and many of our plants had a lot of fungal diseases due to the rainy spring.

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So, now the option is to get a great fall garden to help stock your pantry and freezer with preserved vegetables for the winter. Fall gardens are a great way to grow many of our spring vegetable crops again for more harvest or to get harvest from plants that may not have been very productive in the spring. The good thing about a fall garden is that you can have less insect pressure on the plants in the fall because the peak numbers for many of our insect pests is in the summer, and should be tapering off by the fall. Hopefully you already planted your fall garden. They need to be planted in the beginning to the middle of August to ensure a harvest before frost hits.

If you didn’t get you fall garden planted in the beginning part of August, you still may have a chance to extend your growing season. You can build a coldframe. A coldframe is described by Missouri Extension as “a protected plant bed with no artificial heat added”. This is a good way to keep summer plants protected a bit longer into the fall or keep fall plantings a lot further into the fall. You build a box frame that is higher in the back than it is in the front and cover it with transparent plastic. This box is placed over the garden to increase the temperature of it by 5-10 degrees. You can even get a few more degrees warmer if you place a blanket over top of that on really cold nights.

Photo from Iowa State University Extension

Coldframe Photo from Iowa State University Extension

A coldframe garden should be placed on the south side of a building to receive the highest amount of sunlight to keep it warmest. If it gets warm during the day, you can lift the lid of the cold frame and prop it up to ventilate the garden. A coldframe can also be used in the spring to harden off any plants that you grow from seed indoors.

Coldframes are great to use to get a little more production out of some of our summer vegetable crops, especially if we see an early frost. It is also a great way to extend the growing period for many of our fall vegetable crops. This will allow us to go further into the fall.