Windbreaks are very important to many acreage owners throughout Nebraska. A windbreak is used to block the wind, as the name implies. Winter winds can be very strong and a windbreak will help to reduce those winds, which will in turn reduce heating bills. Windbreaks can be built from a variety of trees and shrubs which are typically fairly tolerant of many problems. However, we do still see problems from bagworms, some fungal diseases, and weeds growing around the trees. A windbreak weed that is quite prevalent this year is wild cucumber or burcucumber.
About Wild Cucumber
Wild cucumber is an annual weed that grows up and over our windbreak trees. Due to all the rain we saw this spring, it is growing voraciously over our trees across the Nebraska countryside. It vines and has leaves similar to cucumber plants. The leaves are arranged alternately along the stem and have five triangular-shaped lobes on the leaves. The leaves are large, 4-10 cm long and 4-13 cm wide. If left on the trees long enough, a fruit will develop. The fruits of wild cucumber resemble a shorter, stouter cucumber with spines all around the outside. The plant climbs up onto our desired trees through the use of tendrils that twist around small branches to hold the plant up as it grows.
There is also a burcucumber plant which is closely related to wild cucumber. Burcucumber is also an annual weed that vines up and over windbreak trees. The leaves of burcucumber are more rounded and the lobes are not as deep as the lobes on the leaves of wild cucumber. Also, the fruits of burcucumber are much smaller and held in a groups. Wild cucumber and burcucumber are similar enough that management for both plants is the same and the names are often used interchangeably.
Managing Wild Cucumber
Wild cucumber is a plant with a shallow root system, so it pulls very easily. At this time of the year, this is really the only way to manage wild cucumber. Don’t spray 2,4-D or any other herbicide on the vines because anything that would control the wild cucumber can damage or even kill the trees that wild cucumber is vining up on. It would be best to pull it off and kill the plant before any fruits are produced to reduce the seedbed. However, at this time of the year they have already begun to produce fruits.
Since wild cucumber is an annual plant, it can be controlled with a pre-emergence herbicide in the spring. Products containing simazine will work to control this weed before it emerges next spring. Early May would be a great time to apply the chemical around the trees in your windbreak to make sure it is in the soil before the wild cucumber germinates. If you are having troubles with this weed this year due to the excess moisture, it would be beneficial to use the simazine next spring or you could have a similar or worse problem next year.
This is the Q&A for the Yard and Garden show for August 5, 2016. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through August 5, 2016. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.
Guest Host: Graham Herbst, Community Forester Specialist with the Nebraska Forest Service
If you enjoy reading my Q&A from the show each week, take my quick survey at: http://go.unl.edu/9b24 and be entered to win a free plant book or some free UNL gifts.
1. The first question of the day was a walk-in client wondering what the weird structures in his yard were?
A. These would be fungal formations. The one that popped open is a puffball and the other is a type of mushroom. Neither of these are edible, they are both poisonous. They will develop in a yard from decaying roots of old or removed trees. They can be removed manually if you would like or they will go away on their own.
2. A caller has a small tree that is leaning that looks like a palm tree, what is it and why is it leaning?
A. After visiting the home after the show, it was determined that the tree was a sumac. It is leaning because that is the growth habit of a sumac. They tend to form a colony and lean every direction for sunlight.
3. A caller has a zucchini plant that just all of a sudden started dying off. Is this plant just done for the year or can something else be wrong with it?
A. This is probably due to squash vine borer. There is no way to fix the problem once it has gotten to the point of wilt and death. When you remove the plant, cut open the stalk to see the borer caterpillar. For the remaining plants use sevin, eight, or bifenthrin at the base of the plants to reduce the chances of those plants getting the borer as well. You can also wrap the base of the plant with aluminum foil or a toilet paper tube to protect it from borers laying eggs to bore into the plants.
4. A caller has cedar trees that have pine cone structures all over them that are killing the trees. What are these and how can they be controlled?
A. Those would be bagworms. At this time of the year it is too late to control them as their feeding has greatly reduced and possibly stopped for the year. Once they are in their bag the sprays cannot penetrate the bags to get to them so there is no need to spray now. Pick off and destroy all the bags you can get to and next spring watch for them sooner to spray at the correct time of the year.
5. With bagworms, will sevin work for spraying them?
A. Yes. Sevin, eight, bifenthrin, tempo, malathion, or bT are all good insecticides to use when the bagworms are actively feeding.
6. A caller has wild cucumber growing on trees. How can this be controlled?
A. This weed has shallow roots and will pull out easily. You can treat with a herbicide, but not as a spray because that would harm or even kill the tree it is growing on. You can paint roundup on the leaves to help control it.
7. This caller has a mature maple tree that has mushrooms growing in the center of it. Can it survive?
A. It is best to manage the trees shape throughout the life of the tree to help it from having to have large branches removed. At this point there is no way to fix the hole and decay that have already begun. If the tree is in a location that it will not hit structures or people it can be left up longer, but it would be best to have a certified arborist come take a look at it to determine if the tree is safe to stand or needs to be removed.
8. A caller has a tree that the roots were exposed during work on the house nearby and then the roots were covered back up. Now, there are a lot of tree suckers coming up throughout the lawn. Can Tordon be used to control these?
A. Tordon is not labeled for use in a landscape setting. Also, using any type of insecticide on the suckers could harm or even kill the main tree. Since these suckers are all growing in the lawn, it would be best to just continually mow them off. The suckers appeared because the tree was stressed from the construction around the roots. Sucker stop can be used to slow the growth of the suckers but not completely eliminate them.
9. An email question was asked how to control locusts that are taking over a pasture?
A. Grazon is a good choice for pastures as a full foliage treatment during June. You can cut the stump and do a basal treatment anytime. Another choice would include Dicamba or a Trimec product that contains dicamba.
10. Another email question came in with a cottonwood tree that has brown tips on the leaves and lots of ants on the tree. Are the ants causing the problem? Can this be controlled?
A. The brown tips could be from sunscald which is due to the heat and drought we have faced lately. Aphids are probably also present on the tree which would bring the ants in to feed on their honeydew excretions. The ants are not harmful to the tree. The aphids are not causing much of a problem. Control measures are not necessary. Mulch the tree and water it to help with sunscald.
11. A caller from Iowa has hostas that were variegated in the leaves for the past 20+ years and now the leaves are solid green. What is causing this?
A. This is called reversion. The plant is a hybrid or cultivar that has reverted back to the original plant or parent plant with solid green leaves. It will not turn back into the variegated form.
12. A caller wanted to know why windbreaks and trees along creeks are being removed?
A. Sometimes the trees get old and start to become a hazard after they die. It also allows for more farming areas. These windbreaks are beneficial to wildlife, insects, and soil microbes and to help reduce water pollution from pesticide and fertilizer runoff.
13. The last caller of the 2016 season wanted to know when to transplant clematis, iris, peony, spirea, and general perennials?
A. all of these can be transplanted in the fall. Wait until mid to late September before doing this to get through the hot, dry weather. Could be done in the spring with some of these as well, but fall would be great.
Thanks for all of the great questions on the show and for reading the blog posts! I look forward to another great season of Yard and Garden Live in 2017!! Keep reading my blog for other great updates on keeping your yards and gardens “Green and Growing”!
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.
It is summer. Our gardens are out in full force and finally beginning to produce edible products. One of the biggest problems in gardens, are the weeds. There are many different types of weeds that come into our gardens, and control of these pests is very difficult.
Wild cucumber and burcucumber are two very similar vining weeds that can be found in your vegetable garden, flower garden, and growing up the sides of trees in a windbreak. These vines looks a lot like a cucumber vine that we intentionally grow in our gardens. The wild cucumber has deeper lobes than burcucumber but both will vine up and hold onto plants and other objects, such as tomato cages, with tendrils.
Bindweed is another common problem anywhere in the landscape. This weed has arrowhead shaped leaves and a small, petunia-shaped, white or pink flower. This weed vines and holds onto plants with the stems of the vine rather than using tendrils. Bindweed is an invasive weed that can climb up on your plants and cause decreased growth and other issues as the bindweed covers the leaves and plants.
Good control for either of these vining weeds would include many different broadleaf herbicides. If applied early in the spring or late in the fall, 2,4-D can be used for both of these weeds. 2,4-D should not be applied when the temperatures for 72 hours are predicted to be above 80 degrees Fahrenheit. Products that contain the active ingredient of Triclopyr will also work for these weeds and can be used if the temperatures for 24 hours is predicted to be below 80 degrees Fahrenheit. If the weeds are growing in and among other desired plants, the best option would be a stump treatment after cutting the weed back or painting it on the leaves of the weed being careful to not get the herbicide on the desired plants.
In a vegetable garden, most herbicides are not advised for use due to the movement of the pesticide. Broadleaf herbicides would work for these vining weeds, however, they would also cause damage and possibly death of the crops growing in your garden because most of our vegetable garden plants are broadleaf plants as well. These herbicides can spread to our desired vegetable plants through direct spray, wind movement, through the soil, and by turning into a gas and moving toward the desired plants.
The best control for many weeds in our vegetable gardens would be mulch and hand pulling. Good mulch choices include straw, hay, wood chip mulch, or grass clippings. Be cautious when using grass clippings on your garden. Many herbicide labels now have more conservative recommendations that state that grass clippings from lawns to which a herbicide has been applied should never be used as mulch. If this is stated on the herbicide label, that must be followed. If the label does not state this, it is recommended to wait 3-5 mowings from application of herbicides to use of the mulch. The safest option is to avoid using grass clippings on your gardens if the lawn has been treated with herbicides that growing season. If you are unsure of where the clippings came from or when or if they have been treated this season, avoid use of these clippings as mulch to avoid any contamination from the herbicides.