Which Herbicide to use…

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Photo by Nic Colgrove

Spring is coming. And with the onset of warm weather and more spring rains, comes many different lawn weeds. Each year we tend to find new herbicides in the garden center of our favorite stores. However, when dealing with pesticides, it is very important to know what you are purchasing and how to correctly use it so as to not harm the environment, pollinators, and beneficial plants.

One of the things we all need to remember when using pesticides is to use the right product for the job and to know what you are using. To use the trade name Roundup isn’t going to be enough anymore. There are a lot of new Roundup brand products that each have a different combination of chemicals.

Roundup 365 is a new product from Scotts that contains both glyphosate, which is the active ingredient in the general Roundup product, as well as Imazapic. Imazapic is a selective herbicide used to control annual and perennial grasses as well as some broadleaf weeds. It has a trait that allows it to last longer in the soil than a regular glyphosate product which is essentially deactivated when it hits the soil. In accordance with the label, Roundup 365 should only be used in cracks and crevices in sidewalks, driveways, walkways, and tennis courts, amongst patios and paths, along fences, foundations, curbs, retaining walls, and landscape borders, and in gravel areas and parking areas. It is not to be used in areas where planting or seeding will occur for the next year or in the root zone of plants or in any other garden setting where desired plants are. Also, be careful when applying this to fenced areas as it should not be applied where there are desired plants on the other side of the fence that could be damaged with the application of this product.

Roundup for Lawns is another new product made by Scotts that actually contains no glyphosate. Roundup for Lawns contains MCPA, Quinclorac, Dicamba, and Sulfentrazone. MCPA is a herbicide similar to 2,4-D for broadleaf weeds. Quinclorac is a post-emergent crabgrass and annual grass herbicide. Sulfentrazone is the active ingredient found in Sedgehammer that is often used on yellow nutsedge. Dicamba is one of the 3 active ingredients in Trimec that is used for broadleaf weed control in a lawn. This product can be used over an established lawn because it has no ingredients that will kill established turfgrass.

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*Reference to commercial products or trade names is made with the understanding that no discrimination is intended of those not mentioned and no endorsement by University of Nebraska–Lincoln Extension is implied for those mentioned.

Dicamba is a pesticide that we should be very careful with, as well as any pesticide that contains dicamba which includes Roundup for Lawns and Trimec. Dicamba can turn into a gas and move to non-target plants as a vapor in temperatures of 85 degrees and above. This volatilization can occur for the day and even a couple of days after application. So Dicamba products shouldn’t be used in the summer months. Also, be very careful with Dicamba products in your lawn around trees and shrubs. This product can cause injury to these plants when it moves through the soil and comes into contact with the roots. Limit use of this product to no more than twice per growing season around tree roots to avoid injury.

Each of these Roundup products are labeled for different uses. So, make sure that you always read and follow the label instructions provided with the product to ensure that you are using the product correctly and so that you don’t harm the environment or any non-target plants. Always keep the label and product instructions with the product so you will always know how and where to properly apply it.

*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.

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Yard and Garden: March 24, 2017

Yard & Garden for blog, 2017

This is the Q&A for the Yard and Garden show for March 24, 2017. 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 July 28, 2017. 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: Cole Thompson, Assistant Professor of Integrated Turfgrass Management at UNL

1. The first question of the year was a caller who had 2 peach trees that were three years old when they died last year. He cut the trees off and now there is suckers coming up from the ground where those trees were. Will these trees grow and produce peaches?

A. These trees will grow and will most likely produce fruit. However, they will not be a strong growth and the peaches produced may not be the variety that he originally planted. Many of our fruit trees are grafted to a hardier rootstock. If they die back or produce suckers, that growth will be the type of tree that the roots are not the type that the scion, or top part of the graft union, was. Also, because it is from a sucker, it is not going to grow as strong and upright as the main tree. He can try to keep them going but it would be best to plant new trees as well, if he has the space for both, he can keep both the suckers and new trees. If he only had room for a couple of trees, I would suggest starting the trees over from new trees.

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*Reference to commercial products or trade names is made with the understanding that no discrimination is intended of those not mentioned and no endorsement by University of Nebraska–Lincoln Extension is implied for those mentioned.

2. This caller wanted to know what the difference is between Roundup and Roundup 365?

A. Roundup 365 contains a chemical called imazapic which gives the traditional glyphosate product more of a soil residual. The Roundup 365 is labeled only for use on and around hardscape areas such as patios, gravel paths, and driveways. The label claims that it lasts in the soil for up to 12 months, so it should not be used around trees, shrubs, or areas you plan to reseed. Regular Roundup can be used in an area around plants and where you plan to seed after the recommended wait time. You would need to be much more careful with the Roundup 365 because of the soil residual around other plants.

3. A caller has pussy willow branches that were brought indoors and placed in water to begin rooting. They have now developed roots. Can they be planted outdoors now?

A. Yes, as long as the roots have begun to form and the ground can be worked, it would be fine to plant them outdoors now.

4. When is the best time to reseed a Fescue lawn in Southeast Nebraska?

A. Fall is the best time to reseed a lawn, but it can also be done fairly effectively in the spring. It is harder in the spring due to the weeds that compete with the grass seedlings. If you plan to reseed in the spring, it is best to wait until late April to early May for that. If you seed earlier in April, increase the seeding rate to compensate for the loss due to the colder temperatures. When you seed, you can apply tenacity or a mesotrione product to the seedbed to help with weeds. Tenacity is safe for use at seeding. It is also a good idea to seed with a starter fertilizer to help get your seed started strong.

5. This caller has a birch that was cut down last fall. The remaining stump is oozing a lot of liquid right now. How do they kill the birch entirely to stop the liquid from oozing out of the stump.

A. Birch trees are one of the species of trees that tend to “Bleed” heavily in the spring if they are pruned. They have a high sap flow in the spring which will lead to the oozing of large amounts of sap through any open wounds. On a normal pruning cut to a tree with high sap flow, it is not harmful to the tree. This tree still has living roots and the wound from cutting it off is exposed so the sap still will flow through. This tree either needs to be treated with chemicals to kill it or the stump needs to be ground out to stop this sap flow and to be able to plant new plants in the area. You can drill new holes into the tree and apply 2,4-D to those holes to start to kill the tree. With chemicals, it will take a few years to fully kill the stump.

6. Can raspberries be transplanted now?

A. Yes, raspberries should be planted as early as the ground can be worked in the spring, so now would be fine. It is best if the soil was prepared last year by spraying all the weeds and incorporating organic matter. This will help to ensure you have a raspberry planting to last many years.

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7. A caller planted grass last fall and held the seed to the seedbed with a biodegradable plastic barrier designed for seeding turf. However, now the plastic is not breaking down and it is getting stuck in the lawnmower. Is there anything they can do to break it down quicker? It will disturb the lawn too much to try to pull it out now.

A. Pulling it out without disturbing the lawn would be the quickest, but if that is not safe to do without tearing up the lawn, that isn’t the best option. Try to water it down or hope for rain, the moisture may help to break it down faster than it sitting dry. This winter was quite dry which may have delayed the breaking down process.

8. This caller had a giant tree fall in his yard. He has removed most of the tree but about 5 feet of the trunk is still standing in the yard. What can he do with the stump?

A. It would be best to cut that trunk off at the ground level and grind the stump out so that you can replant either with turf or with a new tree. If you don’t want to grind it out now or replant, you can cut it down to the ground level and place soil over it to allow it to naturally break down under the soil.

9. A caller has been growing watermelons but they tend to wither and die early in the year. What is wrong and how can he improve his crop?

A. It sounds like this caller has squash vine borers that get into his vines in the summer months. Squash vine borer is a type of moth larvae that gets into the stem of the vines and blocks the movement of water and nutrients through the plant. They are very common in melons, squash, cucumbers, and pumpkins. To avoid the damage from this insect, use a spray or dust formulation of sevin or eight on the base of the plant regularly through the growing season starting in June. You can also use aluminum foil or a toilet paper tube around the base of the plant to act as a barrier between the plant and the female squash vine borer adult who is trying to lay her eggs on the plant.

10. This caller has 25 bur oak trees that were planted 4 feet apart with the idea that some would die to space them out further. Most did not die and are still planted too closely. Will they grow that close together or should some be removed?

A. Bur oaks grow quite large, but in a forested area they will grow fairly close together. They will grow this closely together, however it will shade out many of the branches and it will cause conditions that are conducive to diseases when trees don’t have the space to have good airflow. It would be best to remove some of the trees so that the trees left behind are given 20 feet or more between them. They are only 10-12 feet tall at this time so they would still be fine to be spaded out and transplanted to another location if you can find someone to spade them and someone to plant them somewhere else.

11. Is it too early to plant onions? Is it time to cut back mums that are left from last fall?

A. Late March to early April is the best time to plant onions. Wait to cut back perennials from last fall. The dead plant material will protect them from freezing temperatures for another week or two. The plant material can be removed in the beginning to the middle of April.

12. This caller has a yard with high dog traffic. What type of grass would be best to stay growing through the dog traffic?

A. High traffic lawns will decline. Increasing the fertility will improve growth in this area. Also, if you could limit the traffic patterns from time to time through the lawn, this would help as well. Kentucky Bluegrass will recover better in high traffic areas.

13. A caller has a bean field area that he is trying to turn back to a grass area. What type of grass would do good in this area for an non-irrigated recreational area on an acreage?

A. Buffalograss would be great for an acreage area. Once it becomes established it wouldn’t have to be irrigated much or mowed at all. It is a very low maintenance grass species that is native and you can choose many different newer varieties. UNL has good seed selections. Because this was a bean field it might be over-tilled so a roller may be necessary to firm the soil up before planting. Buffalograss is a warm season grass so it should be seeded May 1st.

14. The final caller of the day has an established cedar windbreak. Some of the trees were removed recently and there is a bare area in the nearby trees where they were shaded out from the removed trees. This area is only 7 feet from the house. What can be planted in place of these trees to help block the bare area in the windbreak?

A. Because this is so close to the house, don’t go with anything too big. A larger shrub may be a good choice such as a viburnum, serviceberry, some dogwoods or even some lilacs may help fill in. Some slender growing trees may also work, but full size trees may grow into the house.