Questions on: Weed Control

Ron Smith, Horticulturist, NDSU Extension Service


Q: I need your expertise! We have a lawn that has been taken over by clover. We did one application of granular weed killer, but it did nothing to alleviate the problem. What do you suggest? Also, when is the best time to move perennials? I need to thin out and relocate some of the plants. (e-mail reference)

A: Glad to help! Granular herbicides typically have half the horsepower effectiveness that the liquid applications do. Also, the effectiveness is better if applied later in the season. Toward fall, the material can be absorbed internally and translocated to give a complete kill. Use Trimec because it will control clover. Here are some rules in moving perennials: spring flowering perennials, move in the fall; fall flowering perennials, move in the spring, and midsummer flowering perennials, move in spring or fall.


Q: We are having problems with mushrooms coming up in our lawn. The largest group is where we had to have an elm tree removed because of storm damage. The tree was removed at least three years ago, but the mushrooms still keep coming up. We had an underground sprinkling system installed last year, so the top layer of the sod and soil was removed and reseeded, but that did not solve the problem. Is there anything we could use to get rid of the mushrooms? (Mobridge, S.D.)

A: Not really. The mushrooms need to run their course, which is digesting the decaying organic matter from the old tree that was taken out years ago. If you back off on the watering somewhat, that will stop or at least slow down the showing of the mushrooms.


Q: I have a question about controlling weeds in my garden. I have grass sprouting up all over the place in a bed of pinks and blue star creeper. Is there a spray for getting rid of the grass without hurting the flowers? I have tried pulling up the grass, but the runners have crept under the plants. I am a 12-year-old amateur gardener. (e-mail reference)

A: There is a product known as Vantage that is good at controlling grass in a garden setting. See if your parents can locate some at a local garden store or a national chain and have them apply it following label directions. It should do the job for you.


Q: Much to my dismay, I have read that there is no solution to quackgrass in northern lawns. I regularly mulch when mowing. Does quackgrass spread faster if you mulch compared with bagging the grass? (e-mail reference)

A: It makes little difference whether you bag or mulch. Mowing high (3 inches) will help sequester it somewhat. Unless you want to dig up an entire colony and resod, there is no legally effective way of getting rid of quackgrass. Roundup stops it temporarily, but the blasted stuff returns before the end of the year.


Q: What herbicides will control fescue growing in Kentucky bluegrass? I heard Lesco TFC would do it. Can a homeowner buy it or does it need to be applied by a certified lawn professional? Is it labeled for North Dakota? I canít find any meaningful information on this. (Fargo, N.D.)

A: Tall fescue control in Kentucky bluegrass is possible, but only with a nonselective such as Roundup. TFC used to be available, but has been taken off the market by the company. As far as I know, no one else has picked up the right to market the product. Very short mowing in the fall of the year may selectively kill tall fescue, at least in North Dakota.!


Q: Last spring our lawn came up nice and green, but there was a lot of quack grass mixed in. Is there a way of getting rid of the quack grass without killing the other grass or using Roundup? (West Fargo, N.D.)

A: Sorry, the answer is no. Roundup kills quack grass, but needs to be repeatedly applied. However, it comes back even in the best of lawns!


Q: I found a grass herbicide in my garage with the brand name Ornamec. The mixing instructions are not on the container, so I donít know how to mix it. It says for use on unwanted grasses in and around ornamental plants. The active ingredient is phenoxylpropanoate, which contains 0.125 pounds of isomer (fluazifop-P-butyl) per gallon. I can also read that it has 1.70 percent of the "p" word and 98.30 percent inert ingredients. (Email reference)

A: I cannot find the active ingredients listed in any of my references, so I cannot tell you what to do. You might check with the pesticide coordinator or specialist of your stateís Extension Service to see if they can be of assistance. Be sure to do this because you might have something that would now be considered off label and would need to be disposed of in the proper legal manner.


Q: What are your thoughts on Banvil (dicamba) for kochia control in turfgrass? Do you have any other options that you would recommend? (Hettinger, N.D.)

A: Banvel is very effective if applied when the plants are young and actively growing.


Q: What would be our options for controlling orchardgrass in a lawn? Is there any selective herbicide for control or are we limited to spot spaying and reseeding? (Hettinger, N.D.)

A: Orchardgrass is a perennial so there is no selective herbicide for control. Your options are limited to spot spraying and reseeding.


Q: During this dry spell, some weeds started growing in my lawn that look scary. Last year you identified one as knob weed. Another weed I have looks somewhat similar but has a broader leaf. Could it be chickweed? Both of these plants seem to endure heat and dry weather very well. How do I treat it and can I use the winterize fertilizer and weed control product? When can I use it? (Portland, N.D.)

A: The winterizer fertilizer can be applied separately from pre emergent weed control, which you want to apply early next spring, before the forsythia comes into bloom. Both will be more effective and you will get more bang for your buck.


Q: I have broad leaf grass in my yard that I want to get rid of. It must have been in some seed I purchased to over-seed thin areas and patch bare spots. It has a broad leaf with clasping auricles with pubescence on auricle margins and no pubescences on the top or underside of the leaf. It grows prostrate to the ground. (I had help with the description from an agronomy graduate.) Can you tell me what it is and how I can get rid of it without applying roundup on my whole yard and starting over? (Casselton, N.D.)

A: What you are describing (and I thank you for doing it so well!) comes closest to quackgrass, agropyron repens. That's the good news. The bad news, there is nothing that is selective to remove it from a lawn situation. Live with it or start new by using Roundup. I doubt that it came in with the seed. If it was any kind of quality seed, quack would have been removed in the cleaning process. Sorry.


Q: Last summer the city seeded grass on my newly worked boulevard. It came up very well and looks good but I have a lot of white clover, hop clover and pigeon grass. I have been able to control the clover by spot spraying with Weed Be Gone. Is there anything that can be used to spot spray the pigeon grass? (Fargo, N.D.)

A: Donít worry about the pigeon grass. Your lawn grass will eventually crowd it out. Apply a pre-emergence next spring and fertilize around Memorial Day and you should be free of any pigeon grass or any other annual grasses.


Q: I have white clover taking over my lawn. What can I do to control it? (E-mail reference)

A: Spray it with a herbicide known as "Clover & Chickweed Killer" or Trimec. You also need to fertilize your lawn. Clover invasion is a pretty good sign of insufficient nutrient levels, especially nitrogen.


Q: We have an increasing amount of clover taking over our lawn. How do we get rid of it? (Crosby, N.D.)

A: The Ortho company has a chickweed and clover killer that is on the market. If unavailable, try to locate a general-purpose broadleaf weed herbicide that contains 2,4 D and mecoprop. Another option is Trimec. Be careful using these products under and around woody plants. Clover emerging in a lawn usually means insufficient fertility levels. I suggest fertilizing with a complete lawn fertilizer if that is the case. Be sure to water in well after application.


Q: What can I use to get rid of moss that is growing in my lawn? I have heard that ammonia will work. Is that true? (Pelican Rapids, Minn.)

A: I don't know about ammonia. I do know that the moss will return if you don't take corrective action. You should do core aeration. It will cut down surface moisture, which encourages moss to become established. Pruning the grass will allow more sunlight penetration and air circulation to take place. Plant an adapted species of shade grass such as creeping red fescue cultivars.


Q: I have a yard full of mushrooms and don't know how to get rid of them. Weíve had a few on our boulevard where we had some trees but now theyíre growing in our front and backyard. Any suggestions? (Fargo, N.D.)

A: Just ignore them. With all the recent rain, mushrooms have been sprouting up everywhere. When we settle into summer heat and extended periods without rain, they will disappear. There is no material available that will remove them.


Q: Please help! My yard is being held hostage by an awful case of creeping Charlie. My dad insisted upon taking care of it himself instead of hiring a professional. He succeeded in killing the entire lawn but not the creeping Charlie. It survived and is now flourishing. I canít get rid of it! I think it's quite possible that I have the most unattractive yard on the face of the earth. I would love if you could offer some words of advice that wouldn't be too costly since there is a lot of ground to cover. (E-mail reference)

A: Anything difficult to control is not usually done cheaply. What you should hope for is competency. I suggest that you turn to a certified lawn care operator who would have material of high enough octane to take care of good old creeping Charlie.


Q: My husband sprayed our lawn for dandelions with 2,4-D. The dandelions are still standing like tin soldiers. Did we use the wrong spray? What should have we used? Does 2,4-D work well on other weeds? (Grand Forks, N.D.)

A: Defiant dandelions! The formulation may not have been strong enough or there was a rain right after the application. Usually, within 24 hours the dandelion stems will begin curling and gradually die. It works on many broadleaf weeds but you may need something stronger such as Trimec.


Q: How do you kill mushrooms coming up in a newly seeded lawn? (Linton, N.D.)

A: You don't. They will come back again when the moisture conditions are right. To eliminate mushrooms, get rid of the decaying organic matter they are feeding on. Some people pour a 10 percent solution of bleach into the soil at the base of the mushrooms but that is only a temporary solution and potentially harmful.


Q: We have a variety of mushrooms (brown/white, different shapes) growing in many places in our yard. Do you know of anything that kills them or prevents them from coming back without hurting our grass? We've been told the previous owners of our home cut down a few trees and that's where some of the larger areas of mushrooms are. However, they are scattered in some other areas as well. To complicate matters, we recently seeded parts of our lawn and are watering often. Should we wait for the grass to take before trying to fight the mushrooms in those areas? (Groton, S.D.)

A: What you are seeing are the fruiting bodies of the decaying process from the tree stumps, roots, and other rotting organic matter in the soil. There is nothing that can be used to selectively take care of the mushrooms. Simply mow them or kick them off. When you quit watering so much or when the spring rains let up, the mushrooms will temporarily disappear. They will appear again when soil moisture levels increase. The alternative is to dig everything up and remove all the existing decaying material which is too much work for most people.


Q: How do you kill creeping bellflower in an established lawn? (Mandan, N.D.)

A: Itís difficult so you need to call out the big guns of herbicides. You need a 3-way product that contains 2,4-D, MCPP and Dicamba. There are several companies out there that sell this formula or one similar to it. A common one is Trimec which is usually available on the market.


Q: I planted a new lawn last fall. When can I start to fertilize and kill the weeds? Can granules be used or should I use liquid sprays? (Salem, S.D.)

A: The grass should be fertilized about 5-7 days either side of the Memorial Day weekend. Herbicide can be applied sometime after the third mowing. Damage will occur if applied when the grass is too tender. Be sure to get the dilution correct and don't over-apply.


Q: I was told when I purchased Trimec that it would not kill the grass, but it did. Will the creeping Jenny be back in the spring? How close can one spray to a hedge area and not kill it? How late in the fall can a person spray with Trimec? (E-mail reference)

A: I suppose TRIMEC could kill grass, but the label should have addressed that possibility. Perhaps the formulation was too strong? Whether or not the creeping Jenny will be back next spring depends on whether or not you got it before it dropped some seed. Fall is the best time for application, as the material is translocated better throughout the entire growing system of the plant. Since TRIMEC has soil activity, you had better stay away from the hedge to the point where you are not going to impact the root system, depending on the size and age of the hedge.


Q: We have a problem in our yard. There are dandelions and bull thistles growing in our lawn. Which is the most effective way to control them, spraying or granules, and when? (McHenry, N.D.)

A: Now and with spray.


Q: A homeowner here in Minot has field pennycress growing in a lawn seeded last fall. It is a heavy infestation and the weeds are already more than 3 inches tall. A TRIMEC label says "Do not apply to newly seeded grasses until well established." If he doesn't spray, he may end up with a forest of weeds. What would you recommend? ( Minot, N.D.)

A: Worry not. Have the homeowner cut the grass three to five times this spring to "toughen" it up a little, then make the application after that last cutting. Apply the herbicide at label rates and all should be well. He should not apply herbicide if you are in a hot spell -- 80's or higher -- for at least a day or two after the intended application. It will probably take another application late this summer or early fall to finally do it in, but an application now should keep it in check somewhat and hopefully weaken it enough for the coup de grace later in the season.


Q: Our family moved into our new home last fall -- too late to put the lawn in, unfortunately. So we're going to seed it this spring. The final site preparation was done with a track loader, so the soil was packed pretty firmly and was left pretty rough. We evened out some of the biggest humps and holes last fall with a small tractor and our open winter has helped to break down the big lumps and clods. Our plan for this spring is to rototill the entire yard, rake out any lumps and rocks and finish leveling out the site (maintaining proper grade away from the house, of course). Per the recommendation in your circular "Turfgrass Establishment and Maintenance for Home Lawns and Athletic Fields" we'll probably go over the lawn with a ballast roller and apply a starter fertilizer before seeding. I know we're in for a summer of watering and weed battles. Can I apply the fertilizer and seed by making two trips (perpendicular) with a broadcast spreader? In the publication you mention the use of a preemergence herbicide to control annual grass-type weeds with a fall seeding. Is it appropriate to use that herbicide with spring seeding? We're planning to get to work and get the lawn seeded as soon as the soil is dry enough to till. Do we need to be concerned about frost? Any other advice or suggestions? (Fargo, N.D.)

A: Boy, do you ever do your homework! First, the last question, no, you don't have to worry about frost. In fact, frost seems to aid in getting the seed to germinate. Now, concerning the weeds. Unless you can find Tupersan (siduron) which is the only pre-emergent on the market that will control grassy weeds like foxtail and barnyard grass while allowing the bluegrass and other cool-season grasses to germinate, don't apply anything else. The weeds and grass will have to co-exist for awhile, until the grass matures somewhat, for about 5 mowings. Then, you can get a post-emergent herbicide and apply it to kill off the grassy weeds before they go to seed. This should be done before the first of July, keeping an eye on the weather for rain and excessively high temperatures. Fertilize the lawn this fall with a complete fertilizer; mow high and frequently (2.5 to 3 inches high) without waiting for every seed to germinate and often enough that you don't leave windrows of grass when you are finished. This will require attention to accomplish this with the flushes of growth that take place in the spring.


Q: We recently built a new home, had several loads of black dirt hauled in and have a huge problem. We have not been able to get anything to grow but crabgrass. We have reseeded twice. We did spray the crabgrass (which had little effect); now our linden tree is dropping its leaves. We can only conclude that the soil must have been treated with some kind of herbicide. Can you help? (Watertown, S.D.)

A: Your information is too spotty: Did you backfill around the linden with these several loads of soil? If so, when did that take place? As little as 6 to 8 inches of soil over the rootzone of the linden could cause problems with survival. Crabgrass is an annual and easily controlled with a pre-emergent herbicide in the early spring. If you are going to be seeding your lawn, as opposed to sodding it, then you can only use a product called Tupersan (siduron). It is an effective annual grassy weed control that will allow the typical lawn grass seed to germinate. All other herbicides will prevent the lawn grasses from germinating for up to 12 weeks. It could well be that the topsoil came from a former wheat field where broad-leaf herbicides were heavily used. If so, then the residue could be migrating to the roots of the linden and being taken up and gradually killing it. To test the soil, try growing a bean or tomato plant in it. If either die, that is likely the problem. The only options open to you then are the complete removal of the soil you brought in or generous incorporation of activated charcoal into the soil to absorb the herbicide.


Q: In one of your answers to a problem you stated very emphatically that weed and feed applications are a pet peeve of yours. Will you tell me why you do not use the weed and feed products? (Carrington, N.D.)

A: For a number of reasons: Very few, if any, lawns have a weed infestation bad enough to make a blanket application of anything containing a herbicide. If the lawn is that bad, start over from scratch. The active ingredient is lower in the weed and feed than it is in the herbicide only, so weed control is not nearly as effective. Handling of the weed and feed is typically not done properly. Consumers tend to handle it like a fertilizer only, not something containing a pesticide. Environmentally, weed and feed applications are a disaster on a small scale. Broadcast applications of herbicides are not needed in most lawn situations, just spot applications where weeds tend to be. I try to encourage people to solve weed problems in lawns through preventive good cultural practices: Mow high ( 2 Ĺ-3 inches) with a sharp mower, alternating directions with each mowing. Maintain good, balanced soil fertility to optimize grass growth. Water properly, neither over nor under watering. Too much water on typical home lawn soils can lead to weed infestations as much as too little water. Correct compaction when needed via timely core aeration. I could say more, but I am running out of room. I believe my point has been made!


Q: Lawn care companiesí big promotion is four applications of weed control and fertilizer throughout the spring, summer and into fall. I would like your opinion on these multiple treatments. Also, what would be some questions the homeowner should ask the company regarding, the amount of herbicide and fertilizer that should be applied during the four shot treatment? Does it do any good? What should the homeowner know or ask to get the best return on investment? (Bismarck, N.D.)

A: Good questions! In fact, I just published an article on the very subject, so I guess that makes me an "expert!" The applications are usually of both pre-emergence and post-emergence herbicides combined with fertilizer, which can either be a straight nitrogen or a "complete" fertilizer containing nitrogen, phosphorus and potassium (N, P and K). The pre-emergence herbicide is applied first, early in the season to control any weed seed germination. Subsequent applications are usually of post-emergence herbicides that should be spot applied as weeds become noted in the turfgrass and are usually for broadleafed weeds like dandelion, thistle, plantain, etc. If broadleaf herbicides are applied in a blanket fashion and not selectively, there is a potential for problems with woody ornamentals, depending on what they are using for the herbicide. As far as the fertilizer goes, the applications are usually light enough to not burn or over-stimulate the turf but to keep it growing in a steady, healthy manner. Kind of like eating several small meals throughout the day, rather than pigging out on a Sunday morning brunch. Questions to ask a potential lawn care service provider include: length of time in business; training in handling of pesticides and fertilizers; are their broadleaf herbicide applications selectively applied to only where the weed(s) exist or is a blanket application made over the entire lawn; can they provide an organic service, and a list of reference clientele. A good lawn care service provider will have many lawns to refer you to and will proudly do so. As far as doing good goes, research has shown that homeowners bungle the task way more often than any service company personnel do. They over-apply fertilizer and pesticides, often using "revenge" spraying to "get those #@!&!! weeds" and as a result compromise the quality of their home environment and possibly their community. Lawn care service providers daily make up mixes and calculate square feet for accurate application. The homeowner is on a learning curve every time he tries it, getting it right sometimes, blowing it most of the time. In most cases a lawn care service is a good investment.


Q: Enclosed is a sample of a weed that is taking over my newly planted lawn. (Bowdon, N.D.)

A: The weed is a beautiful sample of purslane, which is an annual, producing over 52,000 seeds per plant. If you can wait, the frost will kill it, but you likely donít want to wait that long! So, Iíd suggest using a formulation of 2,4-D to control.


Q: We are having trouble establishing a new lawn. Pigeon grass is coming up everywhere in the soil including flower beds and the garden. Is there a spray to use in the lawn once it has been mowed several times, or if nothing is done this year, will it be in the lawn next spring? Is there anything that can be used in the garden or flower beds besides constantly hoeing? (Aberdeen, S.D.)

A: Your best bet is to live with the foxtail for now and use a herbicide containing pendimethalin early next spring before new growth begins. I am afraid that anything you would apply right now would hurt the new grass seedlings and inhibit further germination of the desired seed. For the flower bed, you can use a product known as Preen. Clean cultivate first, then apply.


Q: I have a road ditch that is too steep to mow. What would be a good ground cover to plant to choke out the weeds and grass and not need mowing? ( Hillsboro, N.D.)

A: You ask for a lot, and I don't think I have the answer. Crown vetch needs mowing at about 6 inches to keep it looking decent, any grasses would need mowing, wooly speedwell needs perfect drainage, prostrate junipers would cover, but grass would still grow through it. I'm going to put your question to the reading public and see if someone else has had a similar problem and has come up with a satisfactory answer. Any that I get, I'll relay back to you.


Q: When we bought this farmstead it was over-run with dandelions and nothing works on them except 2,4-D, so my husband has been spraying them every spring and fall. We feel like this year we will be close to having control. We have more than five acres of grass so there is no spot spraying or hand digging except in the vegetable garden. How long after he sprays do I have to wait before using the grass clippings as mulch in my vegetable garden? I know 2,4-D can stay in the ground a while, but will it be on the grass leaves after a few weeks and some spring rains? (E-mail reference, Carrington, N.D.)

A: Give the grass about three mowings after the 2,4-D has been applied. Any residue should be gone or broken down by sunlight by then.


Q: My husband and I started a new lawn last August and are wondering what the first step would be for it this spring, because we have several problems. First, last summer we had black dirt and we had millions of these little brown bugs. They reminded me of sunflower mites. Some people called them soil bugs. In the fall they would get into my home if I opened the windows in the evening. I'm talking hundreds of them in my home, and they were very bothersome. They could get right through the screens in the windows. We planted trees, and whenever I would water them, those little brown bugs would surface on the rocks around the trees and there were just thousands of them. Do you know what these might be and are they harmful? Second, when we started moving dirt around to get the ground level for seeding, we saw a couple of grubs. I'm pretty sure thatís what they were, because they were white, fluffy worms and we were told they are a problem around our neighborhood. Therefore, we feel we should treat them early enough this spring before they start chewing off our newly planted grass. Third, because it is a newly planted grass, it is sparse in some areas and also very weedy, so we feel we will need to spray for weeds soon. We know that people fertilize their grass very early in the spring, too. So, as you can see I have many concerns and questions as to where to begin, and I feel very overwhelmed by it all. Based on these circumstances could you please tell me what you think is the best thing to do first, and the steps I need to take this spring to have a nice-looking lawn this summer. We do have a sprinkler system and we planted a Kentucky bluegrass mix from a seed house in Bismarck. (E-mail reference, Napoleon, N.D.)

A: Those troublesome gnats will probably be gone this spring. First things first. Yes, there will be plenty of weeds, but not nearly as bad if you had tried to plant the grass in the spring. Activate your irrigation system in May, not April. Water only if the grass needs it. When you mow the lawn for the third time this spring (at 3 inches, by the way) then you can apply a broad-leaf herbicide to control your weeds. A week on either side of Memorial Day weekend, apply some fertilizer, the lawn type, such as 28-3-6 or something similar. Right around the same weekend would be a good time to apply some grub control. Several products on the market can be watered in with your irrigation system. Grubs are a reality in everybody's lawn, so don't worry about them, as there are natural predators that often keep them in check. Manage your irrigation system so that you are applying about 1 inch of water per week either through rainfall or irrigation cycling. This should be enough to keep the lawn green and healthy. Since you have an irrigation system, make another application of fertilizer--lightly this time, about 0.75 pounds of actual nitrogen per1000 square feet. Around Labor Day weekend, again apply herbicide as needed in troublesome spots and over-seed as needed. Another application of fertilizer at this time would also be good, at the same rate as your first one. If those pesky bugs return this spring, catch some, preserve them in denatured alcohol, and send them to me for ID. We can then figure out what to do with them.


Q: We live on 5 acres north of Bismarck and have established tree rows. We would like to plant grass in them this year to help with the weeds. What advice do you have for a low maintenance grass? Also part of our land is still "native" grasses (I use the term loosely) and has become overrun with thistles. We spray with Roundup but they just keep coming. Is there any kind of preemergent weed killer we could use? If so, when do we apply? They seem to keep on coming up all summer long! (E-mail reference, Bismarck, N.D.) 

A: The grass I would recommend between your trees would be a sheep fescue/hard fescue combination. Both are bunch grasses that are drought tolerant and shade tolerant -- up to a point. The sheep fescue is more drought tolerant and somewhat shade tolerant; the hard fescue is more shade tolerant and somewhat drought tolerant. One will fill in where the other fails. I would suggest using Confront to control thistle. It is a product that has triclopyr and clopyralid as active ingredients and has done an excellent job of taking thistle out of turf for me, because of the excellent systemic action it has. Canada thistle has to be prevented from going to seed, either by mowing before it flowers or getting it with a herbicide like Confront. This would include perimeter areas around your property, as the seed can travel great distances. The best remedy for controlling Canada thistle is persistence and aggressiveness on your part. Don't give up the vigil! 


Q: I have the weed speedwell in my lawn. What can I use to get rid of it? It has taken over a part of the country cemetery also. (E-mail reference, Forman, N.D.)

A: All the speedwells I know in this part of the country are annuals, so a pre-emergent that will control broadleaf annuals should do the job. If the pre-emergence opportunity is missed, then Trimec should take it out. Try to get the weed in the early stages of growth when it is most vulnerable to herbicides


Q: I think my lawn is plagued by ground ivy, but I also need to know how to get rid of it. I also have some plant that has bluish purple star-shaped flowers that I would like to get rid of.

Is crabgrass best treated with spray or pellet chemical treatment, and is fall the best time for treatment? (e-mail)

A: Ground ivy will take a couple of applications of Trimec to control it. The same chemical will also take care of the violets -- the purple flowers.

Crabgrass should be dead now from the frosts. Being an annual, it is best controlled by a pre-emergent herbicide in the early spring.


Q: Is there a product we can use on our lawn to get rid of mushrooms? This summer we've even had mushrooms in the sunniest, driest part of our yard! 

Also, I have a flower bed next to the foundation on the south side of our house. Three sides of the bed are surrounded by a small brick/cement wall so the entire bed is enclosed in cement. For the last eight summers we have tried to grow a variety of flowers and/or shrubs in this bed with absolutely no luck. We've replaced some of the dirt and added mulch and compost but whatever we plant dies. Any suggestions? (Jamestown, N.D.)

A: First, there is no known chemical product that can be applied to control mushrooms. They will eventually decrease and disappear.

And second, my best guess is that the plants are being killed off by extreme heat buildup. If there is no free drainage, that too could be a problem! Try planting some heat-loving plants such as potentilla, vinca, and portulaca. If those plants die, then it is something else that is doing them in. Do you get any weed growth? If not, then a toxic residue is there and all soil needs removing.


Q: Our lawn seems to be the only one around with an abundance of white clover. We have tried to mow it, but that does no good. Is there anything we can do to get rid of it so it won't come back next year? (Orient, S.D.)

A: White clover used to be part of grass seed mixes when I was a kid. Then someone called it a "weed," and the battle began! Today there are many clover herbicides available. Refer to recommendations in the NDSU Extension Service publication titled "Weed Control in North Dakota Lawns" (H-1009). Products such as Trimec or Confront are herbicidal compounds that have a synergistic action which takes out clover. The best time to apply the herbicide is when the clover is actively growing, or in late August to early September.


Q: We had the lawn sprayed last spring, but it did not kill this one weed. How do I get rid of it? (Rugby, N.D.)

A: The weed is Glechoma, also known as ground ivy. It has a nasty root system and so the best lawn spray to use is Trimec, the strongest herbicide on the market. You should be able to find it all most home and garden centers. Remember to follow the label instructions.


Q: Ugly grass is taking over my lawn. (Groton, S.D.)

A: Your sample was nimblewill, a perennial, creeping grass that resembles bentgrass but turns brown in winter. There is no selective herbicide for it, so your only option is to use Roundup to kill it, and then seed with a desirable grass like common Kentucky bluegrass.


Q: I have a couple of questions for you. What can be done to control moss but won't kill the grass?  Mice have feasted on the bark of an apple tree this winter. What should be done to the chewed area? (Stanley, N.D., e-mail)

A: Moss development in turf areas is the result of too much moisture lingering in too shady a location. Permanent elimination of moss and algae can be achieved by allowing the soil to dry or drain better. This can often be accomplished via selective pruning, (if the dense shade is tree caused), core aeration and/or regrading the soil surface. Temporary relief can be achieved with the application of about four to six pounds of iron sulfate or about 10 ounces of ferrous ammonium sulfate per 100 square feet.

If the trees have not been girdled, then simply take a sharp knife and make clean edges around the damaged areas. No need to put on any type of dressing. The tree will begin a healing process faster that way, if it is going to heal over at all. 


Q: Could you please identify the enclosed weed and tell me what to spray to get rid of it? I also would like to know what to spray to get rid of the grass in my strawberry patch. (Erie, N.D.)

A: The sample you sent in was purslane, a prolific seed-producing annual that is best controlled with a preemergence herbicide like DEPA. Or, you can give up and cultivate it as a salad green.

If the quack grass is especially bad, you may want to dig it up and begin again. Refer to the extension publication "Weed Control in North Dakota Lawns" (H-1009).


Q: Can you tell me what products contain Dacthal, Betasan and Tupersan? I am looking for these to treat foxtail next spring. When is the best time to fertilize my lawn in the fall? I also would like to know why my onions didn't get very big this year and were soft? I have also enclosed a weed I would like identified. (Winner, S.D.)

A: The weed is broadleaf plantain. This, and other broadleaves, can be controlled with 2, 4-D type products, such as Weed-B-Gone, Trimex etc.

You likely had the wrong cultivar of onion. In our climatic region, select only long-day types. Sweet onions are the Spanish or Walla-Walla types. Sweet pickling types are `Silver Queen' and `White Portugal.' Onions need full sun, well-drained soil and ample moisture. The best onions I've ever seen (and tasted) came from a grower near Williston, ND.

The best time to fertilize the lawn is in the fall, with a slow-release material. You can still do it, as long as the soil isn't frozen.

Tupersan is sold as "Crabgrass Preventer and Weed Killer" by Bonide. Betasan can be sold as is or under the name Bensulide, by Green Light; and Dacthal is sold as DCPA by many companies.


Q. I read your garden tips every week and find them very interesting and helpful. I have never seen a question about pigeon grass. It is growing in our lawn and I would like to know what to do to get rid of it or control it.  Redfield, S.D.)

A. Pigeon grass is a regional name given to green and yellow foxtail. It is a bunch-type annual that sets seed in late summer, and is generally only a lawn pest when the turf  is getting initially established from seed, or when the turf has become thin from low nutrition, excessive wear or extended drought.

It is easily controlled with preemergence herbicides in the early spring. Dacthal (DCPA), Pendimethalin (PREM), and Siduron (Tupersan) are three examples. Also, keep your lawn vigorous through regular fertilization, mowing and irrigation.


Q: Lately my lawn has come up with some coarse clumps of grass that spread like wildfire. You can even feel these clumps when you step on them. (Steele, N.D.)

A: I believe it is mat muhly Muhlenbergia richardsonis, a rhizomatous perennial. I know of no selective herbicide that will take it out of your lawn. If the clumps are too extensive in number to dig up, then my only suggestion is to use Roundup as a spot spray or to completely renovate you lawn.


Q: Do you know what is the best way to get rid of grape hyacinth in a lawn? (e-mail)

A: Mow `em down to keep them from making the all important photosynthates for growth and survival. Or, if you choose to use a 2,4-D type herbicide, you will need to add a wetting agent because the foliage doesn't soak up herbicides too well.


Q: I planted a large area of new lawn last fall, including an area where a new shelter belt is planted. The grass is coming up but so are the weeds. In some areas there is shepherd's purse growing so thick that I am sure it is competing too much with the grass. What can I do about the weeds? There are too many to pull out by hand. At what point can I apply a broadleaf weed killer? Do I need to fertilize the new lawn this spring? Every year I put down pre-emergent crabgrass herbicide, and every year I have tons of crabgrass. I will try again this year, but would like to know when I should put it down. Can you give me an approximate date? Is it OK to cut potentillas way down, maybe a foot above the ground? I have some that seem so overgrown. I am planting dahlias in my garden for the first time this year. Can I plant them now or do I need to wait until the frost free date? Sorry I have so many questions, but it seems like every time I go outside, I think of something else! (Fargo, N.D.,e-mail)

A: You can apply the broadleaf weed herbicide to your new lawn when the weeds are actively growing. It is best to get them in the juvenile stage, as control is much more effective. It would do the lawn good to receive some fertilizer this spring about mid-May. Are you sure you are fighting crabgrass and not quackgrass? Many people get the two turned around. In many weed-and-feed products on the market, the concentration of the herbicide is usually lower than it is when purchased straight without any fertilizer included. The active ingredient (AI) in crabgrass control products is usually pendimethalin or oxadiazon, and in some cases, siduron. All of these are pre-emergence materials that have to be applied BEFORE germination takes place. Another point of confusion for consumers is the fact that some weed-and-feed combinations go after the broadleaf weeds, such as dandelion and broadleaf plantain, and are post-emergence materials that are effective only AFTER the weeds have emerged. Neither of these has any effect on quackgrass, which is a cool-season, rhizomateous, perennial grass. There is no selective product on the market for controlling this weed. Crabgrass starts germination about the time the lilacs are beginning to bloom. Any pre-emergence herbicide needs to be applied just prior to that time, or about when the forsythia stop blooming in your area. Yes, cut the potentilla back as far as possible. We did it to ours this year, as they have just become a tangle of unattractive branches. Better to have attractive fresh-looking foliage and growth rather than something that looks like it was used for mortar practice! With the arrival of May, I would say you can put your dahlias out anytime now. Just keep an eye to the weather, in case a cold snap hits and the tubers have begun to emerge succulent growth. Just toss a sheet or newspaper over the new growth.


Q: Around a spot in our lawn where a damaged elm was removed a year ago we've got a lot of mushrooms. The recent rains have brought them up a couple of times a week. A neighbor says the chips from the tree have helped the fungi to grow. Interesting theory: Is it so? The mushrooms aren't a problem. I just mow 'em. But they raise a question. Our lot produces a lot of limbs and branches every year. I'm thinking about buying a chipper to convert this stuff into mulch. But my enthusiasm for the idea will wane if putting the chips on our garden beds would nurture an extensive stand of mushrooms. A few of them are fine. Lots and lots aren't. Do you have thoughts or advice? (Bismarck, N.D., e-mail)

A: Get the chipper. Some mushrooms may come up as a result of using the chips, but your yard will not be covered in them. Yes, your neighbor is partially right. The "old" chips or other decaying organic matter in that old elm spot are contributing to the growth of mushrooms. I have them showing up on football fields that have not had trees growing in that area since I have been at NDSU. Mushrooms will grow on thatch, rotting roots, construction debris or dead bodies! Give us a week of warm, dry weather and they will be forgotten!


Q: What can we use to get rid of white clover? I used Curtail, but the grass goes too. I didnít know that it would run all over the yard, but it is starting to take over. Would 2-4D work? Also, why wonít grass grow where a tree stump was? (Campbell, M.N.)

A: If you can find a lawn care operator that uses Confront for broadleaf weed control, that will do it better than anything else. If you cannot find anyone who uses Confront, try a couple of applications of Trimec. You are correct. White Dutch clover will move into a low fertility lawn and eventually take over unless checked. The grass is not growing where the tree stump was is likely due to alleopathic compounds remaining in the soil. Excavate some of the soil and replace. That should take care of the problem.


Q: Can you tell me what the enclosed weed is and how to eradicate it from a lawn? It grows on rather dry soil and I would like to know of a way to get rid of it without destroying the grass. (Braddock, N.D.)

A: What a nasty one! You sent me a sample of sandbur -- Cenchrus panciflorus -- a shallow-rooted summer annual. It is best controlled with a pre-emergence in the spring with a herbicide that contains Oxadiazon, Oryzalin, or a combination of Oryzalin and Benefin.


Q: The lawn directly in front of our home is heavily infested with the enclosed specimen. I would say that it is either quack grass or crab grass. What would be the best way to get rid of it? (Fargo, N.D.)

A: How about neither? It is tall or meadow fescue, and unfortunately there is no selective option for ridding it. If your lawn is truly heavily infested with this clumpy, coarse-textured grass, I suggest a complete wipe-out with Round Up next spring or early summer, and reseeding.


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