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Don Kinzler, Published April 09 2010

Raking is best way to deal with snow mold

Q: I have a lot of snow mold on my lawn. I have been raking those spots, but is there a different process to kill the mold that would work better?

(e-mail reference)

A: This disease rarely kills home bluegrass lawns, although young seedlings from a late-fall seeding may be killed. Sod laid in the fall will be OK. Fungicide applications are not recommended when snow mold occurs in a home lawn. Spring fungicide applications will not effectively control or prevent the disease or hasten spring turf recovery. The best way to speed up the recovery process is to remove dead and matted material by lightly raking. This will promote air circulation and drying. Fertilizing lightly with nitrogen this spring (especially if no fertilizer was applied the previous fall) will help speed the growth of new grass from the underground stems that were not harmed by the snow mold fungus. Lawns that appear slow to recover this spring will benefit from core aeration. Follow that with an overseeding using the same grass species already present in the lawn. Contrary to popular belief, late-season fertilization does not encourage snow mold or increase its severity. In fact, late-season fertilization will encourage a more rapid healing and recovery on lawns afflicted with snow mold.


Q: What can you tell me about using newspapers as a weed barrier? My garden has a large walking path that I cover with woodchips. I want to redo the path because weeds are coming through really bad. My plan is to clean out the old chips and spray the area with a broadleaf killer. I then would put down the newspaper cover, followed by a black weed barrier and wood chips. Will this work or do you have a better idea? Do you have any hints that you can give me? The garden is next to a river, so we have every kind of weed there is. I’ve tried Roundup, but it only works for a short time. (e-mail reference)

A: Newspapers make a good weed barrier. However, the newspapers will break down eventually. Covering the area with a black plastic weed barrier and wood chips also works and is more permanent. No matter what you do, weeds will be an ongoing problem because you live adjacent to a river. I can’t give you any better advice than what you have come up with.


Q: Thank you for the information on tulips that is displayed on your Web site. I have more information that I think your readers will find useful. I have lots of squirrels that love to dig up tulip bulbs. I have been very successful in keeping the squirrels from digging up my bulbs by planting a crocus with each cluster of bulbs. The squirrels do not find the crocus plants to be a delicacy, so they leave everything alone. (Kentucky)

A: Good advice from Kentucky. My readers will appreciate your advice because they will not have to worry about losing tulips to these critters any longer.


Q: I would like to plant some small boxwoods to line a walkway. I have read that most boxwoods only are hardy to zone 5. Are there any that are hardy to zone 4?

If so, would you recommend any particular variety? Also, I have a rosy glow barberry bush that I would like to move. Do you think it could be moved and when is a good time to do it? (Oakes, N.D.)

A: Unfortunately, boxwood is not hardy enough for North Dakota, not even down in Oakes. The barberry should move without too much trouble. I would move it when the frost is out of the ground but before new growth begins.


Q: I have three tall Norway spruce trees near my house in the woods in northern New Jersey. Any of the trees could crush my house if one or more fell over, but I hate to take them down. By looking at the trees, it appears that about one-third of the height would have to be cut down to reduce the chance of them toppling. Can that be done without killing them? (New Jersey)

A: Good idea to be thinking about this. During the recent minihurricane the East Coast went through, my parents had a spruce fall over on their property, but there was no damage because it fell on the driveway. You can have the trees pruned to reduce the sail effect from the wind and not harm the tree. I would suggest that you contact an International Society of Arboriculture certified arborist do the job. To locate one in your area, go to: www.treesaregood.com/findtreeservices/FindTreeCareService.aspx. Be sure to check credentials and ask for references.


Q: I have a question about cedar trees. This winter, deer ate the trees starting at the 6-foot level and down. Is there a way to get this part to fill in again?

Should we trim it? (e-mail reference)

A: If the deer left any foliage where they grazed, the trees eventually will fill in. If there is nothing but bare wood remaining, then that is the way the trees will remain and no amount of manipulation on your part will correct this damage.


Q: I have a muscadine vine that was here when I moved in 14 years ago. It is very large. There is one trunk that goes into the ground that looks like it is dead but then branches out over my patio. We get lots of grapes from the portion of the vine that covers the patio. Unfortunately, not many people are interested in the grapes, so they fall on the patio and stain the cement purple. I would like to remove it, but my son would like some cuttings first. It is now in a dormant state. Should we take a cutting from the top or try digging it up from the base? (Montgomery, Ala.)

A: Cuttings should be taken from the top of the vine. Do it now while the plant is dormant. It is a shame that no one can make good use of the fruit from this good old vine. Are there any amateur wine makers in your neighborhood?


Q: I found your name on a Web site and hope you can offer some help. I have several arborvitae trees where my dogs urinate. The trees were healthy when I moved here 1½ years ago. However, some of the lower branches are dead. I don’t see any evidence of bugs. Could the dog urine have caused this problem? Is there anything I can do to neutralize the urine? As a point of information, I never water the trees because we get enough rain. Also, there is gravel on top of the soil to make it easier to clean up after the dogs. Any suggestions other than getting rid of the dogs? Do I need to transplant these beauties? (e-mail reference)

A: Dog urine will burn off the foliage that they urinate on. There isn’t anything you can do to neutralize it unless one is right behind the dog and washes off the urine immediately. Is fencing a possibility? If you can, get them transplanted by someone who knows what to do. The burned-off foliage probably never will grow back. If that is your hope with the transplanting, forget it.


Q: I have a 25-year-old iris bed. The iris plants are rhizomes, so no bulbs.

They flower every year, but the grassy weeds keep getting ahead of us. Is there a herbicide that we can use to keep the weeds away or at least to a minimum? I spend hours every few weeks pulling out the weeds. (New Jersey)

A: Look for grass control herbicides that contain the active ingredient known as sethoxydim. If you follow the directions on the label, you should be able to use it on your iris plants safely.


Q: Can you recommend a different variety of tree that is similar in leaf shape and bark to patmore and green ash trees? (e-mail reference)

A: I can give you a list of trees with pinnately compounded leaves, which is about the only characteristic that would be consistent. Since you didn’t tell me where it is you live, check with local authorities to be sure the one you are interested in isn’t considered invasive in your part of the country. The tree list includes amur cork, honey locust, black locust, box elder maple and black walnut.


Q: We have been having troubles with a worm that burrows through the stem of our vine plants about 2 inches above ground. The worm leaves a visible hole, especially on our winter squash. It killed our cucumbers and summer squash plants. I found one in the stem of a buttercup squash last fall. It was about 1 to 1¼ inches long and about the thickness of an earthworm. It had an off-white color. They seem to start doing their damage after the first of August. We do use Sevin to control the cucumber beetles, but it doesn’t seem to affect this worm. Is there anything we could use at planting time, such as a seed or ground treatment? How about controlling it during the growing season? (e-mail reference)

A: This is squash vine borer causing your problem. It is an especially nasty pest because the borer, a grubby white caterpillar, hides inside the hollow vines of popular squash family plants, such as pumpkins and zucchini, as it does its dirty work. Gardeners generally don’t notice anything wrong until the whole plant starts wilting. By then, it’s too late to save the plant. The trick will be to focus on prevention. The problem begins in late spring when a moth lays its eggs at the base of your squash plants. Each female will lay about 200 eggs.

The eggs are so small they are almost impossible to spot. The eggs hatch in a week or two. The grubs that emerge quickly tunnel into the hollow plant stems the eggs were attached to. These hungry youngsters feed, hidden from view, for a month or so and then drop down into the soil to pupate. Rotate your planting of squash, cucumbers and pumpkins with a crop that is entirely different, such as beans, corn or tomatoes. Floating row covers will help prevent the moth from getting to the squash plants. If you keep them covered until the first of July, all the egg-laying activity should be finished and you can remove the covers.

You could use a material such as Dipel, which is an organic control that will stop the critter from eating too much of the vine before it expires. Whatever you do, don’t use the floating row cover technique where you had squash vine borer activity the year before! If you do that, the adult females will be in squash heaven because they will be protected from the elements. Depending on your powers of observation, you may have some success with deworming the vines.

At the first signs of the sawdustlike frass, slit the vines lengthwise near where the damage is found and remove the borers. The stems should be covered immediately with soil. Sanitation also is important. After harvest is complete, the vines should be removed from the garden and composted to prevent the remaining borers from completing larval development. Burying a few nodes along each vine will encourage rooting at these nodes. This will lessen the impact if squash vine borers girdle the base of the vine.


To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail ronald.smith@ndsu.edu.