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Don Kinzler, Published October 18 2012

Hortiscope: Take care of crabgrass problem in the spring

Q: I have a couple of questions related to fall lawn preparation. I have some large areas of crabgrass in my lawn, so I am wondering how I can get rid of it before winter hits. Should I apply Roundup on the plants and then reseed? Is there an easier way to deal with crabgrass? I do not have a sprinkler system and have neglected my lawn when it comes to watering. The grass in my backyard is very dry. It is nearly tan in color and thin in coverage. What do I need to do to this area to prepare for winter? Do I start to water the grass or leave it dormant? Any suggestions would be greatly appreciated. (West Fargo)

A: Crabgrass can be controlled next spring with an application of a pre-emergent herbicide labeled for crabgrass control. Apply according to directions when the lilacs are starting to come into bloom. If you have not watered your lawn all summer, I advise doing so several times between now and freeze-up. You still might be able to save some grass by doing so. If you fail to do this, nature will fill the vacuum for you with her own selection of weeds. No one can predict what kind of winter lies ahead for us. It could be a cold and droughty winter. If this winter is a mirror image of our past summer, your grass will be history without any water in the soil.

Q: I have a patch of Queen Anne raspberries. This is my third year of harvesting the berries. The first harvest year, I had an excellent yield of large, well-developed berries. The second year, only an area in the center of the patch had a good yield. The rest of the plants had berries but were not worth picking because they were the size of peas and would fall apart as soon as they were picked. This year, the patch was reduced to about 10 feet of good berries in the center of the patch. I add about 2 inches of compost in the spring, water occasionally but add no other fertilizer. I have attached some photos to show the size of those clusters that crumble. I look forward to your input. (email)

A: This progressive decline is a pretty good indication of a virus that got started and spread systemically and systematically throughout your berry planting. With virus problems, there is nothing that can be done to correct the problem. Viruses are spread by piercing-sucking insects, such as leaf hoppers and aphids, which find raspberry plantings a good meal.

Q: You were in our yard this summer looking at our grass and also looking at our two dying willow trees. We are in the process of replacing the trees. We had them removed this week and I took soil samples to NDSU to be tested. That will take about two weeks. How late this fall can we successfully plant new trees? We are planning to have two large trees moved in using a tree spade truck. What do you recommend? I’m a little concerned about the dry conditions and how that will affect the new trees. I would appreciate your advice. Thank you. (email reference)

A: The trees can be planted right up until the ground freezes. In fact, in the old days of my youth, we did some post-Christmas plantings of evergreens that came through the winter just fine. As to what to recommend, I would suggest the new honeylocust developed by NDSU. It was researched for more than 10 years at various sites around the state and came through with flying colors. It is also one of the most drought-resistant deciduous trees available in our region. Go to http://search.linders.com/12070003/Plant/3561/Northern_Acclaim_Honeylocust for more information.

Q: When we last corresponded, I was planning to overseed my lawn using a good Kentucky bluegrass blend. I fertilized the last week of August and watered well before seeding on Sept. 6. I watered religiously after seeding. I was expecting to at least see some of the perennial ryegrass within 10 days. It’s now been three weeks and I have seen nothing. I went over the lawn in three directions, so I know there is sufficient seed there. Any ideas what I did wrong? Do you think the seed will come up next spring or did I just waste $100? I’m still watering. (email)

A: You didn’t waste any money. You should start to see some little nubs of grass seedlings popping up sooner or later this fall. The snow covering will protect the seedlings from freezing. The seed that might not make an appearance would be the Kentucky bluegrass. That should burst through next spring when the soil starts thawing. Assuming you didn’t bury the seed and that your seed was fresh and had decent germination test results, this naked ground that is now causing concern will be a thing of the past.

Q: I have a problem with my iris plants. This summer, the leaves started turning brown, which I thought was normal for iris plants. When I dug them up, some of the rhizomes were dry husks, with only some fibrous material inside. I do not know exactly what caused the damage. I wonder if there were insects eating the rhizomes. I treated the soil by incorporating a 6 percent Malathion powder and dusted all of the surviving rhizomes with the same powder. Do you have any idea or suggestions on what happened and what the proper treatment should be? (email)

A: This sounds like iris borers found juicy rhizomes to feed upon. Your treatment with Malathion was a little late. Go to www.extension.umn.edu/

yardandgarden/ygbriefs/e122irisborer.html for information on controlling iris borers that involves cultural practices and the most effective use of insecticides.

Q: A few days ago, I had to remove my bleeding heart roots in preparation for a wooden planter to be built. How long can the roots remain out of the ground? (email)

A: That depends on how the plant was handled. If you have the roots held in damp, unmilled sphagnum moss at a low, but above freezing temperature, they could stay out of the ground for many weeks. If they are not being held in that or a similar manner, then it is anyone’s guess as to how long they can hold up.

Q: I have a question on planting American arborvitaes as a hedge. I am planting six of them along the outside of the fence that borders my neighbor’s property. To grow a hedge, I understand that I need to space the trees 3 feet apart. However, how far from my neighbor’s property line can I plant the first tree? (email)

A: I think you mean how close to my neighbor’s property line instead of how far. Technically speaking, you will be OK as long as you are not disturbing the soil on your neighbor’s property. In situations like this, I advise communicating with neighbors before undertaking a major project that may impact both properties. You also might check the zoning ordinances where you live to be sure that what you intend to do is legal.

Q: We have a local resident that has some lilacs that seem to be dying. The upper branches are dying on a few of the bushes. The bushes appear to be very old. They also are in a very crowded space. There is a fence on one side, evergreen trees on two sides and more trees on the fourth side. Any ideas? You input is always appreciated. (email)

A: This is a good example of a survival of the species fight. At this point, the lilacs don’t stand a chance. They have been weakened by herbicide drift and are surrounded by superior and more vigorous species that are intercepting the resources for survival such as light, water and nutrients. My suggestion is to put the lilacs out of their misery and allow the other species to occupy the space.

Q: I live in Indiana and have a hibiscus that I have moved inside for the past 12 years. This year, it bloomed the best it ever has. I do nothing special to it, accept plant it in the ground and in a medium-sized pot when I take it inside. I have had it in the garage with no light and in a room that has a skylight. To be honest, it doesn’t seem to matter where I put it. One year, it looked like it died, so I cut it back to almost nothing. It sprang back and continued to flourish. What is the life expectancy of a hibiscus? It seems to be getting better as the years go by. (email)

A: The answer is simple: The plant has discovered the fountain of youth because of your loving or indifferent touch. In reality, I have no idea what the life span of a hibiscus would be. I wouldn’t suggest changing a single thing with your routine to keep it in this youthful vigor. The next time you carry out a major pruning, I’d suggest attempting to root some of the cuttings to see if this good fortune can be passed on. If so, you could start your own business!


To contact Ron Smith for answers to your questions, email ronald.smith@ndsu.edu.