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Don Kinzler, Published April 27 2012

Hortiscope: Most grasses need sun

Q: We have an area of lawn that doesn’t get a lot of sunlight because of tall trees and a neighbor’s new fence. The grass is dying even though we water and fertilize the area. Some areas have been dead for years along the side of the house. With the new fence put up by our new neighbor, even grass away from the house is dying. Is there a grass that would flourish in really shady areas? We have a lawn service that fertilizes for us and we mulch when mowing. (email)

A: Even shade-tolerant grass species will not do well if the sun is blocked entirely. You might want to try a couple of procedures to see what happens. Try to locate a garden center or seed supplier that sells straight seed (not mixed).

What you want is creeping red fescue seed. Get the navigator cultivar if possible. Sow it at 2 to 3 pounds per 1,000 square feet. If you only can get shady grass mixes, then use that. Hire a competent International Society of Arboriculture certified arborist to prune the canopy of your mature trees carefully so that the sun/shade reaching the grass is at least dappled. Don’t push the fertilizer too heavily, and mow at the maximum height of 3-plus inches.

Mulch the clippings each time you mow. Overfertilized turf is soft and succulent but more intolerant of wear and vulnerable to insect and disease activity. A heavily shaded lawn needs about half the nitrogen fertilizer of turf grown in full sun. Your lawn service should adjust the application rates when treating your shaded area. If this advice doesn’t result in a grass cover to your satisfaction, then opt for a low-maintenance, shade-tolerant ground cover to replace the dead grass and give up fighting a losing battle.

Q: I am writing to you because we had a car accident last night in our front yard. The driver hit one of our old (250 years) oak trees. The car struck the tree at about 90 mph and took the bark off the majority of the lower part of the tree. I would like to save it if possible. Can you help me with this? (email)

A: As long as some bark is remaining on the trunk, there is every chance of saving it, especially a tree that old. I hope the driver and any passengers survived the impact. Contact an ISA certified arborist in your area to look at the tree. To locate someone, go to www.treesaregood.com/findtreeservices/FindTreeCareService.aspx and provide the necessary information. Without seeing the extent of the damage, I only can give you basic guidelines on how the arborist will go about saving the tree. The torn and damaged bark will be cut back to where it is still attached to the xylem cylinder. No tree wound dressing should be applied. If the tree is healthy, it will compartmentalize this big wound and begin the slow process of regrowing new bark over the exposed area. The arborist should check the tree for soundness and stability. A vehicle impact of the intensity you describe could have jarred some of the roots loose, so the tree may need support and fertilizer.

Q: I have a large green ash tree in my yard. Parts of the tree are dying and do not have leaves. There is no yellowing and the entire branch is not dead. I am concerned because it is very early spring and only parts of the branches have buds. I see no signs of bugs and the tree gets plenty of water. I am wondering if I should be concerned because I would hate to lose the tree. (Denver, Colo.)

A: There definitely is cause for concern. Get in touch with an ISA certified arborist to see what the cause of this dieback is so that corrective action can be taken while there is still a chance to save the tree. At the very least, you need to have the dead wood removed so that it will not serve as a residence for any potential pathogens or destructive insects.

Q: I hope that you can help me with my ornamental grass question. I have been trying to figure out what the name of the ornamental grass is that I have seen in a couple of spots in West Fargo. I have asked a couple of nurseries, but nobody seems to know. It is tall and has white, long, gorgeous plumage. It can be found at the Sheyenne Crossings assisted-living facility in West Fargo. It also is growing at the new Titan Machinery building. If you need a picture, let me know. (email)

A: I believe the grass you are talking about is Miscanthus sinensis ‘Gracillimus.’It tops out at around 6 feet and is winter hardy to our area. If this isn’t it, then a photo would be needed.

Q: I will be transplanting about a half dozen blue and black spruce pines from one side of my yard to another. They average about 25 feet tall. Can you give me some tips as to the best way to ensure they survive the transplant? How much should I water them? Should I be putting anything in the bottom of the hole prior to placing the pines in their new location? I also heard it’s best to position the tree facing the same direction it was facing when it was pulled from its old location. I was told to fill the hole half full of water prior to placing the tree. Are these wise tips or should I be doing something else? I would appreciate your advice and insight on this because I would like the pines to survive the shock of the move. (Leonard, N.D.)

A: There is some truth and nontruth in what you’ve been told. Basically, no fertilizer or vitamins are needed to accomplish a successful transplanting.

Assuming you will be moving the pines with a tree spade, filling half the hole with water is a good idea. It will fill the pores of the soil surrounding the root ball with water, which means water will not be pulled away from the roots.

As to the orientation of the tree having to be the same as it was at the old site, it is not true. That was something I was taught back in the 1950s in my horticulture and forestry classes and has been parroted to everyone in the business ever since. Research shows that there is no benefit from going through all that effort. If the tree is going to become established, it will do so regardless of how it is oriented. The major key to success in transplanting is to capture as much of the root system as possible in the move. In a perfect world, the trees to be moved would have their roots pruned to the ball size of last year at this time. This would allow for root regeneration and make the move to the new site stress free. Even with the largest tree spade, some roots will be severed and left behind. Water in the trees using some common sense. Don’t think that perpetually soaking them is going to do the trick. Opt for a good soaking after planting the trees. Cover the area with organic mulch about 3 to 4 inches thick. This will keep the soil uniformly moist and the root temperatures cool. I hope this information helps and that the transplanting is successful.

Q: The bark on my Schubert chokecherry tree is becoming dark. The bark also is cracking and splitting. By late summer, the leaves begin to turn yellow and start falling off. I have sought advice from local greenhouses. The best guess is that it might be a burrowing insect. Any suggestions on how to solve the problem? Thanks and I appreciate your assistance. (email)

A: Chokecherry trees deserve their own book on the plethora of insect and disease problems they can play host to! Without seeing your tree in person and without being able to ask you a bunch of spontaneous questions, it is impossible for me to diagnose what is causing the problem. It could be a bacterial or fungal canker, which is more likely than the problem being boring insect larva.

With your description and nothing else, I would advise removing the tree. Based on the state you say it is in, the chances of it surviving don’t appear to be hopeful at this point. Sorry.

Q: My chokecherry trees are starting to show symptoms of black knot disease. Is there a spray I can use for this problem? Would pruning the trees help? Also, I have two miniature rose plants along the south side of my house. Can I uncover them now? They are starting to get leaves. (email)

A: Yes, you can uncover your rose bushes. Keep a vigil on the weather so you are ready to provide some protection if the temperatures dip below freezing, which it is bound to do. Black knot is a fungal disease that is difficult to control just by pruning. However, pruning is one of the necessary steps. Cut a good 6 inches back beyond the visible fungal knot. Spray the tree with lime sulfur while the buds are closed. Once the buds open, spray with benomyl and captan. Be sure to follow label directions to avoid toxic damage to the tree. This is a very difficult disease to control, so the possibility of eventually having to remove the trees should be considered.

Q: I purchased two hackberries from a local nursery. They’ve been sitting in the same spot at the nursery for about two years, so the roots have started growing into the ground. The nursery wants to scrap them and refund my money because the roots have grown into the drain lines of the beds. I told them the roots can be pruned and the trees saved, but they’re not sure. What do you think? Hackberries are tough trees, so they should be able to withstand the pruning, especially in early spring. (email)

A: Yes, hackberry trees are a tough species. However, they don’t take well to being transplanted, especially when the roots have grown outside the root ball and into the drain lines.

Why not compromise with the nursery? Offer to purchase the trees at a reduced price with no replacement guarantee. That way, you’d get what you want at a reduced risk and the nursery would be off the hook for a guarantee. If the nursery is going to scrap them anyway, who has anything to lose? Make the offer because it is worth a try.


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 email ronald.smith@ndsu.edu.