October 2, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I'm planning to patch an area of lawn where I trenched in an underground water pipe. The soil is predominately shale and I believe some clay. The trench is approximately 12 inches wide by 140 feet long. It is on the edge of the lot alongside a lilac hedge. What is the best type of lawn seed mixture to use? (Jamestown, N.D.)

A: I would go with a creeping red fescue such as Dawson, ruby, or navigator. It’s a tough turfgrass species, needs little water, helps to sequester weeds, germinates rather quickly and looks good.

Q: Are zucchini, green bean or tomato leaves toxic to cattle? (Cando, N.D.)

A: Tomatoes are definitely toxic to livestock. The only green bean species that is toxic to livestock that I have listed is Phaseolus lunatus. With squash, it depends on the nitrate levels found in the foliage.

Q: We recently bought a home that has many daylilies. They look very crowded but I am not sure when or how to divide them. Is the best time in the fall or spring? Is there any other special care they need? (Ashley, N.D.)

A: The best time is in the fall, but you are cutting it fairly close. I'd suggest getting to it before the first of the month or else wait until next spring. Daylilies are so tough that they can literally be divided at any time the ground isn't frozen.

Q: Our backyard slopes down to the river and is difficult to mow. We're thinking about putting in some plantings. The area gets approximately six hours of sunlight, can be slightly wet in early spring and sometimes flooded for a short time. A beaver helps himself to trees along the bank so we don’t want them to entice him. (Valley City, N.D.)

A: I suggest lily of the valley for your situation. It is one of the toughest plants in the temperate zone. Once established, it will need very little, if any, maintenance.

Q: I'm looking for advice on when and how to properly trim a flower crab tree. I have five of them in my front yard in close proximity to each other. They are approximately 15 to 20 feet tall and spread. They seem a bit overgrown and branchy. Should I prune them? What time of year is best and what guidelines or methods should I follow for pruning them? (Fargo, N.D.)

A: The best time to prune is in the early spring before they leaf out. A balmy day in late February or March would be a good time. Prune to open the crown so it can get more sunlight by removing some of the inner branches. Always cut back to lateral branches and never leave any stubs.

Q: Is there such a thing as a fairy ring? My sister has this ring on her lawn that seems to be getting bigger every year. It is a green spot with some lighter green coloring and brown in the middle. Someone told her it is called a fairy ring. We have never heard of such a thing. Is there a spray to take care of the problem or will she have to dig it out and put new dirt in and replant? (Oakes, N.D.)

A: There isn’t a spray available to control the problem. Regular fertilization will mask the effects as it spreads and eventually runs its course. It is the result of decaying organic matter in the soil from old tree stumps, wooden foundations, or excessive thatch. It will outgrow itself in due time unless you are willing to dig up the lawn and replace it with fresh topsoil and then replant.

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: The person who sprayed my lawn for dandelions this fall used a small amount of Banvil along with 2,4 D. I was going to dig up a small portion of lawn this fall and turn it into a flowerbed. How long does Banvil stay in the soil? If I plant the flowers now, will they survive and flower in the spring? (Ashley, N.D.)

A: I would dig up the soil this fall and let it lay fallow over winter. Bring in a pot full of soil and plant a tomato in it. If there is a toxic level of Banvil present, it will show on the tomato plant because they are very sensitive to this product. If no symptoms appear, then you are home free. If the plant shows a reaction, then you have to excavate the soil or add activated charcoal to the planting area to absorb the chemical.

Q: I have a two-year-old flowering crab apple tree that was given to our family to mark the birth of our first son. Now the tree looks horrible. The leaves are all spotted, yellow and sickly looking and some of the branches are black. Is there any hope of curing this poor thing? (E-mail reference)

A: Clean up all fallen leaves and fruit this fall. Next March, spray the tree with lime sulfur. It does a good job of sanitizing the tree's surface so be complete in the coverage. After the leaves have elongated, spray the tree with a bordeaux mixture, which is a fungicide that will prevent some of the disease problems you are citing. Also, don't be afraid to prune it next spring before leaf out.

Q: I planted 20 bur oak trees this spring. They were about 2 feet tall when I planted them and some have grown more than a foot. About half have grown very well, but the rest seem to be having some problems. As summer went on, some of the leaves began to turn yellow and now have dried up. The trunks of the trees still seem limber. They have all received the same amount of water. They are planted in a row about 25 feet apart. The problem trees are spread sporadically in the row. I was told they might be short of iron. If that were the case, would it not affect all of the trees? (Aberdeen, S.D.)

A: Bur oak is native to our region of the country so I doubt it would be suffering from an iron deficiency. I think what you are seeing more of is the genetic variation that exists in seedlings. I wouldn’t apply anything now. Perhaps next spring, as the leaves are unfolding, you could add some chelated iron. It certainly would not hurt and is bound to improve things in most cases.

Q: Can you scatter blue grass seed in a lawn to thicken it up without adding soil or scratching the soil first? When is the best time and what about fertilizing? (E-mail reference)

A: Oh how the retailers love that kind of thinking! I wish it were that easy. You should, at the very least, scratch up the surface before applying the seed then drag it in with the back of a broom (leaf) rake. The scratching can be accomplished with a power rake or de-thatcher.

Q: I have a question about onions. The onions are still in the ground and have lots of little onion sets on the green tops. Do these sets contain seeds? Can the seeds be planted? (Lakota, N.D.)

A: Those "seeds" will grow into nice onions next year. I have had them volunteer in my garden with no help at all. Planting them about 2 inches deep should get them easily through the winter.

Q: I planted a 75-foot hedge of arborvitae last spring. They did very well until recently when I noticed browning over the entire plant. Is this a normal transition into fall or is there a problem? When I purchased them it was recommended that I don't fertilize for a full year. Is that right or can I give them a feeding of Miracle-Gro? (E-mail reference)

A: Probably just some normal older foliage senescence. Fertilize in the early spring as things begin growing and again around the end of June. Prior to winter's arrival, spray the foliage with Wilt Pruf for protection against winter desiccation.

Q: When is the best time to plant lilac seeds and how deep? (Lehr, N.D.)

A: Plant them now at about 2 inches deep.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu