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Published December 03, 2010, 12:00 AM

Hortiscope: Weather, fungus could create grass spots

Q: I have a lot of yellow spots on my grass. What causes this problem, and what can or should be done? Thank you in advance for any help that you can provide.

By: Don Kinzler, INFORUM

Q: I have a lot of yellow spots on my grass. What causes this problem, and what can or should be done? Thank you in advance for any help that you can provide. (e-mail reference)

A: This is likely a weather-related problem. Our wide shifts in temperatures with the accompanying shorter day lengths are confusing our cool-season grasses.

It also could be a problem known as yellow tuft. This is a fungus brought on by standing water or dew and cool night temperatures. Other possible causes are buried construction debris or scorch, which is brought on by bright, sunny days like we’ve been having and cool, near freezing nights. Keep in mind that most home lawns are not a monoculture of just one grass. The lawn is a mixture or blend of various cool-season grasses, such as Kentucky blue, fine or creeping fescue and perennial rye, that have differing environmental requirements and could be pushed to manifesting this yellowing everyone is seeing. The good news is that just about all are self-correcting when the weather changes, which it will, so there is no action needed on your part.


Q: I have a zebra plant that is more than 10 years old. It has one very long stalk. The problem is that it only has leaves near the top of the stalk. The remaining lower portion does not have leaves. It also seems to be growing taller each week. How can I get it to sprout leaves on the lower portion of the stalk?

I’m afraid to cut it because I don’t want to kill it. Any suggestions or advice would be greatly appreciated. (e-mail reference)

A: Put your fear to rest and cut it back. Take the cutting and root it in water or a pasteurized potting soil mixture. The cut stub will break out with new growth. Since you told me that it is exhibiting vigor, but no bushiness, the new growth should begin manifesting itself in two weeks or less. You then can enjoy two of these fascinating, easy-to-grow houseplants.


Q: I have tried to grow rutabagas in my garden for the past two years but haven’t had much luck. Last year, I salvaged about half of the crop. This year, I had to throw away the entire crop. From my research, the culprit seems to be something called cabbage maggot. What can I do next year to harvest an unblemished crop of rutabagas? Is there something I can add to the soil or with the seed? Any assistance you can give me would be appreciated. (e-mail reference)

A: Rutabagas or any vegetable in the cruciferous family, such as cabbage and broccoli, will attract the cabbage maggot. The adult is a fly that emerges in the spring with the sprouting of early crops. The fly lays her eggs adjacent to the emerging seedlings. After hatching, they devour or destroy the roots of the crops. This insect overwinters in the soil as pupae from the previous growing season. Control is possible without using chemicals. The starting point is crop rotation. Grow the following year’s crop as far away as possible from the fields that were used to grow rutabagas or related crops. Do not grow crops of early and late rutabagas close together or near early broccoli, cabbage, cauliflower or other cruciferous crops. I know in garden situations this is sometimes difficult, but if you can plant somewhere else, that would be a big first step.

Also try companion planting. Intermix chives and borage with the rutabagas. The aromas given off by these and other aromatic plants will confuse the flies and limit their success at locating the rutabaga crop. The best nonchemical control is to use a floating row cover of woven geotextile. This has to be installed at the time of seeding, but it is not a technique to use if the area carried a crop of rutabagas the previous year. Be sure to get all edges of the cover buried in the soil and make it loose enough to allow for crop growth. Lime or wood ash is another nonchemical method to try. Sprinkle the ash or lime around the planting area. This supposedly makes the soil inhospitable to maggot development.

Chemicals are a moving target. Check your local garden centers to see what is available on the market where you live and apply according to label directions.


Q: We have a 12-foot-tall amur maple that produces a multitude of seeds.

However, the seeds never fall off. The seeds are hanging on tightly when the next seeds are produced. Is this normal or some mutation? (e-mail reference)

A: If this has been recurring every year, then this is normal for this particular tree. The seeds will drop some years but not others. You also can expect a variation in the seed crop each year. Some years, expect a heavy crop of seeds, while other years you may not. What you want to watch out for is a year when there is an overwhelming crop of seeds. By that, I mean much more than in any previous year. This often is a signal the tree is under excess stress from environmental conditions or insect and disease activity.


Q: I live in northwestern Louisiana. My neighbor and I have fairly young autumn blaze maples. During the spring, they both have beautiful leaves, but his are a darker green than mine. My tree grew like crazy after the first year, but his did not. My neighbor has wonderful, colored leaves this fall, while the leaves on my tree fell off. We both water the same and use the same fertilizer. His tree seems to be planted slightly deeper than mine, but I do manage to pile the dirt on top of the roots and also make sure I do not choke the tree. The same thing also happened to my summer red and Japanese maples. The summer red was planted last year and the Japanese maple has been in my yard for 10 years. (e-mail reference)

A: Assistance will come best by contacting your local Extension Service agent.

Go to www.lsuagcenter.com/en/our_offices/parishes to find the office nearest you. There are too many variables in plant growth and environmental locations to make a judgment from here in North Dakota, especially when the problem is not clearly defined. Something is at play that I am unable to ascertain. If the county agent is unable to solve the problem, he or she can line you up with someone at Louisiana State University who would be able to do so.


Q: Can I split a weigela into more than one plant? (e-mail reference)

A: Assuming you are talking about a mature, large plant, then yes. You would do so while the plant is dormant and just prior to spring growth next year.


Q: I enjoy your column in the Bismarck Tribune and wonder if you might have an idea of what caused a condition on the new growth of our hackberry tree this summer. The tree has been at its location along a sunny slope for about four years. This summer, I noticed the leaves on the new growth were curled inward or cupped and the color was paler than the other leaves. The leaves on the new growth were the first to drop this fall. I had not noticed this condition in prior years. I used Bayer tree treatment in the spring for the last two years. I have not seen evidence of insect damage or disease. I’d appreciate your thoughts and if there is anything I should do in the future. (e-mail reference)

A: In spite of what companies might try to promote, annual treatments with insecticides (topically applied or a systemic uptake) are totally unnecessary.

Hackberry trees, especially, are good candidates for not needing any intensive preventative care from destructive insects. The reaction you are seeing might be from excessive insecticide use, herbicide drift or some other factor. Tom Kalb, NDSU horticulture specialist in Bismarck, is receiving a copy of this message and will get in touch with you to determine what may be going on with your hackberry. Thank you for the nice comment about the column in the Bismarck Tribune.


Q: In Colorado and some other states, we have a treat around this time of year called Daffy Apples that come in packs or singles. I’ve now found my second insect inside an apple within three weeks. It appears to be an insect that bores into the apple. Because the Daffy Apple is encased in either regular or red caramel, plus a coating of peanuts, you can’t see these holes. You get to a point where you don’t want to eat another covered apple. We’re lucky that we cut our apples into small sections before eating them! Have you heard of such a boring-type insect? I don’t like worms, either, but an insect just totally turns me off. Should I pitch the two apples I have left and contact the Daffy Apple Co.? Any input you could provide would be greatly appreciated. (e-mail reference)

A: The apple maggot and the coddling moth are the two insect species that are the dominant apple borers. The adult form of these insects lays eggs just under the skin of the apples, which then hatch into the juvenile or maggot stage and begin feeding and tunneling their way through the apple as it matures.

Unfortunately, the outside of the apple doesn’t show obvious symptoms of this insect activity. However, you can see dimples where the eggs were inserted below the skin. To protect the apples, practice good sanitation techniques by picking up all the fallen apples. Also, set up physical and pheromone traps, and follow a controlled spray program. I don’t know anything about the company you’ve been getting your coated apples from, but I would inform it of your displeasure and say that you won’t buy anymore apples unless the company can assure you that the apples will be free of insect infestations. The apple company might be getting apples from an organic source that is not following prescribed techniques to keep these pests under control.


Q: I have a crepe myrtle that’s been in the same spot for five years. I want to move it about 10 feet. I know the best time to do this is in the fall or spring.

I was going to dig a trench, then dig around the tree and move it in the trench to where I want it. Any tips in doing that? Also, I plan on doing it in November or December. (e-mail reference)

A: Whenever the plant is in full dormancy is the best time to move the tree as long as the soil is not frozen. The trick or tip I can give you is to dig it into as big a rootball as you can handle. Rock the rootball back to one side and slip a piece of burlap under it and then do the other side. You should have the plant rootball in a cradle of burlap that will help you tow or lift it to the new location. Once there, just leave the burlap in place to rot. Backfill the tree to the same depth it was at the original planting site and water in completely.


Q: I have a ponderosa pine that is several years old. There is a branch at the base of the tree that is making the tree look like it has two main trunks. Would it be better to leave it alone or cut the shorter branch off during the dormant season? I get mixed views when I ask people. (e-mail reference)

A: Cut off the branch. However, I’d suggest waiting until early next spring before new growth begins. This is the right approach to take because the tree will heal quickly with the spring surges of growth. I don’t know why there would be mixed responses to your question.


Q: I grew up in southern Louisiana. My parents had a variety of fruit trees on their property. One tree had thorns on it and produced an apple-tasting fruit.

The mature fruit was oval and had the texture of an apple with a seed in the middle. My parents always called it a Ju Ju tree. However, I can’t find anything like it. It died during a freeze one year, so I really would like to find another one. It would be great if you could help me. (e-mail reference)

A: This is the jujube tree. I haven’t given this tree a single thought since I moved out of the South! Go to http://en.wikipedia.org/wiki/Jujube for a description of the tree. Most nurseries or mail order catalogs in the south should carry this popular plant.


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.

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