July 22, 2004

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: We were in Saint Cloud this past weekend and noticed some very deep colored lilacs. We picked some and also noted how compact the blooms were. Are you aware of the variety? (e-mail reference)

A: There are as many lilac varieties as there are Smiths in the phonebook! Visit your local nurseries and see if you can catch some in bloom to find out what they are.

Q: What is the best way to control weeds in a newly planted peony bed? Is mulch a viable option? If we mulch, does it have to be removed and replaced each fall? (e-mail reference)

A: Mulch with an organic material that is free of weed seed. I would think pine nuggets would look and function well. It does not need to be removed in the fall.

Q: I just bought two good-sized calla lilies. The fuchsia colored lily has several beautiful blooms, but the leaves are turning yellow at a rapid pace. The lighter pink lily doesn't have nearly as many blooms and the leaves are slowly turning yellow. They are in a good spot for sunlight and I give them a good amount of water every week. Is there something else that I should be doing? (e-mail reference)

A: Are they in a drafty location? Are you using water from a softener? Is the pot free-draining? These are the only possibilities that I can think of.

Q: My daughter-in-law just gave me a darling ficus. At her house it was receiving some light from the west. It lost most of its leaves since she purchased it. The front has leaves while the back has none. I checked for bugs but didn't find any. The leaves are tender and green, none are yellow. Its trunk is braided. I've placed it in a corner that has northwest and east light. The only direct light will be from the northwest and then only in the late afternoon. It gets filtered light from the east during the morning hours. Is this enough light? The soil is not wet, but lightly damp. We keep the house at about 74 degrees. Can you please advise what I should do to make it happy, healthy and bring it back to full leaves? (e-mail reference)

A: Ficus have a bad habit of doing that after they are brought home. Give it about six weeks in that location and it should begin leafing-out with permanent leaves. They are quick to "pout" when they are moved from their perfect location (florist or nursery). They usually recover, as long as the owner doesn't overwater or fertilize.

Q: Last summer, after it was particularly wet, a couple of my Linden trees started losing their leaves. I fertilized the trees in the fall, but this spring the trees don’t look much better. Anything I should do? (e-mail reference)

A: No, just wait to see if they pull out of it. If they don't, but they mean a lot to you, get a professional arborist to see if there is anything that can be done.

Q: I have radishes that are flowering. Is there something wrong? I was told I might be giving them too much water. We also have very hard soil. I picked a few just to see if they were ready, but they weren't. Should I let them continue to grow or should I pull them? (e-mail reference)

A: Pull them out. They somehow received enough cold to cause them to go into their reproductive cycle. Once they have started to do that, they are not putting any energy into root development.

Q: Something very odd has happened to my peonies. In previous years they have had a wonderful smell, but this year they don't smell at all! I've searched the internet, but can't find a reason for this. (e-mail reference)

A: I don't know either. Are you trying to smell them at the wrong time? Is evening better? Are the flowers too young or old to give off an aroma? Is it too cool? I’ll let you know if I find an answer.

Q: What effect, if any, does trimec broadleaf spray have on pine trees? Would 2, 4-D be a better choice for broadleaf control? (e-mail reference)

A: It could have negative impacts as it is soil active. If you can control them with a 2, 4-D product, do so.

Q: We moved into our house in December. This spring, to my delight, I noticed a large, healthy looking lilac bush. However, it never bloomed. I do not know what the previous owner may have done to it. If he pruned too late last year, and accidentally removed the flowers for this spring, will they ever bloom again? If I do not prune this year, will it bloom next year? (e-mail reference)

A: Yes, it will probably bloom next year if you don't prune it this summer.

Q: I have a client with newly planted grass that is coming up. The broadleaves are also coming up. Any suggestions on how to control the broadleaves? Mowing seems to be an obvious answer, hoping the Kentucky blue grass chokes out the weeds. As far as chemical control, I am concerned that the grass might get dinged a bit. (Fargo, N.D.)

A: The grass would be sensitive to herbicide applications right now because of the heat. I would suggest having the client wait until late August to apply broadleaf herbicides. They will be more effective then and the grass will be tough enough to tolerate it.

Q: Someone called me about young tomato plants that they purchased about a week ago. They were doing very well, but they have white spots on the leaves and they are curling. They still have the plants in the house. Do you have any idea what could be wrong? (Carson, N.D.)

A: Yes, the fact they are not yet planted in the garden! Tell them to get them in the ground ASAP. Tomato plants sitting in the house at this time of year are not going to look good. They should recover when transplanted if they haven't been kept in too dark a location.

Q: Is it possible to plant evergreen trees from pine cones? (e-mail reference)

A: Only if you collect the seed out of the cones before the squirrels and birds get to them.

Q: I recently bought a large jade plant. It's looking pretty good, but I noticed some bugs. They are tiny black bugs on the leaves, mostly in the center of each bud where new growth is starting. I also see some white dust. Is this something you've heard of? Is there something I can do to get rid of these little pests? (e-mail reference)

A: I would suggest attacking the insect with Insecticidal Soap, a product that is safe to use on houseplants and around people. It should take care of whatever that bug happens to be. It needs to contact the insect to be effective, so be sure to get complete coverage. The dust could be powdery mildew, mealybugs, scale or aphids. If it is a general gray covering on some of the upper surface of the leaves, then it is likely powdery mildew. It can be controlled with a fungicide containing benomyl. If it appears to concentrate on the underside of new leaf growth near veins or at the juncture of the leaf petiole attachment to the stem, then it is one of the insect pests. In some cases, the Insecticidal Soap will take care of the problem insects. In other cases, you will have to purchase houseplant oil with resmethrin added.

Q: My ash trees were starting to bud nicely, but then got hit with frost. They now have no leaves and the buds are drying up. They are located in a shelterbelt near our farm. Will they come back? (Dickinson, N.D.)

A: The trees should recover. Mother Nature has a backup to irrational weather so the species can survive. This happened to lots of plants all over the state this year.

Q: I read one of your answers about a hollyhock invasion. I have the same problem, only it's not just in my flower beds. I have it everywhere including in my lawn, garden and under my trees. I dug up every single plant last year which took me weeks to do. I also sprayed with Round-Up. This year there seems to be even more than last year. Is there a stronger weed killer? I'm going crazy because there are literally hundreds of plants coming up. (e-mail reference)

A: Employ the services of a professional lawn care operator that is licensed to handle restricted pesticides which would include herbicides. Since hollyhock is a broadleaf and growing in a turfgrass situation, it can be selectively removed. The firm may have to resort to spot spraying in certain situations where there is a chance of damaging desirable ornamentals.

Q: I have a radiant crab tree that was planted in the spring of 1999. It has been growing just fine, but it never has any blossoms or berries. (Harvey, N.D.)

A: I question whether it is a crabapple. If it is, it may not be a true radiant crabapple or a variety that is hardy enough for our area. You can try traumatic stimulation to get it to bloom next year. Avoid fertilizing with nitrogen. At the outer edge of the canopy, take a straight-edged spade and drive it into the soil as far as possible in four to six places. This will cut some of the roots and hopefully shock or stimulate the plant to go into a reproductive cycle. It may just be living too much of the good life and not have the motivation to go into a reproductive cycle.

Q: I hope to try Karl Forester ornamental grass as my new perennial. Can I plant it on the south side of my house along the foundation? I am concerned that the location could be too hot and dry. Do you have other suggestions for a suitable location? (e-mail reference)

A: Karl Forester grass seems to be doing well in a wide variety of locations around the state. I would think it could survive the heat if you would be kind enough to supply the water, at least for the first year and during any future extended droughts.

Q: We have more than two dozen healthy, mature blue spruce trees in our yard. This spring the new growth at the top of one of the trees is very bright red, but it looks very healthy. What caused the color change and is it something to be concerned about? (e-mail reference)

A: Red growth could be a reaction to cold temperatures, a phosphorus deficiency or maturation of this particular plant. If you are concerned, have the soil tested for phosphorus at its base or around the root system.

Q: I recently planted accent deep pink impatiens in my back yard. After planting, we had seven days of very heavy rain. The leaves are now turning yellow and have black spots. Do you know why this happened? (e-mail reference)

A: Probably because of the saturated soil and cool temperatures. They will very likely die, at least the ones with the black spots and yellow leaves unless it is just a reaction to the weather and not a disease. You might try spraying with a common fungicide like Daconil 2787 to see if you can control any further disease development.

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

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