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Hortiscope

Ron Smith answers questions about the world of plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I got a greenhouse this year, so I am learning on the go. The tomatoes took off, but now they are not doing well. The bottoms of the tomatoes are turning black and the bottoms of the plants are yellow and drying up. I did leave town and had someone take care of my plants for about two weeks. I think it got too hot in the greenhouse. Also, I am not sure if the plants did not get enough water or too much water. I thought that maybe you could give me some idea of what I need to do next. (e-mail reference)

A: All you can do now is try to keep the moisture level adequate in the root zone and keep the temperatures from reaching extreme highs.

Q: I put too much fertilizer on my azaleas. How can I fix what I have done? The plants look terrible. (e-mail reference)

A: It might be too late, but repeat flushing of the plants with watering will remove the salts from the root zone through leaching. Do it at least three times, with about a two-hour spacing between each watering.

Q: I have yellow mushrooms growing out of the soil at the base of the stem of my dieffenbachia. I have had the plant for six years and never had this problem. Will they harm the plant and should I dig them out? I would appreciate a reply. (e-mail reference)

A: Dig them out because they are unsightly. However, the mushrooms will not harm the plant. These are saprophytes digesting the organic matter in the potting mix.

Q: I have a question about my schefflera octophylla. It's looking sickly and not growing. I haven't seen a new shoot in almost a year. The leaves are a very light green and paper dry. They used to turn yellow before they turned brown and fell off, but I haven't seen a yellow leaf in several months. They've all turned straight from green to brown. The leaves hang on by a thread, so a little gust of wind can knock them off. It also is weighed down to the point that I can see the roots in the soil. The only thing holding it up is the pot. It doesn't have any diseases as far as I know. I was gone for two weeks and nobody watered it. After I got back, one of the branches was drooping a lot more than it was before I left. I accidentally watered it with ginger ale once and frequently the cats use the soil as a litter box. It has been moved several times and gotten sick in most of them. I've moved it back to the spot it likes the best, but it hasn't improved any. I am hoping to salvage it and start a new plant that is healthier. The schefflera is 20-plus years old, so I am reluctant to part with it. Is there any way I can save it or have I killed it? I water it every Sunday and don't use fertilizer. I live in Wyoming, so the schefflera doesn't get much sunlight and planting it outdoors is out of the question. What can I do to bring it back to life? How fast is it supposed to grow? What is the average lifespan of a schefflera octophylla? Does watering it with a carbonated beverage do any harm to it? What does cat urine do? (e-mail reference)

A: Once life is gone out of a plant, there is no resurrection. The way you describe your plant, it sounds like it has reached that point of no return. The fact that you were able to get 20-plus years out of it is something to take pride in. Cat urine is rich in salts, which isn’t good for the plant. The ginger ale should not harm the plant unless you dumped it with a glass full of ice. I advise getting rid of this one and start with a young plant that you can work with. Learn from your past mistakes and keep the cats out of the pots!

Q: We had Japanese beetles in our yard last year. They destroyed many of our plants. Also, one day we had a big hatch of new beetles. How can we get rid of them? (e-mail reference)

A: Japanese beetles lay eggs in the soil. The grubs feed on the roots. Meanwhile, the adults are voracious feeders on many species of woody plants. Spraying the adults is difficult and puts more pesticide into the air than is desired. The best method for control is a soil-applied material in the spring as they migrate to the surface. The trick is to keep them from getting into the reproductive lifecycle of adulthood. Here is a paragraph lifted from an Ohio State University fact sheet (HYG 2504): "Larvae that have matured by June pupate and the adult beetles emerge from the last week of June through July. On warm, sunny days, the new beetles crawl onto low- growing plants and warm for a while before taking flight. The first beetles out of the ground seek suitable food plants and begin to feed as soon as possible. These early arrivals begin to release a congregation pheromone (odor) which is attractive to adults that emerge later. These odors attract additional adults to gather in masses on the unfortunate plants first selected. In cool weather, the adults may feign death by dropping from the plants, but normally they will take flight. Newly emerged females release an additional sex pheromone that attracts males. The first mating usually takes place on turf with several male suitors awaiting the emergence of a new female. Mating also is common on the food plants and several matings by both males and females is common." They can be controlled by trapping, biological control, changing cultural practices or using approved soil insecticides. The entire fact sheet is available at http://ohioline.osu.edu/hyg-fact/2000/2504.html.

Q: Is there some correlation between petunia plants and toads? The petunias are planted by the house. Landscaping bricks form the planter. The petunia bed is loaded with toads. Do you have any suggestions or explanations? (e-mail reference)

A: You have nothing to worry about! The toads like the setting because it is moist, and provides cover and a ready supply of insects. Toads are one of a gardener's best friends.

Q: I was in Tennessee and saw lilac shrubs that had been trimmed to be more treelike. I live in Chicago and would like to do the same. Can you tell me the best way to do this or direct me to a Web site? What time of year would be best? (e-mail reference)

A: The treelike forms are a particular type that are developed at the nursery and grafted to nonsuckering rootstock. With common lilacs already established, you would be fighting a losing battle. Visit some of the better garden centers in the Chicago area and you will see some of the species I am referencing.

Q: I purchased a new home and have hired someone to do the landscaping, place black dirt, install a sprinkler system and seed grass. I would like to plant several trees and some shrubs along the house. There will be 5 inches of topsoil put in place before the grass is seeded. The subsoil can become dry because it is located on higher ground. (Mandan, N.D.)

A: The 5 inches of topsoil is about as much as most trees get in their native environment. With a sprinkler system, you should not have a problem with moisture when needed. Try to have the irrigation contractor design the system so that the spray does not directly affect the trees. Don't overwater. That is a common mistake people who have a sprinkler system installed! Be sure the system is programmed properly. A standard 20 minutes for each station is incorrect. Each area needs to be considered separately. If the irrigation contractor never has heard of this, get another one to do the installation.

Q: Is there a way to promote a longer stem on gerbera daisies? Mine are flowering nicely, but have almost no stem and look stumpy! The ones in floral shops seem to have nice long stems and work well for use as cut flowers. Mine are growing in a sunny location in Minnesota. Any hints? Many thanks. (e-mail reference)

A: I would say the full sun is making the plants stockier, unless the gerberas are a different variety grown for the longer stems. Why not stop in and ask a florist to see if that is the case? Sometimes filtered sun will result in more stretched stems as well, but that is just a guess.

Q: I read your response about why apples fall off too early. I have a tree that bears many apples each year. What's different this year is that the apples are falling off too early. The weather is not too much different from previous years. The wind also has been mild. Sometimes I watch the apples fall without any wind blowing. I wonder if there is any other reason, such as lack of a certain nutrient. We live in southern California and the tree is an Israel specie called Anna. (e-mail reference)

A: I don't know what you read, but when there is a heavy load of apples set from a very successful pollination, the tree will form an abscission layer at the point of fruit attachment and drop any excess fruit. This keeps the tree from exhausting all energy reserves and allows it to bear some fruit the following year. Some growers will hand pick the crowded, small fruit to allow the king fruit (first fruit set) to get to maximum size. Mother Nature helps the tree along from a survival standpoint, while man assists with some hand picking early in the season. A June or early July apple drop is completely normal in most situations.

Q: I ran across your Web site while looking for information about northstar cherry fruit. If you have any information about this species, I would be very grateful for your expertise. I planted a tree last summer that produced about 80 cherries this year. However, the cherries were quite small. Do cherries grow larger in diameter as the years go by and the tree becomes more mature? Other descriptions I've read describe northstar as producing a medium to large cherry. The ones I've grown this year are almost not worth the effort to cook, in my estimation. Once pitted, I don’t have much of a cherry left. (e-mail reference)

A: If they set one cherry or a thousand, at age 3 or 30, the fruit should be about the size for the species. I don’t think you have a northstar cherry. That is the only explanation I can come up with.

Q: Does it matter if you mow a lawn in one direction every time you mow? I always have changed directions with each mowing, but have been told this is a waste of time. (e-mail reference)

A: If it is a waste of time, then tell your critic to answer why professional golf course superintendents and sports turf managers go to all the trouble of alternating their mowing directions. While mowing in the same direction every time will not kill or otherwise harm the grass, the alternation of mowing will result in a more pleasing appearance and giving it a more upright growth habit. No big deal unless you happen to be a competitive golfer whose income depends on minimal interference from any putting green graininess. In addition, altering the mowing pattern helps spread the compaction that comes from going the same direction every time you mow. My advice is to keep doing what you have been and don't worry about the criticism!

Q: Several years ago, I mistakenly sprayed a week killer on one of my shrubs. After it died, I replaced it with a new shrub. That shrub also died, as did the one I replaced it with this summer. Is it possible that the weed killer is still in the soil and the reason the new plants are dying? If so, how do I get rid of the weed killer? (e-mail reference)

A: It is very possible. Excavate the soil and replace it with fresh topsoil. Mix in some activated charcoal to absorb any weed killer that still might be lingering in the surrounding soil. Depending on the material that you used, it will, in time, break down to the point that you can plant something again in the contaminated soil.

Q: I received a crown of thorns plant a couple of years ago. I just repotted the plant because it was flowering regularly, but growing out of its pot. I keep it indoors and have it in an area that gets indirect sun. Should I be taking it outside during the summer months and giving it full sun? Any help would be appreciated. (e-mail reference)

A: The crown of thorns definitely would benefit from being summered outdoors, but keep it out of direct sunlight. Either under the shade of a tree or on the north side of the house would provide good, bright, indirect light without hurting the plant.

Q: I've recently radically cut a couple of old lilacs that were struggling after an adjacent driveway renovation. They did have some green, but not much. How long before I know if they will come back or need to be replaced? Do I need to wait until next spring or will I see new shoots pop out this season? (e-mail reference)

A: If you don't see new growth emerging in a couple of weeks, they will not amount to much of anything worthwhile. Get them replaced before the snow flies if you can find any in stock at local nurseries.

Q: We live on a farm and have a lot of deer problems with our trees. We put fences around them when they are small; however, we would like to put tubes or something else around the trunks when they get bigger so they are easier to mow around. We found some 4-inch straight pieces of drain tile that we could cut to fit over the trunk, but the drain tile pieces are black. Would they heat up and damage the trees or cause them to warm up too much during the winter? Do you have any other ideas that might be better? We have many trees, so it is important to keep the cost down. (e-mail reference)

A: I’m afraid the black drain tile would elevate the temperature of the trunk too high. Have you considered simple tree paper wrap or white tile if you can locate it?

Q: Last fall, we planted three flowering crabapple trees. This spring, one of the trees leafed out and bloomed beautifully, but the other two did not. One has sucker branches coming from the base and the other has one new branch growing about 15 inches from the bottom. What can I do so they will grow from the top? I don't want to dig them up and replace them. We planted them to be shade trees for our overly sunny front yard. (e-mail reference)

A: The trees with growth just from the base are dead. What you are seeing is the rootstock sending up sucker growth because it is not being inhibited by the grafted budwood. Replace them at your earliest convenience.

Q: We have a climbing rose bush that my mother started 50 years ago from a plant that her grandmother had when they homesteaded in the late 1800s.The current plant appears very healthy and sends out new plants/runners every spring. We would like to move part of it and start in a new location. When and how best do we accomplish this? We live in extreme southeastern South Dakota. (e-mail reference)

A: Now is not the time. Do it early next spring before new growth begins or this fall after the plants go dormant. Spring is the better choice of the two.


NDSU Agriculture Communication

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