May 22, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I’m looking for any ideas regarding the planting of trees in my front yard which faces directly west. We do not have air conditioning so by late afternoon during the summer it is hotter in my house than it is outside. I need something that grows fast, is easy to mow around and is full of leaves to block the sun. I was thinking a laurel leaf willow but any other suggestion would be greatly appreciated. (Saskatchewan, Canada)

A: Poplars will grow the fastest, but you would not be thanking me for the suggestion a few years from now! One of my favorite trees is the linden. It seems to have everything going for it: dense foliage, relatively fast growth, attractive flowers in summer, and in some cases, a halfway decent fall color. A cultivar to look for in your region is harvest gold which was introduced in your country. American linden cultivars include frontyard which grows to 70 feet tall and sentry which gets to approximately 60 feet tall. A little leaf linden cultivar is norlin which was introduced in Manitoba by the Jefferies nursery. The best thing to do is visit local nurseries and see what the nursery owner recommends. Often advice from a distance can miss the mark completely so I like to make suggestions and follow it up by encouraging local visits.

Q: Some of my evergreen’s leaves have turned brown and are falling off. My neighbor suggested I use muriatic acid because the plants are being infected by insects. Would muriatic acid work? (E-mail reference)

A: I don't know where people ever got the idea that hydrochloric acid is good for evergreens. I have never seen any research to support this claim. It is a little early for evergreens to be infested by insects. Even if they are, muriatic acid is not an insecticide. I don't mean to sound like I am picking on you - I'm not, but I am writing this for you as well as others who may be thinking of asking the same question. There are lots of maladies that can mimic the symptoms you describe. I’m guessing from your e-mail address that you are in Ontario, Canada. I would suggest that you contact the horticulture department at the university in Guleph. Send them a sample or have someone in extension come out and check the tree to accurately determine what the cause could be. The problem could be winter desiccation, drought response from last summer, needle cast, canker or (hopefully not!) more than one of these maladies.

Q: This is the second year I’ve had my honey locust. The trunk and limbs appear green yet there are no buds. Is it just too early or is my tree "toast?" It gets plenty of water, probably too much. I don't know what to do about that because the sprinkler system controls the amount. It’s either the grass or the tree. I have removed all the mulch that was under the tree. It has pretty good run-off and is in the open on the west side of my deck. (E-mail reference)

A: It is a little early to give up on the tree. The irrigation system can be adjusted so that the system comes on just before the grass shows symptoms of wilting. Most lawns are watered too often anyway. I’ve had an irrigation system in my yard for 17 years and I find that, if I manually control the cycling, my lawn, trees and water bill are far more attractive to me!

Q: About three months ago I purchased a beautiful Norway pine. It has three trees actually coming out of the pot. Now three months later it has started to turn grayish brown from the bottom up and the branches are falling off. What did I do wrong and is there anything I can do to save this beautiful plant? (E-mail reference)

A: The plant should have been planted as soon as the soil thawed. I suggest getting them out of the container and planted as soon as possible.

Q: I have previously been using Dacthal as a pre-emergent chemical for weed control in new and old strawberry plantings. I have recently learned that Dacthal is no longer available. Is there an alternative chemical that can be used? (Bismarck, N.D.)

A: The only other pre-emergent available on the market for strawberries is Devrinol..

Q: I planted three lilac bushes last year. I believe two are primrose and one is a sensation. I’m not sure if I am supposed to prune it before it blooms. Can you please tell me the proper thing to do for lilacs at this stage? They were very small when they were planted but now they are about four to four and one half feet tall but thin. They have never bloomed but I’m assuming that’s because of plant immaturity. What do I need to do so they are not tall and spindly and yet not hurt my chances it will blossom? (E-mail reference)

A: Prune them right after they have blossomed which should be sometime in early July.

Q: I have a few schefflera plants which are single-stemmed. They are growing indoors and have plenty of water and light. Is there a way to promote more stem growth so each plant will branch out? The plants are now 8 to 24 inches tall. I would love to use some as bonsai projects if I can get them to branch out. (E-mail reference)

A: Go ahead and prune them back or simply pinch out the growing tip and they will branch out.

Q: We have some land two hours north of Montreal, Canada. The area undergoes the regular four seasons. We are right next to a river where cedars usually grow. We must have 20 or more cedar trees, 30 feet high or more, within 3 to 25 feet of the water. Two years ago, in the fall, all the leaves on one cedar turned brown. The same thing has now happed to two others and they look completely dead. Do you have any idea what may be happening or what I need to look for? I have not seen many other trees affected in our area however some neighbors say that it has happened to other trees. We get some flooding in the spring for about two weeks but the trees have always been exposed to it for the last 30-40 years. There are no other outward signs. (E-mail reference)

A: First I need to get the name straight. By "cedar" do you mean arborvitae, juniper, or true cedar - Cedrus spp? Generally plants that turn completely brown are being hit from the roots through anaerobic conditions, a change in the water table, or a root rot organism is spreading through root grafting. If the latter is the case, there is little you can do except to remove the affected plants when they show the symptoms, being sure to get roots and all.

Q: I have two 25-year-old lindens in my yard that have trunks in excess of two and one half feet in diameter. There are many large roots protruding above the soil and no grass growing beneath the trees. I would like to install a landscape block circle and plant shade plants. Can I cut out some of the roots without damaging the tree in order too get the blocks level? (E-mail reference)

A: Probably, but make sure you are out by the canopy spread of the tree so the roots still have some anchoring capability.

Q: I'd really appreciate it if you could help me find a cure to my ailing emerald arborvitae. There are some spots that have turned literally black (as if it's burning) and some that are brown. Why are the leaves turning black and how can I prevent it? Also, you mentioned that spikes are not good for the roots. Does that mean I have to dig out the roots? (E-mail reference)

A: The blackening is likely due to a bacterial slime from too much watering or too wet a season. Some of the browning could be due to normal needle decline on the older growth. It could be winter burn if it is on the outer growth. It depends on how long you have had the spikes in. If you just put them in this spring, then you can remove them. If they have been in since last year, then it isn't worth it.

Q: I'm a little puzzled about one of my Colorado spruce. Why would all the budding needles be a rose pink in color? The top and bottom of the tree have normal budding. I think it's about eight years old. (Onaka, S.D.)

A: I believe you are looking at bud scales which have reacted to sun exposure. It’s nothing to worry about, they will fall off and the new growth will be normal.

Q: I read your article about drying flowers with great interest. I’m looking for a way to accelerate and perhaps improve the drying process. What would be the effect of putting the flowers in a vacuum? Has any work been done in this area? (E-mail reference)

A: I have never heard of this as a method of drying flowers but have as a way of preserving them after the flowers have dried. Nothing ventured, nothing gained. Give it a try!

Q: I have a plump four-leaf jade plant. I would like to have it branch out like a bush. It's only three inches high with a skinny stem. I've had it for five months. I've never had a plant before but have always been fascinated by jade plants. How do I prune my plant to branch out with a thick stem? (E-mail reference)

A: Simply pinch it back to another leaf with your thumbnail and index finger. That will cause the plant to branch.

Q: I have a tulip that has a very distinct color. I have been unable to find any bulbs like it so I’m thinking about trying to collect its seeds. Do you know how to do this? Do they need to be dried and when is the best time to plant? (E-mail reference)

A: Allow the pods on top of the flower stalk to dry, then harvest and clean. Sow the seed to encourage bulb development in mid-September to probably early October if you live south of North Dakota. Keep them cool and dark in a brown paper bag.

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