Questions on: Linden/Basswood

Ron Smith, Horticulturist, NDSU Extension Service

Q: After reading your column on the subject, I noticed what looks like cottony maple scale on our linden trees. This is the first time I've noticed it. The trees were planted on our boulevard more than 10 years ago, so the trees are large. Would the same form of treatment be recommended? Where do I find Advanced Tree and Shrub Insect Control? Does the cottony scale kill the tree if left untreated? We have one in the row that looks yellowish and is not as full of leaves as the others, but I could not find evidence of the scale on it. (Milnor, N.D.)

A: You are better off taking care of this pest next spring as the trees begin to leaf out. The product is available at most private garden centers in our area. Something else is affecting the tree with yellow foliage because there is no evidence of the scale infestation.

Q: I have a 27-year-old linden tree that is sick. The leaves are pale green and small. It appears to have some black substance on the bark. It was like this last year, but not as bad. Can it be saved? Thanks! (Oakes, N.D.)

A: The tree has an aphid or cottony cushion scale problem. Carefully check the leaves or get an ISA-certified arborist to check the tree and make recommendations. Only an on-site visit or possibly a sample sent to our Plant Diagnostic Lab in Waldron Hall on the NDSU campus in Fargo could give you a positive determination. Address the sample to Kasia Kinzer at the above location. The zip code is 58105. Send it dry in a plastic bag at the beginning of the week. That way it won’t sit in the post office during the weekend.

Q: We have two small American lindens on our boulevard. The leaves are covered with raised green pods and some of the leaves are starting to look tough. Is this an insect or a disease problem? Is there anything we can spray on the trees? (Fargo, N.D.)

A: The trees in the boulevard are the responsibility of the Fargo Forestry Department, which you are charged for each month. Contact it for an evaluation of what is going on with your trees. It may be something that is cosmetic and not lethal.

Q: I planted three linden trees in the latter part of June. Right after planting, the leaves started browning and almost all the leaves fell off. The limbs seem to be alive and pliable. I will appreciate any help you can give me. (Portland, N.D.)

A: I suggest that you check the planting depth because many trees are planted too deeply. The crown should be even with the surrounding soil surface, not below it. If this is the case, pull the soil back to the crown. The fact that the stems are still green and flexible is a good sign that they may releaf next spring.

Q: We recently purchased a Linden tree. The leaves started dropping off in less than a week, so we watered the tree, but the leaves kept dropping. I used a root feeder to water the tree outside of the soil line. It did not help and the leaves kept falling. There are about 10 leaves left on the tree. Will this tree survive? Could the roots have been damaged because it was 92 degrees the day we planted the tree? My neighbor said I should not use a root feeder for a new planting. Is that correct? (e-mail reference)

A: The tree is going through transplant shock. Your neighbor is correct, the root feeder creates a hole where the water comes out and could contribute to the drying of the roots. Surface watering is more than adequate. Going into the fall, I would keep it moist, but not soggy. Chances are good the tree will leaf out nicely for you next spring.

Q: Some of the leaves on my linden tree are curled and shrunken. When you peel the leaves, there is a white substance near where the leaf is attached to the stem. Can you identify the problem and what can be done to fix it? My next question is about my apple tree. I think it is being “nailed” by a woodpecker. It is full of holes that look like they were made by someone pounding a nail into the tree trunk. They follow the circumference of the tree in a nice even line. Also, where I had previously cut a branch off the tree (and sprayed the area with the black spray paint to seal tree wounds), something has hollowed out a nice little cave. Is it a woodpecker that is having its way with my tree? I heard woodpeckers attack trees when they are infested with bugs. I lost a pussy willow tree a few years ago. It had the same type of holes in the trunk that are now on my apple tree. When I cut the pussy willow down, the trunk had live worms or larva inside of it. (West Fargo, N.D.)

A: The linden looks like it could be showing the results of leafhopper damage or herbicide drift from lawn applications to control dandelions and other broadleaf weeds. The apple tree is being nailed by yellow-bellied sapsuckers, which are in the woodpecker family. They are doing it because it is a smorgasbord of insect larvae for them to feed on. Your apple tree is likely doomed, but I can say exactly when. As to what is going to deliver the fatal blow, my bet would be with the disease problems the tree appears to have. The sapsucker is doing only what comes naturally.

Q: I have a little leaf linden that is doing great, but I have a problem with wasps. I’m sure it’s because of the nectar on the top and edge of the leaves. For the last few years there have been swarms of wasps flying from leaf to leaf. Is there something I can do to limit or completely stop them from bugging us? (e-mail reference)

A: I would suggest pheromone or nectar traps. The traps are sold at retail outlets that handle garden products. That way, no deadly pesticide has to be used and no one gets stung!

Q: I have noticed this year that the linden tree in our yard is attracting a lot of flies. Should I be concerned about the tree’s survival? (e-mail reference)

A: If you look closely, I think you will see some insects known as aphids or scale on the stems and leaves. These insects excrete honeydew from their feeding, which is a strong attractant for flies, ants and yellow jacket wasps. Aphids are easily controlled with contact sprays such as Insecticidal soap or Sevin. Scale is more of a challenge to control. The best route is to apply dormant oil next spring before leafing takes place. You might want to contact an International Society of Arboriculture certified arborist to inspect the tree and give you a recommendation.

Q: Our basswood was planted last August and has done well until now. The leaves are yellow and falling off. We have clay soil and did have a very rainy period. (e-mail reference)

A: If you haven't planted it too deep, and if you can allow the soil to dry without any supplemental irrigation, it may recover. You might want to contact the nursery where you purchased it to see if they have any advice. It sounds like it was suffering from too much water and not enough air in the rootzone during the rainy period.

Q: I recently found out the beautiful tree in my backyard is a linden. I brought a branch to my local tree spraying company and found out that the white spots on the back of the leaves are cottony maple scale. I've noticed them on the tree the last two years. What do you recommend as a treatment? Is there another alternative to spraying? (e-mail reference)

A: Give your tree company a chance to serve you since they identified the pest. There are summer oils and insecticidal soaps that can be applied that will help control this pest without polluting the neighborhood or putting you or your children in danger. If they are a good, full-service company with Certified ISA arborists, they should be able to offer you some alternatives other than a highly toxic spray. Some action needs to be taken because, if left unchecked, these pests will multiply and eventually weaken the tree, predisposing it to further attacks from other insects and disease organisms.

Q: We purchased two greenspire lindens about three years ago. I would like to know about making tea out of the flowers. Is there a better variety of linden to use or is the greenspire a good choice? Do I pick the small flower clusters as soon as they appear or wait until they dry? I have a dehydrator and need to know how or what to do to make tea. (e-mail reference)

A: The flowers are dried in a dehydrator. Harvest when fresh off the tree. Place one teaspoon in a cup of boiling water and allow to steep for about 10 minutes. Store the flowers in a clean, air-tight container in a cool location or freeze in a ziplock freezer bag.

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 love the looks of the small leaf linden and I hear they are a very hardy tree. Toward fall of last year I planted one in my front yard. I made the hole larger and filled it with gravel, sand and soil to help with drainage. Then we received tons of rain. I noticed the tree start to lose its leaves early as if it were going dormant for the winter. Will the tree survive? So far this spring it hasn't produced any leaves but the tree still looks like it’s alive. The branches are very flexible and it has buds but I’m not sure if they have swelled much yet. (Twin Cities, Minn.)

A: The person that told you what to do when you planted gave you some poor advice. It may be too late to reset the tree. If you can, don’t use gravel or sand because it’s not needed. If the tree has already leafed out, then let it go for the season and watch the water requirements. Replant it when dormant, either this fall or early next spring.

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 recently tried a delicious tea made out of the flowers of a linden tree. This made sense, after all, they do drip nectar. But I was wondering if the tree had to be a specific type of linden? If so, which type is best for making tea? I would really appreciate some help as I would like to purchase one, not only for its sweet scent and pretty form, but also to make some of that tea! (E-mail reference)

A: The flowers from the little-leaf and large-leaf linden (Tilia cordata & Tilia platyphyllos) make the best tea. If anyone in your family has heart problems, they should not consume linden flower tea. Enjoying it as an occasional tea for relaxation will do no harm but excessive consumption (5-6 cups daily) may cause heart damage over a period of time.

Q: I have a little leaf linden tree that we planted 11 or 12 years ago. I the past three years it has started to "sucker." I cut them off but they keep coming back. Is there a way to remedy this situation? (Marion, S.D.)

A: The best and only remedy available now is to cut the sucker growth back as it appears. Growth inhibitors for this purpose have been mostly taken off the market due to EPA regulations. If you can find a material that is used for inhibiting potato sprouting -- Maleic hydrazide, aka MH -- you may experience some success in keeping these vigorous growths at bay.

Q: We have a little-leaf linden in our back yard that has grown much too tall and too wide for the space. It is with great reluctance that we have to have it removed. Do you happen to know if the wood of the linden is "good" for anything? As I see it, our choices are: have the people who take the tree down haul the wood away, just stack it and dry it for burning (we have neighbors with fireplaces and wood stoves), or try to contact woodcrafter-type people who might be interested in working with it. Do you have any suggestions?

A: You are a very conscientious person! In the long run, it would be easier to simply have it cut down and hauled away. If you have it cut to firewood size, there will be a premium charge for doing so. And woodcrafters may or may not want it, leaving you with a pile to dispose of.

Q: I noticed my 10- year-old linden tree in the front yard is showing signs of trouble. The leaves are very small and some limbs do not have leaves at all. It appears some buds popped but got zapped by our cold weather this spring and never matured. I am encouraged to see some green on my tree although the linden across the street is fully leaved and looks great. Anything you can recommend to coax it along? I did lay the hose by the base to limit the stress of our dry conditions. (Carrington, N.D.)

A: Fickle Mother Nature, how she can frustrate us at times! If your linden has been where it is for 10 years or more, I don't think you have anything to worry about. There is bound to be some damage and the difference between the two trees could be the exposure they have as no two sites are exactly alike, and unless cloned, neither are the trees. Give it 30 days and I'll bet that the tree will green up nicely for you. Keep the water to it -- not soggy, but don't allow it to go too long without water if we don't get soaking rains on a regular basis. You might also want to give it a shot of fertilizer this month.

Q: I would like to purchase a American linden but I am not sure of the cultivar I am looking for. I first saw the tree when it was planted along the entrance and around the driveway where I work and fell in love with it. I found out it was a linden by taking a leaf to the garden shop. They did not have any of the trees in stock. The trees where I work are short and they grow in a shape like the dogwood. You wrote that there are many cultivars of the American linden on the market: Boulevard, Dakota, Douglas, Fastigata, Legend, Lincoln, Redmons, Rosehill and Sentry. Could you tell me which one I am interested in by the description I gave you? If I can't find the one I want around here, is it a good idea to mail order for one and if so where can I order it from? I would love to have that tree! (E-mail reference, Fort Washington, Md.)

A: The closest I can come to making a recommendation based on what you have told me are either the 'Dakota' or the 'Rosehill,' which do not grown in the upright or pyramidal shape but with more of a rounded, open crown that is roughly reminiscent of a dogwood tree. As far as ordering from a garden catalog, I advise against it for shade trees. For seeds, perennials, fruit trees, exotics, etc. the catalogs are usually fine. I would suggest that you contact the Maryland Nurseryman's Association (should be able to get their number from a local garden center or nursery) and ask where they could suggest getting such a tree. If you get no satisfaction from that route, then I suggest making contact with their counterpart in Pennsylvania. They have a huge, functioning organization. I share your love for Lindens. I have one (Redmond) planted in my front yard.

Q: Our linden tree was planted two years ago. It is approximately 10 feet tall and doing rather well except that it has developed vertical cracks in its trunk. There are several, all on one side and running up about 10 inches, some of which are 1/4 to 3/8 inches wide. It is as though the tree had a growth spurt and the trunk couldn't keep up with it. I'm concerned that this might encourage borers. Is this normal for this tree, and what if anything should be done? (E-mail reference)

A: Splitting like that is not normal. I assume you purchased the tree locally. Since I don't know where you live, this is important, as there are differences in trees coming from different parts of the country that can affect their hardiness. There is nothing to be done except to wait for it to heal naturally over the ensuing years. As autumn approaches, wrap the tree to protect it from further sunscald damage, and avoid pruning any lower branches for at least the next two to three years, to provide shade protection on the trunk. Lindens are pretty tough. I don't think you have anything to worry about.

Q: I am looking for some good mail order companies to purchase American linden/basswood trees. (E-mail reference)

A: When it comes to making a purchase like a Linden tree, I am against shopping via mail order catalogs. You are much better off going to a local nursery or garden center and making a selection for yourself. You will pay more, but you will get it back in spades with quality and guarantees from the local nursery.

Q: We planted a Linden (Greenspire, I believe) two years ago. It appears to be struggling. It’s about 12 feet tall. The outer branches have clumps of growth with green heart-shaped leaves and yellowish fragrant flowering. Nearly all of the green leaves have a slight curling, but are not completely curled or damaged. However, clumps of leaf/flowering are sporadic along the outer branches. At some points there are 1-foot stretches of bare branch between growth clumps. There is growth on the tips of all outer branches. We planted the tree in a lawn area that is watered three or four times per week for 45 minutes during the hot summer season. The lawn area is ever so slightly sloped to the tree. Did we plant this tree too deep? Or could we possibly being drowning the tree with too much watering? (E-mail reference, Erie, Col.)

A: Trees--lindens especially--and lawn sprinkler systems are usually not meant for each other. In the situation that you described, I would say it is being drowned from too much water. I also advise you to replace the tree. It might live, but it will likely not be a property asset. Lindens are beautiful trees--one of nature's finest and most beautiful--and can be a real asset to your property. Replanting (or having it done for you) with another will reward you down the road with a tree that will increase the value of your property. Also, I would suggest you get an irrigation contractor in to have them adjust your sprinkler system so the water stream is not impacting the tree. It can be done for little cost, and it will be worth it!

Q: In late spring and summer the most incredible fragrance comes from these trees down the block. I took a branch with flowers to a florist to find out what kind of tree it was. He said linden. A quick search on the Internet revealed that there are different kinds of linden trees. Can you point me in the right direction to find out exactly what type of linden tree these are and how I might someday be able to fill a backyard with them? The scent is so addictive I have become obsessed. (E-mail reference, Chicago, Ill.)

A: Linden blossom fragrance can create a fantastic environment. You'll make all kinds of points by planting a little leaf linden. Some of the cultivars to consider are Greenspire, Norlin and Shamrock. American linden cultivars to consider are Legend, Redmond, and Sentry. I suggest visiting a local garden center to see what they have available and make a selection. You cannot go wrong with any of these that I mentioned. They simply have different forms of growth and vary in eventual height and spread.

Q: I want to plant some fragrant linden trees on my farm. I also wish to raise honeybees. While reading an article on linden it was noted that some lindens were toxic to honeybees. Unfortunately, the article didn't specify which are. I am hoping that you would know and be able to advise me which lindens are known to be nontoxic to honeybees. Also, which linden would grow in zone 7/6. (e-mail)

A: The linden that is toxic to bees is Tilia tomentosa, or silver linden. The American linden--T. americaniais used for honey production, and has a high market value. It is hardy in your area as well as up here in certain locations. There are many cultivars of the American linden that you will find on the market: Boulevard, Dakota, Douglas, Fastigata, Legend, Lincoln, Redmons, Rosehill and Sentry.

Q: We want to plant a couple of backyard shade trees next spring, probably basswood or ash. In a recent column you spoke of Autumn Blaze maple. I am not familiar with this tree. How might it compare overall with ash or basswood?

Also, last fall I put in a grape. It really grew this year, but no blossoms. Do you need two? Should I cut it down for winter? (Aneta, N.D.)

A: The Autumn Blaze maple has striking fall color--red to orange,whereas the ash has yellow only and the linden has none. As far as dependability goes, you won't go wrong with any of them.

I assume you planted a Beta grape. If so, there is no need to do anything. Anything else needs protection by laying the vine over in a trench.

Q: The leaves from my linden tree are telling me it has a problem. Will it kill the tree? (Parkston, S.D.)

A: It looks as if your linden is suffering from a fungal leaf blight and environmental stress. Control the blight next spring with a spray of bordeaux mixture, ferbam or zineb at bud break, again when leaves are half grown, and finally when fully expanded. Don't allow the tree to become drought stressed. Water deeply once a week if there is inadequate rainfall.

Q: Enclosed is a leaf from a Linden basswood tree. I just planted it last year, and this year it appears the leaves are full of rust or fungus. This has occurred in the last few weeks. There was no sign of it earlier. Is it serious? What can I do this year or next to prevent this happening again? (Portland, N.D.)

A: You have a couple of things wrong with your tree: scorch along the leaf edges and Cercospora microsora--a leaf spot fungus. I am also concerned about the size of the leaves. I suspect that your tree may be planted too deeply. If this is the case, dig it up and re-set it this fall or next spring while it is dormant. This action alone may correct the problem.

Spray the tree next spring with a lime sulfur mixture before it leafs out. Then follow up with Captan or Benomyl after the leaves have unfolded. But I encourage you to seriously check the way the tree has been planted. If improperly done, or planted too deep, all the spray in the world will not make a difference.

Q: My American linden tree is 3 years old and has hardly grown up from its original 5 feet! It leafs out in the spring and then the leaves start to curl and it looks sick. (Reeder, N.D.)

A: Your tree is a little leaf linden--same genus, different species. Not an important distinction in addressing your problem. The symptoms your tree is showing is leaf scorch - brought on by a couple of environmental factors: windy exposed sites and high soil pH and soil salts. Both of these situations are not needed for this effect. These are beautiful trees with the investment in time and effort. Try spraying them with an anti-desiccant next spring after full-leaf expansion. A commonly available one on the market is Wilt-Pruf.

Q: Can you tell me what is wrong with my ash trees this year? They are a little curly and dried out. I also am wondering what is wrong with my basswood tree? (Sioux Falls, S.D.)

A: There are a couple of problems. Some of the spots are symptomatic of ash anthracnose which hit the tree earlier in the year, and the other is more serious—it appears to be an environmental problem—salts accumulating, drought stress, excess water in the root zone or some spray damage. The symptoms are not distinct enough to say exactly what the cause is. If possible, core aerate around the dripline of the tree and be sure to pick up all fallen leaves this fall.

Your basswood appears ravaged, but it does not appear to be suffering from herbicide damage of any sort. Most of the problem appears to be physical—hail or insect damage—or perhaps planted too deeply? These are generally easy trees to grow, so this one must have gotten off to a bad start. If the tree is still small, you might consider replacing it, or you can try nursing it along with a couple of applications of Miracle-Gro.

Q: Last fall we noticed numerous bugs invading our linden tree. At first glance, the bugs resembled box elder bugs, but we don't think they were. The tree has many holes bored into the bark but looks healthy this spring. Will this kill the tree? Will the bugs spread to other trees? What can we do to get rid of the bugs? (Enderlin, N.D., e-mail)

A: The insects you saw could be any number of characters, as the lindens are not subject to severe attack from any particular species in our region. With the numerous ashes that we have planted, it could have been the redheaded ash borer, the apple tree borer, or it could have been a social species of insect that caused no direct damage to your tree. The holes could have been a coincidence of activity from the redheaded sapsucker. If the holes appear as a ring around the tree, that is the likely culprit.

You say the tree appears healthy now, and if that is the case, I would leave well enough alone, and not spray anything unless positive identification can be made of the problem. The best protection against borers is to maintain a healthy tree—most especially keeping it from becoming drought stressed. The stressed tree appears to be a "flag" to attract the borers in the area, making a bad situation worse.

Q: I would like to know about a tree, which has no name as far as I'm concerned. The leaves get very large, about the size of your hand. Then later on in the season it gets little white cluster of  lowers which smell very sweet. Also, they drip sticky juice, almost like honey. I would like to know the name of the tree because it has beautiful foliage. (Litchville, N.D.)

A: Piece of cake! American linden. One of my favorites. Which cultivar, I can't tell, but at least you know the species!

Q: I would like your opinion of good varieties of American linden trees and which ones would not be desirable for the Grand Forks area. (Grand Forks, N.D., e-mail)

A: A good cultivar of American linden? They are all good, with differing characteristics. First of all, the "pure" cultivars of American Linden: Dakotah American linden, a South Dakota introduction (but rarely available); Front Yard linden, an introduction from Bailey Nursery of Minnesota; Boulevard American linden, dependably hardy for all of North Dakota and developing a narrow, pyramidal form that gets approximately 50 feet high and 25 feet wide; and Redmond linden, a nice pyramidal form and one that I have on my property, which is doing quite well after getting off to a slow start.

Then there are the American linden hybrids: Dropmore linden, Glenleven linden, Norlin linden, Shamrock linden and Wascana linden.

These are all northern introductions that should do well in your area. I have no data on their rates or forms of growth. I would suggest sticking to one of the cultivars rather than the hybrids and visiting a couple of the local nurseries or garden centers in your area to see what else they can tell you besides what I have listed here. I would definitely recommend purchasing locally, rather than through a mail order catalog in this instance.

Q: Enclosed is a sample of leaves from my linden trees. Can you tell me what is causing the leaves to curl and turn brown and what to do to cure the problem? (Moorhead, Minn.)

A: Your lindens are showing a number of problems: herbicide injury, a fungal leaf spot disease, and root zone problems—either a root-rot, elevated water table, solid compaction, or some of all the above!

With the herbicidal injury, (curled leaves) you can only hope the trees will outgrow that. With the fungal leaf spots, spray new foliage next spring with an all-purpose fungicide, like Daconil 2787. With the root problem, either reduce watering, move the plants, raise them, cone aerate or accept the fact they will die in a year or so.

Thanks for writing. Sorry the news wasn't better.

Q: Enclosed is a twig from my basswood tree, and I'm wondering if I should spray the tree this fall. It seems to have a cottony growth, and the leaves are already almost all off the tree. Can you tell me what can be done to save the tree? (Ada, Minn.)

A: Spraying when the tree is dormant (free of leaves either in the fall or early spring) with dormant oil will kill the cottony cushion scale that have heavily infested your tree.

Once free of this pest, the tree should rebound nicely provided it has not been weakened extensively.

If all leaves have dropped off by the time you receive this, scrape the bark back on a twig with your thumb nail and see if the cambium is still green. If it is, use the dormant oil now and again next spring. If the cambial tissue is brown, check several locations on the tree. If they are all brown, then it is too late—the tree is dead. Good luck I hope you can save the tree!

Q: Can you tell me what is wrong with this tree? It seems to be losing its leaves. (Harvey, N.D.)

A: The tree leaves are from what appears to be a Redmond linden. The plant is suffering from a disease known as leaf blight (Cercospora microsora). Control by gathering and destroying fallen leaves. Next spring, prior to leaf-opening, spray with lime-sulfur.

Apply Benlate after leaves fully open, but before the spotting on the foliage develops.

Q: My sister in Spearfish, S.D., has this tree in her front yard and no one can tell us what kind of tree it is. It is huge with these beautiful big leaves. (Bison, S.D.)

A: The sample was in excellent shape, thank you!

The tree is American linden or basswood (Tilia americana). They do get quite large, and are quite durable for our prairie region of the country.

There are several cultivars which this tree may be one of:

Dakota, a round headed form introduced by Ben Gilbertson from South Dakota. Redmond, perhaps one of the most handsome street or lawn trees in the United States, with a dense, pyramidal shape.  Rosebill, an improved, faster growing selection that develops an open crown.

Q: I have a Norlan linden that has been leafspotting two of its three years of life. Last year it lost its leaves three times, but it leafed out again each time. The leaves discolor and soon dry up and become brittle. Can you please tell me what I can do to remedy this problem? Enclosed is a sample. (Mohall, N.D.)

A: The linden sample was very symptomatic of anthracnose. You can spray with Bordeaux mixture to help control the spread when it is in leaf.

Next spring before leaf-out, but just as buds are swelling, spray with lime sulfur. After leaf-out, spray with Bordeaux mix two to three times more at two-week intervals.

Q: These hackberry and linden leaves are from trees planted last year. They were translucent, yellow and puckered. (Mohall, N.D.)

A: The samples you sent me showed extensive herbicide damage (likely 2,4-D). They are likely not to survive.

Q. I never miss reading your column in the Sun Country. It is very helpful. I want to plant old-fashioned lilacs, either a sugar maple or Norway maple, and an American linden, all purchased from Gurney's. Can I still plant them this fall, and do you have any hints that will help them survive our winters? Thank you. (Sykeston, N.D.)

A. Gurney's is a regional mail-order supplier, and their stock is usually quite successful at getting established in our area.

First, I suggest you stay away from those two maples and go with the linden. The biggest mistake people make is planting too deeply. When the stock comes in, note the soil line on the trunk and plant to that depth, water in well, but do not fertilize for   the first year. Healthy stock should take off next year.

Q: In our courtyard in southern France we have planted one linden/lime tree three years ago (that's all there is room for). It was 12 years old and has grown well since then, but last year we detected dark scraggly tears on the bark going up the trunk, mostly about 1 to 2 inches long. In addition, we noticed two holes going into the trunk, higher up, which were deep and wide enough to put four fingers into. At the place where we bought the tree, they suggested that it has worms, which eat the tree from the inside. We started to spray it once a month with a liquid insecticide with but stopped during the winter because some branches had become dry and brittle and broke off. Now the tree has produced large bright green leaves, so at least some of it remains healthy. But we don't know whether the spraying eliminates the pest. What kind of pests befall such a tree? Someone visiting from the United States suggested to do a root treatment. What is that, and how does one do it? I can't very well supply you with a sample of a branch, but I would really appreciate hearing from you. (Geneva, France, e-mail)

A: Most likely your tree is being infested with a European cousin of the American plum borer, or the redheaded ash borer. Once they have infested the tree, it is almost impossible to control their damage. Eventually, they will destroy the entire tree. My suggestion is to remove the tree and have it replaced with something available locally that is more site adapted. Local nursery personnel should be able to help you with a selection. Spraying the tree or injecting it with anything now is of no use. It is simply a waste of time and money, along with putting unnecessary pesticides into the environment.

Q: I am noticing a problem with a linden tree that the builder installed at the front of the house. I am enclosing a leaf cutting. The tree is approximately 13 feet high now and is planted inside of a built up stone wall. It is approximately 8 feet from the front window of the house and 5 feet from two sides of the stone wall. From what I have read about the size and shape of this tree, it appears to me that this tree is not appropriate as part of the front foundation planting and that it will cause problems in the future. (Somers, N.Y.)

A: Your linden is a cultivar of the littleleaf linden - Tilia cordata - most likely the ‘Greenspire’ which is one of the most common cultivars on the market. This is an excellent shade tree for lawns and other large areas. The problem will likely come not with the roots, but with the tree’s spread. This cultivar can reach 40 feet in 10 years, with a 30 foot spread. The roots are deep, coarse laterals, so they should not exert any lateral pressure as a silver maple or American elm would. These trees do prune beautifully. Europeans often shape them into hedges, so the spread can be easily controlled on your part, if you so choose. If you can, get your contractor to move the tree further into your lawn to compensate for the eventual size. Do this either in the fall or early spring when the tree is leafless (dormant).

Q: I have a Redmond linden, planted in 1983, which has become a very nice tree. Someone told me that they are shaped like a deciduous fir, tapering to the top, and I find this is true. My question is how close to the ground to let it grow? I have removed some of the down-growing bottom branches so that it clears the ground and the trunk is probably clear up to about 4 feet. Is there a guide to growing these trees? (Ellendale, N.D.)

A: What you are doing with your Redmond linden is correct. If you wanted to limb it up farther, that would be correct also. In essence, whatever you are happy with! It is your tree. The small leaf-like appendages are bracts that drop after the flowers. They break down easily and blow away quickly. This temporary mess is a small price to pay for such a beautiful tree. 

Q: Can you tell me what kind of tree the enclosed sample comes from? Also, are little leaf linden trees fast growing and what size is a good one to plant? (Larger the better, right?) We also have to reseed our front yard and I am wondering what kind of grass to plant? (Walhalla, N.D.)

A: The partial leaf sample looks like a green ash. If they are oppositely arranged on the stem, that’s what it is. If not, it’s something else. Lindens take two to three years establishing their root system with very little aerial growth being evident. Then they take off, being moderately fast growers. No, the smaller the better, as less of the root system is disturbed or lost. I’d suggest a 5- to 15- gallon container- grown tree for best results. For the lawn I’d suggest Fairway Crested Wheatgrass without knowing another thing. Now is the time to get it established. Sow at 4 to 5 pounds. per 100 square feet.

Q: We have what we think is a large leafed linden in our front yard. Every couple years or so, the tree produces billions (upon billions!) of quarter- inch round green pods or fruit which turn brownish grey, dry up and drop to the ground. When this happens, it seems that the lawn beneath suffocates; the grass gets sparse, and is not as green. Trying to rake up these round pods is totally futile. My questions are, first, is this a linden, and second (actually a lawn question) is there anything I can put on the lawn to sort of break down the pods faster? (E-mail reference, Chicago, Ill.)

A: I cannot tell for certain of course, that what your are describing is a linden, but it certainly sounds like it. If it is, this is the first time I have heard of the linden fruit causing anything other than a temporary mess on the lawn. While I know of nothing that you can apply that will break these "pods" down, I suggest vacuuming them up with a rotary mower with a bagger attached, whether or not the lawn needs mowing. If that doesn't work, try renting a "Billy Goat," which is a lawn vacuum that sucks up everything but the rooted grass (hopefully)! Lindens and lawns are completely compatible; that is why they are so frequently used in landscape situations.

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