hom Use Roundup with extreme care
BY KEITH STANGLER
Q. Can I use Roundup under my evergreen trees?
A. Yes, so long as you do not get any Roundup on the evergreen foliage. Even a little drift will cause injury, especially now when your trees have new, tender growth. It would be safer to use Roundup there in the fall when the new growth has "hardened," and is less susceptible to Roundup injury.
Q. We have a three-year-old clump birch. This year two of the three stems leafed out really nice but the third has no leaves at all. We are planning to remove the stem that shows no sign of life. Would you guess this to be a result of birch borer?
A. It is difficult to me to speculate why that part of the clump died without seeing it. Birch borer injury usually shows up at the very top first, the top one-fourth or one-third failing to leaf out, but the rest of the tree looks normal. The next year, more fails to leaf out -- just lower than the first dead area. This proceeds downward until the tree is entirely dead. That one stem that is dead was possibly injured in the digging/transplanting process, possibly the root was injured or just not enough root taken for that one tree. Whatever the reason, you can still enjoy your two-stem clump.
Q. What are some good pear tree varieties to plant here? I do not want any that get too large. I know I have to plant two different varieties so they will cross.
A. Parker, Patten and Luscious are all good varieties. I saw Bartlett offered in a local garden lot recently. Don't buy Bartlett, even though it is a very good quality pear -- it is just not hardy enough for long-term survival here in Zone 4. Purchase dwarf trees for smaller size. Your local county Extension office has a University of Minnesota bulletin on fruit varieties good for southern Minnesota. You just might pick one up for some entertaining reading.
Q. The leaves on my maple trees have some small, some large brown areas on them. The brown areas are not round or square, just patchy on the leaves. Should I be concerned?
A. This is probably a fungus disease called Anthracnose. Anthracnose is fairly common here, usually showing up after a cool, wet period (remember May?) This disease results in some leaf drop, a nuisance to the homeowner, but is seldom life-threatening to the tree. It is worse some years than others, depending on weather. A newly planted tree might benefit from a couple of spray applications a week or 10 days apart to prevent further infections, but established trees seldom warrant treatment.
Q. We planted two new shade trees a month or so ago and since then the soil there has settled and now our trees are 3 to 4 inches lower than the original soil around them. I know that shade trees should not be planted lower than they were at the nursery. So, do we dig them back up and re-set them, leave them alone, add soil to bring it up to the level surrounding the trees, or what?
A. This problem resulted from digging the hole too deep at the start, then adding loose soil back in the hole so the tree would be planted at the proper depth. When the hole is dug to exactly the correct depth without having to add loose soil back in to achieve proper depth, this problem does not occur. The best solution now would be to wait until the leaves fall from your tree this fall, then replant the tree at the correct depth.
Keith Stangler has 36 years experience as a horticulturist. For comment or questions call (507) 285-7739 or (800) 562-1758.