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Sprouting tulips should be left alone in the cold

Q: I have two maple trees, but only one leafed out last year. They both had buds. I suspect the one froze out. Will my tree leaf out this spring? I also have a big perennial garden with two arbors. Both of them are covered with honeysuckle vines that are 10 years old. Last year, both vines were covered with aphids.

I didn't bother to spray them because the vines are very large and thick. I didn't think that I could get them all. Will aphids kill my vines or will they be OK? Should I cut them back all the way to the ground and let them start over?

A: The failure of a tree to leaf out in the spring could be due to a number of factors, such as root rot, verticillium wilt, borers girdling the tree's cambial tissue or freeze damage.

If no leaves emerged in 2009, then I am certain there will be none this year because the tree is dead. Mother Nature has designed trees that are adapted to our area to have more buds in reserve that would not be vulnerable to freezing out. This means there will be a late flush of leaves to get the plant through the summer.

Now let's look at your honeysuckle vine. Spraying into the canopy is not something needed any longer with plant-feeding insects. There are systemic insecticides that can be applied around the base, such as Bayer Advanced Tree and Shrub Insect Control that will kill them as they feed.

You can cut them back early this spring before new growth begins. This is a good idea because the new growth generated by the energy stored in the crown would pick up the systemic insecticide and offer protection to the plant through the growing season. It would be more effective on the new succulent growth where the aphids would be feeding.

Q: Our tulips have sprouted even though the temperatures are in the 10-degree range and we have snow. Should we cover them, dig them up or what? The ground is frozen.

A: They should be OK, so leave them alone. Anything you would do to them would cause more harm. Tulips are winter weather hardy. The biggest threats to the plant are field mice and rabbits, which would be attracted to any covering you place over the plants.

Q: For the second year in a row, my cucumber vines died midsummer. The problem then spread to my squash and pumpkin vines. I have been told this is caused by something in my soil. I also saw on the Internet that cucumbers and squash should not be planted next to each other for more than a year. Do you know the reason for this? If I plant my cucumbers on the opposite end of the garden, will that help fix the problem this year?

A: Crop rotation every year fools diseases and plant-destructive insects into not settling in and raising a family. Continuous cropping with the same species or family of vegetables will encourage the entrenchment of these characters, so the gardener will be fighting a losing battle. In a nutshell, the more you can plant away from or use different crops (cucumbers followed by beans, for example), the lower the incidence of disease and insect problems. Also, look for disease-resistant cultivars when making seed purchases.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail