More recent landscape questions and answers

Horticulture

Mum problems

I have nine mum plants in pots. They are wilty, breaking off, drooping and not looking very healthy. Some flowers are turning brown as well. I have also noticed a large amounts of flies, moths and flying bugs around them. The pots are located in partial shade and are not being over or under watered. What is going on with my flowers?

My first guess would have been overwatering, as what you describe sounds exactly like too much water. Are the pots draining properly? Are they pots you have used in the past, or pots that came with the mums? There may be something in the soil feeding on the base of the plant and roots, causing deterioration, and the other insects are byproducts coming in to feed on the decomposing material.

Mary K. Kroening
Horticulture Specialist

Cottonwood suckers

I have a cottonwood tree which continually sends up shoots from its roots. Unless I cut off each one by hand a complete thicket soon surrounds the tree. Is there any way to discourage the suckers other than constant hand pruning?

There is a product called Sucker Stopper, manufactured by Monterey Chemical Co. This is a growth regulator that can be sprayed on the cut surface of the suckers just after you cut them off. It will probably not totally eliminate the problem, but it should reduce the suckering somewhat.

Chris Starbuck
State Extension Specialist
Woody Ornamentals

Green egg-shaped fruits on vine

I have a vine growing in my backyard that has green egg-shaped fruits. The leaves have points. What is it?

One possibility that fits your description would be maypop passionflower (Passiflora incarnata), a vine that has three-lobed leaves and egg shaped green fruit at this time of year. Maypop information and photos are available at the United States Dpartment of Agriculture's PLANTS Database.

Simeon Wright
Plant Diagnostic Clinic Coordinator

Euonymous appear sticky and white

I had 10 euonymus sunspot shrubs. Last year, only one lost all of its leaves and it was sticky and white. I removed it. Now two more have the same problem and it seems to be spreading to surrounding shrubs. Is this only common with this type shrub? What do I need to do?

In Missouri we sometimes see high populations of scale insects on euonymous that cause the plants to appear sticky and white. See photo right. Information on scale insect management can be found in G7274, Aphids, Scales, and Mites on Garden and Landscape Plants.

Simeon Wright
Plant Diagnostic Clinic Coordinator

Right time to prune pin oak

I have mature pin oak I bought from a nursery and planted in 1980. It has a few dead, lower branches that I would like to remove, plus I need to prune some larger, higher branches that overhang our roof and our neighbor's driveway. I have read many articles. Some say not to prune oaks from April through October to prevent oak wilt. Some say to prune in dry weather, July. Others say prune in late winter or very early spring, but not in the fall at all. Still others say prune just before leaves form in early spring. My neighbor wants me to prune them now. Is it safe to prune in mid-October or is it better at a different time?

As you seem to have found in your reading, the main reason to avoid pruning oaks during the growing season is that the sap coming from pruning wounds is attractive to a beetle that spreads the oak wilt fungus. In my opinion, there is little likelihood that the beetles will be active this late in the season. So, it should be okay to prune off the lower, dead branches. To be perfectly safe, you might convince your neighbor to let you hold off on pruning the larger branches until the plant is fully dormant in mid to late November. In my opinion is should be fine to prune any time between November and mid-March. The larger branches sound like a job for a professional.

Chris Starbuck
State Extension Specialist
Woody Ornamentals