Column
Bagworms, Pruning Evergreens, and Pumpkins
By John Fulton

[June 15, 2015]  Bagworms - Bagworms are an insect that conjures up images for many people. There are bagworms, and there are other larvae that live in a bag for at least part of their life cycle. We have bagworms, Eastern Tent Caterpillar, and Fall Webworms.

For the true “bagworm,” the insect that constructs a small bag like an ice cream cone from the leaf material of the tree or shrub it is on, the year-in and year-out treatment time for bagworms is June 15. You can mark this date on your calendar for next year and be within a few days of the correct treatment time. With a very cool spring, a week later may be a possibility This season’s yo-yo temperatures really even out. The idea is to have all the eggs hatched before treatment.

The next problem is what to use. The traditional standby has been Sevin, but the B.t. products such as Dipel and Thuricide have really taken the majority of the market. Many other products will work, but the B.t. products have several good points including safety to mammals and toxicity to larger bagworms. Since they are bacteria that affect only the larvae of moths and butterflies, it does take a while for the bacteria to build up to the point where they can kill the bagworm. I won’t get into the discussion about Monarch butterflies lighting in the tree just after treatment. And an item to note: there are several different strains of B.t. now on the market. One is for control of mosquito larvae, so make sure you get the correct one by reading on the label what insects will be controlled.

If you are in doubt about whether you have bagworms, check your trees and shrubs around June 15. You can actually see the small bags as the larvae build them. They become very noticeable at about 1/16 of an inch long. Treat bagworms early, since larger ones are more difficult to control, but try to ensure the eggs are all hatched out.

Most people think that bagworms only affect evergreens. Evergreens seem to be their preferred host group, but bagworms have a huge number of potential hosts. Through the years I have seen them on oak trees, grape vines, apples, and about any other growing thing you can think of.


Pruning Evergreens

This is the time of year, the last half of June, to prune evergreens. This includes both needle-type and broadleaf evergreens. If you’re wondering what a broadleaf evergreen is, that includes holly, rhododendron, and azalea. The logic behind pruning your evergreens at this time is to allow sufficient time for regrowth to become hardened off before winter, and to keep new growth from becoming too rank before the winter months.

Pruning evergreens is part art and part science, but mostly art. A few simple rules to follow make the job results much more pleasing. Upright growing evergreens, such as pines and spruces, should not have the main leader cut off. This will destroy the natural shape, and will make the resulting growth more susceptible to breaking off. If individual branches are being cut off, they should be cut back to a bud. This will allow the bud to become the new main branch. You can also control growth direction of branches in this way. If you are growing trees for cut Christmas trees, all bets are off, as you are only dealing with trees through the first seven years of their life or so. 

Make sure you use the proper equipment. Individual pruning cuts are best done with bypass loppers or pruning shears. These make clean cuts without much damage to the remaining wood. The old anvil type shears and loppers cut to a point, then crush the remaining wood. For yews, junipers, and arborvitae that are trained to a certain size of shape, you will want to use hedge shears (electric or manual) that are sharp and properly tightened. Most of these types of shears can cut up to about a quarter of an inch in size.

When pruning evergreens, remember the “dead zone.” This is the area toward the center of the plant that doesn’t receive much light. It also has few needles or active buds. Cutting into the dead zone will cause many years (or forever) of little green growth. Also remember to prune so that the base of plants is wider that the top. This allows sunlight to hit the bottom area as well, and keeps plants from browning from the bottom up.


Pumpkins

The primary use of pumpkins grown at home is for the Halloween symbols that we have come to know. The correct time to seed pumpkins for use at the end of October is around June 15, or Father’s Day. Earlier seeded pumpkins tend to mature earlier and are rotten by the time you want to display them. Make sure you keep plants, especially new runners, treated for vine borers. Beetles that can transmit wilt virus also must be prevented with sprays or dusts.

[By JOHN FULTON, COUNTY EXTENSION DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]