---

Codling moths have become one the most serious pests in Minnesota orchards. It is the larva, not the moth that is responsible for all the destruction.

The first codling moths appeared around 1750. It was accidentally introduced in the eastern parts of the United States. As pioneers moved west and settled, the codling moth went along with them. Originally the insect was a native of Europe, but now can be found in all parts of the world.

The codling moth winters in its larvae stage in a cocoon which is about three-fourths of an inch long. The worm just about fills the cavity of its homespun winter shelter. Cocoons are usually found under the loose bark of trees, in cracks and crevices of tree trunks, and attached to the trunk just below the surface of the ground. They can also be found in protected places in boxes, sacks, trash and packing sheds.

The adult moth is grayish with a chocolate brown patch and some bronze metallic scales at the tip of each forewing. Body length is about 9 mm or 3/8 inches long with a wing span of 20 mm long.

The larva is a pinkish-white caterpillar with a brown head capsule. Body length is about 15 mm when mature. The larva feed inside the fruit and on the seeds. They overwinter as a mature larva.

There are two types of codling moth injury. One is superficial stings, and the other is internal injury to the fruit. Superficial stings occur when larvae penetrate the fruit skin but are unable to continue inward. Some factors include unsuitable weather and insecticide sprays. This type of injury is common with first generation larvae.

Internal injury results when larvae successfully penetrate apple skins, making deep entry into the fruit core. The developing larvae burrow within the fruit leaving frass that looks like rotting fruit. The larvae will exit the apple leaving a small hole on the side of the fruit.

Before I realized I had codling moth in my orchard, I thought the hole on the side of the fruit was caused by twigs punching a hole on a windy days. One only had to open the apple to realize that there was a real problem.

Another problem, especially if you sell apples is the fruit may look fine on the outside, but may be seriously damaged within.

It's difficult to write about control of the codling moth. Those that grow apples for a living use tarps, count degree days, and use a multitude of chemicals to control this pest. Those that have a few trees are very limited as to what they can do.

Most available pesticides are targeted against the larvae. The timing of application of treatment depends on the material being used to target the pest stage.

Different classes of insecticide that are available include Guthion, and Imidan which are broad-spectrum pesticides. Confirm, BT and Spinosad are reduced-risk pesticides. I would suggest you ask a feed store for help but be sure the label says it is for controlling the codling moth and be sure to follow the label.

+++++

The popular Monday night plant clinics have begun! On Mondays, from 4:30-7 p.m., volunteer Master Gardeners are available to answer your garden questions.

You can stop by the office at 38780 8th Ave., in North Branch, or you can call the Extension office at 651-674-4417 to speak with a Master Gardener during this time.

+++++

Chisago County

Master Gardeners sponsor speaker on global changes in Minnesota forests

Lee E. Frelich who is the Director of the University of Minnesota Center for Hardwood Ecology, St. Paul, and senior member of the graduate faculty, in the Natural Resources Science and Management, Ecology, and Conservation Biology programs will be speaking on Global Change in Minnesota Forests June 26, at 6:30 p.m., at the Senior Center (located at the corner of 6th and Maple Streets) in North Branch. There is no charge for the class.

Climate warming will cause a northward range shift of a few hundred miles for most tree species native to the region. In addition, warmer temperatures will facilitate change in native insect communities, invasive earthworms, invasive plants, invasive tree diseases and pests, and higher deer populations. All of these factors will work together along with the high rate of change to transform forests to an unknown transitional vegetation type, and eventually after several centuries to different forest types or to savanna like vegetation.

He teaches a course on the ecology fires and other disturbances in forests. Frelich is the author of 60 scientific publications on forest ecology, and has been listed among the top 1 percent of all scientists in the world by the Science Citation Index in the Ecology and Environment category. Frelich and graduate students have appeared more than 100 times in the news media including such venues as the New York Times, Wall Street Journal, CBS Radio Osgood Files, public radio and TV, Newsweek and National Geographic.

Frelich is also Vice President of the Eastern Native Tree Society, and Chair of the Minnesota Department of Natural Resources Commissioners Advisory Committee on Natural Areas and Nongame Wildlife. Current research interests include: the big blowdown of July 4, 1999, in the BWCAW, invasion by exotic earthworms in forests, impacts of deer browsing in forests, and regional patterns of tree height in the eastern U.S.

---