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We receive many calls this time of year regarding pest control of fruit trees, mainly apple trees. There are many kinds of insects ready to invade your fruit trees and unfortunately it takes insecticides to control them. There are gardeners with one or two trees who use organic control and to them I say, "If it ain't broke don't fix it." I have tried organic control for my 85 apple trees and it was a disaster.

One of the insects that is a pest for most apple trees is the apple maggot fly. The apple maggot is native to eastern North America. They have one adult generation in Minnesota from late June to early September. They develop from eggs laid in the fruit by small black and white flies. The flies begin to emerge from the soil where they have wintered during the winter. Once they leave the soil it takes about a week and they are laying eggs. Many eggs may be laid in a single apple and are inserted under the skin of the fruit.

A mistake beginning gardeners make is with the sticky red ball traps. These traps do nothing to control the apple maggot, but only tell you when to spray. Another mistake is to spray at the wrong time and using the wrong type of spray.

Use a general orchard (all-purpose fruit tree) spray, which can be purchased at most garden centers. The best of all is if you can find a garden center or feed mill where they are really up on their knowledge of proper pest control. The next best spray could be Sevin or Imidan.

The first injury is due to adult female egg-laying punctures tunneling inside the fruit resulting in brown streaks and decay. This should not be confused with plum curculios. This insect can infest up to 90 percent of unsprayed apples in a home yard. These insects over winter as adult weevils in the plant debris on the ground. Curculios are not quite 1/4 inch long. They have mottled brown, black and gray coloring and a bumpy appearance. They move to apple trees to lay eggs about the time the trees bloom. As the female weevils deposit their eggs into apples, they create crescent shaped scars on the apple skin. Severely attacked apples become deformed and knotty-looking. Larvae feed for about two weeks then exit from fallen apples and pupate in the soil. They later emerge in the summer and hibernate. There is one generation per year.

The codling moth is becoming the main problem in Minnesota orchards. They over winter as mature larvae. The moths start to appear in spring as the last petals fall from apple blossoms. Female moths lay eggs on fruit and nearby leaves, which hatch in 6-14 days, depending on temperature. Codling moths can damage apples by burrowing through the apple into the core, either from the side or from the end. This causes small damaged areas as where the larvae start to feed but then stop. After feeding for about three weeks, full grown larvae exit the fruit in late July and pupate on the trunk or larger branches of the tree. A second generation can occur starting in late July or August.

The control of plum curculios and codling moth is most effective if applications begin 7-10 days after petals fall and then every 10-14 days therefore through-out the season. When you purchase a spray for these insects be sure that the spray you buy controls the insects you are trying to control. Always read the directions on chemical use and apply according to the directions.

We receive many calls about tree problems, but trying to diagnose a tree problem over the phone is like calling the doctor and expecting him to tell you what is wrong when you have a fever. The Master Gardeners can advise you about current problems, like anthracnose, and suggest what to look for if we suspect insect damage, but in many cases we might advise you contact an arborist. An arborist is someone who has specialized training in caring for trees. If you have questions about that s/he recommends, we can help you to understand what they are telling you. We are also ready to help if you need information about how to plant a tree or what tree would be a good choice for your situation.

A good site for information about what an arborist does is: http://www.treesaregood.com/treecare/hire_arborist.asp

Upcoming Classes:

June 23 - Shrub Roses, Flowering Shrubs-Fairview Lakes Regional Health Care Center in Wyoming-cost $4. Please call the office to register. 674-4417.

June 28-Chuck Levine-FREE CLASS!! Topic: Summer plant care and selecting plants for fall color. Chuck is one of the most entertaining and popular speakers from our annual Gardening Bonanza. He has a Masters Degree in Horticulture Education from the Uof MN, teaches horticulture at Hennepin Technical College, and serves on the Board of Directors and Executive Committee at the Mn. State Horticultural Society. This class will be held from 6:30-7:30 at the Senior Center in North Branch.

Ways to access information:

Master Gardeners will be offering free plant clinics every Monday night from 4:30-8:00 at the Extension office in North Branch. Stop by 38780 Eighth Ave. (the Anderson Chiropractic Building) or call 651-674-4417 to speak with a Master Gardener. During the rest of the week, you can leave a message and a Master Gardener will return your call.

You can also click on 'Ask a Master Gardener' next to the cute little flower on the right hand side of the page. Here you can search 1000's of answers from Master Gardeners around the state. If you don't find your answer you can submit a question online or search for University publications.

Bell Museum of Natural History - For information about snakes, skunks, raccoons or other wildlife around your yard, call the wildlife information line at (612) 624-1374 or www.bellmuseum.org

To see the latest Yard and Garden newsletter, go to: http://www.extension.umn.edu/yardandgarden/YGLNews/YGLNews.html

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