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More gardeners are becoming aware of our Plant Clinics at the Extension office on Monday evenings from 4:30-8 p.m. Last Monday night I was helping with the Plant Clinic when a home owner came in with a grotesque looking ash branch. The branch had tumor like clusters that covered most of the branch. We looked in tree disease books and the internet and determined that the problem was Ash flower galls.

Galls are abnormal plant growth that can be caused by insects, mites, or plant disease. On Ash trees a tiny eriophyid mite causes the male flowers to grow into round greenish, structures. Sometimes the lumpy growth also causes leaf distortion. During the late summer the galls will turn dark brown and woody and will remain on the tree for more than one season.

Ash flower gall mites are too small to be seen with the unaided eye. These worm shaped mites spend the winter on birds and begin feeding and initiate gall growth early in the spring. Once the gall starts growing it is too late to treat the plant.

Ash flower gall does not harm the health of the tree but in some years will make a tree look unsightly. In rare situations the weight of the gall tissue can cause branches to be strained. Some trees seem to be more prone to the problem.

The mites must be killed before the galls are growing in the spring, so timing is everything. Look for the first signs of green in the opening flower buds. Larger trees are more difficult to treat, and because this is considered a cosmetic problem, treatment is rarely suggested. Young trees differ in how they are affected. Consider replacing highly susceptible trees. An application of carbaryl (Sevin) in the spring when the first blossoms begins to form will reduce the number of galls.

Another gall affects oak trees in a different way. One common type of gall on oaks is called the jumping oak gall, caused by a tiny cynipid wasp. In Minnesota, jumping oak gall is found on white and bur oak. In early spring, adult females emerge from last year’s galls. They lay eggs on opening leaf buds which forms blister-like galls. Later in the summer, male and female adults emerge. After mating, females lay eggs on mature leaves. Seed-like galls form on the upper leaf surface. There is one insect in each gall.

When mature, these galls fall to the ground. The larvae remain active inside the gall and can cause the gall to jump several inches off the ground. This is very similar to a Mexican jumping bean which is due to the activity of a Mexican bean beetle larvae moving inside the bean. These jumping galls are just a curiosity and are harmless to people.

Jumping oak gall rarely, if at all, have any lasting effect on oak trees. Although these galls can be abundant they are not likely to remain more than a year or two, so no control is necessary.

So if you see tumor-like growths on the leaves of your tree, they are probably a type of gall and not harmful to the health of your tree. The galls can be many shapes, sizes and colors. Bring a sample to one of our plant clinics and a Master Gardener can confirm it for you.

Submitted by

Jerry Vitalis

Chisago County

Master Gardener

Upcoming Classes

•July 14, 6:30-8 p.m.

Annuals for season-long bloom

Fairview Regional Medical Center, Wyoming

Cost: $4

Please call the office to register. 674-4417.For information on upcoming topics in the Summer 2005 Flowering Gardening Series and how to buy tickets, call or stop by the Chisago County Extension Office, 38780 8th Ave, North Branch, or visit our website to download a ticket order form at: www.extension.umn. edu/county/chisago.

July 26––FREE CLASS!

Dave Hanson––Trees, Trees, Trees

We receive more questions on trees than any other topic. Come learn about selection, planting and care, pruning, diseases and how to contact an arborist. Dave is a Research Specialist and Tree Care Advisor Coordinator, Urban and Community Forestry, University of MN, Department of Forest Resources. If he doesn’t have the answer to your question, he will know who does!

In Your Yard and Garden

This is the time of year it seems we are constantly watering our plants. Plants in the ground will do better if watered deeply a couple of times a week instead of being sprinkled lightly every day. Most plants (and lawns too) do well with 1-inch of rain per week. Container plants are a different story! On very hot and windy days, they may need to be watered twice a day.

Many of us like to take advantage of the great sales at the garden centers this time of year. Since the weather is warm, we don’t think about hardening off these new plants. If you buy plants that are inside a greenhouse and plant them in direct sun, they will suffer. I like to move them into larger pots and keep them near my deck where they will get watered often. Once they start putting on some new growth, it’s time to move them into their permanent location.

If you have plants that are susceptible to fungal diseases; black spot on roses, powdery mildew on monarda or phlox, now would be the time to use a fungicide to prevent the plants from becoming defoliated and unsightly. The fungicide will not correct any spots there may be already, but it will prevent it from spreading up the plant.

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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