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Showing posts from July, 2015

Seeding your lawn this fall? Here are some considerations (Part 1 of 2)

Lawns in Minnesota take a beating. This is no surprise due to the extreme weather swings that we have from season to season and even within seasons. Fortunately this year has been a banner year for lawn care with plenty of rain, mild temperatures and low dew points. However, the current ten day forecast is setting us up to have some of the highest temperatures we’ve seen this summer, with dew points in the 70's. We may have another month of hot weather and then it will be time to seed bare areas in your lawn or conduct lawn renovations. With that, now is the time to start thinking about seed selection and purchasing.

Depending on the condition of your lawn and your goals going forward, I may recommend one of several renovation options and seed mixtures. Ideally, this work would be carried out from mid-August to mid-September. Renovation strategies can be grouped into four categories:

Lawn improvement- conducted when less than 20% weeds or bare soil are present. The goal is…

Tiger swallowtail caterpillars

Jeffrey Hahn, Extension Entomologist

People have been finding tiger swallowtail caterpillars in the landscape recently. They have been on the move as they look for places to pupate. Upon first sight, this insect is quite mysterious looking. It is up to a little over two inches in length. The body is either brownish or greenish with a yellow stripe circling the body somewhat near the head.

What stands out, however, are two large yellow and blue eyespots in front of the yellow stripe. This gives the
caterpillar a rather menacing appearance. To further enhance this threatening look, the caterpillar can swing its head from side to side, mimicking a snake. And if that was not enough to keep someone at bay, it can evert a forked structure called an osmeterium near the head. This structure can not only startle someone but can also emit a foul odor to help protect the caterpillar.

Despite all of its bluster, a tiger swallowtail caterpillar is perfectly harmless to people. Don’t be a…

Cedar Apple, Quince and Hawthorn Rust

M. Grabowski, UMN Extension Educator

Several rust fungi are now showing up in brilliant colors on hawthorn, apple, crabapple and other trees and shrubs in the Rosaceae family. Infected leaves have bright orange, yellow or red spots. Infected fruit are covered with small tube like fungal structures, that pour out large quantities of powdery orange fungal spores. Cedar apple rust, hawthorn rust and quince rust are all caused by fungi in the genus Gymnosporangium. The Gymnosporangium rust fungi infect juniper for half of their life cycle. On cool wet spring days gelatinous bright orange spores can be found on galls or cankers on juniper trees. Those spores cause the infections on trees and shrubs in the Rosaceae family. In turn spores produced by the Rosaceae trees and shrubs will infect junipers.

As a result of this unique life cycle, leaf spots may grow slightly bigger, but no new leaf spots or fruit infections will form this year on the Rosaceae trees and shrubs. The Gymnosporangium r…

Garlic Rust

M. Grabowski, UMN Extension Educator

Orange and black elliptical spots on garlic leaves and stems are signs of garlic rust. Cause by the fungus Puccinia allii, garlic rust can infect several members of the allium family including garlic, onion, chives and leeks. Severe infection can result in yellow, withered leaves and reduced bulb size. Not much is known about the biology of the garlic rust fungus. Infection occurs in cool moist conditions and two different types of spores are commonly found on infected plants. The orange spots produce urediniospores. These are easily spread from plant to plant during the growing season resulting in new leaf spots. The black spots produce teliospores. These tough spores survive in plant debris and start new infections the following growing season.

If garlic rust appears in the garden, remove all leaf and stem debris from the garden after harvest. These infected leaves and stems can be burned, buried in an area where no alliums will be grown or compos…

Japanese beetle management options

Jeffrey Hahn, Extension Entomologist

Japanese beetles are being found in gardens and yards now. Although the first discovery of these pests was recorded on June, 18, it hasn’t been until more recently that they have become more abundant. Japanese beetles are challenging to deal with, especially when they are numerous. The following are non-chemical and chemical options for managing them.


A good non-chemical method is physical removal. To be effective, it should be done every day (or at least as regularly as possible). If you can only handpick these pests once a day, research shows the best time to do so is during early evening. Have a container of soapy water with you so that beetles that are brushed or picked off the plants end up in the water where they are killed.

For smaller plants, consider using a fabric barrier, like cheesecloth. The fabric is placed around the plants, preventing the Japanese beetles from getting at them. You can make your own or buy them from a gar…

Mints - friend or foe?

Plants in the Mint family have a well-know reputation for being aggressive. Some, like creeping Charlie Glechoma hederacea) are common pests for many homeowners and gardeners. Wild mint (Mentha arvensis) is a Minnesota wildflower.

Mints can most easily be identified by their square stem and fragrant leaves when crushed. Mints are aggressive and have rhizomatous root systems and creeping above-ground stems, making them difficult to eradicate. Mints grow well in sun and shade, and are adaptable to various soils. Many mints are grown for culinary use, and mints - including creeping Charlie - are good sources of nectar for pollinators. Still, some people want to eliminate large areas of wild mint (and creeping Charlie) from their landscape. There are essentially three options: (1) treating the area with a broadleaf herbicide with glyphosate + triclopyr. (2) Solarization using clear plastic sheeting. (3) Dig out the plants, removing as much of the plant root as possible.

(1) Sp…

From eXtension Ask an Expert: 'William Baffin' Rose

Q: I have a 'William Baffin' rose bush growing in the lawn area of my landscape. It has well over 50 hips forming after a really fabulous bloom. Do I cut them off now or leave them on the plant? Will the rose re-bloom? 
A: 'William Baffin' is a repeat climbing rose; that is, it most likely will set more buds and bloom till frost. Pruning off the early hips will encourage the plant to put more energy into blooming rather than setting seed (the hips). You may decide to leave the later season hips on the plant as winter interest.
As a "climbing rose", 'William Baffin' requires
 support. Unsupported, it is a sprawling rose. Often climbing roses are trained along arbors, walls, fences, etc. Provide a strong trellis and tie the canes along the trellis. This will support the plant and allow light to reach the canes, improving plant health and bloom. Use a soft / padded tie material to avoid girdling the stems. You can purchase various types of …

Anthracnose Blights Shade Trees

M. Grabowski, UMN Extension Educator