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Showing posts from June, 2016

Water Wisely: Five steps to conserving water in your garden

Watch for lecanium scale

Jeffrey Hahn, Extension Entomologist

Lecanium scales, Parthenolecanium spp., have been commonly reported this year on a variety of hardwood trees, including oak, crabapple, ironwood, hickory, and maple. Look closely for them as appear as 1/8 inch reddish brown helmet shaped insects. They are typically clustered together along branches. Adults are covered by a waxing shell and move very little while newly hatched scales, called crawlers, are mobile but lack the waxy covering.

Scale insects use piercing-sucking mouthparts to feed on sap in the phloem layer of plants. The damage caused by this feeding varies. In most cases, especially on large healthy trees, little to no damage occurs. As scale infestations grow larger and more persistent, branch dieback can occur, and under extreme situations, plant death. Soft scales, like lecanium scale, are also prolific honeydew producers. Honeydew is a clear, sticky waste material. Its presence in a landscape can be very annoying.

Ther…

Spotted wing drosophila now active

Jeffrey Hahn, Extension Entomologist

If you grow raspberries, blueberries, blackberries, cherries, strawberries, or other soft-skinned fruit, beware that spotted wing Drosophila (SWD) has been detected. They were first discovered in apple cider vinegar traps in several locations in the Twin Cities on June 13. This is about two weeks earlier than they have been detected the last several years in Minnesota.

This small fly has become a very damaging pest in both commercial fields and home gardens. The larvae tunnel into ripening fruit causing brown, sunken, soft areas in the fruit, rendering them inedible. If you have susceptible fruit in your garden, monitor for SWD to determine if this insect is present in your garden. The adults look just like a typical fruit fly that you might find in your home except males have a dark spot on the tip of the wings.

If you find SWD in your garden, it is necessary to protect your crops with an insecticide application. There are several product…

Inspect for wasp nests

Jeffrey Hahn, Extension Entomologist

Now is a good time to inspect your home for wasp nests that are being constructed. It is easy to overlook nests when they are small and there are only a few wasps present. However, that is the best time to treat them when you can find them. Some wasp nests are built out in the open, e.g. under an eaves, and are the easiest to find and control.

If a small, exposed nest is discovered, there are a couple of options for controlling it. Regardless of which method you use, deal with nests at night when the wasps are not very active. The easiest method is to spray a wasp and hornet insecticide into the nest to kill all of its inhabitants. If you want to control it nonchemically, remove the nest by placing a clear glass or plastic container over it and moving the jar so the nest is knocked down into the container. Slide a piece of cardboard (or something similar) so you can bring the jar down without the wasps getting out. Then slide the lid on…

Squash vine borers are out now

Jeffrey Hahn, Extension Entomologist

Are you growing squash, pumpkins, cucumbers, or melons in your garden this year? If so, now is a great time to start monitoring for squash vine borers. In fact a gardener in Minneapolis has already spotted several adults flying around his plants. Squash vine borers are a potentially devastating pest as the larvae bore into the stems, causing plants to wilt and eventually die. The best management is well timed insecticide treatments when adults are active and laying eggs.

Adult squash vine borers are day time flying moths that resemble wasps. They are about 1/2 inch long with an orange abdomen with black dots. The first pair of wings is an iridescent green while the back pair of wings (which may not always be seen plainly) is clear. There are a couple of methods for detecting them in your garden - watch for them flying around while you are in your garden and/or place yellow containers (like pans or pails) half filled with soapy water. Thes…

Bountiful blister beetles

Jeffrey Hahn, Extension Entomologist

There have been a lot of sightings throughout the state of Say blister beetles. Blister beetles are ant-like with soft wing covers. The Say blister beetle, Lytta sayi, is green with orange and black legs and is about ¾ inch long. These blister beetles have been conspicuously feeding, sometimes in large groups, on a variety of flowers, including lupine, iris, false indigo and prairie indigo (Baptisia), lilac and mountain ash. They have also been known to feed on rose, daylily, and peony.

All blister beetles secrete a defensive oil called cantharidin which can be very irritating and even raise blisters when skin is exposed to it. Fortunately, Say blister beetles generally do not possess a sufficient concentration of this substance to cause very severe problems to people.

If Say blister beetles are in your garden, there are several options for their management. First consider whether the damage can be tolerated; if it can then just ignore them. Also…

What's up with those ragged looking elms?

Kathy Zuzek, Extension Educator
Siberian elm is a non-native tree that was introduced into the United States from Asia in the 1860’s for its hardiness, rapid growth rate, and its ability to grow in a wide range of soils.  This 50-70' tree is often found growing in yards and along boulevards where it produces prolific seed that germinates easily and quickly to form thickets of new seedlings under parent trees.  Wind can carry seed to other areas and Siberian elm has also naturalized throughout Minnesota.  It invades prairies, stream banks, and disturbed open areas with sparse vegetation.  The Minnesota Department of Natural Resources lists Siberian elm on its Invasive Terrestrial Plant page because it can invade and dominate disturbed prairies in a few years’ time.
You may have noticed Siberian elms in the landscape this spring that look sick or stressed with sparse foliage and open brown canopies.  Unfortunately, seed production on this weedy species was even heavier than normal …

Frost Damage on Trees and Shrubs

Kathy Zuzek, Extension Educator

If you are seeing damaged leaves on shrubs and trees, it may be due to the below-freezing
temperatures that occurred throughout Minnesota between May 14 and 18. Nighttime temperatures around much of the state dropped into the 20’s and the succulent newly-emerged leaves of some trees and shrubs froze. Frost damage first appears as water-soaked wilted tissue that later turns brown or black as it shrivels, curls, and dies. Entire leaf kill results in eventual leaf drop. Partially injured leaves may remain on plants as misshapen leaves.

Healthy trees and shrubs will not be greatly impacted by frost damage because they use stored energy reserves to produce new replacement leaves. When frost damage occurs, trees and shrubs initiate a stress response that 1) stimulates dormant buds near damaged leaves to expand into new leaves and/or 2) stimulates production of new adventitious buds that will develop into new foliage to replace damaged leaves.

Slowing down leaf spot spread

M. Grabowski, UMN Extension Educator

In the flower garden and in the vegetable garden, the first leaf spot diseases have appeared. At this stage, garden plants still look good and it is easy to overlook a few small spots on lower leaves.
Where did these spots come from? Many are caused by fungal or bacterial plant pathogens that survive in the soil in last years infected plant debris. Splashing rain or irrigation carries fungal spores or bacteria from the soil onto new leaves. These start new infections that become leaf spots. Each leaf spot eventually produce fungal spores or bacteria that can be spread to neighboring plants or within the plant canopy. 
 Leaf spot pathogens spread in splashing rain or irrigation or by sticking to hands and tools. Some can move on wind or moist air currents. With time and the right weather conditions, a few small leaf spots in June can grow into a devastating disease that causes leaves to turn brown, wilt or fall off.
Although there is no way to cur…

Supporting Minnesota butterflies with little bluestem, Schizachyrium scoparium

By Nicole Roth, Applied Plant Science Graduate Student and Mary H. Meyer, Professor and Extension Horticulturalist

Introduction: 150 years ago, when traveling through western and southern Minnesota, you would have seen a landscape filled with native wildflowers, grasses and dancing butterflies as far as the eye could see. If you can imagine, one-third of Minnesota was once covered in tall-grass prairies, an essential habitat for many species of butterflies, as well as other insects, birds, and wildlife. Today, only 1% of Minnesota's prairies remain mainly due to agricultural and housing developments. People have recently become more aware of the importance of planting prairie flowers to help support our butterflies and other pollinators, but most people are still unaware of the importance of growing native grasses to support native butterflies.
Background: Native grasses are essential larval (caterpillar) host plants for many species of prairie dependent butterflies. The larva feed …