Yard and Garden News

Apple maggot flies recognize and identify apples through a series of visual and chemical clues. The red sphere traps and the yellow square traps both covered with a sticky substance as well as scented lures aid in capture of apple maggot flies and will indicate their presence. However, it is unlikely that such traps will effectively protect your apples.

Karl Foord

Photo 2: Apple fruit after thinning

I have tried plastic bags which can work although they make the tree look phantasmagorical (i.e. nightmarish - please forgive - I always wanted to use that word in a sentence). I have also found that they can collect water and if faced toward the south can heat up and cause damage to the apple skin.

Karl Foord

Photo 3: Apple fruit with maggot barrier I

So this year I am trying Maggot Barriers that I purchased from the Seattle Tree Fruit Society although there are other suppliers of this product that can be found on the web. The Seattle Tree Fruit Society web site does show pictures of their recommendations for attaching the barrier. The maggot barriers are the so called "footies" which serve as single use protective socks that can be used to try on shoes if you have no socks.

Karl Foord

Photo 4: Apple fruit with maggot barrier II

The maggot barriers may confuse the flies who no longer recognize the apples because of the different color and texture of the footie covering the apple. The barriers may physically inhibit the maggots from depositing their eggs under the skin of the apple. However, mosquitoes don't seem to have any problem getting their proboscis through our woven shirts, so I wonder if apple maggot flies would really have a problem getting their ovipositor through the mesh of the footie.

Karl Foord

Photo 5: Apple fruit with maggot barrier III

This is the procedure that I am using. First thin the flower to one fruit per cluster (Photos 1 & 2). Then slip the sock/barrier over the apple and secure with a rubber band. I have three examples: the first with the apple at the end of the sock (photo 3), the second with the apple in the middle of the sock (photo 4), and finally the apple with most of the sock above the apple (photo 5). (note the last photo was taken with a flash which is why the color is so different)

I will let you know how this works for me.

For more information on apple maggot including other methods of control please use the following link. apple maggot

Bright orange slimy fungus in junipers

2013-06-05T20:50:43Z

M. Grabowski, UMN Extension

Photo 1: Cedar Apple Rust Gall on Juniper

M. Grabowski, UMN Extension Educator

There is nothing that catches the eye so much as a bright orange slimy tentacle-like fungus hanging from a landscape juniper tree. What is that thing? you might ask. The answer is cedar apple rust, one of several Gymnosporangium rust fungi that infect junipers in the state of Minnesota. Gymnosporangium rust fungi are unique in that they spend part of their life infecting juniper trees, causing unusual brightly colored galls, and the other part of their life infecting leaves, fruits, and green stems of trees or shrubs in the Rosaceae family. The Rosaceae family includes crabapples, hawthorns and serviceberry. Different Gymnosporangium rusts infect different trees and shrubs.

On junipers, the cedar apple rust results in brown woody galls that can grow to over an inch in diameter. With wet weather, the galls produce bright orange tentacle like spore producing structures. These release spores that are carried to nearby crabapple or apple trees, later to become bright orange and red leaf spots. Cedar apple rust galls on juniper can dry down and rehydrate multiple times in one spring. With repeat rain events in Minnesota this year, the cedar apple rusts have been putting on a colorful show. The good news is the galls will dry up and die when warm dry weather arrives. Juniper trees are rarely harmed by cedar apple rust galls although gardeners might notice some dieback on branch tips girdled by large galls.

More information about cedar apple rust and other Gymnosporangium rusts can be found on the UMN Extension webpage, including information on how to identify and manage the different diseases on different host plants.

Anthracnose of shade trees thrives in cool wet spring

2013-06-05T15:47:18Z

M. Grabowski, UMN Extension

Photo 1: Anthracnose on Maple

M. Grabowski, UMN Extension Educator

As cool wet weather persists in Minnesota this year, a common leaf blight disease of shade trees known as anthracnose thrives and spreads. Anthracnose is a fungal disease that causes leaf blotches, leaf distortion, shoot blight, and leaf drop. This disease is caused by several related fungi that thrive in cool wet conditions. Ash, maple and oak trees are all commonly infected with anthracnose and symptoms of the disease have been seen on all of these trees this spring. Despite blackening of leaves and shoots, anthracnose actually only results in a minor stress on the health of the tree. Only young growing leaves and shoots are susceptible to infection. Mature leaves are relatively resistant to the disease. Once warm dry weather arrives in Minnesota, leaves will mature and trees will replace lost leaves with a new flush of growth. As long as cool wet weather persists, however, expect this fungal disease to spread throughout the trees canopy. More information can be found about this disease at the UMN Extension publication on anthracnose in shade trees.

June 1 Issue of Yard and Garden News

2013-06-03T04:20:43Z

In this issue:

Using Extension Information and the Pesticide Label to Safely and Correctly Solve a Pest Problem

Carpenter ants in spring

Using Extension Information and the Pesticide Label to Safely and Correctly Solve a Pest Problem

2013-06-02T04:39:57Z

Karl Foord - Extension Educator, Horticulture

This spring I noticed the black color on the branches of my Taylor's Sunburst Pine (Pinus contorta 'Taylor's Sunburst'). I remember seeing the same thing on my Uncle Fogy Jack Pine (Pinus banksiana) last year. The cause was the same in both cases Sooty Mold that has formed on the honeydew secretions of the Pine tortoise scale (Toumeyella parvicornis). To confirm this I went to the What's Wrong with My Plant Diagnostic Tool via the Extension Garden web page/Pest Management/Diagnose a Problem link. I tracked through "Evergreen Trees and Shrubs" to "Pine" to Black powdery coating on "needles" and "shoots". This confirmed the Sooty Mold. I also tracked through "Sticky substance coating needles" to confirm the Pine tortoise scale as the culprit.

Karl Foord

Photo 1: Uncle Fogy Pine (Pinus banksiana 'Uncle Fogy'

The scale organism put such stress on my Uncle Fogy Pine that the needles it produced were half the size of the normal needles. Upon removal of the scale the needles returned to normal size (photo 1). I had learned my lesson about the impact of Pine tortoise scale on my trees.

I knew that Imidacloprid had worked on Uncle Fogy so I grabbed the bottle and reread the label - not trusting my memory. I confirmed that yes this product is labeled for soft scales. I also reviewed the precautions about letting the chemical get into aquatic environments - no lakes, streams, or ponds nearby. I agreed with the label that whatever I used to measure the chemical should not be followed by using the same utensil for soup.

There was nothing on the label regarding protective equipment, however the label warned that this chemical can be harmful if absorbed through the skin so I followed my previous procedures of long sleeve shirt, long pants and plastic gloves for handling.

Because this was an evergreen ornamental tree I was not concerned about the potential effects of a systemic pesticide on pollinators because there would be no flowers to pollinate. Also because the product is used as a drench around the plant, I didn't have to worry about airborne spray drifting onto other plants, people, or pets. In addition there were no wet leaf surfaces so there was no issue of reentry to the area or drying time of the product.

The directions called for the tree trunk circumference in inches at a height of 4.5 ft. and that this length in inches should equal the number of ounces of product to be applied to the plant. But there were too many needles to measure the circumference so I estimated the diameter and multiplied by Pi. How often do you get to use the trigonometry you learned in high school? The amount came to @ 5 oz. I added this to a gallon of water as instructed and applied the solution evenly in a circle 2 ft. from the tree trunk. Put the container away and washed up.

I checked the tree every other day or so and several days later the scales were starting to look ill. In approximately two weeks all the scales were dead. My Taylor's Sunburst Pine is looking and growing nicely without having hundreds of Pine tortoise scale stylets sucking its "life's blood" plant sap.

Reading the label wasn't all that painful. Reading size 6 font text definitely required glasses for "mature" eyes. However, I did not skim the label or skip parts. I read carefully and made sure that I understood all parts and the risks involved. Yes following the label is the law. Following the label is also the responsible and intelligent thing to do. By proceeding in this manner I felt in command of the situation and understood that the action I was taking was going to solve the problem with minimal impact to the environment and all the other actors in our theater of life.

Carpenter ants in spring

2013-05-31T20:58:57Z

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: Carpenter ant worker. Note the one segmented petiole and the evenly round thorax in profile.

Although carpenter ants can be found in homes anytime during the year, they seem particularly noticeable in the spring as the weather becomes warm. Many people think of carpenter ants as big, black ants. And it is true the most common species here is black and approaches ½ inch in length. However, you can't always go by size and color; there is another carpenter ant species that is red and black and about 3/16^th inch long. A more sure method is to look for a one-segmented petiole between the thorax and the abdomen (ants either have a one or two segmented petiole. Also examine the shape of the thorax (the middle section of the body). In carpenter ants, the thorax is evenly round in profile while other Minnesota ants have unevenly shaped thoraxes.

Finding carpenter ants inside in the spring can mean that a nest is present there; the sooner they are present indoors with the onset of warm weather, they more likely a nest exists in your home. Also look for signs of coarse sawdust which is a sign of a nest. If you find a swarm of winged carpenter ants indoors, that is a sure sign of an indoor nest. Remember that not all winged ants you see are carpenter ants so be sure they are correctly identified. If you find just one or several carpenter ant queens (winged or wingless) in your home, they probably just wandered into your home accidentally and no nest is present.

Jeff Hahn

Photo 2: Carpenter ant queen. A swarm of queens inside indicates a nest in the home.

There are two types of carpenter ant nests. Parent colonies nest in moisture damaged wood while satellites nests, offshoots of the main colony, can nest in sound wood as well as insulation and hollow doors. Carpenter ants have the potential to damage the wood in buildings as they excavate galleries and tunnels. Fortunately, this damage occurs relatively slowly and it usually takes years for it to become severe enough to be an issue.

If you believe that you have a carpenter ant nest in your home, it is very challenging to control it yourself. It is critical to deliver insecticide to the nest; just killing the foraging workers has no impact on the nest. Typically baits are used for ant problems. However the ant baits available to the general public are not sufficiently attractive or effective to successfully eliminate a carpenter ant nest.

The best control for carpenter ants is to contact a licensed pest management service to treat the nest. An inspection is very important to find the foraging trails and ideally the nest(s). There are several options for treating the nest. Many technicians use a non-repellant residual insecticide (e.g. Termidor), sprayed around the building's exterior. The carpenter ants pick up residue; take it back it to the nest where it gets spread through colony, ultimately eliminating it. Technicians may also set out baits to control carpenter ants. They have a variety of baits and the experience to choose the proper bait that will be most effective (it is not unusual for technicians to use more than one bait to be successful). Keep in mind that baits take time so it is important to be patient and allow carpenter ants to take back sufficient bait to control the nest. If the exact location of the nest is discovered, it can be treated directly, especially with a dust.

For additional information, including preventative steps, see the publication, Carpenter ants.

May 15 Issue of Yard and Garden News

2013-05-16T18:32:05Z

In this month's issue:

Eastern tent caterpillars are now out!

It's Tick Season Now!

Rabbit Damage Revealed on Trees and Shrubs

Snow Molds Blight Minnesota Lawns - For Now

New Report on Bee Health from USDA and EPA

Psyllids Common in Homes this Spring

Strawberry Growers take Note!

Eastern tent caterpillars are now out!

2013-05-15T17:32:59Z

Jeffrey Hahn, Asst. Extension Entomologist

Tom Voigt.

Photo 1: Young eastern tent caterpillars constructing their tent after just emerging.

Be on the watch for eastern tent caterpillars. There was a report of these insects at the end of last week in southeast Minnesota and it was reported in the Twin Cities at the beginning of this week. The caterpillars are bluish black with yellow and a white stripe running the length of the top of its body. They are also mostly smooth except for a series of hairs sticking out along the sides of their bodies. They are two inches long when fully grown.

However, the first sign you'll notice are the silken tents they create in the forks of branches. After the caterpillars first hatch, they'll construct this webbing which serves as a shelter they use at night and during rainy weather. The tent will be small at first but will increase in size and can eventually become quite conspicuous. During the day they crawl out of these tents and feed on tree leaves. Although they are found on a variety of hardwood trees, eastern tent caterpillars are particularly fond of fruit trees, including apple, chokecherry, crabapple, plum, and cherry.

Healthy, well-established trees can tolerate eastern tent caterpillar feeding. Their feeding, as well as the presence of their webs, is just a cosmetic problem and only affects the trees' appearance. However, young trees, as well as unhealthy, stressed trees, are more susceptible to feeding damage and should be protected.

Also consider the size of the caterpillars. As long as they are no more than half their full grown size, i.e. one inch or less, it is worth considering whether to treat them. This is not an issue now as they are just emerging and they are all small. However, if an infestation is discovered later, it is important to check to make sure they are not too large (larger than an inch). The larger they are, the closer they are to being done feeding and then it is not worthwhile to treat them.

Terry Straub

Photo 2: Older eastern tent caterpillars on webbing.

A great non-chemical method to deal with eastern tent caterpillars is to wait until they have retreated back to their webbing at the end of the day or on a rainy day and then pull out the webbing, along with the caterpillars. Then bury or bag them to properly dispose of them (you could burn them if it is permitted where you live).

There are a variety of residual insecticides that you can use if it is desirable to protect your trees. Consider using products that have a low impact on the environment, such as Bacillus thuringiensis, spinosad, and insecticidal soap. Bacillus thuringiensis is a particularly good product if the tree is flowering since it will not harm visiting honey bees. If you use insecticidal soap, the product needs to directly contact the insects. There is no residual activity so you may need to repeat the treatment.

It's Tick Season Now!

2013-05-09T19:22:13Z

Jeffrey Hahn, Asst. Extension Entomologist

Jeff Hahn

Photo 1: American dog tick that was picked after a hike in the woods.

We have endured a long cold spring but now the weather is finally getting warmer so it is enjoyable to be outside again. Finally, we are ready to enjoy our favorite outdoor activities. You definitely want to get outside but with the return of nice weather also come ticks. Take the proper precautions and protect yourself from these pests.

The two most common ticks in Minnesota are American dog ticks (also called wood ticks) and blacklegged ticks (formerly called deer ticks). While American dog ticks are not important vectors of disease in Minnesota, they are nuisances because they bite us (also dogs too!). Blacklegged ticks are also nuisances but they can be potentially more serious as they transmit diseases, including Lyme disease, anaplasmosis, babesosis, and Powassan encephalitis to people in Minnesota. Of these, Lyme disease is the most common.

You are most likely going to encounter ticks in tall, grassy areas and in the undergrowth of hardwood forests so avoid those areas when possible. When you are out in areas where ticks are known to occur, one of the best methods of protecting yourself is the use of a repellent. You can apply DEET to both skin and clothes, while products containing permethrin should only be applied to clothes. It is also very important to check yourself for ticks after coming back inside. The sooner, you can find any ticks that may have crawled onto you, the sooner you can remove them, hopefully before they have started to bite you. Ticks can't transmit disease if they are not biting.

For more information, see Ticks and their Control and Tick-borne diseases in Minnesota.

Rabbit Damage Revealed on Trees and Shrubs

2013-05-09T16:30:15Z

M.Grabowski, UMN Extension

Photo 1: Rose bush with extensive rabbit damage

As gardeners inspect their landscapes this spring, many trees and shrubs have been found with extensive rabbit damage. Rabbits are one of the most commonly seen mammals in the urban environment. In Minnesota, our most common rabbit is the Eastern cottontail, Sylvilagus floridans.

Rabbits will spend much of their time eating grasses and other herbs but they will also chew on the bark of trees and shrubs and eat the buds of shrubs in the winter and spring. If left unprotected, rabbits will sometimes eat the bark from around the base of a tree or shrub. This is called "girdling" and can kill the plant.

Read Rabbits and Trees and Shrubs by wildlife expert Jennifer Menken of the Bell Museum to learn more about protecting landscape plants from rabbit damage.

Snow Molds Blight Minnesota Lawns - For Now

2013-05-07T15:51:56Z

M. Grabowski, UMN Extension

Photo 1: Pink and gray snow mold on a Minnesota lawn

Michelle Grabowski, UMN Extension Educator

Persistent cold weather and late snow fall mixed with freezing rain have created ideal conditions for the growth of snow molds this year. Snow molds are caused by fungal pathogens that thrive in cold temperatures (just above freezing to about 60F) and high humidity.

M.Grabowski, UMN Extension

Photo 2: Small round patch of pink snow mold with a light center and dark border

Two types of snow mold are common in Minnesota. Pink snow mold, caused by the fungus Microdochium nivale, results in round dead patches in lawns that can be an inch or two across or as large as a dinner plate. These dead patches are often pale tan in color, matted down and may have a dark brown border. In sunlight pink snow mold patches turn pink to salmon colored as the fungus produces spores of these colors.

M.Grabowski, UMN Extension

Photo 3: Pink matted grass in a pink snow mold patch

Gray snow mold, caused by several species of Typhula, also cause pale gray to tan patches of matted down brittle grass that can spread up to 3 feet across. If the matted down grass of gray snow mold is examined closely, gardeners can see small black dots, about the size of a pen tip. These black dots are sclerotia, resting structures produced by the fungus that allow it to survive through harsh conditions. It is not uncommon to find both pink and gray snow mold in the same lawn.

M.Grabowski, UMN Extension

Photo 3: Large irregular matted patch of gray snow mold

M.Grabowski, UMN Extension

Photo 5: Small black sclerotia of gray snow mold

The good news is that although snow molds thrive in cold wet conditions, they go dormant as the weather becomes warm and dry. In many cases the snow mold fungi blight the grass leaves but do not kill the crown. In these situations, the grass will recover as the fungal pathogen goes dormant. In severe cases of snow mold, the grass plant may die and gardeners will need to reseed the infected area.

For now there are a few things that gardeners can do to speed the fungal pathogen into dormancy. Remove or spread out any remaining snow piles, so the snow melts quickly and the grass below is exposed to sun and air. Rake the lawn to remove any leaf debris and to fluff up matted down patches of turf. This will help improve air movement around the grass plants so leaves dry quickly after dew or rain. A light application of fertilizer in the infected patch can help grass recover. If no recovery is seen, reseed the area, taking care to rake away matted down grass so that seed has good contact with the soil below. Fungicides are not effective in controlling snow mold once the disease is established and should not be used at this time of year.

New Report on Bee Health from USDA and EPA

2013-05-06T20:43:45Z

Jeffrey Hahn, Asst. Extension Entomologist

The following is from a news release that was issued on May 2, 2013

The United States Department of Agriculture (USDA) and the U.S. Environmental Protection Agency (EPA) released a comprehensive report last week on honey bee health. The report states that there are multiple factors playing a role in honey bee colony declines, including parasites and disease, genetics, poor nutrition and pesticide exposure.

In October 2012, a National Stakeholders Conference on Honey Bee Health, led by federal researchers and managers, along with Pennsylvania State University, was convened to synthesize the current state of knowledge regarding the primary factors that scientists believe have the greatest impact on managed bee health.

Key findings include:

Parasites and Disease Present Risks to Honey Bees:
• The parasitic Varroa mite is recognized as the major factor underlying colony loss in the U.S. and other countries. There is widespread resistance to the chemicals beekeepers use to control mites within the hive. New virus species have been found in the U.S. and several of these have been associated with Colony Collapse Disorder (CCD).

Increased Genetic Diversity is Needed:
• U.S. honeybee colonies need increased genetic diversity. Genetic variation improves bees thermoregulation (the ability to keep body temperature steady even if the surrounding environment is different), disease resistance and worker productivity.
• Honey bee breeding should emphasize traits such as hygienic behavior that confer improved resistance to Varroa mites and diseases (such as American foulbrood).

Poor Nutrition Among Honey Bee Colonies:
• Nutrition has a major impact on individual bee and colony longevity. A nutrition-poor diet can make bees more susceptible to harm from disease and parasites. Bees need better forage and a variety of plants to support colony health.
• Federal and state partners should consider actions affecting land management to maximize available nutritional forage to promote and enhance good bee health and to protect bees by keeping them away from pesticide-treated fields.

There is a Need for Improved Collaboration and Information Sharing:
• Best Management Practices associated with bees and pesticide use, exist, but are not widely or systematically followed by members of the crop-producing industry. There is a need for informed and coordinated communication between growers and beekeepers and effective collaboration between stakeholders on practices to protect bees from pesticides.
• Beekeepers emphasized the need for accurate and timely bee kill incident reporting, monitoring, and enforcement.

Additional Research is Needed to Determine Risks Presented by Pesticides:
• The most pressing pesticide research questions relate to determining actual pesticide exposures and effects of pesticides to bees in the field and the potential for impacts on bee health and productivity of whole honey bee colonies.

Those involved in developing the report include USDA's Office of Pest Management Policy (OPMP), National Institute of Food and Agriculture (NIFA), Agricultural Research Services (ARS), Animal and Plant Health Inspection Service (APHIS), Natural Resource Conservation Service (NRCS) as well as the EPA and Pennsylvania State University. The report will provide important input to the Colony Collapse Disorder Steering Committee, led by the USDA, EPA and the National Agricultural Statistics Service (NASS).

An estimated one-third of all food and beverages are made possible by pollination, mainly by honey bees. In the United States, pollination contributes to crop production worth $20-30 billion in agricultural production annually. A decline in managed bee colonies puts great pressure on the sectors of agriculture reliant on commercial pollination services. This is evident from reports of shortages of bees available for the pollination of many crops.

The Colony Collapse Steering Committee was formed in response to a sudden and widespread disappearance of adult honey bees from beehives, which first occurred in 2006. The Committee will consider the report's recommendations and update the CCD Action Plan which will outline major priorities to be addressed in the next 5-10 years and serve as a reference document for policy makers, legislators and the public and will help coordinate the federal strategy in response to honey bee losses.

To view the report, which represents the consensus of the scientific community studying honey bees, please visit: http://www.usda.gov/documents/ReportHoneyBeeHealth.pdf