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Extension > Yard and Garden News > July 2014

Thursday, July 31, 2014

Managing Cherry Disease Problems



M. Grabowski, UMN Extension


Photo 1:



Michelle Grabowski, UMN Extension Educator

Several disease problems have been observed on cherry trees this summer including powdery mildew and brown rot. When disease problems arise in the garden it is critical to identify what pathogen is causing the problem. There are different strategies to manage each disease and it is important to know what time of year management strategies should be applied. Many garden diseases can be significantly reduced if not eliminated with well timed cultural control strategies.

Find out more about identification and proper management of disease and insect problems of cherry, plum and apricot trees in the new UMN Extension publication Pest Management for the Home Stone Fruit Orchard.

Watch for Masked Hunters

Jeffrey Hahn, Extension Entomologist



Jeff Hahn, Univ of Minnesota Extension

Photo 1: Masked hunter adult - they can bite if you are not careful

Some people have been encountering a 3/4 inch long, dark colored, somewhat slender insect in their homes lately. This insect is a masked hunter, Reduvius personatus, a type of assassin bug (family Reduviidae). A masked hunter is a predator, feeding on a variety of insects. It can accidentally wander into homes during summer and is considered to be just a nuisance invader. No more than a few are usually seen at a time.

Fortunately, a masked hunter is not aggressive towards people, although it is capable of inflicting a painful bite if it feels threatened. It also is not a carrier of any disease. This is important as a masked hunter has been confused with kissing bugs which do transmit Chagas disease. Chagas disease is a potentially serious illness caused by a protozoan organism.

Kissing bugs also belong to the assassin bug family which helps explain the confusion between them. However, while kissing bugs belong to the subfamily Triatominae, masked hunters are in the Reduviinae subfamily. Kissing bugs are found in South America, as well as Central America and southern Mexico and are not native to the U.S. They get their name because of their habit of biting people on the face at night.

There is not any special control for masked hunters. Physical removal is the only necessary action that needs to be taken. If possible, capture and release any found outdoors. For more information, see Masked hunters.

Friday, July 18, 2014

Hollyhock Rust at its Worst



M. Grabowski, UMN Extension


Photo 1: Hollyhock rust on leaves



Michelle Grabowski, UMN Extension Educator


Frequent rains this spring and early summer have created favorable conditions for hollyhock rust. Hollyhock rust is caused by the fungal pathogen Puccinia malvacearum, which infects hollyhocks and related weeds like roundleaf mallow (Malva neglecta).

Early symptoms of hollyhock rust are easily missed. Small waxy yellow bumps form on the lower surface of the lower leaves of the plant. With age, these pustules turn reddish brown and a bright orange spot develops on the upper leaf surface. In wet years, spores from these early infections easily spread to infect leaves, stems, petioles and even flower bracts. Heavily infected leaves turn yellow and may wither and curl. This significantly reduces the plant's ability to do photosynthesis. The hollyhock rust fungi can survive from one season to the next in infected live crowns, as spores in infected plant debris, or on seed from infected plants.



M. Grabowski, UMN Extension


Photo 2: Hollyhock rust on stem and flower bracts




Unfortunately it is too late to prevent hollyhock rust this season. Keep plants as dry as possible by avoiding sprinkler irrigation and pulling weeds to improve air circulation around the plants. This will help to reduce spread of existing infections. Gardeners with infected plants should cut off the plant at ground level after flowering is complete. Infected plant material should be removed from the garden and buried, placed in a compost pile that heats up or taken to a municipal compost facility. Next year, mulch around the base of the plant to reduce the spread of spores from plant debris. Scout plants in early spring. Look for yellow waxy pustules on the lower leaf surface. Infected leaves should be removed and buried or composted.

Diseases in the Vegetable Garden

Michelle Grabowski, UMN Extension Educator


M. Grabowski, UMN Extension


Photo 1: Black rot is a bacterial disease of broccoli, cabbage, cauliflower and other brassicas.




This years frequent rains have created ideal conditions for many fungal and bacterial diseases in the vegetable garden. These pathogens need moisture to reproduce, spread and start new infections. Although gardeners can't change the weather, a few things can be done help plants dry out after rain or dew and to reduce the spread of disease.

1. Space plants to allow for air movement around the plants and through the foliage. Dense planting results in fruit and foliage that stay wet longer; a favorable condition for many pathogens.

2. Pull weeds. Weeds crowd the vegetable plant, steal nutrients and reduce air movement in the garden.

3. Completely mulch the soil with landscape fabric, plastic mulch, straw or wood chips. Many pathogens survive in plant debris and soil. Rain and irrigation splash water, soil and pathogens onto the lower


M. Grabowski, UMN Extension


Photo 2: Angular leaf spot on cucumber




leaves of the plant. Mulch provides a barrier that reduces splash dispersal of the pathogen from soil to plant. In addition, mulch keeps moisture in the soil and reduces humidity in the plant canopy.

4. Stake vining plants like tomatoes, cucumbers and runner beans. This will improve air movement around the plant and facilitate drying of the leaves and fruit.

5. Do not work in plants when leaves and fruit are wet. Fungal and bacterial pathogens reproduce under wet conditions and can easily be spread on a gardeners hands or tools at this time. Wait until plants have dried completely before working in the garden.

6. Pinch off heavily infected leaves and fruit and remove them from the garden. Many leaf spot and fruit rot diseases produce new fungal spores or bacteria in every leaf spot. These pathogens are easily


M. Grabowski, UMN Extension


Photo 3: Early blight on tomato



spread through the plant to new leaves and developing fruit. Infected plant material can be buried, placed in a compost that heats up or taken to a municipal compost facility.

Remember many plants tolerate some leaf infection and still produce a good crop. Use the steps above to reduce the spread of disease and minimize it's impact on your final harvest.

Wednesday, July 16, 2014

Join a CSA (Community Supported Agriculture) and visit that Farm!

Karl Foord, Extension Educator - Horticulture




Karl Foord

Photo 1: Some of the plastic tunnels that provide optimum growing conditions on the Untiedt Vegetable Farm



Karl Foord

Photo 2: Sweet corn on Untiedt Farm



Karl Foord

Photo 3: Trellised tomatoes on the Untiedt Farm



Karl Foord

Photo 4: More trellised tomatoes on the Untiedt Farm



Karl Foord

Photo 5: Trellised cucumbers on the Untiedt Farm



Karl Foord

Photo 6: Trellised cantaloupe on the Untiedt Farm



Karl Foord

Photo 7: Onions on Untiedt Farm



Karl Foord

Photo 8: Honeybee hives on the Untiedt Farm



Karl Foord

Photo 9: Protective tree barriers on Untiedt Farm

If you are not already a member of a CSA (Community Supported Agriculture), I highly recommend that you consider becoming one. To be a member one pays an up front fee and receives weekly a box of currently maturing vegetables for 17 weeks of the season. This prepayment helps the farmer to achieve better cash flow for the operation and the member/shareholder gets a greater understanding how their local food is produced here in Minnesota.

To better understand where my food comes from I attended my CSA Farmer's field day. It was an enlightening experience. Not only did I see where my food comes from but also listened to Jerry Untiedt discuss how he handles various issues such as pest control and water management. I was especially impressed with the system developed for water management. All the water that runs off Jerry's plastic tunnels (Photo 1) is channeled into a natural wet area that acts in a holding capacity. When Jerry needs the water back, he pumps it back from the wet area and waters his crops.

You can see from the photos that Jerry's soil is quite sandy. With the amount of rain we have had this spring a great deal of applied fertilizer would simply have been flushed through the system and end up in our waterways. Note the sweet corn field (Photo 2) and the green plastic under the crop. This has been placed there to avoid such a loss for the farmer and then pollution for those downstream. I was very proud to know that the food I am eating is produced in a system that has been developed to avoid such problems.

Most of the vegetable acreage is under plastic providing optimal conditions for growth. This being among others: 1) lack of rain water falling on the leaves and potentially creating disease problems, 2) protection from the strong winds that buffet and damage the plants, 3) an enclosed space permitting the use of beneficial insects to control pests - in an open field they are more likely to disperse than protect your plants, and 4) keeping the plants within an optimum growing temperature - especially critical given Minnesota's unpredictable weather patterns.

To make optimal use of space, a number of the crops are trellised such as tomatoes (Photos 3 & 4) cucumbers (Photo 5), as well as cantaloupe (Photo 6). Other crops that cannot be trellised also do extremely well in the tunnels (Photo 7).

Jerry has honeybees (photo 8) and bumble bees on site to provide pollination services.

Jerry has realized that the winds in Minnesota can play havoc with plastic houses. To provide protection he has surrounded the farm with fast growing trees that slow the wind down (Photo 9). In my opinion, Jerry has been extremely innovative and environmentally sensitive as he goes about producing superior produce.

Adopt a farmer and get a first hand experience of where your food comes from.

Apple Maggots Foiled Again!

Karl Foord, Extension Educator - Horticulture



Karl Foord

Photo 1: Apples showing maggot damage next to protected apple



Karl Foord

Photo 2: Larger apple maggot trapped in nylon guard after exiting apple



Karl Foord

Photo 3: Apple maggot enters apple through flower end and leaves frass



Karl Foord

Photo 4: Small apple cut to reveal resident maggot



Karl Foord

Photo 5: enlarged view of apple maggot resident in small apple

The nylon apple maggot barriers are doing a pretty good job in protecting the apples from the attack by maggots (Photo 1). One fly did manage to oviposit her egg through the nylon mesh. The apple was ruined but at least the maggot was trapped in the barrier sock (Photo 2). Many of the unprotected apples were attacked at the flower end of the fruit (Photo 3). One of these fruits has been cut open to reveal the small apple maggot seen in the lower right half of the right hand slice (Photo 4). Photo 5 is a close up of the same slice. It is obviously critical to get these barriers in place prior to the arrival of the maggots.

The best system would have been to remove all the unprotected apples and give the maggots no chance to feed on any apples. Alas time did not permit. However, it would be best to remove the small damaged apples and get them off-site and not allow the population to build.

Pseudoscorpions are Curious, Harmless

Jeffrey Hahn, Extension Entomologist

Bunni Olson, Univ. of MN Extension

Photo 1: Pseudoscorpions look fierce but are harmless to people

A small, 1/5th inch long, reddish or brownish 'bug' with two large 'pinchers' is sometimes found in homes. Although it looks like a tick or scorpion, it is actually a pseudoscorpion. A pseudoscorpion is not an insect but is a type of arachnid, so it is related to spiders, ticks, and true scorpions. Pseudoscorpions have eight legs and pincher-like pedipalps (part of their mouthparts). They lack the stinger that true scorpions possess.

Pseudoscorpions are predators on a variety of small insects and other arthropods, like springtails, booklice, and mites. They are found in a variety of habitats, such as leaf litter, moss, and under stones and tree bark, and occasionally buildings. Despite their appearance, they are harmless to people. If you find a pseudoscorpion in your home, just physically remove it or ignore it. If possible, capture and release it outdoors. Fortunately, we rarely see more than one or two pseudoscorpions at a time. For more information, see Pseudoscorpions in homes.

Tuesday, July 15, 2014

Gypsy Moth Quarantine in Minnesota

Jeffrey Hahn, Extension Entomologist

(The following has been slightly modified from a June 30, 2014 news release from the Minnesota Department of Agriculture (MDA).

Bill McNee, Wisconsin Dept of Natural Resources

Photo 1: Lake and Cook counties are now under quarantine for gypsy moth



Due to the high number of gypsy moths trapped in northeast Minnesota in 2013, the Minnesota Department of Agriculture (MDA) has placed Lake and Cook counties under quarantine effective July 1, 2014.This is the first time a quarantine for gypsy moth has been established in Minnesota. A quarantine helps to prevent gypsy moths from being moved by human activity to uninfested counties.

Outdoor items in the quarantined counties, like logs and firewood, camping equipment and patio furniture, that could be infested with gypsy moth must be inspected and certified as gypsy moth-free before moving to a non-quarantined area. This is done in two ways:

  • Homeowners, campers and others who live in and visit the proposed quarantine will need to self-inspect outdoor household items, like RVs, camping equipment and patio furniture, before moving those items out of the quarantine.
  • A compliance agreement allows items regulated by the U.S. Department of Agriculture (USDA), including firewood, pulp wood, and saw logs, to move out of the quarantine area or to be received by a business or individual outside Lake and Cook counties. The compliance agreement outlines practices for safe handling, transportation and storage to mitigate the spread of gypsy moth. Compliance agreements are documents prepared and agreed to by the company, city, county, agency, or organization interested in moving the regulated article and the MDA, or USDA in the case of interstate movement.

The MDA has been tracking and treating gypsy moth in Minnesota for decades. Since April 2013, MDA staff has been in discussions with the timber and nursery industries, as well as local, state, federal, and tribal officials on a potential quarantine. When 2013 trapping results showed a record number of gypsy moths, 90 percent of which were located in Lake and Cook counties, an advisory group recommended a quarantine of the two northeastern most counties in the state to the Commissioner of Agriculture.

Details of the quarantine can be found at here. For questions on gypsy moth or the quarantine, call MDA's Arrest the Pest Hotline at 888-545-6684 (voicemail) or email gypsy.moth@state.mn.us.

Friday, July 4, 2014

Repairing Lawns Following Flooding

The month of June was a wet one. Many homeowners, grounds managers, and golf course superintendents are finally starting to see some of the flood waters recede, although standing water is still covering many of our landscapes. The University of Minnesota's Climatology Working Group is calling June of 2014 the wettest month on record. In the Twin Cities we saw 11.36 inches of rain for the month, almost 7 inches above average and falling just short of the 11.67 inch record set in 1874.

We are starting to see a wide range of damage to lawns and turfgrass throughout the state. In situations where standing water was present for greater than 7-10 days, the turf is almost certainly dead and will need to be repaired. Turfgrass covered for less time has a greater chance of recovery, but every situation is different. Unfortunately, there is not good information regarding how long turfgrass can survive under standing water because there are so many potential mechanisms of damage. These mechanisms can be separated into 2 groups: primary damage from waterlogging and secondary damage after the water has gone.

Primary damage includes such factors as water temperature and water depth. Water temperature will probably be the most important factor determining survival, with turfgrass death occurring in only a few days when water temperatures are 80 degrees F and higher (note: we did not see water temperatures this high during recent floods, unless it was very shallow and stagnant). When water temperatures are lower the turf can still die, with lack of oxygen being the primary culprit. If the turf is completely submerged, this will be a worse case than if some of the leaves and crowns are exposed.

Secondary damage might be associated with sediment buildup, fungal diseases, moss and algae, and weed infestation. While we have very little control over the primary mechanisms causing damage, now is the time to start thinking about how to reduce damage that could be caused by the secondary mechanisms. The primary disease you could expect to occur after flooding is pythium blight. Look for circular or irregular patterns of dead turf inside of healthy turf areas. For more information on pythium blight, follow this link to a fact sheet from Purdue University Extension: Pythium Blight. Remember that plant disease samples can be submitted to the University of Minnesota Plant Disease Clinic for correct identification and control recommendations. If you have confirmed that you lawn is infected with pythium or other diseases, I recommend contacting a lawn care contractor to carry out the control measures.

To this point I've been recommending that homeowners be patient and assess the damage as it presents itself. Turf that appears to be dead following the receding of flood waters should be monitored for several days; if no green tissue appears within 7-10 days, you can assume it is dead and should start forming a renovation plan. In many cases, you might be surprised with the amount of turf that recovers when the conditions are right. In situations where sediment or debris buildup has occurred, you will want to act fast to remove it. The previous Turfgrass Extension Educator, Bob Mugaas, wrote a great article addressing repair of areas where sediment has built up in the 2010 edition of the Yard and Garden News. That article can be found here: Repairing Flooded Lawns

Timing of repair can be difficult. The cool-season grasses that we grow in Minnesota do not establish well in the middle of the summer due to the high heat and diseases that may occur. If at all possible, I recommend waiting to seed until temperatures cool in the early fall around mid- to late-August. Fall seeded lawns will have a much better chance of a successful establishment. With that being said, recovery in the short term could be promoted by aerating your soil once it is dry and/or applying light rates of nitrogen based fertilizer.

Choice of turfgrass seed can be very important. If flooding is a common occurrence on your lawn, I would recommend Kentucky bluegrass over perennial ryegrass or fine fescues. The University of Minnesota Extension has numerous resources to help you in repair process. Please follow these links for more information:

Purchasing Turfgrass Seed

Finding the Right Grass Seed

Renovating an Existing Lawn

Lawn Diseases

Weed Control

Finally, feel free to reach out if we can be of help. You can contact me directly at: sjbauer@umn.edu or 763-767-3518

Tuesday, July 1, 2014

July 1 2014 Issue of Yard and Garden News

In this issue:

Extension publications: New & Revised

Start Trapping for Spotted Wing Drosophila

Rose Chafers are Here

Blossom blight blasts crabapple blossoms

Don't be Fooled by Fungus Killed Flies

Squash Vine Borers are Out Now

Japanese Beetles Have Arrived

Beauty is in the Eye of the Beholder

Beauty is in the Eye of the Beholder

Karl Foord, Extension Educator - Horticulture



Karl Foord

Photo 1: Native bee nesting site on U of MN St. Paul campus



Karl Foord

Photo 2: Native bee leaving nest to forage - nest hole lower right of photo



Karl Foord

Photo 3: Native bee nesting site on Como Ave. St. Paul



Karl Foord

Photo 4: Native bee navigating grass in front of nesting site



Karl Foord

Photo 5: Native bee approaching nest with pollen load



Karl Foord

Photo 6: Native bee nesting site - Purgatory Park, Minnetonka



Karl Foord

Photo 7: Native bees at hole entrances



Karl Foord

Photo 8: Bauer Berry Farm - Champlin, MN; Note each flag represents a single nest



Karl Foord

Photo 9: Nest entrance hole Bauer Berry Farm - Champlin, MN

One of the projects I am engaged in this summer is the identification and location of the nests of native bees. My partner in this effort is Heather Holm, who is the author of a recently published book entitled, "Pollinators of Native Plants". With additional help from Joel Gardner, a bee biologist and graduate student at the University of Minnesota, and Colleen Satyshur, the research coordinator at the Cedar Creek Ecosystem Science Reserve, we have been able to identify a half dozen different nesting sites of ground nesting native bees. These sites have included areas on: 1) the University of Minnesota campus (Photos 1 & 2), 2) the front of an apartment complex on Como Avenue in St. Paul (Photos 3, 4 & 5) , 3) Purgatory Park, Minnetonka (Photo 6 & 7), 4) a pick-your-own blueberry farm in Champlin Minnesota (Photo 8 & 9), 5) a pick-your-own blueberry farm in Maiden Rock, Wisconsin, and 6) a residence in Chaska.

These sites had several features in common. There was a degree of exposed soil and the areas were mostly untended e.g. ignored or left alone. The fact that these areas are undisturbed by human activity is a critical feature. However, this also means that the areas might not meet the standards of tidiness and neatness often embraced by most urban and suburban neighborhoods.

My upbringing left me with the impression that areas with exposed dirt and perhaps a few weeds were the sign of a slovenly, lazy person. One who did not care enough about their own property to maintain the unspoken but expected standard of tidiness. One key aspect of this standard seems to be a weedless dark green lawn.

The lawn is an English invention indicating aristocratic status. In essence a demonstration that the owner could afford to keep land not being used for buildings or food production.

Wealthy families in America began mimicking such English landscaping styles in the late 1700's. The first lawnmowers were invented in the 1830s in England. The subsequent improvement of these machines permitted middle-class families to imitate aristocratic landscapes and grow finely trimmed lawns in their back gardens.

Jump to the 20th century and behold the increased value of a home through landscaping and its most prominent feature - the well manicured lawn. Maintaining such a lawn may require fertilizers, pesticides, and gasoline powered mowing and maintenance equipment as well as water, depending on location.

The University of Minnesota Turf program is searching for ways to reduce the environmental impact of lawns through drought-tolerant, slower growing species as just one of their approaches.

It was the interest in native bees and their nesting sites that has had me reconsider the negative associations associated with some open ground and untidy areas. I now consider such areas to be an important and purposeful part of my landscape, as it provides nesting sites for native bees.

For what used to be an eyesore, is now a place of beauty when occupied by our fascinating native pollinators.

Perhaps it is time to reconsider lawns in terms of their benefits and ecological impacts.

Japanese Beetles Have Arrived

Jeffrey Hahn, Extension Entomologist

Japanese beetles have started showing up in gardens; the first discoveries of them were made in late June. It does not appear the late spring slowed down their emergence too much as the first week of July is about when we expect to see these beetles. It will be interesting to see how abundant they are this year. Because they were well insulated under the snow, it is not expected that last winter's cold weather had much effect on their populations.

However, a factor that does impact their relative numbers is the soil moisture at the time eggs are laid. The eggs and young white grubs are particularly susceptible to dry soil conditions. Eggs are laid soon after adults start to emerge, generally early to mid-July. However, older grubs are much more tolerant of dry soil. So the number of Japanese beetles that are present this year is related to soil moisture last summer. Although we have experienced drought in many recent years, 2013 was a fairly wet year. We could expect Japanese beetle numbers to be rebounding in at least in some areas.



Jeff Hahn, Univ. of MN Extension

Photo 1: Handpicking Japanese beetles on daily basis and putting them in soapy water can effectively reduce feeding injury on plants.

There are a variety of methods for managing Japanese beetles including physical removal. A research paper in Horticultural Entomology from this year examined the effectiveness of handpicking Japanese beetles daily on a small scale (i.e. a home landscape). This research looked particularly at the effectiveness of removing Japanese beetles at different times of the day.

The researchers found that physically removing Japanese beetles on a daily basis in general helped to significantly reduce damage on grapes compared to removing no beetles. This is because damaged leaves give off a chemical volatile which attracts Japanese beetles and increases colonization and damage to plants. Keeping numbers of Japanese beetles low helps to reduce the attractiveness of them to plants. The researchers additionally found that the best time to remove Japanese beetles is at 7:00 p.m. (compared to 8:00 a.m. and 2:00 p.m.). This is because Japanese beetle activity peaks in mid-afternoon and feeding continues overnight. Grape leaves damaged overnight were more effective in recruiting new Japanese beetles than freshly injured ones. Reducing Japanese beetles at this time was the most effective time to minimize feeding injury to plants through physical removal.



Jeff Hahn, Univ. of MN Extension

Photo 2: If you have had problems with Japanese beetle grubs, treat them preventatively now.

If you have had a problem with Japanese beetle grubs in the past, now is the best time to treat them preventatively. By the time eggs are laid and grubs hatch, about two to three weeks, the insecticide will be taken up by the grass and the young grubs will be exposed to it.

For those looking for a low impact approach to treating white grubs, consider parasitic nematodes, especially Heterorhabditis species. Apply nematodes late in the evening. Be sure that they are watered in and that the soil is kept moist for at least a week (two to three weeks is even better). Parasitic nematodes are available from garden catalogs or biological control companies. Milky spore disease is also a low impact insecticide; however in research trials it has not been very effective against Japanese beetle grubs.

There are several traditional preventative insecticide options that are very effective. Look for imidacloprid (various trade names) or clothianidin (Green Light Grub Control with Arena), both neonicotinoids, or chlorantraniliprole (Scott's GrubEx) a type of anthranilic diamide. If Japanese white grubs are not treated preventatively now, they can be treated curatively with Trichlorfon (Dylox) or chlorantraniliprole (Scott's GrubEx) until mid to late August. After that, the grubs are generally too large to manage very well with any insecticide.

Remember to only treat the grubs if you are experiencing problems in your lawn. It is not effective to control grubs to reduce the number of adults that are seeing. Adult beetles are good fliers and can easily fly into your yard from the surrounding neighborhood.


For more information see, Japanese beetle management in Minnesota.
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