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Extension > Yard and Garden News > January 2011

Monday, January 31, 2011

Contents: February 1, 2011

In this issue of the Yard and Garden News:

The Rotting of the Harvest

Michelle Grabowski, UMN Extension Educator

Storage vegetables are a great way to keep eating healthy and local throughout Minnesota's long winter. A wide variety of vegetables will keep for one to several months with minimal preparation. Common storage vegetables include carrots, beets, parsnips, turnips, cabbage, kohlrabi, potatoes, onions, garlic, winter squash and celeriac.

Under ideal conditions winter squash can keep for 2-6 months (depending on variety), onions keep up to 4 months, potatoes keep up to 6 months, and carrots keep up to 8 months. It is important to remember that each vegetable has specific moisture and temperature requirements to maintain them in good condition during storage. In her publication 'Harvesting and Storing Home Garden Vegetables', Dr. Cindy Tong of the University of Minnesota Department of Horticulture, provides a detailed table on what environmental conditions each vegetable requires. In addition, Dr. Tong talks about different places in the home that these conditions could be found or created.

Photo 1: Dark, soft, sunken spots on this pumpkin are the early stages of storage rot.
M. Grabowski, UMN Extension.

Whether you grow vegetables in your own garden, receive them as part of a CSA, or purchase them from the farmers market, always select undamaged produce for storage. Small wounds are easy entry points for storage rot fungi and bacteria. Produce with even a small area of rot will continue to rot and can spread the pathogen to neighboring produce in the refrigerator or on the pantry shelf.

Storage rot fungi often infect vegetables while they are growing in the field, but symptoms may not show up until weeks later in storage. The 2010 growing season had regular rains and warm weather. These are ideal conditions for fungal plant pathogens. Many common garden vegetables suffered from severe leaf spot and fruit rot diseases in the field. It is likely that even healthy looking vegetables put into storage contained some unseen latent infections.

It is important to inspect storage vegetables regularly through the winter. At this time of year, fungal rot can frequently be found in storage vegetables, particularly those in less than ideal conditions. Look for soft sunken spots or dark discolored areas on the surface of the vegetable. Fluffy white cottony growth is an indication of fungal activity and can often be found at the stem end or base of the vegetables, where two vegetables touch together, or areas where humidity is high. Powdery black, blue green or even pink fungal spores may been present.

Photo 2: Fusarium basal rot on shallot.
M.Grabowski, UMN Extension.

If early signs of rot are found, these vegetables should be immediately removed from the storage bin. If caught early enough, rotted areas can be cut out and the remaining healthy tissue can be used for dinner. If left, however, these minor infections can grow until the vegetable completely collapses from rot. In many cases the disease will spread to infect and rot neighboring vegetables. It is possible for an entire bin of vegetables to succumb to rot started on one fruit.

If you do not have ideal vegetable storage facilities in your home, look for stores that carry local Minnesota storage vegetables. Often these vegetables are labeled with the Minnesota Grown label.

Mosquitoes Out of Season

Jeffrey Hahn, Asst. UMN Extension Entomologist

Photo 1: Anopheles punctipennis.
Bunni Olson.

When living in Minnesota, we know that mosquitoes are a fact of life. However, we at least can take consolation that this is a problem during the summer and not something we need to deal with in the dead of winter. And yet, a homeowner e-mailed that she was finding odd insects in her home that she said looked just like mosquitoes. She sent an image that showed what looked like a mosquito but with banded wings. Mosquitoes typically do not have banded wings but there are some closely related insect groups, like crane flies, that commonly do.

However, the long proboscis (mouthparts) and scales on its wings give the insect away as a mosquito. You can identify it as female because its antennae with few hairs on it and is not feather-like as a male would be. You can even identify the mosquito as an Anopheles sp. from the long palps adjacent to the proboscis. The wings have alternating black and light colored patches on their wings which are distinctive and diagnostic for the species Anopheles punctipennis (no common name).

Anopheles punctipennis, like other Anopheles species, spends winters in Minnesota in a diapause, a period of inactivity somewhat similar to hibernation. In fall, this species seeks dark, quiet, protected areas and commonly are found in abandoned buildings, hollow trees, caves, garages, and basements where they would normally stay for the winter. For individuals overwintering indoors, it is possible for some movement by a person or pet near to where they are resting to cause them to become active. Fortunately, Anopheles punctipennis is not known to transmit any disease and in fact are very unlikely to even bite now. They are just a nuisance and you do not need to take any special control measures against them.

What's New in Hardy Compact Shrubs?

Kathy Zuzek, UMN Extension Educator


Photo 1: Fall color of burning bush. Kathy Zuzek.

Plantsmen and plant breeders have been busy developing and selecting compact and small-stature colorful shrubs in the last few years. Some of those cultivars that will grow in our northern gardens are Fire Ball® burning bush, Little Lime™ hydrangea, Northern Accents® Sigrid rose, and Oso Happy™ Petit Pink rose. Photo2.jpg

Photo 2: Green flowers of Limelight & Little Lime. Bailey Nurseries.

Burning bush (Euonymus alatus) is a highlight in our Minnesota fall landscapes where it grows as a large shrub or small tree in landscapes and adds bright red to our fall landscapes when grown in full sun. In partial shade, burning bush provides wonderful combinations of pink and green in fall. 'Compactus', a commonly grown cultivar in Minnesota, grows to 6-8'. Although it is rates as hardy to Zone 4 (or hardy to -30° F), it often suffers some stem injury when winter temperatures drop to -25°F. Photo3.jpg

Photo 3: Little Devil ninebark. Bailey Nurseries.

Fire Ball® burning bush is a plant selected for its superior winter hardiness and tighter branching by Cole Nursery in Ohio. This is really not such a new cultivar as it was selected years ago. But it has been recently rebranded and is finally being widely marketed. Fire Ball's height and width are 5-6' and in Michigan where this plant has been tested, no winter injury was seen on stems of Fire Ball® during the harsh winters that did injure 'Compactus'.


Photo 4: Northern Accents Sigrid. Kathy Zuzek.

Hardy hydrangeas in Minnesota are the panicle hydrangea (Hydrangea paniculata) and the smooth hydrangea (H. arborescens), and many wonderful cultivars have been developed or selected among both species. Limelight® panicle hydrangea is a popular 8-foot tall cultivar whose new flowers emerge in tones of soft lime green and ivory and then mature to pink and burgundy in fall. A new introduction from Spring Meadow Nursery is Little Lime™ hydrangea with green and ivory flowers on a 3-5' plant and rated as Zone 3 hardy (hardy to -40°F.)Photo5.jpg

Photo 5: Oso Happy™ Petit Pink. David Zlesak.

Ninebarks (Physocarpus opulifolius) are large plants that can reach 8-10 feet in height and width. Several cultivars have been selected for their gold or red-purple foliage and some of these have more compact growth habits of 5-7 feet. The newest and smallest addition to the ninebark collection was bred here in Minnesota by Dr. David Zlesak and is named Little Devil™. Little Devil is a upright ninebark that grows to 3 or 4 feet in height and width with smaller burgundy leaves and white-pink flower clusters that pair beautifully with the small plant stature. Little Devil is listed as Zone 3 hardy.

Two new small statured roses are available this year for northern landscapes. The fourth cultivar of the University of Minnesota's Northern Accents® collection is Sigrid, with its double red flowers. Like its predecessors, Sigrid is a repeat-flowering polyantha rose with a 3' compact dense plant habit, large sprays of 1" flowers, and a high level of blackspot tolerance. Sigrid is crown-hardy in Zone 4 hardy.

Oso Happy™ Petit Pink rose is another Minnesota introduction from Dr. David Zlesak. Petit Pink is a Zone 4 hardy, repeat-flowering miniature rose whose pink and yellow petals add lots of warmth to a landscape. Petit Pink dies back in winter to the crown or within a few inches of the ground and then grows back into a 2.5'x 3' rounded dense plant.

Position Statement on Ash Conservation/EAB Management Now Available

Jeffrey Hahn, Asst. UMN Extension Entomologist

A position statement was released in January strongly advocating the conservation of ash as a part of an integrated pest management program, along with tree inventories and strategic removal / replacement of unhealthy ash. Cost-effective, environmentally sound emerald ash borer (EAB) treatment protocols are now available that can help preserve ash trees. This document is supported by a combination of university scientists with expertise in EAB management, commercial arborists, municipal foresters, public works officials, and non-governmental organizations (NGOs).

This is a very important document that should help guide us as we deal with EAB in Minnesota. Below is the text for the document. To see the original document, click here,

Coalition for Urban Ash Tree Conservation
- Emerald Ash Borer Management Statement -

Emerald ash borer has killed millions of ash trees since its discovery in 2002 and the number of dead ash is increasing rapidly. Ash species are abundant in planted and natural areas of urban forests, representing 10 - 40% of the canopy cover in many communities.

Ash trees provide substantial economic and ecosystem benefits to taxpayers, ranging from increased property value, to storm water mitigation, to decreased energy demands ( ( this link is no longer available).

Consequently, widespread ash mortality in urban forests and residential landscapes is having devastating economic and environmental impacts. Indeed, EAB is predicted to cause an unprecedented $10-20 billion in losses to urban forests over the next 10 years. (

After its initial discovery, regulatory agencies attempted to eradicate EAB through removal and destruction of all ash trees in infested areas. Unfortunately, this proved unsuccessful and was soon abandoned.

Thumbnail image for michigan park.JPG
Photo 1: Ash stumps in park in Michigan cut down due to EAB.
Credit: Jeff Hahn

Since then, university scientists have developed and refined treatment protocols that can protect healthy ash trees from EAB and help conserve the urban forest. However, despite availability of cost-effective treatments, many municipalities, property managers, and homeowners continue to rationalize tree removal as the only viable management strategy for EAB. This is based on erroneous beliefs that tree removal slows the spread of EAB, or that treatment is not effective, economical, or environmentally sound. Current science supports conservation via treatment as a sensible and effective tool for managing healthy ash trees in urban settings. In many cases, tree conservation is economically and environmentally superior to tree removal.
Based on research conducted by university scientists, and careful review of the potential impacts on human health and the environment, the Environmental Protection Agency (EPA) has registered three systemic insecticides for control of EAB - dinotefuran is registered for basal trunk bark or soil application, emamectin benzoate for trunk injection only, and imidacloprid for soil application or trunk injection.

When applied using formulations, products, and protocols documented as effective by university research, these treatments can provide environmentally sound control of EAB, sufficient to maintain a functional and aesthetically pleasing ash canopy.

Treatment is most appropriate after EAB infestation has been detected within 15 miles, and is most effective when applied before trees are infested. However, treatment can also save ash trees with a low level of EAB infestation. Spring is the ideal time for treatment, but soil application in fall can be effective in some situations.

Different treatment regimens will be optimal under different situations -- no one treatment plan or application method is best under all circumstances.

A program of sustained treatment will be needed to conserve trees through peak EAB infestation. However, as the local EAB population declines due to death of untreated ash, it is possible that treatment frequency may be reduced. Research on this question and other aspects of EAB management is ongoing, requiring practitioners to stay current.

Up-to-date information about EAB insecticides, application protocols, and effectiveness can be found at:

In summary, urban ash conservation can be less costly than removal, especially when the significant environmental and economic benefits of established trees are considered (, Furthermore, ash conservation can circumvent the substantial environmental impacts caused by wholesale deforestation of the urban landscape, as well as the documented public safety risks associated with standing dead ash trees and their removal. [See original document (link above) for authors and their affiliations]

Hand Pollination of Apple Trees?

Karl Foord, UMN Extension Educator

Business Week.
I recently attended a conference on native pollinators presented by Jennifer Hopwood of the Xerces Society. The Xerces Society (founded in 1971) has worked to conserve invertebrates and their habitat by focusing on conservation policy, advocacy, education, and research.

One rather alarming topic presented at the conference involved Maoxian County in the Chinese province of Sichuan (see map). In this region farmers have been forced to pollinate their apples and pears by hand because there are insufficient natural insect pollinators to ensure proper fruit set and thus a crop. These are high value crops that must be free of cosmetic defects to be marketable. To achieve this, the growers have resorting to spraying when there is the least hint of a problem. This has resulted in marketable material, but at the cost of having destroyed all the native pollinators in the region. There are beekeeping services but these individuals hesitate to locate their bees in the area because of the danger presented to their hives by the pesticide use strategies of the fruit producers. The result hand pollination by humans. This report comes from one county in a province that produces a little more than 1% of Chinese apples. Nonetheless, the province still produces some 409,000 metric tons of apples (in 2009). And this pollination problem is not an isolated case, but rather extends to other countries in the region such as Pakistan, India, and Nepal.

Such a situation does not translate well into American agriculture especially considering labor wages. If we were to do so it would look like this: It takes twenty Chinese workers working for 10 hours to pollinate a half acre (see pictures). Translated into an orchard in the United States where the workers were paid $9 per hour, it would cost the growers $3,600 in pollination services. This would probably double the cost of apples.

How can we best relate to this situation? A certain amount of the problem comes from an ignorance of the complexities involved in the relationships between insect pollinators and crop plants. However, we in the U.S. are not immune, even though the problems we face may be different. Our commercially managed honeybee populations are facing a number of challenges as noted by Dr. Marla Spivak in a previous article. We have also seen a dramatic decline in a number of native bumblebee species that were previously quite numerous. The exact causes for such a decline have not been definitively identified, however it is likely that there is no one cause but rather a series of causes. And again the complexity we face with biological systems rears its head.

Hand pollination of fruit crops is about as unsustainable as a system can get. The fact that it exists anywhere sends me a strong signal to be extremely vigilant about land management, pollinator habitat, and pesticide use to avoid such an outcome in our fruit production systems.


Pollination problems in China

Status Review of Three Formerly Common Species of Bumble Bee in the Subgenus Bombus

Calendar: February 1, 2011

Chrysanthemum 'My Favorite.' Julie Weisenhorn.
  • Why not give a blooming plant, rather than cut flowers for Valentine's Day this year? Choices can range from inexpensive African violets, chrysanthemums, or miniature roses to large azaleas and exotic orchids. Their flowers will last much longer than bouquets of floral arrangements, and with continued care, many can be grown as houseplants and made to re-bloom. Wrap the plant well, then place it in a good-sized plastic bag to trap warm air before putting it in a pre-warmed car to bring to your valentine.

  • Assemble equipment you'll need to start seeds indoors: pots, trays, fluorescent lights that can be raised or lowered, a timer, and, for best results, a heating device to put under containers of germinating seeds. help avoid diseases by using fresh potting soil that drains readily, along with tools and containers that are clean or disinfected. Cool, soggy growing conditions and poor air circulation also favor disease development.

  • Improve your winter landscape by adding plants to your garden and landscape next spring. Spruce, pines, and fir trees are obvious choices, but consider ornamental grasses and other tall perennials that can stand up to the snow. Shrubs such as red twig and and flowering dogwoods add color, as do many flowering crabapples that hold their fruit all winter.
Be sure to visit the U of M Extension - Garden website for more ideas to beat the winter blues!
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