Yard & Garden Line News Volume 3 Number 2                                                               February 1, 2001

Features this issue: Carpenter Ant Activity in Winter Let the Sun Shine Scratch the Planting Itch With Onions The Bell Tolls For Dursban And Diazinon Editorial Notes

Carpenter Ant Activity in Winter
Colleen Cannon, Extension Entomologist

The black carpenter ant (clockwise from upper left: winged queen, male, major worker, media, minor worker.) Photo credit: L. Hansen & R. Akre

Carpenter ant damage to wood. Photo credit: L. Hansen & R. Akre

Small carpenter ant colony containing workers and brood. Photo credit: R. Fell

For most of us, winter is a season with much to endure - short days, slippery sidewalks, cold feet. For insects, whose body temperatures are much closer to ambient temperatures, winter is a test of survival. Normal activities, such as walking, flying, feeding, or reproducing, become impossible for most insects. As a result, the majority of insects will either die or spend the winter in a state of hibernation. Even those insects that invade our homes in the fall do not remain active, but instead seek out protected hibernation sites indoors. One of the few exceptions is the carpenter ant.

Carpenter ants are one of the largest and most common ants. There are 43 species of carpenter ants in the U. S., though the most common species in our area is Camponotus pennsylvanicus, the black carpenter ant. The queen, at nearly ¾ inch, is the largest member of the colony and the largest ant in Minnesota. The workers of the black carpenter ant can vary in size from approximately ¼ - ½ inch in length. All sizes are found within the colony, though older colonies tend to be larger and produce bigger workers. Once a colony is approximately three years old, it produces winged ants, or swarmers. Unlike workers, which are sterile females, these winged individuals are males and females capable of reproducing. Swarmers are released from the nest in spring and summer to mate and start new colonies.

Carpenter ants are named for their habit of excavating smooth-walled tunnels in wood. They do not eat wood, but merely scrape out tunnels, or galleries, ejecting the sawdust-like scrapings. They seem to favor wood that has been softened by moisture. Carpenter ants will nest in trees, decorative timbers like railroad ties, and structural wood. Carpenter ants also tend to locate their nests in pre-existing cavities, such as tree hollows and wall voids, as well as in soft material like fiberglass insulation.

When carpenter ants nest away from man-made structures, they prepare for winter as do other insects. In late summer, they build up their body's fat reserves and increase the supply of glycerol in their blood. The increased fat will provide them with calories during the months without foraging. The glycerol will act as an antifreeze, allowing them to endure temperatures down to -22°C. As the days get shorter, they reduce feeding and other activities, and cluster together within the nest. By late fall, the colony is fully dormant. The colony will remain inactive, neither feeding nor drinking, for up to 6 months.

The ants start to resume activity in early spring, though they must wait for air temperatures to warm to at least 10°C before they can forage outdoors.

When the ants nest in heated man-made structures, their activity cycle differs slightly from that described above. Colonies will slowly reduce foraging and brood rearing activities as fall approaches, just as those in unheated sites will do. In October or November, the colony will cluster together and become entirely inactive. At that time, the homeowner will no longer see ants foraging about the house. However, the ants do not remain dormant for long. Nests that are well insulated or in internal walls receive enough heat to enable the ants to emerge from hibernation as early as January. Naturally, once activity has been resumed, the ants must have food and water. For this reason, homeowners may notice ants mainly in the kitchen or bathroom. Ants can be common around dishwashers, which are a source of both food and water.

For the homeowner, seeing carpenter ants in the home now brings both good news and bad news. The presence of active carpenter ants so early in the year is clear evidence that the home is infested. While this may not be what the homeowner would like to hear, it does simplify treatment. Normally, in order to eliminate a carpenter ant problem, all carpenter ant nests in and around the home must be located and treated. In warm months, this necessitates a complete inspection of the structure's interior and exterior, including the grounds and surrounding property. In winter, the inspection can be limited to the interior of the structure itself.

The homeowner can hire a professional to treat the problem, or can try to locate the nest him- or herself. Clues to nest location can be gotten by observing the ants. At this time of year, ants are searching for sugar and water, so place a small amount of sugar water or diluted honey in spot where ants are crawling. Foragers encountering the sweets will feed and return to the nest to share food with other colony members. The path of foragers leaving the food will indicate the direction of the nest. Follow foragers as far as possible. Typically, they will disappear behind a baseboard or cabinet, or into a crack or an electric outlet, which may mean the nest is near. Drilling a small hole into each wall void in that area will allow the application of boric acid or an insecticidal dust. Alternatively, one can avoid the work of nest location by mixing a self-made bait. Adding a toxicant, such as boric acid, to a food upon which the ants have been seen feeding will produce the best results (¼ teaspoon boric acid to 4 tablespoons food). (Read and follow all label instructions when using any insecticide.) Be observant and be patient -- treating carpenter ants at this time of year is a slower process than treatments in summer when the ants are more active.

Let the Sun Shine
Deborah Brown, Extension Horticulturist

Heartleaf philodendron. Photo credit: Deb Brown

As inhabitants of northern latitudes, we all recognize the importance of sunlight. Our short winter days can't help but heighten this awareness. How many times have you heard fellow-Minnesotans say they don't mind the cold, as long as it's sunny? Few would argue that sunlight lifts our spirits and makes winters bearable.

Now, let's consider indoor plants. They don't just "feel" good in sunny weather -- their very existence depends on light, granted, not necessarily sunlight.

If your houseplants have been languishing since mid-October, barely growing because light has been so limited, take heart. By the end of this month or early next, they'll emerge from their winter doldrums. Leaf buds will unfurl at rates unheard of in December or January and luxuriant new growth will herald the arrival of longer, sunnier days -- and the need to resume fertilizing.

Why are light levels so important? Through the process of photosynthesis, all plants -- whether they live indoors or out -- convert light energy into carbohydrates for growth and development. Without sufficient light, their rate of photosynthesis drops so less food energy is produced and stored.

Houseplants may look fine for a while growing where light is inadequate, because they can live off reserve carbohydrate supplies. Next they'll grow stretched and spindly. And once those reserves are depleted, plants will deteriorate rapidly.

Typically, the first sign you'll see is that they drop lots of leaves, but lack the food energy needed to grow more. They look less and less attractive, with most of their foliage clustered near branch tips. Sometimes they're attacked by mites or insects that seem drawn to any plant that's already growing poorly. These unfortunate plants usually they end up in the trash or compost pile before they actually die.

How can you provide enough light for houseplants to hold their own in a Minnesota winter? You can install additional lighting meant specially for houseplants. But, if like most people, you don't plan to use supplementary lighting, the most sensible approach to dealing with our low light winters is to choose your plants carefully. Pick houseplants that will grow well in the light levels that exist in your home under the worst, rather than best, conditions.

Peace lily flower. Photo credit: U of MN Extension Service

Houseplants with high light requirements thrive in a south or southwest-facing bay window or patio door, year-round. Medium light plants grow well in a west or south-facing window in winter, but need only an east window in spring and summer. But low light plants are the most versatile. They're always fine in north or east-facing windows, and also do well located several feet from brighter windows.

The same low light plants that can be counted upon to look good in your home throughout winter can be found gracing interior landscapes in hotels, restaurants and office buildings where sunshine seldom penetrates.

While light levels aren't high in these interior spaces, they are roughly equivalent to those found in north-facing windows. And houseplants can perform perfectly well when lit by large fluorescent, halogen, metal halide or high pressure sodium lights recessed into the ceiling, rather than sunlight streaming through a window.

Your choice of houseplants is definitely more limited when light levels are low, but some of these plants are very attractive. The following are tough customers; they'll look good regardless of the season. And it won't be winter forever!

Chinese Evergreen Aglaonema species
Known for beautifully patterned silver and green foliage, Chinese evergreens could be considered the dieffenbachia's compact cousins. Excellent as table-top specimens, they lack the tall, gangly stems associated with dumbcane, and grow well in far less light. If you're lucky they'll develop small, canoe-shaped flowering structures that are followed by bright red berries. A word of caution, though. The berries are not edible, and should be kept out of the reach of young children.

Low light Sanseverias. Photo credit: U of MN Extension Service

Peace Lily Spathiphyllum species
Characterized by large, arching, rich green leaves, peace lilies are among the few houseplants that bloom consistently in relatively low light. Their lovely pure white "flowers" slightly resemble those of Jack-in-the-pulpit, to which they're related. (They're both members of the Araceae family.) Each flower lasts upwards of four weeks before it begins to turn muddy-colored and greenish and should be removed.

Pothos and Heartleaf Philodendron Epipremnum aureum and Philodendron scandens oxycardium
Lend your home a touch of the jungle by adding one or both of these prolific houseplants. In their native environment these vining plants grow from the ground up the sides of trees, but in your home they're perfect for hanging containers. If stems grow too long you can prune them back, forcing them to branch, or twine them in large hanging loops. They need never look scraggly, even though they might actually be stretched due to extreme low light.

Parlor Palm or Bamboo Palm Chamaedorea elegans or Chamaedorea erumpens
Most palms actually run the risk of outgrowing their surroundings in a home setting. This won't happen with either of these compact yet delicate-looking plants. Both are sold as small table-top specimens or mid-size floor plants, usually with several stems to a pot. As they grow taller, they also send out "suckers" or smaller plants at the base of the larger ones. This results in full, attractive plants with fronds arising from many growing points.

Snake Plant (known also by its more colorful name, mother-in-law's tongue) Sansevieria trifasciata laurentii
These stiff, vertical plants consist of variegated green and silver strap-like, leathery leaves with yellow bands on the edges, emerging directly from horizontal rhizomes. Though there might be heated discussion as to whether they qualify as good-looking, no one would disagree they are the toughest and most carefree of all houseplants. Large specimens, two to three feet tall, add a dramatic, sculptural look that works with any decor. When they're happy in their environment, they send up spikes of tiny pinkish flowers; a welcome sign, especially this time of year.

Scratch the Planting Itch With Onions
Beth Jarvis, Yard & Garden Line

Egyptian walking onion. Photo credit: Beth Jarvis

Are you itching to start planting? It's much too early to start most seeds but onions are one exception.

Onions, as members of the allium family, are cousins of garlic, chives, leeks and shallots. They're mostly biennials as they grow vegetatively the first year then bloom the second.

There are a few perennial onions. You'll find them in catalogs under multiplier onions or Egyptian walking onions. Multiplier onions increase by producing new bulbs in a clump. Walking onions send up a flower stalk that sets numerous marble-sized bulbs at the top. When the weight of the bulb cluster becomes too great, the flower stalk collapses and the little bulbs take root where they land, hence they "walk". These onions are perhaps best used for green onions.

Starting onions:

Onions can be started three way: sets, direct seeding and transplanting.

Sets:

Sets are onions that were planted from seed last year. You can find sets for white, yellow and sometimes, red onions in garden centers, mail order catalogs and even some grocery stores. You can raise you own sets but you'll need to direct seed them in July so they can grow big enough to harvest by fall then store over winter.

Onion sets should not be sprouting when you buy them, but should be firm and marble size. Big sets may split into two bulbs or produce a flower stalk very early. (When an onion sends up a flower stalk, pull the onion and use it as it won't grow any larger.)

Tolerant of some frost, onions can be planted outside when temperatures reach 48 degrees, around the middle of April in the Twin Cities. Plant onion sets, pointy end up, 1 ½ to 2" below soil, 3 to 4" apart and firm the soil around the bulbs.

If you want to raise a winter's worth of onions, you'll need to plant onions from seed or seedlings in addition to onions from sets. Onions from sets don't store as long as the others. Remember, onions from sets are in their second year, so they're more likely to send up flower stalks in summer.

Direct seeding:

You'll probably be most successful direct seeding green onions (also called scallions) as our short season makes success with bulb types less likely. Green onions don't form bulbs.

Buy only as much seed as you will use this year. Onion seeds doesn't remain viable for much over a year.

Cover seeds with ½" of soil and water well.

Transplants:

Start onions from seed in February and transplant onion seedlings outside in May. Starting your own transplants gives you something to plant indoors now, more choices of varieties to raise, and will give you bigger onions by fall.

Onions, chard and carrots. Photo credit: Beth Jarvis

Perhaps the most important thing to remember is day length, especially if you're ordering seed from a national mail order firm. As strange as it seems to us during this gloomy winter, with only 10 hours of daylight, we need to buy long day onion plant seeds because our summer days can be almost 16 hours long.

In the south, day length varies less and averages about 12 hours of light per day. Onions for southern gardeners are "short day" onions and when short day onions are exposed to 12 hours of light, they start to form bulbs. You can raise short day onions in Minnesota but plants in our gardens are exposed to 12 hours of light early in the season, so all you'll get is small onions.

Long day varieties start to bulb when day lengths reach 14 to 16 hours in late June. If you start onion seeds under lights, remember to turn the grow lights off to give the plants a suitable night. Onion seedlings will bulb too early if exposed to long days at any time during their development. You will not get anything bigger than sets. (I hate to admit that the voice of experience in this case is mine. I left the lights on for days on some seedlings and still had only sets by fall.)

Some cultivars of full size onions to consider include: White Sweet Spanish, Yellow Sweet Spanish, Walla Walla, Red Burgermaster, Early Yellow Globe, Southport Red Globe, Redwing and Superstar. Suitable onions will be labeled "early" or long day designations.

Keep onion seedlings trimmed to 4 inches. Research has shown that this will increase the ultimate yield by producing healthier plants. Physical manipulation of seedlings has long been known to increase stem sturdiness. In this case, trimmng the stems with scissors provides the movement that encourages the stems to stiffen. Also, by keeping the stems at a uniform, lower height, supplimental lights can be positioned closer to the plants, providing maximum exposure.

Onion seedlings need to be hardened off before transplanting outside, after danger of frost has passed. This means the seedlings will need to be exposed to outdoor conditions gradually, over a 2 week period.

Add fertilizer, based on a soil test, at planting, again when leaves are 4 to 6" tall and when bulbs are starting to swell Plant seedlings plant 4" apart. Poke a hole with your finger in the soil deep enough to accommodate the seedling roots, then press soil around seedling. Keep them well watered, about an inch a week. Watering is critical when the bulbs start to swell. Water stress produces stronger flavored bulbs.

Mature onions. Photo credit: Beth Jarvis

Harvest

Onions are edible at any stage. Immature bulb-forming onions can be thinned from the garden and eaten. (These immature bulb onions are also called scallions.)

Onions are ripe when 1/4 to 1/2 of the tops have fallen over and bulbs have developed a papery skin. (For storage onions, 50% or more to the tops should have fallen over.) Gently push down the other plants, taking care to not break the stalks. Leave the onions in the ground for several days then pull them and let them cure in a warm, airy place out of the elements for a week or two.

When properly dried for storage, onions will have a dry, shrunken neck and dry outer scales When storage onions are dry, hang them in mesh bags, old nylons or braid the tops and store them in a cool, dry site.

Mature, cured onions are physiologically dormant with the length of dormancy cultivar-dependent. Cool storage will prolong dormancy. Recommended storage temperature is 32 degrees, though onions should not freeze. Onions will start to sprout at temperatures over 40 degrees.

There is absolutely no truth to the story that potatoes and onions should not be stored together because one makes the other sprout. The truth is, they have different storage temperature requirements and the optimal storage temperature for potatoes is 40 degrees, the temperature at which onions sprout.

The Bell Tolls For Dursban And Diazinon
John F. Kyhl, Entomology technician

Last summer, the United States Environmental Protection Agency (EPA) announced that chlorpyrifos (Dursban) will be phased out. In December, the EPA announced that diazinon will also be phased out. Both insecticides have been widely used and found in many products from indoor insect sprays to building perimeter treatments to fruit and garden insecticides.

Sowbugs. Photo credit: Jeff Hahn

While certain commercial nursery and agricultural uses will continue, all home and garden labels will be phased out within the next few years. The announcement of the phase-out has caused 'panic' for some users of these products, their concern that they will not have any alternate products to treat some insect pests. However, both Dursban and diazinon can still be purchased in retail stores and applied this year. In fact, diazinon can be purchased for household use until December 2002, and for home lawn, garden, and turf uses until August 2003. If you have any insecticides containing Dursban or diazinon, you can continue use them after the sales deadline.

In many cases, there are also alternatives for Dursban and diazinon available now. The remainder of this article will discuss other insecticides for managing specific groups of pests.

Leaf feeders (caterpillars, leaf beetles, sawflies, etc.): Caterpillars and other leaf feeding insects are controlled by a wide variety of products. For caterpillars, Bt var. kurstaki (e.g., Dipel) is an excellent choice. Bt var. kurstaki is specific to butterfly and moth caterpillars, and has a negligible effect on beneficial insects. Btvar. tenebrionis (e.g., M-trak) works well on small leaf beetle larvae. Bt products have no effect on sawflies. Also effective are soaps (e.g., Safer's), oils (e.g., Sunspray), acephate (e.g., Orthene), carbaryl (e.g., Sevin), or malathion (e.g., Malathion). Two relatively new products, also available for leaf feeding insect control, are permethrin (e.g., Eight) and bifenthrin (e.g., Ortho Houseplant and Garden Insect Killer).

Sucking insects (aphids, scales, plant bugs, etc.): Many of these insects are soft bodied and can be controlled with soaps or oils, less toxic products or acephate (e.g., Orthene)or cygon (e.g. dimethoate), malathion, or carbaryl (e.g., Sevin) [carabaryl is generally not effective against aphids]. Newer available products contain permethrin or bifenthrin.

Borers (wood borers, bark beetles, etc.): The best replacement for Dursban is permethrin.

White grubs. Photo credit: John Kyhl

Turf pests (white grubs, sod webworms, etc.): Many new products are now available for turf insect control, including deltamethrin (e.g., Delta Eight), imidocloprid (e.g., Season Long Grub Control), trichlorfon (e.g., 24 Hour Grub Control), and halofenizide (e.g., Grub-B-Gon). These products are active against grubs and other turf pests. Acephate (e.g., Orthene) is also effective against many turf pests.

Garden and fruit pests (e.g., cabbage looper, Colorado potato beetle, fruit pests, etc.): There are many effective options for garden pests, such as permethrin, bifenthrin, esfenvalerate (e.g. Bug-B-Gon Multi-Insect Liquid). Other options include soaps, oils, and Bt products (see above) carbaryl and malathion are also effective on many pests.

Soil pests in garden (root maggots, wireworms, etc): At this time, none of the companies contacted had suggestions for the replacement of diazinon to control soil insects. Bonide is in the process of introducing a granular product containing permethrin (Eight Yard & Garden Granules) that will most likely be available for the 2002 growing season. However, it is not clear whether this product will be labeled for soil pests. Recall, though, that diazinon granules should still be available for the next three growing seasons.

Household pests - Indoor (roaches, spiders, ants, etc.): ). Newer products on the market contain synthetic pyrethroids as their active ingredients such as bifenthrin, permethrin, esfenvalerate, and cyfluthrin. Other indoor insect products contain pyrethrins (e.g., Ortho Home Defense), allethrin (Ortho Home Defense Flying Insect Killer), and tetramethrin (e.g., Ortho Home Defense Home and Garden Insect Killer).

Household pests - Outdoor (roaches, spiders, ants, etc.): Bifenthrin, permethrin, and esfenvalerate are available for exterior treatments around buildings.

Read the labels on all insecticides before you purchase and apply them, and be sure that the pesticide is labeled for the target site and/or plant that is intended to be treated. References to commercial products or trade names are made with the understanding that no discrimination is intended and no endorsement by the University of Minnesota Extension Service is implied
Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm
Editorial Notes

Clove currant. Photo credit: Beth Jarvis

We at Yard & Garden are positively thrilled to report that we now have a real, live plant pathologist on staff again! Janna Beckerman started in the Yard & Garden Clinic on January 22. She received her Ph.D. from Texas A & M but has a great deal of experience gardening in the north as she was born and raised in Cleveland, Ohio.

I'd planned to feature a report on a treated lumber trials in February but project leader asked for a bit more time. For June 1, we'll have the latest on research into treated lumber in the landscape. We'll learn about how much if any arsenic leached and how much was absorbed by plants. A forest products expert will present options and alternatives, if needed.

In the months ahead, we'll be learning about soluble salts. You've seen it on soil test reports, but what does it mean?

Thinking about planting grapes this year?? Before you spend your money, see what Doug Foulk, Ramsey Co. Extension horticulturist and fruit scientist, has to say about selecting grapes in Minnesota. That's slated for Mar. 1.

For April 1, Dean Herzfeld, state pesticide applicator training coordinator, will tell what you should know before hiring a lawn care service.

We'll follow that up with the first of two articles on herbicides from Roger Becker, Extension weed scientist. Roger will tell us all about pre-emergence herbicides first, when there's still time to treat for crabgrass. Then he'll follow up, later, with information on post-emergence products. Also this spring, we'll be hearing Vince Fritz, Extension horticulturist, on research he and others are partcipating in on using cabbage to find a treatment for cancer.

Also planned is a piece on conservation biocontrol--what is it?

The clove currant (Ribes odoratum) pictured above is one of my favorite shrubs. It perfumes the late spring garden with its spicy, clove-scented flowers. It's practically identical to R. aureum yellow flowered currant. (There's a slight difference in the flower.) This clump-forming shrub produces arching branches 6 to 8 feet tall with a comparable spread. Good in full sun to partial shade. Produces black fruit in late summer. Hardy to USDA zone 3.

I rely on your comments and questions for ideas for future articles. Please, keep the story ideas coming! We really try to be responsive to your needs.

Please feel free to cut and paste any of the articles for use in your own newsletters. All we ask is that you give our authors credit.

Back issues Yard & Garden Line News are on the Yard & Garden Line home page at www.extension.umn.edu/yardandgarden/. Our home page has clickable links to most of the components of the Yard & Garden Line, such as Bell Museum of Natural History, INFO U and the Soil Testing Lab.

Deb Brown answers gardening questions on Minnesota Public Radio's (MPR) "Midmorning" program on the first Thursday of every month at 10 a.m. Katherine Lanpher hosts the program that is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations.

If you have gardening questions, please call the Yard & Garden Line at (612) 624-4771.

If you would like to receive an e-mail reminder when the next issue of the Yard & Garden Line News is posted to the web, just send an e-mail to: listserv@lists.umn.edu (note: the second E in listserve is omitted), leave the subject line blank, then in the body of the message, type: sub yglnewslist
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Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator

Websites
Sustainable Urban Landscape Information Series. This site contains everything from landscape design planning and lawncare to both herbaceous and woody plant selection databases. The URL is:http://www.sustland.umn.edu


For pesticide info, for both home owner and professionals, check out:

http://www.crc.agri.umn.edu/~mnhelps/

There's also some very interesting reading at Forest Products website. To get there from here, click on: http://www.cnr.umn.edu/FR/extension/
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