Yard & Garden Line News
Volume 5 Number 12                                                               August 15, 2003
Features this issue:
 Make the Most of This Year's Garden
Mulch Monsters
Wasps Common Now
A Trip To the St. Paul Farmers' Market
Editorial Notes

Make the Most of This Year's Garden
Deborah Brown, Extension Horticulturist

Community garden plot. Photo credit: Beth Jarvis
Regardless of this year's gardening successes or setbacks, this is not the time to slack off! Despite the discomfort of hot, humid weather and hoards of hungry mosquitoes, you need to hang in there to get the most from your garden. Watering, weeding -- even replanting -- will all result in increased vegetable yields and a showier display of flowers.

Water regularly
It's important to provide a steady supply of moisture to developing plants, particularly in hot weather. Uneven moisture is responsible for blossom end rot, a common malady of tomatoes and sometimes squash, as well. It also causes knobby potatoes and may also influence the flavor of carrots and cukes, leaving them bitter-tasting.

Make a habit of watering thoroughly to encourage deep rooting. Water early in the day, if possible, when temperatures are at their coolest, so less water will be lost through evaporation.

If you use oozing hoses that allow water to seep into the soil, or trickle irrigation that directs water to the base of each plant, timing is less critical. You could even water in the evening, a time that's best to avoid with overhead sprinkling. (When foliage is wet at night, it often won't dry until the next morning. This creates an ideal environment for plant diseases.)

Keep weeding
Even though most people are less inclined to keep after garden weeds in August, it's as important now as it was earlier this summer. Weeds not only compete with desired plants for moisture and nutrients, they may harbor insects that will feed on them, causing injury and possibly spreading plant disease. And the seeds they produce will remain viable in the soil, ready to sprout, for years to come.

It's okay to incorporate weeds into a compost pile if they're not full of seeds. But if they're loaded with seeds, you probably shouldn't put them in the compost unless it's a good, active pile that heat up well. Otherwise, next time you use your compost you'll be inadvertently spreading those weed seeds.

Replant
Though it's too late to plant most vegetables, you can still make use of the spaces where plants are already through producing. Remove all traces of debris from the earlier plants, and work a little garden fertilizer such as 5-10-10 or 10-10-10 into the soil where you plan to replant.

Obviously, anything you plant in August must be able to mature in a fairly short length of time to be of any value. Right now you should be able to seed kohlrabi, leaf lettuce, radishes, spinach and green onions (bulbing onions that you pick while they're still immature.) You can also plant turnips and beets for their greens, which should grow quite mild and tasty as cooler weather sets in.

Find time to deadhead
Geraniums in need of deadheading Photo credit: Beth Jarvis
"Deadheading" simply means removing flowers once they fade, so plants won't waste energy on seed development. Equally important, many plants slow their flower production once they've set mature or ripe seeds, so it's to your advantage to prevent seed production if you possibly can. Unfortunately, it's a whole lot easier to deadhead large flowers like zinnias or garden lilies than it is bachelor buttons or multiflora petunias. Just do the best you can.

The same principle applies to vegetable gardens. To keep the plants more productive, be sure to harvest or remove any vegetable that develops from a flower – beans, squash, tomatoes, peppers, cukes, and others – to prevent their seeds from ripening.

Ideally, you want to pick vegetables right at just the right stage when they'll be most tender and flavorful, or in the case of tomatoes or melons, when they're perfectly ripe. Sometimes they get away from you though, and become over-mature. You've probably seen snap beans with pods bulging from the large seeds inside, or swollen yellow-orange cucumbers that were hidden beneath leaves and evaded harvest. Even though they're way past their prime, you should to pick them – even if it just means throwing them onto your compost pile or in the trash.

Donate extra produce
As the harvest season shifts into high gear, remember to make good use of any produce your family doesn't need by donating it to a local food shelf. Just make sure ahead of time that they will accept fresh produce – some only take non-perishable items.

Mulch Monsters
Janna Beckerman, Extension Plant Pathologist

The tracks through this dog vomit slime mold are from a mouse, that was neither impressed nor horrified by the squishing through its little feet. Photo credit: James Groth, Dept. of Plant Pathology.
Underneath the leaf litter, hidden in the mulch, or decomposing a fallen log, lurk extraordinary creatures few people will ever become familiarize with. However, this is the time of year, especially after rainy weather, that these creatures come into their own. The myxostelida, commonly referred to as 'slime molds,' have perplexed biologists for over a century. And most of us never even notice them.

Desperately seeking a publicists
Ask anyone in marketing and they will tell you it is all about "the name." If naming rights are everything, then pity the slime mold. The name alone evokes fear and loathing. What if your common name is 'dog vomit slime mold?'. A closely related cousin to the dog vomit slime mold was the cause of a mini-epidemic. Thirty years ago, in a small Dallas suburb, homeowners became alarmed by outbreak of "strange, disgusting, pulsating" yellow growths on their lawns that looked like vomit. Soon, one enterprising yellow blob appeared on a telephone pole, and did what slime molds have been doing for millions of years-- It began to spread. In the resulting panic, firefighters tried to destroy it with blasts from their hoses. This only resulted in the blobs breaking up, increasing in size and crawling at a faster pace. Although as scientists we doubt that this made the slime molds angry, it did provide the environmental conditions to allow it to multiply en masse, and yes, move up the pole. Although this occurrence predated the release of "Invasion of the Body Snatchers," many homeowners expressed a fear that the city was under attack by aliens, perhaps recalling the 1958 film "The Blob" starring Steve McQueen. Eventually, a university scientist identified the oozing slime as the harmless Fuligo septica, also known as the scrambled egg slime mold.

Membership denied
As a group of organisms, slime molds possess both animal and fungal- like characteristics. If that wasn't confusing enough, careful examination of slime molds identified two fundamental differences. This has further split the Myxostelida into two main groups: The cellular slime molds (Arasiomycetes) consist of approximately 70 known species, and plasmodial (or true) slime molds (Myxomycetes), of which there is over 1,000 species. Whittaker, in the original five-kingdom scheme of life (Plants, Animals, Fungi, Bacteria and Protists), situated the slime molds with the fungi, while admitting that they stuck out of his mitten scheme "like a sore thumb." This is the reason plant pathologists and mycologist address slime mold issues. However, it was not for many years later that Balduf and Doolittle gave Whittaker's glove model a sixth finger.

The slime mold that attacked Texas. Photo credit: James Groth, Dept. of Plant Pathology.
Identifying slime molds requires a practiced eye and an appreciation detail. Timing is everything, because slime molds quickly develop into puffy balls of unidentifiable spores. The 'obvious' macro- and microscopic characteristics include what the fruiting bodies look like with respect to size, shape, color and texture, and the presence of deposits of calcium carbonate (lime). Most of these features can be readily observed with a hand lens, although a microscope is needed for identification to species.

Life and death as a slime mold
The slime mold begins life as a microscopic spore. The spore "cracks" open, or a small pore emerges to allow the germinating spore to develop and produce one to four protoplasts. Some protoplasts are flagellated, meaning they have long, whip-like structures that swish back and forth to propel them. Other types are amoeboid. The flagellated cells are called swarm cells, while their tail-less counterparts are called myxamoeba. The availability of water has a lot to do with whether or not a cell is "born" as a swarm cell or myxamoeba, with flagellated cells predominating under wet conditions. All is not predetermined, however: Changing environmental conditions can result in a change in form from myxamoeba to swarm cell or vica versa. However, under dry conditions, only myxamoeba can develop microcysts, which are dormant structures that enable them to persist under inclement conditions.

Life for a solo myxamoeba, or swarm cell must be lonely. The ultimate goal for either cell is fusion. Eventually, either cell fuses with another to form a zygote. The zygote feeds upon bacteria found in decaying wood. As it grows, it divides and increases its size. Eventually, as the zygote feeds and divides, it differentiates into a macroscopic plasmodium, commonly referred to as "the blob". The plasmodium-which ranges in colors from hot pink like the Wolf's Milk Slime Mold (Lycogala epidendrum), neon yellow of Hemitrycha clavata, salmon orange, light purple like Physarum polycephalum or a lovely chocolate brown Stemonitis splendens -functions like a giant amoeba, devouring its prey of bacteria, spores, protests, and yes, and other slime molds. This process of carnivorous bliss continues until its food source runs out. Then, the slime mold begins a remarkable transformation. Starvation induces a signal whereupon our slime mold motors at the lightning speed 1/25" per hour. Its final destination? A suitable location to develop fruiting bodies. If successful, the whole process repeats itself.

The plasmodial blob stage. Photo credit: James Groth, Dept. of Plant Pathology.
But what about the unsuccessful slime mold? Numerous insect larvae, adult slime mold beetles (Anisotoma hori), and many types of flies feast on the unfortunate fruiting bodies of slime molds. Several fungi parasitize slime molds and prevent spores from developing and reproducing. Some slime molds, like P.polycephalum, turn the table and devour spores of slime mold feeding fungi, like Verticillium rexianum or Gliocladium album.

In North America, there are several hundred species of slime molds. In any one location, numerous slime molds can be found. They are commonly found on mulch, particularly cocoa bean mulch, decaying logs, fallen leaves, lawns, and on strawberry leaves.

Although upsetting to people, slime molds are not parasitic, and most do not cause plant disease. However, heavy coverage on grass or plant leaves may cause yellowing of affected plants. This phenomenon is known to cause a change in pallor of homeowners, as well. Both affected plants and homeowners are can recover with educational intervention. Control is not usually necessary and slime molds will disappear during hot, dry weather. Slime molds may be shoveled, brushed, or raked from affected areas and disposed of. Frequent mowing will quickly remove these fungi on rapidly growing grass. Frequent watering, or spraying with a garden hose will only spread slime molds. Which isn't necessarily a bad thing.

A special thanks to James V. Groth for supplying the photographs used in this story.

Additional References
Myxomycetes: A Handbook of Slime Molds. Steven L. Stephenson and Henry Stempen, 1994.
Tom Volk's Fungus Page:  http://botit.botany.wisc.edu/toms_fungi/june99.html
Mykoweb:   http://www.mykoweb.com/
Introduction to the slime molds:  http://www.ucmp.berkeley.edu/protista/slimemolds.html
Origin and evolution of the slime molds (Mycetozoa)
Sandra L. Baldauf* and W. Ford Doolittle:   http://www.pnas.org/cgi/reprint/94/22/12007.pdf

Please check out the new diagnostics web pages at
http://www.extension.umn.edu/projects/yardandgarden/diagnostics/

Wasps Common Now
Jeff Hahn, Assistant Extension Entomologist

Paper wasp and nest. Photo credit: Jeff Hahn
Be on the watch for wasp nests around your home. The sooner a nest is discovered and treated, the easier it can be eliminated. Some may ask, what is the difference between wasps, yellowjackets, and hornets? In this context, wasp is a general term for the social insects in the family Vespidae (sometimes referred to as vespid wasps). Some of the members of this group are solitary, i.e. they live by themselves, including potter and mason wasps.

The social vespid wasps are divided into two groups, the yellowjackets and hornets (Vespinae) and the paper wasps (Polistinae). There are about 11 species of yellowjackets that commonly occur in Minnesota. However, we do not have any true hornets in this state. The European hornet occurs in the eastern U.S. but is not found in Minnesota. The baldfaced hornet is common in Minnesota but despite its name is actually considered to be a type of yellowjacket. The most common species of paper wasp found in Minnesota is Polistes fuscatus.

Yellowjacket nest opening Photo credit: Jeff Hahn
Yellowjackets and hornets possess a short petiole that attaches the abdomen to the thorax. They construct papery nests consisting of cells forming combs. Each nest consists of at least several combs attached to each other in layers and is surrounded by an envelope. A yellowjacket nest can have hundreds to thousands of workers in a nest. This is in contrast to paper wasps which are generally more slender and have a longer stalk that attaches their thorax and abdomen. Paper wasps also construct a paper nest with cells but it consists of just one comb and is not covered by an envelope. Their nests are small, usually with no more than 60 -70 wasps.

Vespid wasps can nest in a variety of locations. Many yellowjackets nest in the ground, taking advantage of old rodent burrows. Other yellowjackets nest in trees or under the eaves, decks, or other horizontal surfaces around homes. Baldfaced hornets and paper wasps also commonly nest in trees or under horizontal surfaces around the outside of homes and other buildings.

When dealing with a wasp nest, first consider the relative risk of stings. If the nest is somewhat remote compared to human traffic, e.g. high in a tree, and wasps do not come in contact with people, then it isn't necessary to treat it and can just be ignored.

However, if the nest is located too close to where people are active and there is a chance for stings, then the nest should be treated as soon as possible. If the nest is in an open site, e.g. hanging in a tree or shrub or on a building, it is relatively easy to control.

Baldfaced hornet nest Photo credit: Jeff Hahn
Use an aerosol can of insecticide labeled for wasps and hornets (or something similar). Active ingredients are often a combination of insecticides. Common examples include tetramethrin and permethrin, tetramethrin and sumithrin, or tralomethrin and allethrin. You may also find products containing mint oil. While it has been reported to control paper wasps, it is unclear how effective mint oil would be against yellowjackets and baldfaced hornets. It probably will be less efficacious when dealing with larger nests.

The best time to treat an exposed wasp nest is at night. The wasps have returned to the nest and are much less active. Just spray directly into the opening where the wasps have been flying back and forth. For paper wasps treat the entire underside of the nest where you see the cells. In either case, check the nest the next day for activity. If after a few days there are still live wasps repeat the treatment.

If you find a yellowjacket nest in the ground, you can first try to control it by pouring soapy water into the nest entrance. If you would rather use an insecticide, try one of the following: bifenthrin, carbaryl, cyfluthrin, deltamethrin, esfenvalerate, lambda-cyhalothrin, or permethrin as a dust or liquid. Dusts are generally more effective than liquids. Once yellowjacket activity ceases, fill in the opening to the burrow with dirt.

Yellowjackets from nest hidden in home Photo credit: Jeff Hahn
The most challenging nest to eliminate are those that are hidden in wall voids or other inaccessible areas. You won't see the nest but you will notice an opening where yellowjackets fly back and forth. Aerosol sprays are generally not effective because the nest entrance is may not be near the opening in the building. In fact an aerosol spray can irritate yellowjackets and cause them to enter the interior of a home. The same result can occur if you seal up the entrance; the yellowjackets will just look for another way out which often leads to the inside of your home.

The best method for eliminating yellowjacket nests in walls is to drill holes in the wall and apply an insecticidal dust into the void area. Although there are not many dusts labeled for this purpose available to the public, look for permethrin (e.g. Bonide Ant Dust). Because of the challenges of making a void treatment, it is best in many cases to contact a experienced pest control service to dispatch those hard to reach nests.

Keep in mind the wasps nests are annual, i.e. they survive for just one season. Once we receive one or two hard frosts, the old queen and the workers will die. Newly mated queens leave their nests during late summer to seek sheltered sites for the winter. When they emerge next spring, they will construct new nests.

Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm


A Trip To the St. Paul Farmers' Market
Beth Jarvis, Yard and Garden Line

Baby bok choy Photo credit: Cindy Tong
One mid-July Saturday morning, a fellow horticulturist friend and I visited the St. Paul Farmers' Market, located at 5th and Wall St. Our goal was to seek out exotic Asian vegetables and try to find out what they were and how to prepare them.

The Market:
The St. Paul Market is celebrating its 150th year this year. Unlike the Minneapolis market, the St. Paul market generally allows only items grown within 50 miles of the market be sold. You can read about the market at: http://www.stpaulfarmersmarket.com/

We arrived about 10 and the place was packed. We opted for the far end of the market where the Hmong growers are concentrated, then worked our way through the rest.

We saw cilantro/coriander AKA Chinese or Mexican parsley, daikon radishes, baby bok choy, round and flat podded peas, mustard greens, collard greens, Asian broccoli, pea tips (the tips of pea vines), squash vine tips, sweet potato vine tips and something that looked like black nightshade (Solanum nigrum). We've pulled it as a weed but that day, we bought some. It's know in China as long kai or long cao.

Black nightshade. Photo credit: Cindy Tong
Hmong spinach
Melon vine tips. Photos: Cindy Tong
Asian vegetables
A sweet Hmong grandmother described in scant English, but with a lively demonstration, how to prepare the nightshade which she likes to boil with peas and eat as soup.

In a number of stalls we saw what was called Chinese spinach, which is an Amaranthus sp. thus related to Love Lies Bleeding, the garden annual. The young man who had a goodly supply in green and some with a reddish cast laughed when my friend commented that she's Chinese but didn't recognize it. With a grin, he said, "Well, Hmong spinach, then."

We also saw lots of fresh basil, both regular and Thai, green and yellow beans, yellow and zucchini summer squash, red and white onions, cabbage, kohlrabi, lettuce, cauliflower, cucumbers, rhubarb, Swiss chard, radishes, new potatoes, and tomatoes.

Judging by the numerous empty cases, the tomato vendors were doing a brisk business, in most likely some of the first homegrown tomatoes of the season. We asked the tomato cultivars and were told ‘Delicious', ‘Jetsetter', ‘Cascade' and one other, ‘Jetstar', perhaps.

We didn't see any fruit but were told the first of the sour cherries has been on offer at a couple of stalls. They'd sold out by 7 a.m. The Minnesota blueberry and strawberry crops had been hard hit by the cold winter with a lot of crop loss.

There were many, many cut flowers in mixed bouquets of snapdragons, cosmos, heliotrope, zinnias, etc. or as separate stems, such as ‘Stargazer' lilies. Bedding plants and potted perennials were also for sale. My friend noted that a lot of former vegetable growers have switched to flowers because there's a better market for flowers.

Bison, lamb, turkey, chicken, eggs, honey and beeswax candles, handcrafted soap and some other craft items were also available.

We'd gone shopping with the express purpose of finding unusual Asian vegetables. In the Twin Cities market, larger grocery stores routinely carry Chinese eggplant, lemon grass, pea pods, fresh coconut, cilantro, daikon radishes, etc. I'm sure we could have found the vegetables we sought in the Asian grocery stores, but it's always fun to visit a farmers' market.

We also wanted to discover the true scientific names of the less common vegetables. We're both vegetable gardeners so we often recognized plants initially by family, eg: "some kind of mustard/cabbage". Later, armed with jpegs, we could identify many of the plants we'd seen in the market using the site below. It has pictures as well as common and scientific names for a lot of Asian vegetables and herbs. Click on Thesaurus. http://www.nre.vic.gov.au/trade/asiaveg/nle-00.htm

Another friend, an early morning patron of the Minneapolis Farmers' Market, has expressed mild frustration/amusement at having been told seemingly every exotic bit of vegetation was "for stir fry". It turns out a lot of the "unusual" Asian vegetables are used in stir fry or used in soup, just like the usual ones, because those are the most common ways to cook.

So, here are some of the vegetables we found, the scientific names and the common names. Extension Home Economists quit giving out recipes at least a decade ago but below are some links to various Asian recipes, probably mostly stir fry, for some of the foods we found. I haven't tried any of the recipes, I just ran Google searches to find these.

Chinese Amaranth
Amaranthus tricolor, A. gangeticus, A. oleraceus
amaranthus, Chinese spinach, edible amaranth, wild blite, careless weed
http://kurma.net/faq/q6.html (has a lot of Indian recipes)

Gai Lan
Brassica oleracea var. alboglabra
Also called Chinese Kale, Chinese Broccoli, Gai Lon, Gai Larn, Kai Laarn
For a photo and a recipe using it see:
http://www.gov.mb.ca/agriculture/food/orienal/cfo01s05.html

Dou Miao
Plain old garden pea vine tops/tips. Pisum sativum
Dou miao (Mandarin) or dau miu (Cantonese). Pronounced: "dough meow."
There are a some recipes at:
http://www.momsinmind.com.sg/vege1.html
http://www.recipezaar.com/50410?path=0FD058
http://www.pbs.org/wgbh/victorygarden/recipes/seascallops_prn.html

Here's an interesting piece on Chinese cabbages, together with some recipes: "Choy to the World"
http://www.consciouschoice.com/cooking/cooking1310.html

This is a retail site with some recipes and product info:
http://www.melissas.com/magazine/index.cfm?article_id=211
click on product information, Asian items

Grow your own:
Here are just 2 web sources I found for seeds. I am including them here as reference because they have pictures of some of the vegetables mentioned above.
http://www.evergreenseeds.com/evergreenseeds/asveglis.html
http://www.seedsofchange.com/

Editorial Notes

Mixed bouquet Butchart Gardens, Vancouver Is., BC Photo credit: Beth Jarvis
Can't believe the state fair starts so soon! Summer has certainly gone quickly!

The arrangement at left was found at Butchart Gardens, Vancouver Island, BC, http://www.butchartgardens.com/main.php a year ago July. It's truly a lovely place to visit.!

Next issue, we'll plan to continue the discussion about pesticides and your neighbors. In the future, you'll also get to meet Dr. Tim Kurtti, who does deer tick research. In a bit, we'll hear about the closest thing we have to Japanesese maple from Stan Hokanson, who id doing winter hardy plants research here. Dave Hanson, who works with Gary Johnson in Urban Forestry, has agreed to pen a piece dispelling myths about tree roots, be they heaving sidewalks, invading basement walls or sewer pipe, or whatever.

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 or to unsubscribe, enter: unsub yglnewslist

Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator


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