Yard & Garden Line News Volume 4 Number 2                                                               February 1, 2002

Features this issue: An A-Peeling Option for Apples Watering Houseplants -- the Right Way Disease-Resistant Plants--Something Special in the Garden Don't Be Alarmed By Yellow Ants Editorial Notes

An A-Peeling Option for Apples
Larry Zilliox, Horticulture Educator, Douglas County

One of the apples. Photo credit: Larry Zilliox

Apple maggot damage, the most common insect problem of apples, can be virtually eliminated without the use of insecticides. At least 2,500 apples from 69 sites scattered around the state were included in this three-year study. A sandwich bag placed on an apple before July 1st eliminates the need for insecticide spraying throughout the summer. The bags prevent apple maggot flies from laying eggs in the apples. (Home apple growers may have other insect problems attacking their apples earlier in the season and need to control them before bagging their apples.)

The first and second year results are available at: http://www.extension.umn.edu/yardandgarden/yglnews/ygln-jan0100.html#apple
http://www.extension.umn.edu/mnimpacts/impact.asp?projectID=1613
http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-Jan0101.html#apples

How Much Time Does It Take?
A common comment from home apple growers is, "I'm not going to bag all of those apples on the tree!" You don't have to. Bag only the apples you'll need and forget the rest. Most people bake a couple of apple pies; make several apple crisp bars and maybe some applesauce. Our experience has shown you can bag fifty apples in several hours. This seems to be enough apples for most families.

Expenses

Apple maggot adult. Photo cedit: Larry  Zilliox

The economics of the bagging was a concern. Our investment for bagging apples ranged from a low of $1.29 for a box of 100 plastic sandwich bags to $2.49 for a box of 50 zipper styled sandwich bags. As stated earlier, fifty apples could be bagged in two hours. This is the only time commitment during the summer. The bags are removed either at picking or before the apples are used.

On the other hand, spraying insecticides involves buying a 2-3 gallon sprayer for $35-40.00. This could be used for ten years, with good care, and bring the cost down to $3.50 -$4.00 per year. Insecticides cost about $10.00/pint.

But, the home apple grower would need to spray weekly to every ten days throughout the summer. Assuming the grower had several trees, it would take approximately one hour to mix the chemicals, spray the trees and clean up the equipment after using it. This procedure would be repeated 8-10 times during the summer.

Whether apple growers bag, spray or do nothing, pick up all fallen apples to reduce the number of maggots in future years.

As Long As You're Up There
An additional step many take during the bagging process is thinning the fruit. It's a convenient time to thin the number of fruit while bagging. We try to leave two fruit per cluster which results in larger fruit of a higher quality.

Conclusion

Author evaluates apple. Photo credit: Hollan Lommen

No matter how you peel it, this apple concept provides bigger, tasty apples that are apple maggot free, organically.

The research clearly shows bagging is a sound means of controlling apple maggot damage in apples. High quality fruit are produced with a minimal of effort. Using the bagging process saves time and money and we reduce the use of insecticides. The high success rate in bagging apples should convince back yard apple growers to accept this as a viable option.

(A light hearted video "Apple Maggots For Lunch--No More" endorsing this procedure can be obtained from: http://www.extension.umn.edu/abstracts/nonweb/abstract.html?item=07655)

Funding for this project was provided by the Intergrated Pest Management Program at the Minnesota Dept. of Agriculture.

Watering Houseplants -- the Right Way
Deborah Brown, Extension Horticulturist

Touch the soil to tell if needs water.

Are you confused about watering your houseplants? Many people consider it a simple matter, watering their plants whenever they think of it. Others are more methodical. They water regularly, according to the calendar, regardless of their plants' needs. Neither of these approaches is best for the plants.

Just what is the right way to water indoor plants? It's important to catch them before there's any sign of wilting. BUT it's a mistake to keep soil wet all the time; it just encourages root rot. Room temperature and humidity, even how sunny or cloudy the weather has been, all affect a plant's water requirements.

Learn to read the signs that your plants need water. Foliage turns a slightly duller, less lively green. Succulent leaves become a little rubbery. The container feels lighter weight as moisture evaporates from the soil. And soil feels dry to the touch, first at the surface, then below it.

Water requirements vary among different groups of houseplants, but regardless of what types of plants you care for, water them thoroughly each and every time you water. Then spill out the extra water that comes through the drain holes.

Cacti and succulents may be allowed to get quite dry between waterings, though when light is good, they'll thrive on additional moisture. Plants with tough leathery leaves such as the old-fashioned rubber tree or ponytail palm can also go for quite a long time from one thorough watering to the next.

Most foliage plants should be watered before much of their root system dries. When you first find the soil surface no longer feels moist, there is still moisture further down in the container. This is good, because for most houseplants it's best to avoid wild swings from extremely dry to extremely wet soil conditions.

Varied particle sizes in potting mix improves drainage.

The type of potting soil in which your plants are growing can have an impact on how often you water. So can the type of container. Always use clean, fresh potting soil that consists of different sized particles. Varied particle size results in good soil drainage. The more moisture you wish the potting soil to retain, the higher its peat content should be.

Layering pebbles or charcoal in the bottom of a solid container will not help soil drainage. Instead, choose containers with drain holes so water can drain freely from the soil. Be sure to spill out any excess water that remains in the tray or saucer after a few minutes. If the container is too large to lift easily off its tray, use a plastic turkey baster to siphon most of the extra water.

Don't use "softened" water unless you really have no choice. It adds chemical salts to the soil which eventually build up and injure roots, just as excess fertilizer does. If you must use softened water, hold your containers over a sink or wash basin and water them heavily each time you water. This flushes much of those salts, even though some new will be added. Of course, pots must have good drain holes for this to work.

Chlorine, which is added to city water supplies to purify it for drinking, is not present in large enough amounts to damage houseplants. Fluorine, added to fight tooth decay, may be a different story. Certain plants, mostly those with long, pointed leaves such as dracaenas and spider plants, are quite sensitive and can develop brown tips. However, water is rarely the only source of fluorine, and most plants have no problem with city water.

What does trouble them is icy cold water. Most of the houseplants we grow originated in the tropics or sub-tropics where rainfall is relatively warm. If you water directly from the tap, adjust it to feel barely lukewarm. Or take the easy way; keep a full watering can at the ready for any time you might want it. Its contents will always be room temperature, making it easy to respond to the needs of individual plants.

Disease-Resistant Plants--Something Special in the Garden
Janna Beckerman, Extension Plant Pathologist

Phlox 'David' has fragrance, color and powdery mildew resistance. Photo credit: Deb Brown.

This year, the Perennial Plant Association has declared that Phlox cv. 'David' to be the 2002 perennial plant of the year. 'David' is a beautiful, white-flowered variety of phlox with dark green foliage. In a field of dozens of other phlox varieties, what made 'David' so special? Unlike other varieties of phlox, 'David' stood out in a mass planting at the Brandywine Conservatory in Pennsylvania not only for its great form but because its foliage was powdery mildew resistant, unlike the other phlox in the plantings. Keen-eyed horticulturists recognized the value of a variety of phlox that was powdery mildew resistant and began propagating 'David.'

By naming 'David' as the Perennial Plant of the Year, the Perennial Plant Association is supporting the best method of plant disease management available. By using plant species or varieties or cultivated varieties (termed cultivars (cv.)) that are genetically resistant to diseases, buyers are immediately implementing the most effective means of controlling plant disease in the landscape. Although most plants do not have resistance to the many common diseases present, it is simple common sense to use those plants that are resistant to known disease problems whenever possible to minimize the impact of disease on the home landscape. Although Phlox 'David' is relatively resistant to powdery mildew, proper culture will aid in mildew prevention. Plants perform best when placed in full sun. To increase air circulation (which allows foliage to dry quickly), thin plants to four to six stems. Finally, all plants should be watered at the base of the plant and not the foliage. This reduces both moisture and humidity that is necessary for both spore germination and spread.

Powdery mildew spoils late summer blooms. Photo credit: Deb Brown.

Genetically modified tobacco lights up all by itself. Photo credit: ©1996 by Griffiths et al. MUN

Resistance to a given disease is recognized or developed in several different ways. In the case of 'David,' Richard Simon of Bluemount Nurseries (Monkton, Maryland) and F.M. Mooberry (Horticultural Coordinator, The Brandywine Conservancy) recognized that one plant was not affected by powdery mildew when all the surrounding plants were. A plant like 'David' may be planted at multiple sites, to determine how complete the resistance is, and if it functions under different site conditions. This also allows researchers to make certain the their potential resistant plant wasn't an "escapee" that somehow managed to avoid as oppose to resist disease. Often times, resistant cultivars are inoculated with the offending disease causing agent to allow researchers to be certain the plant didn't escape disease, but actively resists it.

Resistance isn't just discovered by accident, but a trait that researchers actively breed for. In the case of chestnut blight, breeding programs have been going on for almost a century, trying to develop the right combination of disease resistance present in the shrubby Chinese chestnut, with the desired form of the 100+ foot- American chestnut tree. In breeding for chestnut blight resistance, the susceptible American chestnut tree is crossed with the resistant Chinese chestnut. In the case of breeding for blight resistant American chestnut, resistance is closely linked to the short stature of the Chinese chestnut. This requires that breeders perform additional crosses with the hybrid offspring back to the parent to introduce additional desirable characteristics, in this case height and disease resistance. A crossing plan for incorporating the resistance of Chinese chestnut into the American chestnut can be seen at: http://www.apsnet.org/online/feature/chestnut/images/figure9.htm

The most recent method of developing disease resistance plants is through the integration of foreign DNA (DeoxyriboNucleic Acid-the genetic material that is the blueprint that controls how an organism develops) that consists of a gene to confer resistance to a given disease into the plant genome. The resulting plant is referred to as 'transgenic.' Early attempts to understand this process involved the insertion of a gene that encodes a protein called luciferase from the firefly into the genome of tobacco. Luciferase is the active enzyme that allows fireflies to glow. Insertion of the luciferase gene into tobacco created the first tobacco plant that was able to "light up" by itself. This tobacco plant that "glowed in the dark" demonstrated the power that was available to biologists, and shed light on a new way of studying plant biology. Although still in its infancy, this method of genetic engineering has already changed the way researchers examine and study how disease resistance mechanisms work. Transgenic corn, potato and soybean that possess foreign genes that confer resistance to herbicides or produce their own Bt toxin have been in production for several years; however, these plants are not yet available to the home consumer.

Regardless of how resistance develops, it has an invaluable place in the home landscape. Below, I've included the names of other disease resistant annuals and perennials for you to consider prior to purchasing another variety that may not perform as well under the same disease pressures.

Disease Resistant Annuals and Perennials
Powdery Mildew Resistant			Grey Mold Resistant	Rust Resistant
Phlox	Zinnia	Bee Balm (monarda)	Petunias	Hollyhocks
Rubymine*	'Oklahoma'	'Marshall's Delight'*	Lavender Wave*	A. ficifolia 'Happy Lights'°
'Goldmine' (variegated)*	'Profusion' (pm-tolerant)	'Gardenview Scarlet'*	Tidal Wave *	.
'Laura' *	'Crystal White''	'Fireball'*	.	.
'Miss Lingard'*	'Ruffles'	''Jacob Kline'*°	.	.
'Eva Cullem'*	'Panarama Red'¹	.	.	.
'Katherine' °	.	.	.	.
* Jung Quality Seeds www.jungseed.com
° Select Seeds www.selectseeds.com
¹ Johnny's www.johnnyseeds.com

Test your diagnostic savvy monthly with Disease Watch at: http://www.extension.umn.edu/projects/yardandgarden/PlantPathWeb/Plpa.htm
Don't Be Alarmed By Yellow Ants
Jeff Hahn, Assistant Extension Entomologist

Yellow ant. Photo credit: Jeff Hahn

Although you don't expect to find ants inside during winter, there are several species that you could commonly encounter in homes in Minnesota. One such species is the yellow ant, also called citronella ant. They get their name because they give off a pleasant lemony or citronella smell when they are disturbed or crushed.

You can find yellow ants nesting outdoors in soil under stones, logs, bricks, patio blocks, concrete and other objects they can hide under. Other nests are established in rotted logs or firewood. Yellow ants also commonly live in and around foundation walls and in soil under buildings on concrete slabs.

Yellow ant workers are yellow to reddish-brown color and are about 3/16 inch long. However, you rarely see them foraging for household foods in your home. Instead, they feed almost exclusively on the sugary honeydew that subterranean aphids excrete. Workers are sometimes found throwing bits of dirt and cement particles out of the nest. Despite the appearance of this, they do not damage woodwork or masonry.

When you do find yellow ants in your home, you will more likely find large numbers of winged ants. These swarmers are the nests' reproductives, i.e. new queens and males. Queens are about 5/16 inch long with dark reddish colored bodies. Males are similar but smaller.

Yellow ants normally swarm anytime from spring through summer. However when nests are associated with buildings, the warmth from a furnace or heating duct can fool the swarmers into emerging from their nests early. Winged ants are often found near windows because they are attracted by light. Although these ants are annoying, they are harmless and do not attempt to establish new nests indoors.

The best control when you encounter a yellow ant swarm is to just vacuum them or in some other way physically remove them. If you do nothing, they will die on their own after a few days. Swarms do not normally last more than few days to a week. And you will not necessarily see a yellow ant swarm every year. If you can determine where these ants are moving through the slab, seal it to keep them out of your home. ;

To prevent future swarms may not be possible. Normally a direct treatment of an ant nest with an insecticide is the most effective control of a colony. However this is usually not practical for yellow ants because their nests are under concrete slabs and behind walls, making them hard to find. If the approximate location was determined, it would still be challenging to treat it. It would be necessary to have the slab drilled and an insecticide injected under the it by a professional pest control technician.

Baiting is also an effective control method against most ants. However to be effective, workers need to be attracted to the bait and return it back to the nest. Yellow ant workers rarely forage for food in homes and would rarely find the bait and bring it back to the nest.

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

Verbena bonariensis and friends. Photo credit: Beth Jarvis

The Soil Testing Lab suffered smoke damage last weekend due to an arson fire in a construction trailer parked next to the Crops Research building. Fortunately, the lab wasn't severely damaged. Roger Eliason, lab manager, said it will take a week or two to clean up and get analytical equipment tested. He said they will certainly be ready for the start of spring planting.

Roger wrote about the soil testing lab for us a couple of years ago. To read it, click on: http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-Aug1599.html#soils

In upcoming issues, we'll hear about the annual flower trials, the newest Minnesota strawberry releases, planting pear trees and, in time for tick season, the work of a medical entomologist who studies Lyme disease.

The picture is of Verbena bonariensis, an annual without a common name together with some Platycodon grandiflorus, AKA balloom flower, some Russian sage, Perovskia atriplicifoliaand Rudbeckia hirta, black eyed Susan, for contrast. This was taken at Hennepin County's Noerenberg Memorial Park and I believe the butterfly is a tiger swallowtail.

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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