March, 2001

Dear Editors:

Spring can’t come too soon for the gardening crowd. The recent spate of garden catalogs is a sign that winter will soon lose its grip. That means it’s time also for the spring edition of the MSU lawn and garden news packets. Timely topics for March, April and May include anthracnose in trees, why people garden, ornamental grasses, the many uses of black plastic in the garden, tent caterpillars and birch borers. The Garden Corner is on hand, as usual, with its gardening questions and answers.

The summer packet will be underway soon, so now’s the time to suggest story ideas or submit questions for The Garden Corner. Other comments are welcome, too. It’s good to hear from you!

Sincerely,

Leslie Johnson
Extension Lawn and Garden Editor
ANR Communications
312 Agriculture Hall, MSU
East Lansing, MI 48824-1039
517-432-1555
LKJ/bl

LAWN AND GARDEN RELEASES FOR MARCH, APRIL AND MAY

THE GARDEN CORNER

BLACK PLASTIC OFFERS MANY GARDEN BENEFITS

COOL SPRING WEATHER PROMOTES ANTHRACNOSE

DESIGN, PLANT SELECTION AFFECT LANDSCAPE MAINTENANCE NEEDS

EXTENSION FIELD GUIDES HELP IDENTIFY MICHIGAN REPTILES, AMPHIBIANS AND BUTTERFLIES

FLOWERS FOR CUTTING BRIGHTEN GARDEN, HOME

HANDY TO KNOW LOCAL AVERAGE FROST-FREE DATE

INSPECT LANDSCAPE TREES BEFORE LEAVES COME OUT

ORNAMENTAL GRASSES GROWING IN POPULARITY

ORNAMENTAL GRASSES TOPIC OF NEW BULLETIN

SILKEN NESTS ARE SIGNATURE OF EASTERN TENT CATERPILLAR

SQUASH FAMILY CROPS VARIED, EASY TO GROW

SUNFLOWERS ARE EVERYWHERE -- EVEN IN THE GARDEN!

WHITE BIRCHES FALL PREY TO BIRCH BORERS

WHY DO PEOPLE GARDEN?

WIDE VARIETY OF PLANTS WILL GROW IN CONTAINERS

YOU HAVE ALLIES IN THE WAR AGAINST THE BAD BUGS

2/15/01

THE GARDEN CORNER

Contact: Leslie Johnson

EAST LANSING, Mich. -- The influx of plant and seed catalogs early in the year does more than generate spring fever -– it also starts a flood of gardening questions. Extension specialists at Michigan State University answer timely queries on vegetable garden, flowers, landscape plants, weed control and more.

Q. Which crops can be first into the vegetable garden in the spring?

A. Once the soil is dry enough to work and you’ve loosened it, added organic matter and broadcast a complete fertilizer and worked it in, you can plant peas, lettuce, spinach, carrots, radishes and beets from seed; transplants of the cole crops -- broccoli, cabbage, Chinese cabbage and brussels sprouts; and onion sets. Making several small sowings of salad crops rather than one larger one will keep you supplied with salad makings well into the summer.

Q. Are there any flowers that I can plant from seed along with my early vegetables?

A. Sweet peas are an obvious choice -- like garden peas, they can be planted outdoors as soon as the soil is dry enough to work. Sunflower seedlings tolerate light frost, though not a hard freeze, so you might want to hold off a bit on these. Most other annuals grown from seed must either be started indoors or planted after the danger of frost is past and the soil has warmed up.

Q. My neighbor planted dozens of spring-flowering bulbs last fall but only a few flowered this year. What could have happened?

A. The most common cause for bulb failure in Michigan is poorly drained soil -- bulbs simply rot. Improper storage, either before you buy them or afterward, may kill flower buds. Bulbs planted too near a heated structure may not get the cold treatment they need to flower. Animals munching on bulbs can also prevent flowering. Moles usually eat earthworms and other soil invertebrates but may also eat sprouting bulbs, and mice traveling through mole tunnels surely will. And a variety of animals, from deer to woodchucks, will eat the top growth of many bulbs, including flower buds and stems, right to the ground. The exception is daffodils, which deer won’t eat.

Q. I have an old-fashioned lilac and would like more. Can I root cuttings to grow my own?

A. Yes. Make a slanting 2-inch cut on the upper side of a branch about a foot from the tip. Dust the cut with rooting hormone and then bend the branch down and fasten it to the soil between the plant and the cut, using a wooden peg, U-shaped wire or stone to hold the branch in place. Bend the tip of the branch upright and twist it a half-turn to open the cut. Then place another peg or pin over the branch at the point of the cut and mound 3 to 4 inches of firmly packed soil over the cut. Mulch the mound and water often. By next spring, you should have a rooted plant that you can cut free of the parent plant. Leave it undisturbed for about three weeks after severing it from the parent plant before moving it to its new location.

Q. It appears that I have some poison ivy in a hedge. What can I do about it?

A. First of all, if you have a history of poison ivy poisoning, you need to know that all poison ivy control procedures carry a high risk of exposure to the poisonous oil. If possible, let someone known to be resistant attempt control. Any herbicide that will kill the poison ivy will probably also damage or kill the shrubs it’s involved with. Digging it out when the soil is wet may be effective. If the soil is dry, pieces of root are likely to remain in the soil and form new plants. Never burn poison ivy -- the oil that causes itching, inflammation, swelling and blister formation in sensitive people can be carried in smoke and cause serious problems.

Q. I tried to grow carrots several times with little to no success, but the unusual-colored ones in this year’s seed catalogs have piqued my interest in trying carrots again. Do you have any tips for improving germination?

A. Carrots germinate slowly and do not grow vigorously after they are up. Germination problems are more often problems with crusting soil that prevents the hairlike seedlings from emerging. Try warming the soil with plastic to speed germination and planting radishes in with your carrots to break through the soil crust. Covering seeds with peat moss, sand or sawdust rather than soil is another approach.

Q. How are determinate and indeterminate tomato varieties different?

A. Determinate varieties tend to be compact plants that can be grown unsupported or do very well in cages. They usually flower and set fruit within a relatively short period, and all the fruits usually ripen at about the same time -- within a few days, anyway. Indeterminate varieties continue to grow and set fruit all season, so fruit clusters ripen over a long period.

Q. Do carpenter ants eat wood or merely nest in it?

A. Unlike termites, carpenter ants don’t eat wood -- they excavate it for their nests. An infestation usually begins in moist, decayed wood, so a carpenter ant problem is actually a symptom of a moisture problem. In warm weather, carpenter ants may come indoors to forage for food. If you see carpenter ants indoors in the winter, they are probably nesting indoors. Control, in either case, means finding and treating the nest with an appropriate insecticide or using poison baits that the worker ants will take back to the nest and share with their nestmates. The next step is to repair water-damaged wood and eliminate the moisture problem that allowed the ants to get established.

#lkj#

ANR Communications                                         Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039                             2/15/01

BLACK PLASTIC OFFERS
MANY GARDEN BENEFITS

EAST LANSING, Mich. -- Many gardeners find weed control the bane of their gardening existence. In the search for inexpensive, effective weed control measures, many discover black plastic mulch.

"The idea of plastic may put some people off," says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "But it’s cheap, effective and easy to use, and it benefits the garden in several other ways, also."

Black plastic mulch stops weed growth by cutting off the light, she explains, and eliminates problems with both annual and perennial weeds.

Plastic mulch also helps warm the soil in early spring and so helps plants and seeds get off to a quicker start.

Plastic mulch also reduces the loss of soil moisture by evaporation. This is a plus on light, droughty soils, McLellan notes, but it can be a disadvantage on wet, heavy soils -- it may keep moisture levels too high for adequate aeration and plant root growth.

Using plastic mulch around tomato plants keeps fruits off the ground so they stay cleaner and have less problem with ground rot. Other frequently mulched crops include eggplant, peppers, strawberries, melons, squash, pumpkins and cucumbers. Transplants and seeds are planted through holes made in the plastic. It usually isn’t used around cool-season crops such as broccoli, cabbage and peas because these crops prefer cool soils.

Using black plastic for weed control eliminates the need for repeated cultivation and so reduces the chances of soil compaction, McLellan says. It saves time and labor in the garden and reduces the chance of injury to plant roots, stems and fruits during cultivation. The few weeds that manage to come up in rows or around transplants or hill crops can easily be hand pulled and tossed on the plastic to wither in the summer heat.

Black plastic is a handy tool if you’re converting lawn to garden. Simply spread it over the area to be cleared and let the heat that builds up under it kill off the grass.

Because plastic is lightweight, it needs to be secured somehow so it doesn’t blow and flap and damage crop plants, McLellan points out. One way to anchor plastic is to use a hoe to dig a trench in which to bury 3 to 4 inches on each side of the plastic sheet. Plastic gallon milk jugs filled with water, old tires and other found objects can be used for weight on the plastic.

You can simplify watering by installing soaker hoses or a trickle irrigation system before you put the plastic down, McLellan suggests. A more labor-intensive method is to apply water through the planting holes with a hose. Rain will also find its way to the soil through the planting holes. In areas where water stands on the plastic after a rain, poke a few holes in the plastic to let it drain into the soil.

Black plastic is available at garden centers and hardware stores, through mail order catalogs and at farm supply stores. It’s sold in various thicknesses, which are measured in mils, and in widths ranging from 3 to 15 or 20 feet or more.

A disadvantage of plastic mulch is that it must be pulled up in the fall -- unlike organic mulches, it can’t simply be plowed down at the end of the season. It must be taken up and stored or discarded.

"That bit of labor may seem like a small price to pay for a summer of essentially weed-free gardening," McLellan observes.

#lkj#

ANR Communications                                         Contact: L. Johnson or G. Adams
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555 or 355-0202
East Lansing, MI 48824-1039                             2/15/01

COOL SPRING WEATHER
PROMOTES ANTHRACNOSE

EAST LANSING, Mich. -- Last year on the Michigan State University campus, sycamore trees alongside the Red Cedar River covered the ground with brown-blotched, shrivelled leaves in late spring and early summer.

"A classic case of anthracnose," says Gerry Adams, Extension plant pathologist at MSU. "It’s usually most serious in sycamore trees, though it can affect oak, sugar maple, silver maple, ash, birch, elm, hickory and walnut trees. Typical symptoms are brownish patches on expanding leaves, curled and distorted leaves, and/or twig dieback or bark cankers."

Anthracnose is caused by a fungus, and it tends to be worse in years with cool, wet weather as leaves are expanding in early spring. In addition to leaf loss, it can cause dieback of twigs and branches.

The fungus overwinters in fallen leaves or in cankered twigs on the tree. Rain and wind spread the spores of the fungus to buds and young leaves in early spring. Defoliation may range from minor to severe. Repeated defoliation may weaken a tree and leave it susceptible to attack by other disease organisms and insects, Adams says. Twig dieback can result in the formation of clumps of secondary shoots that give the tree a brushy look.

"Generally, the use of fungicides to control anthracnose on landscape trees is not warranted," Adams says. "Instead, it’s recommended that fertilization and pruning be used to aid the trees in recovering from the stress of the disease."

High-value (specimen) trees with a history of anthracnose can be treated with fungicides in early spring if the disease is reducing the aesthetic qualities of the trees.

Two or three applications and thorough coverage of leaves and twigs are essential for good control, Adams notes. Small trees can be treated with a small hand sprayer; for large, mature trees, the high-pressure spraying equipment used by tree care professionals would be necessary, and the cost of hiring these folks may be prohibitive.

"Protectant fungicides need to be on the tree before the disease is apparent," Adams points out. "If you’re seeing the symptoms for the first time, apply an eradicant fungicide. Leaf symptoms of anthracnose can be mimicked by some environmental conditions or by insect damage. Before spraying, it’s environmentally prudent to take a sample of leaves and twigs to your local Extension office for assistance in getting a positive identification of the problem. If it is anthracnose, rake up and destroy this year’s leaves and twigs in the fall, prune out and destroy cankered twigs, if possible (don’t chip the twigs for use as mulch) and look into the feasibility of spraying next year."

He also recommends fertilizing affected trees in early spring to promote vigorous growth.

#lkj#

DESIGN, PLANT SELECTION AFFECT
LANDSCAPE MAINTENANCE NEEDS

EAST LANSING, Mich. -- Do you ever feel as if your landscape owns you? If you’re not mowing or fertilizing, you’re pruning or planting or weeding or seeding or painting or…. You get the idea.

"If the hours you spend nurturing growing plants and maintaining your home grounds are your idea of heaven on earth, you don’t need to read any further," says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "But if you’d like to cut back on the work and increase the enjoyment, not to mention the time available for other interests, it may be time to analyze the maintenance needs of your landscape and figure out how to reduce them."

Ideally, low maintenance is designed into the landscape, she suggests. Areas are laid out and plants and other materials are chosen to perform well without a continuing major investment of time, money or sweat. So, if you’re starting from scratch, you have an advantage. But even in an established landscape, you can make choices that reduce maintenance needs.

Let’s say your yard features a privet hedge that needs to be pruned twice a year with a border planted each year to annual flowers, a Kentucky bluegrass lawn that has to be fertilized four times a year and watered diligently and mowed frequently to maintain its lush carpet look, a bed of rhododendrons flanking a stand of multistemmed European white birch trees, and a selection of exotic trees and shrubs planted singly about the yard.

In addition to the hedge pruning and the lawn care, you must continually test and adjust the acidity of the soil for the rhododendrons, spray the birch trees for birch leaf miner and bronze birch borer, and mow and trim around each of those isolated trees and shrubs, some of which appear not to have survived last winter’s cold temperatures.

"Adding a plant or structure to your landscape doesn’t imply a commitment to leave it there forever or become a slave to it," McLellan suggests. "It’s OK to rethink those decisions and make new ones that will require less upkeep."

That hedge, for instance, could be replaced by a fence of pressure-treated lumber. Put it up, stain it or let it weather naturally, and forget about it. No pruning required. Eliminate grass and weeds around the base of the fenceposts and use landscape fabric or a thick layer of mulch to minimize weed problems, trimming and mowing difficulty. Or, if you prefer plants, select shrubs that will grow no taller than the height to which you have been pruning the hedge. Use landscape fabric or mulch to control weeds. Plant clumps of perennial grasses or easy-care flowering perennials such as daffodils (spring flowers), iris (early summer), daylilies (early to midsummer; some flower until fall) and maybe chrysanthemums for fall color. Add a few annuals for instant color if you want.

Decide what features of the exotic but struggling trees and shrubs that you like and look for native plants that are similar. Plants native to this part of North America or areas with similar climates will be better adapted to local soils and climate and more likely to not only survive but thrive, McLellan suggests.

"A common plant that’s thriving is likely to add more to the landscape and require less maintenance than an exotic plant that’s just hanging on," she adds.

Grouping plants that require similar conditions and maintenance makes mowing easier by reducing the number of individual plants to be mowed and trimmed around, she points out, and makes care simpler because you don’t have to worry about overwatering one plant to provide enough moisture for the one next to it.

Landscape plants should serve a purpose, whether that’s shading the house or patio, providing a visual screen, serving as a windbreak, acting as a backdrop for a flower garden, framing the house, providing cover for wildlife or forming a natural snow fence. Selecting plants whose mature height and spread fit the planting site and whose requirements for light, soil moisture and protection against wind match conditions the site provides greatly reduces the need for pruning and special care. And selecting plants without hordes of pest and/or disease problems may reduce or even eliminate the need to apply pesticides.

"Some people would see the rhododendrons and white birch trees as problem plants that take too much work," McLellan observes. "Someone else may consider them the spring focal point for the landscape and decide to simplify the rest of the landscape to be able to concentrate on them," McLellan says. "That’s fine -- that’s a personal decision based on a person’s priorities for the landscape and his or her time and other resources. That’s what the whole landscape assessment effort boils down to -- deciding how you want your landscape to look and what you’re willing to do to accomplish that. Someone else might decide to replace the European birches with river birch, a native white-barked birch that isn’t so likely to be killed by birch borers after a few years, and the rhododendrons by some other spring-flowering shrub that has less demanding soil pH requirements. The result is the same sort of spring focal point with less maintenance."

Another gardener might be content to put minimal effort into lawn maintenance in favor of establishing large, sweeping beds of perennial flowers and shrubs, reasoning that the enjoyment from the flower garden justifies the high maintenance, especially when you figure that it means less grass to mow. A neighbor might prefer the manicured lawn look and be willing to put in the time and effort required to achieve and maintain that.

"The bottom line is that there are choices you can make to reduce maintenance needs if you want to," she sums up. "How far you go with it depends on whether that’s a top priority or an incidental consideration, and whether you’re building a landscape from the beginning or working with an established one, what you use your yard and grounds for -– a play area for children vs. a backdrop for patio entertaining, for instance -- what your other interests are and probably a dozen other factors. When it’s time to select a plant or a material for a structure or a patio, driveway or walkway, chances are there are both low- and high-maintenance choices available. If you’re thinking about maintenance when you make those choices, you can make an informed choice that works for you."

#lkj#

ANR Communications                                         Contact: Leslie Johnson
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555
East Lansing, MI 48824-1039                             2/15/01

EXTENSION FIELD GUIDES HELP
IDENTIFY MICHIGAN REPTILES,
AMPHIBIANS AND BUTTERFLIES

EAST LANSING, Mich. -- Owning Michigan State University Extension’s field guides probably won’t bring you fame and fortune on your favorite trivia-based game show. But having the guides to refer to can increase your enjoyment of the outdoors and the critters you encounter there.

Michigan Butterflies and Skippers includes every butterfly ever recorded in the state -- 159 species altogether. Gorgeous color photographs accompany text on each species by lepidopterist Mogens "Mo" Nielsen. The text describes the adults and larvae, and tells what flowers, if any, the adults visit, what plants the larvae feed on, the type of habitat and the counties in which the species is found, and when adults are on the wing. The book also contains sections on Michigan geography and climate as they relate to butterflies, butterfly habitats, butterfly gardening and conservation, and references for further study.

The 252-page softcover book is an encyclopedia of information. It’s available for $19.95 at your county MSU Extension office or the MSU Bulletin Office.

Three field guides cover Michigan’s reptiles and amphibians.

Michigan Snakes (softcover, 76 pages, $8.95) covers the 17 species of snakes found in Michigan. The state’s other reptiles are detailed in Michigan Turtles and Lizards (softcover, 96 pages, $8.95), which details 10 species of turtles and two lizards. Michigan amphibians are found in Michigan Frogs, Toads and Salamanders (softcover, 148 pages, $13.95). Two toads, 12 species of frogs, Michigan’s lone mudpuppy, its single siren species, seven salamanders and two newts come to life on its pages.

Each species description in these field guides includes one or more color photos, tips on distinguishing it from similar species, a map showing where it’s found, and a description of its habitat and habits. Each field guide also includes information on the biology of these species, their study and conservation, and further references.

The field guides and a host of other publications and videotapes on a wide range of topics are available from your county MSU Extension office and from the MSU Bulletin Office, 10-B Agriculture Hall, MSU, East Lansing, MI 48824-1039. A free catalog of educational materials is available upon request.

#lkj#

FLOWERS FOR CUTTING
BRIGHTEN GARDEN, HOME

EAST LANSING, Mich. -- A continuous source of cut flowers for brightening your home interior can be as close as your garden. A wide range of bulbs, annuals and perennials -- from asters, carnations and daisies to sunflowers, peonies, gladiolus and zinnias -- make good cut flowers.

"Some gardeners plant flowers for cutting in rows in a dedicated cutting garden," observes Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "Others incorporate flowers suitable for cutting in their annual and perennial beds. Careful cutting preserves the beauty of the garden while providing flowers to take indoors, too."

Perennials such as asters, achillea (yarrow), daisies, carnations, columbines, coneflowers, heliopsis, hybrid and Oriental lilies, peonies and chrysanthemums, and spring bulbs such as daffodils and tulips make excellent cut flowers, she points out. Favorite annuals for cutting include marigolds, zinnias, celosia, lisianthus, cosmos, salvia, snapdragons, statice and sunflowers. Summer bulbs such as gladiolus, callas and dahlias have to be planted in spring and lifted and stored in the fall, but their fans think their contributions to arrangements are worth the effort.

For filling out bouquets and arrangement, consider planting annual and perennial ornamental grasses and ferns, artemisia and baby’s-breath, she suggests.

Perennials and annuals will produce flowers for cutting quicker if they’re planted in spring as transplants, McLellan notes. Perennials grown from seed will probably not flower until the next year. Annuals, of course, flower the same year. Many will bloom for weeks if they’re seeded in the garden after the danger of frost; others need to be started from seed indoors or purchased as transplants.

"With spring and early summer-flowering perennials and bulbs, summer bulbs, fall-blooming perennials and some well-chosen, quick-to-flower annuals, you should have fresh flowers continually from spring until hard frost," she observes.

#lkj#

ANR Communications                                          Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039                             2/15/01

HANDY TO KNOW LOCAL
AVERAGE FROST-FREE DATE

EAST LANSING, Mich. –- "Plant after the danger of frost is past" is not very helpful advice if you don’t know the average date of the last frost in your locale.

"The average date of the last spring frost is a handy bit of information to have when you’re choosing what to plant and when to plant it," observes Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "Because it’s an average, based on analysis of years of weather data, it’s not a guarantee -- some years the last frost will come earlier and some years later. But it’s a benchmark."

The days between the average dates of the last spring frost and the first fall frost are the local growing season -- the number of frost-free days you can expect in your area. This information is important in choosing varieties.

If your local growing season is 120 days, for instance, you would have a pretty good chance of success with snap beans that produce a crop in about 60 days, tomatoes that take 72 days from transplanting to ripe fruit, flowering annuals that take 80 days from seed to flowers, and squash at 105 days from seed to harvest. If your growing season is 95 days, the squash would be a gamble, and you would probably want to start the flower seeds indoors and set transplants outdoors rather than sow seeds in the garden.

"The longer your local growing season is, the more options you have," McLellan sums up.

Once you have your seeds and plants, the frost-free date becomes a factor in when you plant.

Warm-weather crops such as snap beans and squash from seed, and tomatoes, eggplant and peppers from transplants will not tolerate even a hint of frost. They must be planted after the danger of frost is past or protected against frost if planted earlier and temperatures drop. Warm-weather crops grown from seed will not germinate if the soil is too cold and may rot in cool, moist soil.

Cool-weather crops, on the other hand -- such as peas, lettuce, the cole crops (cabbage, broccoli, etc.), spinach from seed and onions -- will grow in cool soil and even tolerate some light frost. They thrive on the cool temperatures that the warm-weather crops find daunting and tend to be much higher in quality when grown in cool weather, McLellan observes.

The usual recommendation for these crops is to plant in the spring for an early summer harvest and again in midsummer for a fall harvest. The warm air and soil of summer get the seedlings off to a quick start, but the weather is cooling as plants are coming into production.

Gardeners who aren’t afraid to gamble can rush the season a bit by warming the soil with clear or black plastic before planting warm-weather crops and then protecting the tender seedlings with row covers or other devices when temperatures drop. Another approach is to figure out how many days it takes seeds to germinate and then plant about that many days before the local frost-free date. With crops such as sunflowers and sweet corn, whose seedlings can tolerate light frost, the limitation is soil temperature more than air temperature. Again, warming the soil with plastic before sowing seeds can make a big difference.

Information on your local growing season, vegetable variety selection, and garden planning, planting and care is available at your local county MSU Extension office.

#lkj#

INSPECT LANDSCAPE TREES
BEFORE LEAVES COME OUT

EAST LANSING, Mich. -- Early spring, before the trees leaf out, is a good time to inspect, repair or remove damaged or hazardous trees in your yard.

"Snow and ice storms may have broken limbs or split trunks," says Mary McLellan, Extension Master Gardener program coordinator. "Dangling limbs should be removed before they fall and cause property damage or injury."

Damaged areas are easy to see when trees are leafless. How you deal with them depends on the situation.

Branches that are involved with utility lines should be left to the utility companies, she notes. Small branches that can be removed safely from the ground with a pruning saw are fair game for the homeowner. Those that require climbing a ladder or using a chainsaw might better be left to a professional tree service.

To prune damaged limbs back to undamaged wood, use three cuts: the first made upward from the underside of the branch, partway through; the second outside the first cut from above, all the way through; and the third to remove the branch stub.

"The first cut keeps the falling branch from splitting and tearing the stem or limb it's attached to as it falls," McLellan explains. "The second removes the limb, and the third removes the stub, a potential entryway for insects and disease organisms."

If a storm has removed the limb and only the ragged stub remains, begin at step 3, she says.

Less obvious than broken branches or split trunks (which may require the tree to be removed) are trees weakened by internal rot or root rot. Danger signs include large open wounds, poorly healed branch stubs, open cracks, patches of dead bark, dead branches or top dieback, insect holes and trunk cavities. In warm weather, the fruiting bodies of fungi on trunk, roots or major limbs indicate where wood is weakened by rot.

What you need to do about these signs depends on the location of the tree.

"An old oak tree in the middle of a cornfield is a different situation than a maple tree overhanging your house and garage," she points out. "The oak tree could fall without endangering anything, but if the maple tree goes down in a windstorm, it could damage your house, garage and vehicles, take out power lines and possibly injure someone."

A powerful storm can take down even a healthy tree, she notes, so as you inspect your landscape, it's a good idea to note the locations of any large trees near the house or other structures. Are they already leaning toward the house? Do large branches overhang it? If a closer look shows signs of potential hazards, pruning or even removing the tree might be in order.

If you're replacing or adding trees to the landscape, include safety in your consideration of planting sites and tree species, McLellan suggests.

"If you're going to put in a large shade tree, plant it where it can reach its mature size without overhanging the house or other structures," she suggests. "And choose a recommended species that's not known for weak wood and susceptibility to storm damage."

Avoid willows, Siberian elm (also sold as Chinese elm, though this is actually a different species), silver maple, boxelder and other quick-growing, weak-wooded trees. Recommended species include Norway and red maples, littleleaf linden and honeylocust.

#lkj#

ANR Communications                                         Contact: L. Johnson or T. Ellis
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555 or 355-8478
East Lansing, MI 48824-1039                             2/15/01

ORNAMENTAL GRASSES
GROWING IN POPULARITY

EAST LANSING, Mich. -- Not so long ago, pampas grass was about the only ornamental grass you were likely to run into in plant and seed catalogs. Now a variety of perennial and annual grasses in a range of sizes are available.

"Ornamental grasses offer a variety of foliage textures and colors and unusual flowers," observes Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "They range in height from a few inches to several feet and in color from frosty blue to solid green, variegated green and dark red. They can serve as ground covers, specimen plants, borders or background plants in perennials plantings, as well as a source of fresh and dried plant material for arrangements. Some are outstanding sources of fall color; most add interest to the winter landscape as well."

Many ornamental grasses are perennials in their native lands but not hardy in Michigan. These are used here as annuals.

Perennial grasses bought as plants are more expensive than seed but give an impressive display sooner, McLellan notes. Both seeds and plants are planted in the spring, and most grow best in full sun and fertile, well drained soil.

"Because ornamental grasses offer attractive forms, foliage and flowers unlike anything else in the landscape or garden, gardeners are using them more and more," McLellan observes.

Ornamental grasses recommended for use in Michigan include:

-- Miscanthus sinensis zebrinus (zebra grass) and M. sinensis strictus (porcupine grass). These low-maintenance grasses reach 6 to 8 feet in height and have horizontal stripes on their leaves. They are very effective planted in masses 8 to 10 feet across.

-- Miscanthus sinensis gracillimus (maiden grass) and M. sinensis ‘Sarabande’. These reach 5 to 8 feet and have fine-textured leaves. They are good massed in rows or arcs. They are attractive in flower and in winter.

-- Miscanthus sinensis variegatus (variegated Japanese silver grass) and M. sinensis ‘Morning Light’ (silver variegated silver grass). These late-blooming grasses have lengthwise stripes on their leaves. They are interesting as specimen plants. ‘Morning Light’ grows to 4 to 5 feet; variegatus may reach 5 to 7 feet.

-- Miscanthus sinensis purpurascens (purple maiden grass). The purple foliage sets off the flowers, which appear in July-August, and adds interest to the winter landscape. Plants reach 3 to 5 feet in height and look good as specimen plants or in masses.

-- Calamagrostis acutifolia ‘Karl Foerster’ (feather reed grass). This upright grass with early flowers (July) looks excellent all summer and winter. It needs little care and is easy to divide. It reaches 5 to 6 feet in height. It is the 2001 perennial plant of the year.

-- Pennisetum alopecuroides (fountain grass; 3 to 4 feet) and P. alopecuroides ‘Hameln’ (dwarf fountain grass; 1 to 2 feet). Both are excellent in garden settings. They bloom in August.

-- Deschampsia caespitosa ‘Goldstaub’ (tufted hair grass). This early-blooming short (2 to 3 feet) grass is grown for its foliage and as a backdrop for more colorful annuals or perennials as well as for its fine-textured interesting foliage and mound of hairlike flowers.

--Erianthus ravennae (ravenna grass). This is the big one, reaching 9 to 12 feet when in bloom. Blooms are very showy in late summer.

-- Molinia caerulea arundinacea ‘Skyracer’ (tall purple moor grass). Plants reach 7 to 8 feet and throw up big, airy flower heads over dramatic foliage.

-- Panicum virgatum ‘Heavy Metal’ (switch grass; 4 to 5 feet) and P. virgatum ‘Rotstrahlbusch’ (red switch grass; 3 to 4 feet). The metallic blue foliage of ‘Heavy Metal’ and the red leaves of ‘Rotstrahlbusch’ are interesting, and the early flowers are very showy.

#lkj#

ORNAMENTAL GRASSES
TOPIC OF NEW BULLETIN

EAST LANSING, Mich. -- Ornamental grasses, used in European and Asian gardens for centuries, have recently been gaining in popularity in the United States. Varied forms, sizes, colors and textures make them versatile and attractive additions to perennials gardens and landscapes.

Minimal insect and disease problems, low nutrient requirements, low maintenance needs and fast growth are other desirable traits. Many ornamental grasses can be left in place during the winter to add interest to the landscape.

A new publication available from Michigan State University Extension provides homeowners and landscape industry professionals with information on more than six dozen species of ornamental grasses that a six-year study showed to be hardy or marginally hardy in USDA hardiness zone 4a. (Most of Michigan is in zones 4 and 5, so any grass hardy in Minnesota, where the study was done, should be able to survive anywhere in Michigan.)

Tables list the species and notable cultivars, along with their height, origin, season of interest and comments on flowers, fall color, plant form, preferences for soil, moisture and light vs. shade, etc. Gardeners looking for grasses for particular sites can consult lists of plants for water gardens and standing water and shady locations, as well as ground covers as alternatives to mown lawns. Other lists suggest grasses for use in erosion control, grasses that aren’t winter hardy that can be used as annuals, and species with fall color and foliage and/or flowers that provide winter interest.

A section on culture and maintenance of ornamental grasses covers planting, spacing, division and maintenance of established plants.

The information in charts and text is illustrated with color photos and black and white line drawings that include a 12-inch ruler to indicate the relative size of each species.

"Ornamental Grasses for Cold Climates" is available for $10 from your MSU Extension county office or the MSU Bulletin Office, 10-B Agriculture Hall, MSU, East Lansing, MI 48824-1039. Call 517-355-0240 for ordering information.

#lkj#

SILKEN NESTS ARE SIGNATURE
OF EASTERN TENT CATERPILLAR

EAST LANSING, Mich. -- Away from its nest, the eastern tent caterpillar may be confused with other caterpillars, but there’s no mistaking its silken webs.

These nests, seen often in roadside trees in May and June, are constructed where branches or main stems fork, says Tom Ellis, Extension entomologist at Michigan State University.

"The caterpillar colony uses the nest for protection against weather and predators," he explains. "They venture out of the nest several times a day to feed on tree leaves. As the caterpillars increase in size, they add additional layers of silk to the nest."

Small trees hosting large numbers of caterpillars can easily be defoliated, in which case the caterpillars may move to another tree, make a new nest and continue to feed.

Full-grown eastern tent caterpillars may reach 2 or more inches in length. They hatch as leaves are opening in spring from eggs laid the previous summer on tree stems and branches. By mid-June or so, they are ready to spin cocoons for their transformation into adult moths. Adults emerge around the end of June, mate, lay eggs and die.

Eggs are laid in a dark, shiny mass on small twigs of the tree the caterpillars fed on or similar trees nearby. Those eggs overwinter and hatch the next spring to start the cycle again. The mature eastern tent caterpillar is a large, hairy, dark-colored caterpillar with a yellow stripe down the center of its back. It’s often misidentified as a gypsy moth caterpillar, especially when it’s left the nest and is looking for a place to make its cocoon. "They’re easy to tell apart, however," Ellis says. "The eastern tent caterpillar has a stripe on its back; the gypsy moth caterpillar, though it’s also large, hairy and dark-colored, has spots on its back -- five pairs of blue spots and six pairs of red ones." Another similar species is the forest tent caterpillar, which has a series of yellowish keyhole-shaped spots on its back.

Defoliation by eastern tent caterpillar is rarely a concern unless it occurs in valuable fruit or landscape trees, especially if it occurs year after year. Trees that lose more than 60 percent of their leaves will produce a new set. Repeated use of stored energy in this way may weaken a tree and leave it more vulnerable to other pests, diseases and environmental stresses that ordinarily wouldn’t be a problem for a healthy tree. Trees that lose less than 40 percent of their foliage to leaf-eating pests usually suffer no ill effects, Ellis points out. Homeowners who don’t want to take a chance with valuable fruit trees or ornamentals can remove the tents by hand as soon as they see them and/or spray the foliage with Bacillus thuringiensis, a bacterial disease of caterpillars formulated as a pesticide under a number of trade names. Removing and destroying the shiny, dark-colored, foamlike egg masses from trees anytime after midsummer and before early spring is another effective approach.

#lkj#

SQUASH FAMILY CROPS
VARIED, EASY TO GROW

EAST LANSING, Mich. -- It would be hard to find a family of crops with more to offer than squash. Ingredients for salads, soups, main dishes, breads and desserts -- and, of course, vegetable dishes -- are all to be found in the squash family.

"The variety in the squash family is extensive," says Mary McLellan, Master Gardener program coordinator at Michigan State University. "You have long-season and quick-maturing varieties, vine and bush crops, a continuous summer harvest and crops for storage, as well as the makings for household decorations and roasted, salted snacks, not to mention scary jack-o-lanterns."

The two general categories of squash are winter and summer. Winter squashes include pumpkins and ornamental gourds. They take the whole summer to grow and mature their hard-shelled fruits, which then can be stored for use in the winter. Summer squashes are quicker to reach the table and eaten in a more immature state, when they are still small and thin-skinned. Even overlooked zucchini that matures to monster size can be salvaged and the flesh grated for use in breads, cookies and cake.

The most difficult part of growing squash may be deciding which types to plant, McLellan observes. Both summer and winter squash come in a variety of sizes, shapes and colors, from straight green zucchini to yellow crookneck summer squashes and white and more traditional orange pumpkins to pink banana and silvery Hubbard squash. Gourds come in a host of knobby and smooth shapes resembling crowns, penquins, eggs and even geese, with colors ranging from white to tan, yellow and green.

Squash family plants have a well deserved reputation for production. One way to sample a variety without being inundated is to plant two or three hills of summer squash using seeds of several kinds in each hill. Plant four to six seeds in each low mound in late spring, after the soil has warmed up and the danger of frost is past, and thin to one plant of each type. A month or so later, plant again. This staggered planting increases the likelihood that you’ll have healthy plants producing all summer and protects you against loss of the first planting to frost, hail or some other mischance.

"There’s usually less competition to have the first zucchini than the first tomato," McLellan notes, "but gardeners who want to push the season can warm the soil with black plastic and plant seeds through it before the local frost-free date. If you try this, you need to have hot caps or some other cover handy to protect the tender seedlings in case of frost."

Another strategy for getting a head start on the season -- planting seeds indoors and putting crops into the garden as transplants -- doesn’t work as well for squash as it does for tomatoes and peppers, she points out. Squash family crops don’t tolerate having their roots disturbed, so by the time transplants get over the shock of transplanting, plants grown from seed sown directly into the garden have generally caught up with them.

When selecting varieties, be sure to check the days to maturity in the seed catalog or on the seed packets, McLellan advises. Winter squash and gourds, particularly, may require a relatively long growing season. If the variety you want to grow takes 150 days from seed to harvest but your local growing season is 120 days, it very likely won’t have time to mature a crop for you.

Generally, the larger the fruit, the longer it will take to mature.

Choosing varieties for a small garden usually means selecting summer squash or bush-type varieties of winter squash rather than the vining types of winter squash, which tend to sprawl and take up a lot of space.

Squash family crops need full sun and plenty of water. The best soil is well drained and high in organic matter. Mulching helps conserve soil moisture and control weeds.

Vining squash are often planted in hills several feet apart in both directions. Bush types may be planted closer together in either hills or rows. Follow packet directions on spacing and depth of planting.

Winter squash are left to mature on the vine until their shells are hard. Summer squash are picked while they’re immature and their skins are tender. Gourds mature on the vines and then dried and may be varnished for long-term use. Winter squash and pumpkins for storage must be harvested before frost to prevent damage that will shorten their shelf life.

#lkj#

SUNFLOWERS ARE EVERYWHERE --
EVEN IN THE GARDEN!

EAST LANSING, Mich. -- Gardeners who not so long ago had only a few varieties of sunflowers to choose from now have dozens, from dwarf types only 1 to 2 feet tall to the mammoth types that reach 8 to 12 feet tall and have seed heads up to 20 inches across.

Recent developments include varieties with a single stem that produce multiple branches, "pollenless" types for cut flowers, and numerous new varieties in a wide range of colors from white and palest yellow through bright yellow and orange to bronze, rust and dark red. Varieties with bicolored petals are available, also.

Unlike so many other garden flowers, the sunflower is native to North America, notes Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. And its cultivation by indigenous people goes back at least 3,000 years. Sunflowers were introduced to Europe in the 16th century by Spanish explorers returning from the New World. They were grown more for their ornamental value than for seeds or oil until they reached Russia, where they became an important source of oil.

Sunflowers are generally easy to grow, McLellan observes. They’re not choosy about soil type and will grow almost anywhere except in standing water. Good fertile soil results in the largest flower heads and the meatiest seeds, however. Sunflowers are generally very drought resistant and they rarely require pest control. They do require full sun, however, as their name suggests.

For best results, plant in a well prepared soil tilled to a depth of 8 inches and enriched with compost, manure or other organic matter and/or a general purpose fertilizer. Sow seeds ¼ to ½ inch deep and about 6 inches apart. When the first true leaves appear, thin plants according to the directions on the seed packet for spacing (usually 2 to 2 ½ feet apart in rows 3 to 4 feet apart). Sunflower seedlings are somewhat frost resistant, McLellan notes, but they won’t survive a hard freeze. Seeds germinate best when the soil has warmed to 70 degrees and plants grow quickly, so it makes sense to wait to plant until warm weather has arrived in late spring.

Sunflowers thrive in hot summer temperatures and tolerate drought, but they do better with an occasional deep soaking, especially when flower heads are developing and expanding. Because they grow vigorously, they benefit from a booster application of fertilizer when flower heads begin to appear.

Tall, single-headed plants may need staking as the seed head becomes heavier.

Sunflower seeds may be roasted for snacks and used in baking as well as used for wild bird feed.

"If you love sunflowers in the garden, you can have them all year round indoors," McLellan observes. "Sunflowers have become a popular image on fabrics for garments and decorating, in calendars and on greeting cards."

#lkj#

ANR Communications                                         Contact: L. Johnson or D. Smitley
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555 or 355-3385
East Lansing, MI 48824-1039                             2/15/01

WHITE BIRCHES FALL
PREY TO BIRCH BORERS

EAST LANSING, Mich. -- One of life’s ironies is that exotic pests such as gypsy moth and zebra mussels succeed in North America because they lack natural enemies while an exotic landscape plant, the European white birch, is short-lived here because native pests soon kill it.

It starts innocently enough, with wilting of the topmost branches. Soon branches are dying. Then the whole tree dies.

The cause is the bronze birch borer, a ½-inch-long beetle native to North America. It’s found from Newfoundland to British Columbia and as far south as Virginia and New Mexico. The larval stage tunnels beneath the bark of susceptible birch trees, feeding on the inner bark (where the sap-conducting vessels are) and the cambium layer (the region of tree diameter growth). The tunnels interrupt sap flow, girdle the branches or trunk, and destroy the tree’s growing tissue.

Dieback of the upper branches is usually the first sign of borer infestation, says Dave Smitley, Extension entomologist at Michigan State University.

"It may take another five years for the entire tree to die," he observes, "although a tree that’s severely stressed by other pests or environmental factors might not survive that long."

The birch tree most susceptible to borers is the European white birch (Betula pendula). Native birches such as the paper or canoe birch (B. papyrifera), yellow birch (B. lutea) and gray birch (B. populifolia) are also attacked but not so severely. The native river birch (B. nigra) seems to be resistant.

"Unless you’re willing to water frequently and spray European white birches to prevent adults from laying eggs or larvae from boring into the bark, you can just about count on seeing the tops of your trees die sooner or later," Smitley says.

He recommends avoiding the European birches altogether or replacing them with either native birches or some other species entirely. Paper birch lacks the drooping branches of European white birch but does have attractive white, peeling bark. It also has substantially fewer and less severe problems with bronze birch borer. The river birch has salmon-pink, papery bark and is apparently resistant to the beetle.

If you have European white birches in your yard that aren’t yet showing signs of borer injury, you can reduce their susceptibility by watering deeply during dry weather and fertilizing annually. Mulching is also recommended -- it eliminates the need for close mowing or string trimming and so prevents trunk damage from lawn equipment.

If trees are showing signs of borer attack, insecticides labeled for borer control must be applied the next year either when adults are laying eggs or before newly hatched larvae enter the bark. This may require three to four applications at two-week intervals beginning around the first of June.

Another way to prevent borer attack is to apply the systemic insecticide imidacloprid in late October or April over the entire root system of the tree. Arborists can be hired to apply the commercial product, Merit, or homeowners can purchase it as Bayer Season Long Grub Control. Homeowners should apply it under the canopy at the rate recommended for grub control, Smitley says.

It’s also important to protect trees from injury by birch leafminer. These insects attack foliage and feed between the leaf surfaces. A single protective spray of an appropriate insecticide when birch leaves are about half-expanded -- usually in mid-May -- will reduce leafminer attack.

"Vigorously growing trees are less susceptible to borer attack than stressed trees," Smitley explains, "so anything you can do to reduce other sorts of stress will help landscape birches fend off borer attack. Because the single most important factor that makes birch trees susceptible to borers is drought stress, frequent watering to prevent drought stress is critical."

#lkj#

WHY DO PEOPLE GARDEN?

EAST LANSING, Mich. -- Get a bunch of gardeners together and ask why they garden and you’ll probably get at least as many reasons as there are gardeners.

Mary McLellan, Extension Master Gardener program coordinator at Michigan State University, says a lot of those reasons boil down to enjoyment and satisfaction.

Some people have very specific, limited goals for their gardens, such as producing herbs for culinary and craft uses, fresh vegetables for their table, strawberries for jam and jelly, cut flowers or dried flowers. Others have broader objectives.

"Many people tend to grow gardens because it gives them a chance to be outdoors, get some exercise, lower their stress level and learn something new," she observes. "Each year is different, with new challenges to overcome, new crops, varieties and techniques to try. In the flower garden, there’s color to play with and the challenge of selecting plants for seasonlong bloom. People can come at gardening with either a right-brain or left-brain approach and find satisfaction."

Whether you’re fulfilling a creative urge by taking soil, seed, water and fertilizer and creating something that wasn’t there before or stocking the shelves in your pantry, there’s always something new to try. For those who have mastered beginner-level plants, more demanding crops or techniques offer new challenges.

For some families, gardening brings the generations together.

"From selecting what to plant to preparing the soil, sowing the seed or setting plants, weeding, and harvesting and enjoying the fruits, vegetables and flowers you have produced, it’s hard to beat gardening as a family activity," she says.

For those with a competitive nature, there’s always the goal of having the earliest tomato on the block or growing the biggest pumpkin or the tallest sunflower.

It’s possible to take the enjoyment out of gardening by thinking on too grand a scale and planting more than you can care for, she notes. For beginners making the leap from a few houseplants to a flower or vegetable garden, her advice is: think small. A container garden on a patio, a 10- by 15-foot vegetable garden or a flower bed at one corner of the deck is easily manageable with basic people-powered tools. It doesn’t cost much to establish it or take a lot of time and effort to tend it, and it’s more likely to succeed than a big garden that needs more time and labor than you can provide to plant it, keep weeds and pests at bay, and deal with the harvest.

"If you’re gardening for recreation and enjoyment, it’s better to succeed with a small garden than to supersize your garden so it’s just another source of guilt, frustration and stress," she sums up.

#lkj#

WIDE VARIETY OF PLANTS
WILL GROW IN CONTAINERS

EAST LANSING, Mich. -- If the problem is not enough or no room to garden, the solution might be container gardening.

A wide variety of herbs, flowers and vegetables will grow in containers, observes Mary McLellan, Extension Master Gardener program coordinator at Michigan State University.

"Actually, if it can grow in the ground, it can grow in a container," she says, "though keeping the size down may require more work on some plants, such as trees." Container gardening isn’t complicated: simply plant in a soilless growing medium in an appropriate container, water, fertilize occasionally and enjoy -- it’s as simple as that, she suggests. Every year, seed catalogs have more "bush" or "patio" varieties of crops such as cucumbers, squash and tomatoes, along with salad crops such as leaf lettuce, radishes and green onions, spinach and Swiss chard, peppers, herbs and a host of flowering annuals. Clay pots, half barrels and windowboxes are probably the most commonly used containers, but any sturdy container that will hold soil and can be equipped with drainage holes will do -- even the plastic bags that soilless growing media are packaged in. If you want to be able to move the container around, simply set it on a platform with wheels or in a child’s wagon before you fill and plant it. If your container garden will be on an apartment balcony above someone else’s balcony or patio, your containers will need saucers or pans under them to catch the water that drains out of them.

McLellan recommends a soilless potting mix because it provides good drainage, moisture-holding capacity and air spaces for good root growth. And, unlike common garden soil, it’s free of disease organisms, harmful insects and weed seeds, and lightweight.

The major factor in what you can grow in your container garden is how much sunlight is available. Plants that bear fruits -- such as tomatoes and peppers -- most herbs, miniature roses and sun-loving annual flowers -- such as geraniums, petunias, portulaca, marigolds and zinnias -- need full sun most of the day (at least 6 hours). Leafy vegetables such as lettuce and spinach and annuals such as fibrous-rooted begonias, coleus and impatiens will tolerate more shade. A northern exposure would be perfect for tuberous begonias.

Even sun-loving plants can get too much of a good thing in an unshaded southern or western exposure, McLellan notes, especially if the incoming sun is reflected back on them by a nearby light-colored wall. If this is the sort of space you have to work with, choose plants that thrive in full sun and be prepared to give them extra water or shade them.

The medium in containers will dry out quickly on warm, windy days, so check soil moisture regularly and water as needed. Fertilize with a soluble fertilizer every three to four weeks following label directions. Gardening in containers is no guarantee against insect, disease or even weed problems, McLellan points out. There’s also the added hazard of containers blowing over. Inspect plants regularly for problems, and place lightweight containers or top-heavy ones in a sheltered spot during windy or stormy weather.

#lkj#

ANR Communications                                         Contact: L. Johnson or D. Landis
MICHIGAN STATE UNIVERSITY                        Telephone: 517-432-1555 or 353-1829
East Lansing, MI 48824-1039                             2/15/01

YOU HAVE ALLIES IN THE
WAR AGAINST THE BAD BUGS

EAST LANSING, Mich. -- Stroll around your yard and garden in the summer, and you’ll see dozens of kinds of insects. Hundreds more are present that you can’t see -- in the soil, in the grass, in the trees.

Most of these insects are harmless, and some are beneficial in that they help protect your vegetables, flowers, trees and shrubs against damaging pests.

"Often, if you give them a chance, they can keep pest numbers down so that you don’t have to use chemical pesticides," says Doug Landis, Extension entomologist at Michigan State University.

All your allies in the battle of the bugs aren’t insects themselves -- some, such as spiders and predatory mites, are from another branch of the arthropod family tree; others are disease-causing organisms -- viruses, bacteria, protozoans and nematodes.

Spiders and predatory insects such as ladybugs and preying mantids are well known because they are visible and active, large or brightly colored. Parasitoids -- insects that develop inside and kill their host -- tend to be small and go about their business unnoticed.

Pathogens -- organisms that cause disease in insect pests -- are microscopic. If gardeners see anything, it’s the results of their work, such as a dark and mushy caterpillar hanging upside-down from a twig or a fly stuck to a window with white threads.

"Many of these disease-causing organisms require particular environmental conditions -- temperatures in a certain range, high humidity, and so on," Landis explains. "Some of them, such as Bacillus thuringiensis, a bacterial disease of caterpillars, have been formulated as microbial insecticides. The great thing about them is that they’re effective against a limited number of target pests and pose little or no danger to other insects, animals, humans or plants. So spraying Bt to control gypsy moth caterpillars, for instance, doesn’t harm the other natural enemies of the caterpillars."

Use of predators, parasitoids and pathogens to control pests is known as biological control because it uses living things rather than chemicals or cultural methods, Landis explains. Importing natural enemies into the yard or garden is less important to backyard biological control than creating a suitable habitat for natural enemies and avoiding use of chemical pesticides as much as possible.

"The chemical insecticides that kill the green cabbage worms in your broccoli plants also kill the parasitoids and predators that help control these and a host of other pests," he points out. "Spraying with Bt controls the worms and conserves the natural enemies."

Other options available to home gardeners are hand picking when the garden is small and pests are few, using traps or barriers (a saucer of beer to trap slugs; a cardboard collar around pepper transplants to foil cutworms) and using products such as insecticidal soap on limited numbers or parts of plants to selectively control troublesome pests.

Creating a suitable habitat for natural enemies may be as simple as interplanting flowers with your vegetables to provide pollen for predators to feed on until prey become available or mulching flower and vegetable gardens to provide daytime shelter for beetles and other predators that hunt at night.

For more information on natural controls of garden pests, ask for Natural Enemies in Your Garden: A Homeowner’s Guide to Biological Control (E-2719) at your county MSU Extension office, or write to the MSU Bulletin Office, 10-B Agriculture Hall, MSU, East Lansing, MI 48824-1039. The cost is $6.25.

#lkj#