August, 2001
Dear Readers:
If you like your summers hot, you were probably pleased with the recent weather. Who knows what sort of weather fall will bring! One thing is certain: it’s time for the fall edition of the MSU lawn and garden news packet. Timely story topics for September, October and November include growing garlic, choosing a pest control firm, repotting houseplants, fertilizing trees, diagnosing plant problems and using green manure crops. The Garden Corner is on hand, as usual, with its gardening questions and answers.
As I write this, the heat index is somewhere over 100, but I’m already thinking about stories for the winter packet. If you have any suggestions or questions for the winter edition of The Garden Corner, now’s the time to send them along. Other comments are welcome, also -- 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 SEPTEMBER, OCTOBER AND NOVEMBER
DIAGNOSING PLANT PROBLEMS NOT ALWAYS AN EASY TASK
DIDN’T PLANT IN SPRING? YOU GET ANOTHER CHANCE NOW
DISEASE DEVASTATING MICHIGAN OAK TREES
FALL CLEANUP OF HOME ORCHARD REDUCES PEST, DISEASE CARRYOVER
FOR HOME-GROWN GARLIC, TRY PLANTING IN FALL
‘GREEN MANURE’ MAY SOUND YUCKY BUT BENEFITS GARDEN
HARDY KIWIFRUIT CAN BE GROWN IN MICHIGAN GARDENS
LANDSCAPE TREES MAY NEED FERTILIZATION
SUMMER GROWTH MAY MEAN HOUSEPLANTS NEED REPOTTING
USE CARE WHEN CHOOSING PEST CONTROL COMPANY
WHEN DO YOU HARVEST ONIONS? LET THEM TELL YOU!
WINTER CONDITIONS CAN DAMAGE PLANTS
8/15/01
Contact: Leslie Johnson
EAST LANSING, Mich. -- As the seasons change, so do the gardening questions. Michigan State University Extension specialists answer timely questions about topics ranging from household insect pests to fruit growing and vegetable gardening.
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
DIAGNOSING PLANT PROBLEMS
NOT ALWAYS AN EASY TASK
EAST LANSING, Mich. -- "What’s wrong with my plant?" What gardener hasn’t said that at one time or another? Sometimes the answer is simple, but more often, it takes a bit of detective work to determine the cause of plant problems.
Mary McLellan, Extension Master Gardener program coordinator at Michigan State University, recommends using a systematic approach to diagnosing plant problems.
"The first step is proper identification of the plant," she says. "This immediately reduces the number of potential problems by eliminating those that are specific to other types of plants. Reference books used for identification also may offer a list of typical problems for this species."
The next step is to define how the plant with the problem is different from a healthy plant. You may find insects munching foliage, leaves covered with powdery mildew or black moldy spots, or the bark gnawed off the stem of a small tree or shrub. In such instances, diagnosis is simple.
Quite often, however, the problem is not so clearcut. The plant just isn’t growing well, perhaps -- leaves are small or sparse or off-colored. Perhaps a tree is losing its leaves or turning color when it shouldn’t be, an expanse of lawn is turning brown or everything in a corner of the garden is wilting.
"Examine every part of an affected plant, if you can," McLellan advises. "In trees, leaf symptoms often indicate damage to roots, trunk or branches. Then consider whether the problem is appearing in one plant, in multiple plants of the same species or in all the plants in a particular area. This can be an important clue to the source of the problem. Uniform damage to a mixed grouping of plants suggests a cultural or environmental cause -- herbicide drift or pollution, perhaps -- especially if symptoms occur all at once and don’t progress. Damage on one type of plant or related plants only suggests a pest or disease organism that targets that plant family."
Another important part of diagnosis is a site history. When the problem was first noticed, where the plant is located -- in a lawn, near a street, in a low-lying area, in the root zone of a black walnut tree, etc. -- whether it’s newly planted or established, whether construction or changing traffic patterns near the plant might have affected the root system, and whether pesticides or other chemicals (including deicing salt) have been used near the plant -- all these are part of the total picture.
Unusual weather also needs to be considered, she notes.
"Often landscape ornamentals crushed by a heavy snow load don’t show symptoms of damage until the next growing season," she points out, "by which time the homeowner may not make the connection."
Hail, lightning, wind, ice, early or late frost, and excessive rain or drought all may play a role in plant problems.
Soil characteristics such as pH, fertility, drainage, compaction, contaminants and soil depth are other factors. A mismatch between the conditions the plant is adapted to and those of the planting site will leave plants struggling to survive and more susceptible to insect and disease attack.
"Homeowners themselves can be the cause of major plant problems," McLellan observes. "Cultural practices -- watering (or failing to water), fertilizing, pruning, planting, mowing and mulching practices -- can provide plants with the care they need or do them in in short order."
There are many ways to kill plants, she notes, including selecting the wrong plant for the site, planting too deep or too shallow, letting roots dry out before planting, damaging stems with mowers and string trimmers, failing to water or overwatering, fertilizing too much or at the wrong time or not at all, girdling plants with guy wires, allowing roots or stems to be damaged by construction activities, or carelessly using herbicides around them, among others.
"Once a plant has been weakened by environmental or cultural factors, it’s more susceptible to insect and disease problems," she says. "So pest or disease problems may actually be symptoms of some underlying stress."
Diagnosis is the systematic analysis of all these clues to arrive at a probable cause. The next question, of course, is what to do about it.
"Sometimes plants die no matter what you do," McLellan observes. "Sometimes problems are cosmetic -- leaf galls on maple trees are an example -- and you don’t need to do anything. With some problems, plants will die if we don’t do something. The question then is whether the value of the plant justifies taking action to save it. ‘Value’ might be aesthetic or sentimental or economic. However you define ‘valuable’, the decision to treat or remove and replace a plant will be easier if it’s based on information about the plant, the problem and the options."
For help with plant or pest identification, treatment recommendations, and information on plant selection, planting and care, contact your county MSU Extension office.
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
DIDN’T PLANT IN SPRING?
YOU GET ANOTHER CHANCE NOW
EAST LANSING, Mich. -- Maybe it was the weather in the spring, or the kids’ hectic soccer schedule. In any case, your plans to add trees and shrubs to your landscape never materialized.
Well, dust them off and put them into action now -- fall can be a great planting time, says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University.
"Normal fall weather includes ample moisture and cool temperatures," she observes. "The soil is still warm, however, so conditions are just right for good root growth, which is important in getting plants established before winter."
Most landscape plants can be planted in the fall. A few are better planted in spring because of their susceptibility to winter injury. These include some oaks, poplars, red maple, birch, magnolia, dogwood, hawthorn, hornbeam, tulip tree, sweet gum, yellowwood, golden raintree and most fruit trees.
Select plants that offer the ornamental traits you want after reducing the list of potential purchases to those that require the growing conditions that your site provides, McLellan advises. Site characteristics to consider include drainage (some trees and shrubs will thrive in soggy soil; most won’t), exposure to sun and prevailing wind, and soil (sand or clay, compacted or not, fertile or not, etc.).
Another important factor is hardiness. Hardiness is a measure of a plant’s ability to survive a typical winter in a given area, she explains. The entire country is divided into zones. A plant that is hardy in U.S. Department of Agriculture hardiness zone 4, for instance, should do fine anywhere in Michigan, the majority of which is in zone 5. Plants billed as hardy to zone 6 and above may survive a mild Michigan winter or a series of them but is more likely to be killed in its first year or two. If it’s planted in a sheltered spot and does survive, it’s unlikely to perform up to expectations, and it may require a great deal more maintenance than a hardy, well adapted plant.
Plant traits to keep in mind when selecting landscape ornamentals include mature size and shape, which determine spacing from other plants and structures and potential for involvement with overhead utility lines; susceptibility to pests, diseases and other problems, such as storm damage; and ornamental characteristics such as the presence of flowers and fruits, foliage color, interesting bark texture, multiple stems and fall color. Whether you want plants for a windbreak, shade in the summer, a screen between your place and the neighbor’s, a noise filter between your home and a busy road, or a source of food and shelter for wildlife will also enter into the choice.
Once you have analyzed your needs and purchased your plants, it’s important to follow proper planting procedures to get them off to a good start, McLellan says.
At planting time, dig the hole twice as big as the plant’s root ball, she advises, and plant the tree or shrub at its original growing level. This may mean trying it in the hole and adjusting the planting depth by adding a little soil or digging a little deeper. Plenty of room to grow and the proper planting depth make for healthy roots and quick establishment, she explains.
Before filling in the hole, make sure that any non-biodegradable materials -- wire, plastic cord, plastic burlap, etc. -- are removed from the trunk and rootball. Left in place, they will restrict root growth and eventually girdle the trunk.
Fill the hole gently but firmly to eliminate air pockets around the roots. Water to settle the soil and add more as needed. Avoid tramping down the soil around the base of the plant, she advises -- this can compact the soil and make it difficult for roots to penetrate it. Use extra soil to build up a ridge of soil 2 to 4 inches high around the margin of the hole (outside the root area) -- this creates a reservoir for watering.
Mulching around the base of the tree helps conserve soil moisture and protects against alternative thawing and freezing of the soil, which can damage roots and even push some smaller plants right out of the ground. Make sure mulch is over the roots but not up against the trunk or main stems -- this can lead to the bark rotting, she notes. It also makes a hiding place for mice, which can injure or kill plants by gnawing on the bark.
Planting time is the best time to stake and guy trees, if necessary. Large trees in open, windswept areas are most likely to need support. Whether a tree needs one stake, two or three depends on its size -- the bigger the tree, the more support it needs. To prevent damage to the tree trunk, McLellan advises using wide, soft strapping material or padded wire (old garden hose makes good padding) to fasten the tree to the stakes.
If fall rains are scarce, water regularly to promote development of a sturdy root system, she says. Remember that roots need oxygen as well as water, so allow the soil to dry somewhat between waterings. Roots in waterlogged soil will rot.
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ANR Communications
Contact: L. Johnson or D. Fulbright
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-4506
East Lansing, MI 48824-1039
8/15/01
DISEASE DEVASTATING MICHIGAN OAK TREES
EAST LANSING, Mich. -- The latest new exotic tree disease to make the headlines in Michigan is similar in some ways to better known tree killers such as Dutch elm disease but in other ways quite different.
For one thing, says Dennis Fulbright, Michigan State University plant pathologist, it’s not an exotic disease, accidentally imported from Europe or Asia -- it’s a native North American disease. Like Dutch elm disease, it’s caused by a fungus that can be transmitted by insects or passed from tree to tree through root grafting. But it’s a relatively new disease in Michigan -- it’s been present in Michigan forests for only 20 to 30 years. There it actually may play a positive role in forest regeneration by clearing out large trees and making openings where smaller ones can find growing space.
Most oak wilt infections are associated with human activity, Fulbright says -- namely, construction damage to trees or the movement of infected firewood. And it is exploding into what amounts to an epidemic.
The symptoms usually appear in July.
In red oaks (recognized by their leaves, which have pointed tips), leaves turn reddish to bronze at the edges. They may wilt and curl and then drop, or they may turn dark brown and remain attached to the branches. Symptoms usually start at the top of the tree and progress uniformly downward.
"Regardless of the color of the leaves, if red oak leaves fall on your lawn in July, that’s a strong indication that it’s oak wilt," Fulbright says.
Many red oaks die within a few weeks of wilting. In the year that the tree dies, the bark often cracks and splits because of matlike fungal structures called pressure pads that form underneath it. These pads are covered with fungal spores and produce an odor that attracts insects, which may then carry the spores to other trees. Brownish streaking is usually evident in the sapwood of an infected tree showing wilt symptoms.
In white oaks (leaves have rounded lobes), leaves on infected trees generally turn from green to tan, beginning at the tip and progressing through the length of the leaf. Leaves curl and remain attached to the tree. Usually only a few branches on an infected white oak will wilt. Streaking in the sapwood is less evident in infected branches, and fungal pads and cracked bark are rarely found in white oaks.
"Problems other than oak wilt can cause the decline and death of oak trees," Fulbright points out. "Ill health in oak trees can be due to a combination of soil moisture -- too much or too little -- nutrition, weather, boring and defoliating insects, pollution, construction damage, root diseases and other factors. On the other hand, diagnosis of oak wilt in white oaks isn’t easy, so tree deaths attributed to oak decline or defoliation by gypsy moth could actually have been due to oak wilt."
Once a red oak is infected with the fungus, it dies within two to six weeks of wilting. In white oaks, wilting may kill large branches but seldom kills the tree until several years of infection have occurred.
Red oaks usually become infected through their roots. Root grafting occurs when the roots of two trees intermingle and grow together. The fungus moves from the infected tree to the uninfected one through these root connections. White oaks are more likely to be infected by spores carried by insects attracted to the odor of sap from recently pruned or otherwise damaged areas.
Controlling the insects is not a feasible way to protect trees, Fulbright notes, because the most important insect vector of the disease is the common picnic beetle, that small, hard, black, bullet-shaped beetle that gets into overripe fruit, damaged ears of sweet corn, and food at picnics, graduation open houses and other outdoor eating events.
"A better approach is to avoid pruning oak trees from April through at least the end of June," he advises. "Prune during the cold months instead. If you must prune during the warm months or if trees suffer storm or construction damage, clean up such damage immediately and spray pruning wounds with commercial pruning sealer within 24 hours to discourage insect visits to the wounds."
Other preventive measures include protecting oaks against construction damage and bark injuries from mowers, weed trimmers and other landscape equipment. Infected branches on white oaks and red oaks killed by oak wilt should be cut down and the wood removed before April 1 and sent to a sawmill or chipping facility. Oak firewood can also be a source of the fungus. (See the Extension bulletin mentioned below for information on special handling for firewood from infected trees.)
When oak wilt begins to spread through a neighborhood, it takes a community-wide approach to deal with it, Fulbright says. Though cutting down dead trees is the primary means of controlling oak wilt, it doesn’t stop transmission through root grafts, he points out. Trenching between trees to disrupt the root-to-root contact is expensive but necessary and effective in protecting red oaks. Root grafting occurs less often in white oaks, he notes. For white oaks, preventing and quickly repairing injuries is key.
For more information on oak wilt, contact your county MSU Extension office and ask for bulletin E-2764, "Oak Wilt in Michigan." The cost is 75 cents.
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
FALL CLEANUP OF HOME ORCHARD
REDUCES PEST, DISEASE CARRYOVER
EAST LANSING, Mich. -- The harvest may be the climax of the growing season, but care of the home orchard isn’t complete until you’ve carried out a fall cleanup.
"Cleaning up fallen fruits and leaves is a critical part of the pest and disease control program," says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "A fall cleanup removes many insect pests and disease organisms that would otherwise survive the winter to cause problems next year."
Though the major cleanup occurs in the fall, fruits that drop at any time during the growing season and diseased leaves should be cleaned up as soon as possible, she notes. And twigs and branches infected with fire blight should be pruned in winter. The fall cleanup is aimed at reducing the incidence of fungal diseases such as apple scab and insect pests such as apple maggot.
"A fall cleanup may not eliminate the need to use pesticides against these problems," she adds, "but it should make chemical controls more effective."
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ANR Communications
Contact: L. Johnson or R. Goldy
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or
East Lansing, MI 48824-1039
616-944-1477
8/15/01
FOR HOME-GROWN GARLIC,
TRY PLANTING IN FALL
EAST LANSING, Mich. – Were you disappointed with the garlic you planted last spring? If you planted it in a well drained soil, controlled weeds and provided plenty of water during dry weather, problems might have been due to the source of your planting stock and/or the planting time.
For best results with garlic in Michigan, plant in the fall, advises Ron Goldy, Michigan State University Extension district vegetable agent at the Southwest Michigan Research and Extension Center in Benton Harbor.
"Ideally, it should be planted about six weeks before the ground freezes," he says. "This is usually sometime in October. Garlic planted in fall produces larger yields than spring-planted crops."
For home gardeners and commercial growers, Goldy recently wrote "Producing Garlic in Michigan," Extension bulletin E-2722, which is now available at county MSU Extension county offices.
Home gardeners tempted to separate bulbs of garlic from the supermarket and plant these will likely be disappointed, he says. Bulbs sold for home use have been stored at temperatures near 32 degrees, he explains -- this causes physiological changes that reduce yield and quality.
Buy planting stock from a reputable source that can provide specific cultivars free of disease and nematodes, Goldy advises. Cultivars that have performed well in variety trials in Michigan include ‘Music’, ‘German White’ and ‘Polish Softneck’.
Quality bulbs for planting will be free of signs of mold under the skin and between the cloves, and the root plate -- the area where the roots attach to the bulb -- will not be discolored or soft. Store planting stock at 50 degrees F and no more than 60 percent humidity for best results.
Plant in any well drained soil after controlling annual and perennial weeds. Garlic is prone to the same disease and insect problems as onions, so avoid planting where onions have been grown in the past two years. Separate bulbs into cloves just before planting so they don’t dry out. If you want to produce large bulbs, plant cloves 2 to 4 inches deep and 4 inches apart in double rows 12 inches apart with 36 inches between rows. Plant with the root plate down.
"There is a direct correlation between clove size and resulting bulb size," Goldy notes. "Larger cloves produce larger bulbs."
Fertilize following soil test recommendations for pH adjustments, phosphorus and potassium. Apply nitrogen in the fall and twice in the spring before May 1 to promote vigorous vegetative growth. No more is necessary after plants begin to form bulbs, usually in mid-May.
Garlic requires 1 to 2 inches of water per week. Though garlic needs adequate moisture after bulbing, the greatest effect of water occurs when growth is most rapid -- from March to May.
Three products can be harvested from garlic: scapes, green garlic and bulbs.
Scapes are the plant part that produces the garlic "flower" in the summer. They emerge from the center of the plant in mid-June, starting out straight but curling as they get longer, then straightening out again as they mature. They should be removed sometime after they emerge but before the final straightening because maturing them takes energy away from the developing bulb and can reduce yields. They can be used like chives fresh or in cooking.
Green garlic is garlic harvested before bulbing. It looks much like green onions and can be used the same ways. Green garlic can be harvested in the spring whenever the plants are big enough to use.
Garlic bulbs are usually harvested in July, after 30 to 50 percent of the leaves have died back. Harvest during dry weather, Goldy advises, and leave the bulbs on the ground to dry for a few days to a week. Then store in mesh sacks or shallow containers in a well ventilated area to cure. For home use, store cured garlic bulbs near 32 degrees F at 65 to 70 percent humidity. For planting stock, allow bulbs to mature longer in the garden, then harvest, cure and store at no lower than 50 degrees F and 60 percent humidity.
"Achieving the right conditions for storage at home may be difficult," Goldy notes, "so home gardeners might want to figure on buying new planting stock each year rather than trying to grow and store their own."
For more information on growing garlic, contact your MSU Extension county office or the MSU Bulletin Office, 10-B Agriculture Hall, MSU, East Lansing, MI 48824-1039, and ask for bulletin E-2722. The cost is $5. (Mail orders to the bulletin office must be prepaid.)
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
‘GREEN MANURE’ MAY SOUND YUCKY
BUT BENEFITS GARDEN
EAST LANSING, Mich. -- "Green manure" has a very unappealing name, but it can do a lot for your garden.
"Green manure is a grain or grass crop planted in the fall," explains Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "It protects the soil against erosion, and it eventually adds nutrients and organic matter to the soil."
Crops such as rye are usually planted in early fall, she says. They grow enough before winter to help prevent soil erosion by wind and water. In so doing, they take up nitrogen remaining in the soil and help prevent groundwater contamination. When the crop begins growing again in the spring, it helps draw moisture out of the soil. This may make it possible to begin working the garden earlier.
You don’t have to wait until the entire garden is harvested to plant, she notes -- simply work up the soil in harvested areas and plant there.
To plant, disk or till the soil, working in compost or mulches, then broadcast the seed at a rate of about 2 pounds per 1,000 square feet. Then work the soil lightly again.
In the spring, let the cover crop grow until it’s about 12 inches tall. Then plow, disk or till it under. You can do this while the crop is green or kill it first with a herbicide such as Roundup.
If the soil is too wet to work but the cover crop is getting too tall, mow it or hand cut it before turning it under, she suggests.
As the green manure crop breaks down, it will return nutrients to the soil and add organic matter.
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ANR Communications
Contact: L. Johnson or E. Hanson
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 355-2261
East Lansing, MI 48824-1039
8/15/01
HARDY KIWIFRUIT CAN BE GROWN
IN MICHIGAN GARDENS
EAST LANSING, Mich. -- Michigan gardeners looking for an out-of-the-ordinary backyard fruit crop need look no further than hardy kiwifruit (Actinidia species). The two species most suited to Michigan growing conditions – Actinidia arguta (hardy kiwifruit or bower actinidia) and A. kolomikta (kolomikta actinidia) -- are climbing vines with ornamental as well as edible benefits in the landscape.
"Gardeners who want to grow hardy kiwis need to realize that they won’t get the big, brown, fuzzy fruit they find in the supermarket," notes Eric Hanson, Extension horticulturist at Michigan State University. "These vines produce smooth-skinned fruits about the size of grapes. However, because their sugar content is higher than that of the supermarket types, the flavor is superior."
Hardy kiwifruit is the faster growing of the two -- it can reach 20 feet in only two or three growing seasons. Male and female flowers occur on separate plants; one male plant is needed for every six to 10 females for fruit production. Fruits are ¾ inch to 1 ¼ inches long, about ¾ inch wide and greenish yellow with green flesh. Dormant plants tolerate temperatures to -25 degrees F.
Kolomikta actinidia, also a twining vine, is less vigorous (slower growing) but even more cold tolerant -- it is hardy to -45 degrees F. Its fruits are slightly smaller than those of hardy kiwifruit. The foliage emerges purplish and develops a variegated pattern that is said to be more striking in the male plants. Excess shade and fertilizer may reduce leaf coloration, Hanson notes.
For both species, a sunny but protected site is essential -- wind can severely damage vines and fruits, he explains. Though the vines are hardy, low-lying planting sites that are prone to late spring and early fall frosts should be avoided. For best results, plant in a site that provides 150 frost-free days.
Though the plants will tolerate some shade, they prefer full sun, and they need well drained, somewhat acidic soil (pH of 5 to 6.5). On poorly drained soils, plant in raised beds, Hanson suggests. The vines are heavy water users, so plan on watering regularly during hot weather.
Vines need a trellis or sturdy fence to climb on and require pruning in the winter.
The plants are relatively free of diseases and insect pests.
Hardy kiwifruit is one of a baker’s dozen unusual fruits for Michigan described in a recently published Extension bulletin, "Unusual Fruit Plants for Gardens in the North Central Region" (bulletin E-2747), developed by Hanson and Steve Berkheimer, MSU Department of Horticulture. Others include gooseberries, currants, pawpaws and thimbleberries. The publication is available for $2.25 from county MSU Extension offices and the MSU Bulletin Office, 10-B Agriculture Hall, MSU, East Lansing, MI 48824-1039. Call 517-355-0240 for ordering information.
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ANR Communications
Contact: L. Johnson or M. Koelling
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 355-0096
East Lansing, MI 48824-1039
8/15/01
LANDSCAPE TREES
MAY NEED FERTILIZATION
EAST LANSING, Mich. -- Do the trees in your yard have pale green or off-color leaves that are smaller than usual, dead twigs at the ends of branches, and a general lack of growth and vigor? These are often symptoms that trees need fertilization, says Mel Koelling, Extension forestry specialist at Michigan State University.
Like lawns, vegetable crops and flowers, landscape trees depend on sunlight, water and certain nutrients from the soil for good growth, he observes. Poor soil fertility can also stress trees and make them more susceptible to insect attack, disease and other environmental problems.
The best time to fertilize trees is in the fall, he says, after the growing season. Root growth continues into early December or even later, if weather permits. Fertilizing in early September makes nutrients available for that fall root growth.
You can also fertilize in the spring as soon as the soil is free of frost, he notes. Nutrients applied then benefit early spring root growth, which begins well before leaves appear.
"Midsummer fertilization is usually reserved for trees that are recovering from defoliation or some other injury," he says. "It’s usually best to avoid fertilizing in late summer -- this can cause flushes of new growth that may be damaged by cold winter temperatures."
For homeowners, spreading fertilizer on the soil surface or applying dry or liquid fertilizer by way of holes in the tree’s root zone is usually recommended. Surface application can be tricky, he points out, because enough nitrogen to meet the tree’s needs may be too much for the surrounding grass. Dividing the total application into three applications to be made at two-week intervals is one way to protect the lawn. Another is to select a non-burning form of nitrogen such as urea formaldehyde, which can be applied all at once.
Applying the fertilizer into holes throughout the tree’s root zone requires a soil auger and some measuring to distribute holes evenly in concentric circles beginning about 3 feet from the trunk and extending outward past the edge of the crown. The rate for nitrogen is 6 pounds of actual nitrogen per 1,000 square feet. To figure out how much to put in each hole, divide the amount needed by the number of holes. Holes should be 1½ to 2 inches in diameter and 12 to 18 inches deep. After adding the fertilizer, fill the holes with peat or some other organic material, Koelling suggests.
For assistance in identifying tree problems and doing fertilizer calculations, contact your county MSU Extension office.
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
SUMMER GROWTH MAY MEAN
HOUSEPLANTS NEED REPOTTING
EAST LANSING, Mich. -- Because plants need light to grow and the short days of winter don’t provide much, houseplants generally do most of their growing in the summer. This makes fall a good time to check to see if they’ve outgrown their pots.
"A common sign that plants need repotting is soil that dries out very quickly," says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University.
Other indications are soil that seems to be more roots than soil and roots coming out of the drainage hole.
To find out for sure, water the plant, let it drain for a while, and then tip it out of its pot and examine the roots, she suggests. To ease the plant out of its pot, tip the container on its side and rap the rim against a tabletop or bench to loosen the soil ball.
"Soil covered with a thick, tightly matted mass of roots means that the plant needs repotting into a bigger container," McLellan says. "If very few roots are showing and those that you do find are black, soft, slimy or otherwise unhealthy-looking, the plant has problems."
Rotten roots are usually related to overwatering. This can be related to the size of the container, the frequency of watering or the absence of a drainage hole in the container.
"Plant roots need air as well as water," she points out. "Plant roots that sit in saturated soil for long periods of time tend to rot and die."
To repot healthy plants, use a container no more than 1 to 2 inches larger in diameter than the previous one. Avoid planting into a greatly oversized container, McLellan advises -- oversized pots often result in plants being overwatered. If the only choice is a slightly undersized pot or an overlarge one, she recommends using the smaller one.
If the main reason for repotting is to counterbalance the weight of top growth that is making a small pot tippy, the pot that looks proportional to the top of the plant may be too big for the roots. A solution is to repot the plant in a smaller container and set it inside the larger one.
"This is a good approach when you want to use a decorative container but it doesn’t have a drainage hole," she notes. "Pot the plant in a container with a drainage hole and set that on a layer of gravel inside the other."
To repot, start with a clean container. Add a few pebbles or shards of broken clay pot to keep soil from washing out the drainage hole, if you like. Then add a little potting soil and set the plant in the new container and fill in around the root ball. Water to settle the potting mix and add more, if necessary. For room to water without overflowing the pot, make sure the soil surface is ½ inch or so below the rim.
"Most of the problems that people have with houseplants in the winter are related to watering," McLellan observes. "Potting plants only in containers with drainage holes and making sure the soil around the roots is dry before you water will go a long way toward keeping plants healthy over the winter."
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ANR Communications
Contact: L. Johnson or E. Jenkins
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-4494
East Lansing, MI 48824-1039
8/15/01
USE CARE WHEN CHOOSING
PEST CONTROL COMPANY
EAST LANSING, Mich. -- You think you may have a pest problem that requires treatment by a pest control company. The telephone book lists dozens -- how do you choose?
"Take the same time and care in choosing a pest control company as you would a doctor or auto mechanic," advises Erica Jenkins, specialist in the Michigan State University Pesticide Education Program. "Even if you discover a potentially serious problem, such as carpenter ants or termites, you can take time to check out references, investigate a company’s record and learn more about the pest so you can be an educated consumer of pest control services."
She suggests asking friends, neighbors and co-workers for recommendations and interviewing more than one company. It’s also a good idea to have the pest identified and learn as much about it as you can before you talk to pest control company representatives. Your county MSU Extension office can help with pest identification.
Beware of companies that do not have a listed or working telephone number, Jenkins cautions, and those that try to pressure you into immediately signing a contract, especially one that calls for repeated treatments. Beware, also, of companies that claim to be endorsed by the Michigan Department of Agriculture or any other government agency.
"Professional pest control technicians should be well trained in using many pest control methods," she says, "and should be willing and able to answer questions about any pests they find, the consequences of having those pests in the home, and control options including but not limited to use of pesticides. A person who sprays and leaves quickly without discussing control options may use more pesticides than necessary."
All pest control companies applying pesticides for hire must be licensed by the MDA, have liability insurance to protect you in case of an accident, and have state-certified or registered pesticide applicators, Jenkins says. They are also required to display the company name and either a phone number, address or U.S. Department of Transportation census number on the company vehicle.
Companies must provide you with pesticide product labels and material safety data sheets, if you request them. If they apply pesticides, the companies must provide you the following written information: the name, address and telephone number of the company; the full name of the pesticide applicator performing the service; a general description of the problem pest; a list of the pesticides applied; the time, date and rate of pesticide application; and information on the potential hazards of the pesticide application to people, pets and the environment.
"When interviewing a pest control company representative, ask for references," Jenkins suggests. "A reputable company should be happy to supply them. You can also call the MDA, the state attorney-general’s office and the Better Business Bureau to see if any complaints have been lodged against the company."
For a bulletin listing questions to ask before hiring a pest control company, contact your county MSU Extension office and ask for bulletin E-2760, "Choosing a Pest Control Company." A similar bulletin provides guidelines for choosing a lawn care company (E-2771). Single copies are free to Michigan residents.
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
WHEN DO YOU HARVEST ONIONS?
LET THEM TELL YOU!
EAST LANSING, Mich. -- There’s nothing tricky about determining when to harvest onions -- just let the onions tell you!
Onions for storage are ready to harvest when half of the tops start to dry out and fall over on the soil, says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University.
If you have a spading fork, use it to loosen the soil around and under the bulbs. Then it’s easy to pull them by hand. In dry weather, leave them in the garden for a few hours so wind and sun can dry them. If the weather is damp and threatening or the soil is wet, remove them immediately to a garage, carport or other dry, well ventilated area and spread them out to dry for several days.
When all the tops are dry and brown, the onions are ready for storage.
"Any onions that still have thick necks still contain green, moist tissue and won’t keep in storage," she notes. "Keep these separate and use them first. If they go into storage with the rest, they will rot and may ruin the others."
Store only undamaged bulbs. Use those with nicks or soft spots at once, or chop and freeze them. They, too, will rot and cause problems in storage.
Store onions in slatted baskets or boxes or mesh bags in a dark, dry, cool place where they won’t freeze. Inspect them occasionally and discard any soft, moldy or rotten ones as soon as you find them.
"If you planted a storage variety such as Stuttgarter or Spartan Sleeper, cure them properly and provide adequate storage conditions, you should still be enjoying onions from your garden when it’s time to plant next year’s crop," she says.
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ANR Communications
Contact: L. Johnson or M. McLellan
MICHIGAN STATE UNIVERSITY Telephone: 517-432-1555 or 353-3774
East Lansing, MI 48824-1039
8/15/01
WINTER CONDITIONS
CAN DAMAGE PLANTS
EAST LANSING, Mich. -- Like it or not, the shortening days signal that fall is here and winter is coming. Soon gardeners will put their tools away and retreat indoors to await the coming of next year’s seed catalogs.
Landscape ornamentals, however, have to stay out there and take whatever winter throws at them, be it low temperatures, snow, ice, drying wind, gnawing rodents or deicing salt.
"You can’t do much about the weather, but you can reduce the chances of winter injury to plants," says Mary McLellan, Extension Master Gardener program coordinator at Michigan State University. "The first step is choosing plants that are hardy in your area -- that is, plants that have shown they can survive the average low temperature there. A second is to maintain plants properly. Make sure evergreens go into winter well watered, for instance, and that ornamentals aren’t stressed during the growing season by drought, overwatering, poor nutrition, mechanical injury and insect attack."
Plants that are healthy and dormant when winter weather arrives have a better chance of coming through winter in good shape, she adds. This means no late-season fertilization or avoidable late summer pruning that might promote a flush of late growth that wouldn’t have time to harden off before winter.
Sometimes cold temperatures kill only certain parts of a plant, she observes. Flower buds are often the most susceptible. Forsythia shrubs, for instance, will tolerate temperatures of –25 degrees F but will lose the flower buds on exposed stems. Buds protected by an insulating layer of snow will survive.
Smooth-barked trees such as young maples may suffer bark splitting. This injury, called southwest disease, even though it isn’t a disease, occurs when the winter sun heats the tree on the southwest side. After the sun sets, the outer bark cools faster than the tissues beneath it. As it cools, it contracts, and when it can’t contract any more, it splits. This injury usually occurs on the south or west sides of trees, McLellan notes, because that’s where the sun strikes them. To protect young maples and fruit trees and other thin-barked trees, wrap them with tree wrap or shade them on the south and west sides.
Desiccation, or drying out, is a common problem of evergreen plants, particularly broadleaf evergreens. It occurs when winter sun and dry wind extract moisture from the needles or leaves when the soil is frozen and roots can not replace it, McLellan explains. Shielding exposed plants with burlap or canvas fastened to stakes will protect them. Regular watering until the soil freezes and mulching to prevent deep freezing of the soil are also recommended.
Gnawing mice and rabbits can girdle and kill landscape plants. McLellan advises placing cylinders of ¼-inch-mesh hardware cloth around plants. The barrier must reach from a few inches into the soil to at least 18 inches above the usual snow line to keep rodents away from tree trunks and stems. Repellents may give some protection, she notes, but they may need to be reapplied in midwinter, and they may not be effective if other food sources are scarce.
Landscape plants near busy streets may need protection against deicing salt. Both salt spray and salty runoff may injure plants, she points out. Some plants -- such as white pine, oaks and sugar maple -- are more sensitive than others and shouldn’t be planted where they’ll be exposed to deicing salt. For plants already in place, splash guards of burlap or canvas will keep spray off foliage. Shoveling salt-laden snow away from plants and watering heavily in the spring to move accumulated salt out of the root zone will help prevent root damage.
Heavy loads of ice and snow can break limbs from trees and bend shrubs and young trees to the ground, McLellan observes. Quick-growing, soft-wooded trees such as Siberian elm, willow and silver maple are especially prone to breakage. Bending under a load of snow or ice can damage the water-conducting vessels in trees and shrubs, she notes. Plants may die the following growing season, long after the winter storm is forgotten.
"Pruning trees when they’re young to eliminate weak, V-shaped angles of attachment between branches or limbs and trunks will help prevent breakage," McLellan says. "Right-angle or U-shaped attachments are much stronger and less likely to break."
Shrubs and hedges that could be crushed by a load of snow can be wrapped with canvas or burlap and tied so they have less surface area to hold snow, or supported by chicken wire and stakes so snow and ice can’t flatten them.
When ice storms strike, trying to remove the ice can do more damage than leaving plants alone, McLellan notes. Supporting drooping branches may keep them from breaking or at least change the breaking point from the place of attachment to the trunk to the place where the branch rests on the prop. This may prevent major damage to the trunk from large branches tearing off the bark as they fall, she explains.
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