Extension Summer08 Garden Packet-2
Published: May. 28, 2008
NOTE TO EDITORS: This is the second of three installments of University of Illinois Extension's Summer Garden Packet. The final installment will be sent May 30. Thanks. Bob Sampson, Extension Communications Specialist.
May 28, 2008
Source: Martha Smith (309) 836-2363 Contact: Bob Sampson (217) 244-0225 Extension Communications Specialist e-mail: rsampson@uiuc.edu
Pesticide Shelf Life
The shelf life of pesticides is a frequent topic of concern for gardeners, said a University of Illinois Extension horticulture educator.
"'How long is a pesticide good for, and how long should I keep a pesticide?' These are questions I hear quite a bit," said Martha Smith. "Pesticides in general are manufactured, formulated, and packaged to specific standards. However, when stored improperly, they can break down, especially under conditions of high temperature and humidity.
"Dry formulas such as wettable powders (WP) or granular (G) can become caked and compacted. Emulsifiable concentrates (EC) can lose their ability to form emulsions. Some pesticides can actually become more toxic, flammable, or explosive as they break down."
Pesticide formulations that contain low concentrations of active ingredients generally lose effectiveness faster than more concentrated forms. Sometimes a liquid pesticide develops a gas as it deteriorates, making opening and handling containers quite hazardous.
"Certain pesticides have a characteristic odor," she noted. "A strong odor in the storage area may indicate a leak, spill, or improperly sealed container. It may also be a clue that the pesticide is deteriorating because the smell of some chemicals intensifies as they break down.
"If none of these problems are found, chemical odors can be reduced with exhaust fans or by lowering the temperature of the storage area."
Pesticide containers, including fiber and metal drums, pails, cans, bottles, bags, boxes, over packs, and liners, have an important effect on storage and shelf life. If stored for long periods, these containers may eventually corrode, crack, break, tear, or fail to seal properly. The label may become illegible as well.
"If stored in a cool, dry area that is out of direct sunlight, pesticides will generally have an extended shelf life," Smith said. "Protection from temperature extremes is important because heat or cold can shorten a pesticide's shelf life.
"At temperatures below freezing, some liquid formulations separate into their various components and lose their effectiveness. High temperatures cause many pesticides to volatize or break down more rapidly. Extreme heat may also cause glass bottles to break or explode."
One way to ensure avoidance of shelf life or storage problems is to only buy what is needed for one season.
"So many times we buy the sale item because it is a 'deal,'" said Smith. "What we find out is that we only needed a small portion, and now we have to store the leftover chemical."
Before storing chemicals, read the label and follow any specific guidelines listed. Store different groups of pesticides, such as herbicides, insecticides, and fungicides in separate locations within a storage area to prevent cross-contamination from fumes andvapors, as well as accidental use of the wrong type of pesticide.
"Never store chemicals near any type of animal feed," Smith said. "Always store chemicals out of the reach of children, preferably in a locked cabinet."
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May 28, 2008
Source: Richard Hentschel (630) 685-2317 Contact: Bob Sampson Extension Communications Specialist Phone (217) 244-0225; rsampson@uiuc.edu
Home Landscape Pruning
The word "pruning" actually means to cut in layers, and that is what we should all think about when pruning shrubs, said a University of Illinois Extension horticulture specialist.
"We prune to make selective cuts, to maintain the natural form of a plant by preventing overgrowth, rubbing branches, and to direct future growth," said Richard Hentschel. "Over-grown plants become straggly, no longer accenting the landscape and our homes.
"Rather than just cutting the limb off to get it out of the way, cuts should be made to remove the branches without leaving a stub or disfiguring the plant."
Pruning can either promote or restrict growth. Proper pruning can create a shrub with its greatest potential for flowering and a full canopy of foliage.
"Maintenance pruning is a yearly trimming to remove old, heavy wood and shaping the remaining new wood," he noted. "A little pruning every year takes a lot less time than having to go in and try to recover a plant that has not been pruned in several growing seasons.
"This kind of pruning is also called renewal pruning--you renew the plant over time, never losing the bulk or flower show."
Good examples of this approach would be red twig dogwood and lilacs. By removing the older branches you promote the bright red twigs on dogwood and better flowering on the lilac. Another good tip is to snip off the spent blooms on the lilac back to the first leaves below the flower for a better-looking plant the rest of the summer.
Rejuvenation pruning can bring back a troubled plant that is unmanageable using other kinds of pruning. Once rejuvenated, you can do renewal pruning to keep the shrub looking its best. This kind of pruning is most often done in late fall after the plant is dormant for the winter or in early spring before growth resumes. Most pruning books list the best way and time to prune.
To rejuvenate a suitable shrub, remove ALL growth, leaving about a 1-1/2 inch stem showing above the ground.
"Many home gardeners get confused as to the best time to prune for fear of pruning off flower buds, and, as a result, never prune at all," Hentschel said. "Typically, if the plant blooms in the early spring, prune it soon after the bloom show is complete. That leaves the remaining season for the shrub to create blooms for next year.
"If you prune too late in the year, you will be removing flower buds for the coming season. If you look at the buds on a viburnum or lilac in the fall, for example, you will see a big bud at the tip of the branch that is the flower for next year."
For shrubs that bloom later in the spring or summer, pruning in early spring still leaves the possibility for a bloom show. Spireas are a good example of this type of shrub.
"There are always exceptions to the rule, and you should check the pruning book to be sure of the best time to prune," he noted.
If there is a need to slow down a shrub's growth, then a "summer pruning" may be in order. By removing some of the foliage that is supplying the food for the plant, next year's growth should be less. Don't get carried away as you can put your shrub into shock.
"Directional pruning is another term you will see and read about in pruning books," he said. "This technique allows the person pruning to direct the new growth from the shrub. By pruning just above the bud or smaller side branch, the new growth will occur in the direction of that bud or side branch."
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Source: Richard Hentschel (630) 685-2317 Contact: Bob Sampson Extension Communications Specialist Phone (217) 244-0225; rsampson@uiuc.edu
Tools for Pruning
Having the right pruning tools makes the task of pruning the myriad of plants in a home landscape a lot easier and more enjoyable, said a University of Illinois Extension horticulture specialist.
"The adage 'you get what you pay for' really is true when it comes to pruning tools," said Richard Hentschel. "Good pruning tools and saws will last many years."
Pruners and saws come in a wide range of sizes, and each one is designed for a specific use. Hand pruners are good for the smaller branches that can easily be cut using just one hand.
"If you have to use both hands, you are exceeding the limits of the pruner and are likely to spring or bend critical cutting parts, not to mention damage to your wrists and hands," he said. "You may get the branch cut, but now the pruners won't cleanly prune the smaller branches anymore."
The next range of pruners allows you to tackle the larger limbs and branches which are too big for hand pruners. These are often called long-handled pruners or loppers. The pruning heads are larger, allowing the branch to sit farther into the cutting section of the pruner.
"The longer handles give you the needed leverage to cut the branch using both hands and your upper arm and chest muscles," he said. "The longer the handle, the more leverage you will have."
Hentschel said there are also compound long-handled pruners available to the gardener. This style of pruner provides additional force for cutting the larger limbs through a 'compound leverage mechanism.' Gardeners can prune smaller limbs with less effort and can prune larger limbs than possible with normal long-handled pruners.
"Gardeners will also find two kinds of pruning heads available," he noted. "All pruners have a cutting side and an anvil side. Bypass pruners are so named because the cutting blade 'passes by' the anvil side. With the anvil type, the cutting side comes into contact with the anvil side.
"Both styles have benefits. Anvil-type pruners are often associated with pruning younger, tender new growth, while bypass pruners are good for making cuts on older, larger wood."
In either case, he added, when using regular or compound pruners, bypass or anvil types, if you have to use more strength than you have to prune a branch, it is time for the pruning saws.
Pruning saws come in a variety of shapes and sizes. Folding saws are very convenient to carry, use, and store. Most are straight blades, but you can buy curved-blade folding saws.
"By being able to fold the blade away, you get to keep the blade sharper longer," he said. "Unique to pruning saws is their ability to cut through green and dead branches alike.
"Pruning saws have a 'cleaning tooth' that removes the sawdust and a wider 'saw-tooth set' prevents the saw from binding. The common woodworking saw will bind up if you try to cut a green branch."
Straight-bladed saws cut in both directions, while curved blade saws cut on the pulling stroke for the most part.
"The larger saws may be more difficult to use and need to be protected when not in use so the blades remain sharp," said Hentschel.
For pruning cuts too high to reach from the ground or standing on a stable ladder, a pole saw may be what you need. These are most often available as a curved blade on an expandable handle, allowing cuts many feet in the air in the canopies of larger trees.
"These are also available with a combo head, with a pruning head on one side, and the saw on the other," he said. "Be sure the saw blade can be removed easily as it has a tendency to get in the way if you are using the pruner head most of the time.
"A sawhead-only unit may be more valuable in the long run as the pruning portion can get in the way of making a clean saw cut. You can always saw off the smaller branches that you would have used the pole pruner portion for."
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Source: David Robson (217) 782-6515 Contact: Bob Sampson (217) 244-0225 Extension Communications Specialist e-mail: rsampson@uiuc.edu
Galls on Leaves
Bumps or galls are being spotted on leaves, twigs, roots, and flowers of many plants, said a University of Illinois Extension horticulture educator.
"Plant galls often appear as balls, knobs, lumps, or warts of various shapes, sizes, and colors," explained David Robson. "Galls develop from plant tissues that have been irritated and/or stimulated by a parasitic organism. The growth is similar to a cancer-like growth, with cells rapidly developing in a variety of shapes or forms.
"Galls are believed to be caused by powerful plant-growth regulating chemicals produced by the parasite. If the parasite leaves the host or dies, normal cells are again produced."
Aphids, midges, wasps, or mites cause about 95 percent of the known types of galls. Bacteria, fungi, and viruses cause the remaining 5 percent.
"One of the most common galls in central Illinois is the maple bladder gall," he said. "The small, wart-like growth can easily be spotted on silver (soft) maple. Galls are first green, then turn red, and, finally, black."
Hackberry leaf gall forms a tiny nipple on the upper surface of hackberry leaves. So common is this gall that many people believe it is a natural part of hackberry leaves. The gall is first green and then turns purplish brown.
"A dozen different galls can be found on oak and hickory trees," Robson said. "Hickory galls are usually caused by aphids, while oak galls are caused by wasps. Although the galls are common and easy to see, they are seldom important enough to control.
"However, there are times when galls can be serious problems, but this is on stems and twigs rather than leaves."
Gouty and horned oak galls occur on the branches of pin and shingle oaks, as well as a few others, though you seldom find the galls on white oaks and bur oaks.
"These galls do start out as leaf galls, but a secondary stage starts to invade the twigs and limbs," he said. "When that happens, knobs develop that can be smooth (gouty) or knotted. As the gall grows, it girdles the end of the branches which can cause severe dieback to the trees.
"Unfortunately, there is no easy control of the gouty or horned oak galls."
Hand pruning is needed but may be impractical due to the quantity and size of trees.
"Improving the overall health of the tree is critical with regular fertilizing and watering," he said. "In severe cases, the galls may weaken the trees to the point where it's better to remove the tree. Raking up leaves in the fall and composting--or burning where allowed--might reduce the populations somewhat."
Robson noted that the other general insect- and mite-produced galls disfigure twigs and foliage but rarely seriously affect the health and vigor of the host plant. Once gall formations become noticeable, the insect or mite causing the injury is protected from chemical sprays. It is too late to exercise any control other than removing the infested part.
"Hand removal is only practical when there are few galls present," he said. "Chemical sprays are seldom warranted where gall infestations are light.
"Plants with heavy infestation or those that are tremendously unsightly to homeowners can be treated. Spray treatments can be used to prevent future gall formation but must be correctly timed to eradicate the pest once it emerges and before it has had time to induce the gall."
Sprays applied after galls are formed are ineffective, he noted.
"Some gall-producing insect populations can be reduced with a dormant oil spray applied to trunk and branches in the early spring, just before buds open," Robson said. "Some insecticides will control gall formation on elm, hickory, and maple leaves when thoroughly applied to foliage as buds are unfolding.
"Contact your local Extension unit office for the current recommended controls. Make sure to read and follow label directions when applying any chemical. To control most galls, foliage should be thoroughly sprayed before the leaves are fully expanded. It is nearly impossible to treat large established trees. This is mainly an aesthetic problem."
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May 28, 2008
Source: Ron Wolford (773) 233-0476 Contact: Bob Sampson (217) 244-0225 Extension Communications Specialist e-mail: rsampson@uiuc.edu
Moisture and Mulches
Moisture and mulches are important topics to keep in mind when tending a summer garden, said a University of Illinois Extension horticulture educator.
"Think about using organic mulches in the vegetable garden," said Ron Wolford. "Mulches help to hold moisture in the soil and reduce weeds. Organic mulches include compost, shredded bark, leaves, pine needles, cocoa bean hulls, and dried grass.
"Avoid using grass clippings that have been treated with pesticides."
As the organic mulch decays, it adds nutrients to the soil and helps to improve soil structure and drainage.
"Apply a two- to three-inch layer of mulch around plants," he said. "Another application of mulch may need to be added later in the season. Dig mulch into the soil at the end of the growing season."
Wolford recommended using a rain barrel to collect rainwater for use in the garden.
"Rain barrels collect water from downspouts on homes instead of having the water flow into sewer systems," he said. "A one-half inch rainfall will fill a 50- to 55-gallon barrel.
"Water your trees, shrubs, flowers, vegetables, and houseplants with the collected water. One inch of rain over 1,000 square feet of area yields 623 gallons. Rainfall at the rate of one inch per hour will yield about 10 gallons per minute per 1,000 feet."
Vegetables should be watered with the equivalent of one inch of water per week. Watering deeply--eight to 10 inches--will promote deep root development. This will help vegetables tolerate drought periods.
Fertilizer applied around vegetables needs to be dug into the soil. Applying fertilizer to dry soil can cause fertilizer burn. Water the fertilized vegetables.
"Vegetables need on average an inch of moisture per week," Wolford said. "Place a few straight-sided containers in the garden when watering with an overhead sprinkler. An inch of water in the containers is an indication your garden has received the inch it needs."
Apply a two to four-inch layer of organic mulch around trees and shrubs. Mulch the area under the tree to its drip line.
"The drip line is the circle that could be drawn on the soil around a tree directly under the tips of its outermost branches," he explained. "Keep the mulch four to six inches away from the base of the tree or shrub to prevent rot.
"As the mulch decomposes, it can be dug into the soil, thereby adding nutrients to the soil and improving soil structure."
Lawns need about 1-1/2 inches of water per week to maintain a green color. Homeowners should decide whether or not to let the lawn go dormant during hot, dry summer weather.
"Do not let the lawn go dormant and then start watering again to 'green' it up," he cautioned. "This practice uses large amounts of the grass's food reserves."
Lawns should be watered early in the day and not between 10 a.m. and 3 p.m.
"This is the hottest part of the day and you will lose 50 percent of the water applied," he said. "Evening watering increases the chance of disease problems."
During the summer when grass growth slows, the lawn should be mowed at a three-inch height. Lawns mowed at a higher height during the summer will have fewer weed problems and deeper roots.
"Mowing too close just invites weeds," he said. "Don't mow the grass when it is wet and never remove more than one-third of the grass leaf in any one cutting.
"If you mow your lawn on a regular basis, you do not need to collect the clippings. Clippings are 75 to 80 percent water and will decompose down into the lawn. Clippings have some nitrogen content, so less fertilizer is necessary."
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Source: Ron Wolford (773) 233-0476 Contact: Bob Sampson (217) 244-0225 Extension Communications Specialist e-mail: rsampson@uiuc.edu
Pest Problems
A variety of pest and disease problems can challenge the home gardener during the summer, said a University of Illinois Extension horticulture educator.
"Here are some tips for dealing with some of the common problems in gardens and lawns," said Ron Wolford.
During July, be on the lookout for grubs hatching in the lawn.
"It takes about eight to 12 grubs per square foot to cause browning of grass," he said. "Browning occurs in August and September. Patches of brown grass that can be pulled up like a rug have most likely been damaged by root-eating grubs.
"Control grubs as they hatch. Use insecticides like Grub X or Merit. Read and follow all label directions. Apply in early July and water in. Remember, if there is a lack of rain during the egg-laying period, and if you water your lawn and your neighbor doesn't, the adult beetle will lay more eggs in your nice, soft, moist soil. So you might think about reducing your watering during egg-laying time."
August through September is the best time to repair lawns. Seeding bare spots in the lawn during the time will allow the new growth to have enough time to germinate, grow, and harden off before cold temperatures arrive.
"There is less competition from weeds in the fall because a lot of the annual weeds are dying out," he said. "Plus, we are usually blessed with cool temperatures in the fall, which is great for growing grass.
"Ideally, dig the soil to at least six to eight inches deep, spread grass seed over the area, and tamp it down. Keep the soil moist until germination. Cover with weed-free straw to conserve moisture."
If you are laying down sod, water the new sod several times a day for one to two weeks until it begins to knit or take hold. Be sure that the water goes down through the thick sod and moistens the soil underneath for good root development. Do not let sod dry out.
"Reduce favorable breeding sites for mosquitoes that cause West Nile Virus," he said. "Keep your gutters free of debris because clogged roof gutters make great breeding sites.
"Clean and freshen pet dishes, wading pools, and birdbaths. Cut back tall weeds and grass because they can be hiding places for mosquitoes during the day. More information on preventing West Nile Virus can be found at (http://www.urbanext.uiuc.edu/westnile/prevention.html), a service of U of I Extension."
Also keep a lookout for the emerald ash borer. The adult borer is a one-half-inch-long, emerald-green, bullet-shaped beetle. In July and July, look for the beetle on the leaves and trunks of ash trees. Female beetles will lay eggs. The eggs will hatch in two weeks and larvae will bore through the bark into the cambium.
The larvae will feed for a few weeks and disable the tree's ability to uptake food and water. Initial symptoms will include dieback at the top of the tree. The tree will usually die within two years. For more information on the disease, go to (http://web.extension.uiuc.edu/cook/blogs/eb104/index.html), another service of U of I Extension.
"When August arrives, it is the yellow jacket season," Wolford said. "Yellow jackets are responsible for one-half of all human insect stings. They will also sting more than once. They are often confused with honeybees.
"Yellow jackets have very little hair and have bright yellow and black stripes while honeybees are covered with pale, fuzzy, yellow hairs and do not have sharply defined stripes. Encounters between humans and yellow jackets most often occur around food."
Open cans of pop or open garbage cans attract yellow jackets, as do perfumes and bright clothing.
Chemical controls should be avoided because yellow jackets are a beneficial insect.
"They help to pollinate plants," Wolford said. "Instead of chemicals, keep pop and garbage cans covered with lids. Keep rotting fruit under trees cleaned up and avoid wearing brightly colored clothes.
"Above all, do not try to swat them away with your hands and arms. They will only sting if they are disturbed."
Summer is also time to start the annual watch for the dreaded Japanese beetle. These one-half-inch-long, shiny, green-headed beetles love roses and over 3,000 other plants. They are usually most active during the warmest part of the day from 10 a.m. to 3 p.m.
"The beetle will skeletonize leaves in a short period of time," he said. "Advertised Japanese beetle traps are not recommended. These may actually attract more beetles and increase plant damage.
"The insecticide Sevin will offer some control, but use should be limited since Sevin will kill bees. Read and follow all label directions. An alternative control is to pick them off by hand and drop them into soapy water."
Powdery mildew arrives in August. This is a very common problem, especially during wet summers and at the end of the growing season.
"Powdery mildew leaves white spots on leaves, shoots, buds, and stems," he said. "It really doesn't harm the plant, but it doesn't look good.
"To avoid mildew, space plants properly for good air circulation. Try to avoid wetting the foliage when watering because that can help to spread the disease. Buy varieties of plants that are resistant to mildew."
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