Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
September 30, 2009
We had a tremendous buildup in the populations of soybean aphids just before the soybeans started maturing. What does this have to do with horticulture? When the population builds to a large level, or the food source runs out, the aphids grow wings to look for another location. In our case, both of these events occurred at about the same time. This might explain some of the clouds of "gnats" people have been asking about. Well, they aren't gnats, but soybean aphids in many instances. There are some fungus gnats, some other insects such as the insidious flower bugs or minute pirate bugs, but most of the clouds are soybean aphids.
With the build-up in aphid populations, comes a build-up in predator populations. Just think back to high school biology and the rabbits and coyotes graph. Remember the coyotes lag the rabbits by a while. What this means is a build-up in populations of aphid predators for us. Natural aphid controls include lady bugs, syrphid flies, parasitic wasps, and diseases. The end result is a monumental build-up in populations of these natural controls, and it is already underway. It stands to reason if we had over 1000 of these aphids on each soybean plant, it will take quite a few predators to try and control all of them. And if you have a soybean field close, you will probably have more aphids and predators.
The populations of the predators will then put them in the nuisance pest category, since you won't be able to open a door without admitting some of them. If they become too much problem in the house, you can do a quick spray with an aerosol for flying insects. The vacuum cleaner also remains a great way to pick up a few unwanted visitors in the home. As for the aphids, about the only potential problem from them is on garden beans still going. Most pesticides, including, malathion, bifenthrin, permethrin, insecticidal soap, will control aphids.
September 30, 2009
This week really makes it seem like fall, and one of the favorite fall decorations is the pumpkin. It's been a challenging year with many of the diseases common in a wet season, and having a cool year also. Following are some of the cardinal rules for selecting and keeping pumpkins:
September 23, 2009
Spring bulbs may be planted through October. When purchasing bulbs, the bigger the bulb the more expense, but the greater the flower bloom size. Daffodil bulbs sometimes have two bulbs together. Double bulbs may be pulled apart before planting. Spring flowering bulbs generally need well drained soil, and do best under deciduous trees. They will be rather short-lived under evergreens. Large bulbs, such as tulips and daffodils, should be planted six to eight inches deep. Small bulbs are planted about four inches deep. The rule of thumb is to plant bulbs at a depth equal to two to three times the height of the bulb. Plant the bulb with the point up. It is a good idea to map the location, or place a colored golf tee above the bulb. Then mulch with three to four inches of mulch, and water thoroughly after planting.
Check out the Bulbs and More Website at http://urbanext.illinois.edu/bulbs/ for in-depth information.
September 23, 2009
When the entire tree looks like it is dying, the injury, disease, or insect logically must be affecting the trunk or the roots. These areas would cut off the water supply to the entire tree. Look at the entire tree and compare it to nearby trees. Also consider when the problem started and what changed on the site about that same time. Healthy trees don't suddenly die because they are old. Many below ground reasons may cause tree decline. Drought, flooding, compaction of the root zone, poor soils, planting too deeply, inadequate space for roots and many other things could be involved. Often, diagnosing such a problem is a process of elimination. One of the possibilities more difficult to eliminate is root rot. Most gardeners believe that they cannot possibly know the health of a mature tree's roots.
Cankers on the stems, stem tip dieback, off-color foliage, early fall color and early defoliation are also clues that a tree may be stressed by underground causes. To detect the wood rots and root rots, look for mushroom-like fungi growing at the base of the tree or shrub. In wood rot fungi, the conks (also called shelf fungi or fruiting bodies) may be found growing on the trunk or main branches. These are signs of the disease. The actual fungus is probably growing in or on the roots, or inside the wood. One of the most common examples is Ganoderma root rot, which produces a shelf type of fungal structure at the base of many trees, especially honeylocust. The structure is reddish-brown and appears to have been varnished. Its presence indicates invasion by a root rot. Other fungi may indicate wood rots. Wet weather often triggers the formation of these structures. They could easily be confused with fungi growing on dead organic debris near a tree. If, however, they are growing from the tree itself, they are excellent signs of wood rot or root rot.
No chemicals help a tree in decline. Use approved cultural practices, such as proper watering and fertilizing to improve vitality. Cut out dead branches in the dormant season, fertilize in late fall or early spring and keep traffic off the root system. For very old or large trees, fertilization and watering may have no benefit, but these practices sometimes help the tree survive for years.
September 16, 2009
With fall seeming to arrive early, there are several things that could occupy your time. Let's start with grass seedings. A week ago would have probably been better for seeding new grass, but what difference does a few days make? Maybe no difference, and maybe a big one. If you are still interested in trying to get some new grass seed put down, don't delay too long. You will need up to four weeks to get bluegrass germinated, and then an additional period of time to get it sufficiently mature before things freeze up this fall. Figure about four pounds of a blend of Kentucky bluegrass, fine fescue (red or chewings), and perennial ryegrass per 1000 square feet of area for bare ground. If overseeding, cut the rate in half. Go easy with fertilizer if you aren't tilling it in ahead of time, since the salt content of the fertilizer may affect the small grass seeds. The same time frame for grass seedings would also apply to operations such as dethatching and core aeration.
With skyrocketing populations of soybean aphids, we will have a corresponding increase in the numbers of predators of aphids. This means lady bugs, syrphid flies, and other insects that eat aphids will drastically increase in number. The problem comes when the soybeans mature, the aphids die, and the predators look for other food sources. This means they come to your house, and then become nuisance pests. Of course they will clean out most of the aphids in your flowers and other plants around the house as well, but that may be of little consolation when your porch light has a million Asian lady beetles in it. Make sure seals and screens fit tightly, and you can do an area spray with a flying insect killer. The vacuum cleaner remains one of the best tools to use in the home.
Leaves have been falling for quite a while. They will fall more rapidly as the days progress. Try to keep them mowed or picked up to avoid deep piles. On some trees, particularly oaks, this premature leaf fall is, well, premature. It usually indicates disease problems, and in the case of pin oaks, may indicate an eventually terminal disease. Many pin oaks are being infected with bacterial leaf scorch, which causes leaves to look like they have been through a drought and drop early. This is caused by a bacteria plugging up the tissues in trunks and limbs. It is probably transmitted by leafhoppers or treehoppers, but little is known about the disease. There have been no successful treatments in the North-Central States, but they are still working on them. There have been some successful treatments in the south, but those same treatments have struck out here.
Remember to let perennial flowers retain their leaves as long as they are green. These leaves are making food for storage in the roots, bulbs, or crowns for next year. Premature mowing will reduce the food storage, and could lead to weak plants or even death. When the leaves turn brown, they can then be removed. It's too early yet, but remember to leave a couple of inches on things like mums. There is quite a bit of food stored in the above ground portions of these types of plants.
September 15, 2009
Now is a good time to begin harvesting black walnuts, according to Bob Frazee, natural resources educator for University of Illinois Extension. In general, the light colored black walnut kernels will have a milder flavor than the dark ones. If you prefer light colored kernels, Frazee recommends you hull the nuts as soon as they drop from the tree. Allowing the hulls to partially decompose before hulling causes a discoloration of the kernels.
When black walnuts are mature, their hulls will be thick and fleshy. According to Frazee, they can be mashed and removed by hand, but using mechanical devices such as a corn sheller will make the job a lot easier. After hulling, wash the nuts thoroughly, and spread out away from sunlight to dry for two to three weeks. Then store in a cool, dry place.
Because the hard shell can make it difficult to remove the black walnut kernel, Frazee suggests "tempering" the kernels before the shell is cracked. To "temper" the black walnuts, plan to soak the nuts in water for one to two hours, drain and then keep in a closed container for 10 to 12 hours. The kernels will absorb enough moisture to become tough, yet will remain loose in the shell.
For individuals wanting more information about growing your own nut trees, selecting appropriate nut tree varieties, learning about their insect or disease pests or harvesting nuts, a pamphlet entitled "Nut Growing in Illinois" is available online at this University of Illinois Extension website: www.aces.uiuc.edu/~vista/html_pubs/NUTGROW/nuthome.html.
September 9, 2009
With the fall festival season comes the onslaught of yellowjackets, and the calls have been rolling in to the office. Yellowjackets are beneficial insects in the sense that they pollinate plants and feed other insects and carrion (dead meat) to their larvae. Many times they will prey on insects that we identify as pests. Unfortunately, their ability to sting makes them a considerable health concern. Yellowjackets alone are responsible for about one-half of all human insect stings. The stings of social wasps, such as yellowjackets, have evolved as a defense mechanism. The only purpose for the sting is to inflict pain. Yellowjackets are easily provoked and, unlike honeybees, can sting more than once. They will attack in force if their nest is disturbed. Unless a person is allergic to yellowjacket venom, stings are rarely life threatening.
Yellowjackets are most frequently encountered when they scavenge for food. Their habit of feeding on nectar and sugar can create a nuisance. Yellowjackets are attracted to open cups and cans of soda and other sweet liquids. They are also attracted to open cans of garbage, bright flowery clothing, and floral scented perfumes. All outside garbage cans must be kept clean and well covered, to reduce yellowjacket problems. Contact with the wasps can be decreased by reducing these attractions at picnics and other outings. In situations closer to home, the elimination of overripe fruit from gardens and orchards will dramatically decrease the number of scavenging yellowjackets. Holding gatherings indoors and using screens on windows will also help avoid yellowjacket problems.
There are a variety of traps on the market that claim to attract yellowjackets. These traps are baited with the scent of rotting fruit or other odors equally as appetizing to the yellowjackets. It is questionable whether these traps can out-compete the natural and man-made attractants described above. However, it is certain that through proper sanitation and removal of natural and man-made attractants, yellowjacket contact can be reduced. However, in situations where the potential for repeated contact exists, other management methods may be necessary. These traps can also attract more yellowjackets if placed close to the home or patio, so place them to attract the insects away from where you'll be.
Management of each species of yellowjacket differs because of their nesting habits. Both species do not reuse their nests, therefore what was a problem this year may not occur next year. Caulking cracks and crevices in structures in winter and early spring, after the nests have died, will prevent German yellowjackets from constructing nests inside buildings. Openings to active nests should not be caulked. Chemical control for ground-nesting yellowjackets consists of drenching the exit hole with an approved insecticide, such as Sevin, and plugging the hole with treated soil or cotton balls. Yellowjackets that are not killed by the initial treatment will be killed by chewing on the treated cotton ball or tunneling through the soil. Yellowjacket entrance holes in buildings can be treated with approved insecticide dusts. As the yellowjackets walk through the dust they pick it up on their legs and transport it into the nest. When yellowjackets groom themselves they ingest the dust on their legs. It may take up to a week for the colony to die and repeated chemical applications may be necessary. When the entrance hole of an active nest is in a building, the hole should not be plugged with the insecticide or caulked. The yellowjackets may decide to chew through the soft inside wall rather than chew through the insecticide or caulking material.
Implement chemical control measures at dusk or dawn when the wasps are in their nest. Wear protective clothing when attempting to eliminate the nests, such as long sleeved jackets, gloves, and pants. Tape the wrists and ankles to the clothing, to prevent the wasps from getting underneath the clothes. A bee veil or other enclosed form of face and neck protection should also be worn. Yellowjackets will defend their nest, so to avoid being attacked, use a flashlight covered with red cellophane when applying the insecticide at night, since yellowjackets are unable to see red.
September 3, 2009
With the wonderful fall weather we've been having, even in August, the urge to get out and do something is overwhelming. There are plenty of things to be done, if the body and soul are willing.
Let's start with the lawn. As mentioned before, the ideal seeding time is until September 10. Bare soil rates are about four pounds of seed per 1000 square feet and overseeding existing grass is about half that. This is also an excellent time for fall lawn fertilizer. Apply enough to get about a pound of nitrogen per 1000 square feet (about 8 pounds of 12-12-12). This fertilizer application will also help trees and shrubs. Fertilizing and seeding can be done close together, as long as the fertilizer rates don't get out of hand. Too much salt in fertilizer can cause seed germination problems. A couple of weeks from now is also a great time to treat perennial broadleaf weeds in lawns, but you can't mix this operation with seeding. You'll have to wait until spring for the weed control operation. This is also a great time to aerate or dethatch. Grub treatment time is also upon us, since we wait about a month later to help with Japanese beetles.
Watering perennials when the weather is dry should also be on the to-do list. Perennials that lose leaves each fall are putting their last bit of energy into the roots this time of year. After returning to dry conditions, watering is the best way to provide optimum conditions for the critical fall period. Evergreens are even more critical. It is a great idea to provide an inch of water each week for all evergreens, until the ground freezes up for the winter. Evergreens continue to lose water through needles or leaves throughout the winter. A layer of mulch will help stabilize the ground temperatures, but wait until soils get cold to apply mulch. Mulch is intended to prevent wide swings in temperature.
We can also plant spring flowering bulbs. We may be a little on the early side, but it takes time to plan, obtain, and plant bulbs. It's always better to have a bulb in the ground than to try and hold them for another growing season if the weather turns sour on us. Pay particular attention to some of the less common bulbs or colors. Summer flowering bulbs should generally be dug after the first killing frost, since they aren't hardy enough to survive the winter in the ground.
Keep that garden going. It seems like we have entered the prime time this year for many of our garden staples. Tomatoes, squash, and peppers have just hit their main stride in the last couple of weeks. Pay attention to insects and diseases to keep them productive until frost takes them out. You might even have some success with planting some leaf lettuce, mustard greens, or spinach. Spinach sometimes doesn't get big enough for harvest in the fall, but in a mild winter it is ready to roll in the extreme early spring from your fall planting. Pay particular attention to vining crops for beetle control. Beetles are rapidly leaving corn fields and settling on pumpkins and squash. Controlling the beetles will help prevent the wilt virus that can be spread by them. The vining crops have also been attacked by powdery mildew it seems. Fungicides such as Daconil, mancozeb, or the organic neem should help. They should also help the fungal diseases on tomatoes.
A couple of "don'ts" should also be mentioned. It is really a rotten time of year to prune anything. Pruning spurs new growth and it will almost assuredly be winterkilled. Also, don't try and control crabgrass. It is a rapidly dying annual, which means another couple of weeks will turn it brown anyway. Start your control program around April 1 next spring with a preventative treatment.