Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
August 27, 2009
There have been many findings of the emerald ash borer in central Illinois over the two years, including Bloomington, Chenoa, LaSalle County, and Bureau County. What does this mean for us? It means the borers have been active and undetected in areas for a long period of time. That is part of the problem with the emerald ash borer: it can be in a tree for three to five years before any visual symptoms are available to help us diagnose the problem.
Add into the equation there are other diseases and boring insects that cause similar problems, and we end up with some confusion. Much of the information Illinois is using has come to us from Michigan State University, where they have been battling the problem for many years. Symptoms of infestation of emerald ash borer include canopy dieback, shoots coming from the base of the tree, splitting bark, serpentine feeding galleries under the bark, increased woodpecker activity, and "D" shaped exit holes. Remember, many other problems cause many of these same symptoms.
Emerald ash borer does not do well moving from one place to another on its own. Most of the help comes from humans moving firewood, lumber, or other items made from infested trees. This movement of products is why the insect "leapfrogs" from one place to another, often many miles away.
Many people have asked to have their ash trees looked at to see if they have it. That is all well and good, but remember it can be in your tree for up to five years before it shows any symptoms that can be seen. The other question is how do I save my ash tree? To that end, here are some of the things to look at when considering an attempt at insecticidal control.
Phil Nixon, Extension Entomologist, has several things to look at in his list. First, the only certain method to control emerald ash borer is to remove the tree. This sounds extreme, but any control attempt is only effective in the 80 to 90 percent range. Second, the cost of treatment over a span of years should be looked at. It might only cost $35 to treat for one year, but that will really add up over 20 years with increasing costs each year. And third, a tree in a regulated are is subject to removal by governmental agencies regardless of whether it has been treated or shows signs of infestation.
There are treatment options for professionals and homeowners. It is recommended to preventatively treat ash trees no more than 15 miles from known infestations. Control is usually more effective on smaller trees, and treatment is not as effective on trees already infested. The major treatment option for homeowners is to apply Merit (imidacloprid) insecticide as a soil treatment on an annual basis. This treatment will be more effective in the spring, and it takes a month or two to translocate in the tree. Also remember your tree can still be cut down if it is in the zone of a known infestation, whether it has been treated or not.
If you see emerald ash borer or its damage, you may call the Extension Office at 732-8289 or the Illinois Department of Agriculture at (800)641-3934. More information is available online at http://www.IllinoisEAB.com and http://www.emeraldashborer.info/
August 27, 2009
With the severe disease and insect pressure we have had, leaves are falling. As we approach September, some of this is to be expected, but some of it is due to damage from insects and diseases. Severely damaged leaves tend to drop early, especially when the leaf attachment is weakened. The causes are various, including: bacterial leaf scorch on pin oaks and red oaks, apple scab on apples and crabapples, anthracnose on many good quality shade trees, verticillium wilt on quality maples and ash trees, and of course Japanese beetle damage on many types of trees.
Bacterial leaf scorch will be an ongoing problem and is life threatening to trees, as is the verticillium wilt. These diseases plug the tissue that carries water to the plant parts, and have no control. Fertilization is about the only option (fertilize at the lawn rate to prevent problems to other plants). The other disease and insect problems happen on an annual basis, and trees should leaf out normally next year. You may, or may not, have the problems again next year depending on the weather.
August 24, 2009
"Houseplants that have been outside during the summer should be inspected carefully for insects and other pests before bringing them indoors," states David Robson, University of Illinois Extension horticulture educator, Springfield Center.
Houseplants spending the warmer months outside frequently attract a variety of pests. While the plant is outdoors, these pests rarely become a major problem because their numbers are kept low by predatory insects and other animals that eat them and by rainstorms that wash them off of the plant.
Once moved indoors, these pests no longer have their natural enemies and weather problems, so frequently become major problems.
Spider mites are the most common pests brought indoors. These tiny relatives of spiders suck the juices out of the leaves, causing them to turn bronzy and die. They spin fine webbing across leaves and between the leaf and stem; they appear as specks crawling through the webbing or on the leaf underside. Spider mites may be numerous outdoors, but other insects and mites keep them in check by feeding on the harmful mites.
Aphids are soft-bodied insects the size of pinheads that are frequently brought in with your plants. They are commonly green but may be any color. They and their close relatives, the mealybugs, are found on stems and leaves where they feed on plant sap. Mealybugs are about 1/8 of an inch long and are covered with white, waxy strands that make them look like tiny balls of cotton.
Spraying the plant with an insecticidal soap or some pesticides can eliminate spider mites, aphids and mealybugs.
When using these pesticides, take the plant outdoors to spray it if possible. Whether you use these pesticides or the insecticidal soap, treat the plant weekly for at least three weeks. Particularly severe mealybug infestations may require treatments over a two or three month period.
Keep plants separated to avoid spreading insect problems between plants. Segregate plants for at least two months.
Severe insect problems may not be noticeable until furnaces are turned on and the air starts drying.
August 24, 2009
The summer garden has taken its time to mature, but many are finally finding the fruits of their labor are at the peak of quality. The problem has been the unusually cool weather of July. Statewide, July was the coldest on record. One weekend we set record cold temperatures on two of the three nights. Tomatoes are a heat loving crop, and they just did not mature well with that cold weather.
The other problem has been with tomato diseases. As in past years, there are plenty of diseases to go around. The most common are septoria leaf spot and early blight. Both are fungal diseases that can overwinter in plant residue in the soil to reinfect the tomato plant the following season. They both require wet leaves (dew or rain) to infect.
Symptoms of septoria are very small, 1/8" across circular spots, with dark margins and grayish colored centers. You will also find much of the tissue between these spots has turned yellow. Early blight spots are larger, up to 1/2" across and are dark colored. You can find dark concentric rings (somewhat resembling a target) within this area.
It is too late to do much this year, but you can take steps to reduce them next year. First, rotate the area you plant tomatoes in the garden. Do not plant in the same area for at least two years, and also avoid areas where potatoes were planted as well, since they are in the same family and the same diseases can infect both.
Use some sort of ground cover (straw, newspapers, etc.) to prevent soil from splashing on the lower leaves. Since the disease can overwinter in the soil, eliminating the disease containing soil splash will help reduce the disease spread. These diseases spread from lower leaves to upper. When you notice discolored leaves, remove them.
Staking or caging plants will help with air circulation, which will allow leaves to dry quicker. Eliminate all residue from the garden. Compost it. Till the garden in the fall to help aid decomposition of any plant residues. If all else fails, there are some fungicides that can offer some help.
Other tomato diseases that are common would include bacterial spot and bacterial canker. Bacterial spots are very small, 1/16" in diameter and dark colored. In between these spots the leaves will turn yellow. This is one of the only tomato diseases you might find in the upper part of the plant first. Bacterial cankers are much larger dark spots, sometimes over an inch in size. They are almost always found on the margin of the leaf and are brown colored. For both bacterial diseases, follow many of the same recommendations listed above. Copper products can help in their control.
August 21, 2009
The time of year has arrived to put that final push on to prepare your lawn for the upcoming winter months. What you do now will have a big impact on how your lawn will look next spring.
Grub problems have traditionally been found first along walks, driveways, or patios. The current list of products includes imidacloprid and trichlorfon as the chemical active ingredients. Sevin may also be used, but it is specific for Japanese beetle grubs. Sevin also will have an effect on earthworms, which is good and bad. It is good if you have mole problems, and bad if you don't. If label directions are followed, these should provide adequate control of grubs. The insecticide must get to where the grubs are, so make sure to water the liquid formulations in as soon as they are applied.
Seeding of grass should be accomplished by September 10. This is a tried and true date, but the end of the world won't come about if you are a week later. The goal is to give the seed
enough time to germinate and become established before bad weather arrives. Seed at the rate of 4 pounds of seed per 1000 square feet on bare spots, or half that rate on overseedings.
If you have a compacted yard, or have a deep thatch layer, now is also an ideal time to dethatch or aerate. Thatch layers should not be over 1/2 inch deep for optimum growing conditions. When aerating, make sure you use a core type aerator.
Fall fertilization is also a good practice. If you haven't fertilized in the last month, consider applying a fertilizer treatment now. Use about 8 pounds of 13‑13‑13 fertilizer per
1000 square feet of lawn. Try to avoid the high nitrogen fertilizers this late in the year. It's hard enough to keep up with the mowing as it is, and nitrogen promotes top growth. The even analysis fertilizers will also promote root growth, which is what we want going into the late fall and winter.
Crabgrass and other annuals grass weeds can be seen about everywhere. They will die with the first frost, so treatment is not available or recommended in the fall. Make a note of where these grasses are, and an overseeding to thicken up the grasses you want there may help crowd out the annuals.
Last, but not least, is broadleaf weed control. Fall is a particularly good time to treat problem perrenial weeds since they are sending food down to the roots to overwinter. A sprayabout the 3rd or 4th week of September (making sure to use the appropriate product) can do a world of good on the perennial weeds. Remember to be very careful with herbicides around perennial plants since they are also getting ready to overwinter.
August 21, 2009
They're back, and almost a month earlier than last year. During the late summer small insects, known as insidious flower bugs and minute pirate bugs, become real pests by producing painful bites on people. They are about 1/5 of an inch long with black and white markings on the back. They are beneficial insects most of the time while feeding on small insects and their eggs.
They are present all summer in area fields, flower beds, and other landscape areas. Most of the summer the insects are beneficial, but then they become quite the nuisance when their regular food source runs out. Their painful bite is caused by their beak breaking your skin. These insects don't suck blood or inject venom like mosquitoes.
People differ in their response to the bites. Some people react to the bites like mosquito bites, with swelling and itching. Other people have no reaction at all. Control of insidous flower bugs and minute pirate bugs is not practical. They are mobile, and the populations change greatly. Wearing dark clothing on may help, as the insects seem to be attracted to light colors. Repellents are sometimes effective, but not enough to make a recommendation. Try the repellents for yourself and see if they work for you.
August 12, 2009
If you have been following a foundation spray program all year, keep it up. If you haven't been, it is probably time to start. The foundation spray program is your first line of defense against nuisance pests in the house. It cuts down on crickets, millipedes, spiders, ants, and many others that find their way inside.
To accomplish a foundation spray, you would select a material such as permethrin or bifenthrin to begin with. Then spray the foundation and the adjacent foot or two of soil or plant material with the spray mixture. Both these products are cleared on most types of plants. Foundation treatments should be applied every 7-15 days depending on the temperatures. The materials break down quicker in hot weather.
Foundation treatments won't prevent everything from getting in the house, and they certainly won't kill things already in the house. For insects already in the house, you have a few options. The first is mechanical control. This is fancy language for something like a flyswatter, shoe, vacuum cleaner, flypaper, or glue boards. The next is chemical control. This basically means aerosol cans inside the house. The most common ones are for flying insects or ants, although many of the flying insect killers now have permethrin in them and can last quite a while.
August 12, 2009
We are still experiencing a large number of beetles in the garden. This includes not only the Japanese beetles, but also the recently emerged Western corn rootworm beetles. These small black and yellow striped beetles are of concern around cucumbers, melons, and pumpkins since they can carry a wilt virus.
It is a good idea to treat your vining crops with Sevin, permethrin, or bifenthrin on a weekly basis. It is important concentrate on the new runners to help prevent damage from squash vine borers.
The numbers of Japanese beetles seem to be declining somewhat. Of course there are still plenty in many areas, but the population should continue to decline until the last of them are finished off by frost. As favored food sources are consumed, less likely plants may be attacked. This may mean a recheck of things around the landscape. I've recently seen them on marigolds, and seen some limited feeding on red maples. These plants are in the less preferred categories.
August 12, 2009
It has been a banner year for diseases in many plants. The lawns are starting to show some of the diseases as well. Conditions have been ideal for many of the fungi that cause up problems. Humidity makes an ideal environment for many diseases, but there are some that like drier conditions. Dollar spot, brown spot, and rust have been noted in area lawns.
There are treatments available for diseases in home lawns, but they can be rather expensive and time consuming. Treatments would be applied on a 7-14 day basis throughout the season. It isn't recommended for homeowners to treat diseases in the lawn. The recommendation is let nature take its course, and then do some reseeding if needed.
The disease needs a susceptible host, the right environment, and time to cause us problems. If you do some reseeding, use a newer variety with good disease resistance. This attacks the susceptible host part. Also, keep your turf growing well to prevent weakened grass plants from being more susceptible. The diseases will only be present during certain weather, and as the weather changes the diseases will go away.
August 12, 2009
The 2009 Logan County Fair is in the books. It seems like it gets harder to keep up with the pace as the years go by. The many volunteers who pitch in to make things go exceedingly well are to be commended for helping the youth have a positive experience. Running a show, carrying a table, or helping at the auction, your efforts are greatly appreciated.