Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
August 30, 2010
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.
August 30, 2010
A new training program for Master Gardener trainees will be offered in Lincoln at the U of I Extension Office beginning on September 22 and concluding December 1, with no class the week of Thanksgiving. The classes will be held weekly on Wednesdays from 9:00 a.m. until approximately 4:00 p.m. Cost for the training will be $100 per person for those volunteering time through the Logan County group, with supplemental funding of approximately $50 per person being sponsored by the Logan County Master Gardeners. Non-compliance with the volunteer service requirement will result in a bill to recoup the actual cost of the training. The cost to those from other Master Gardener programs will be $150.
Participants completing all ten sessions will then be considered interns with the expectation of 60 hours of volunteer service be completed within program guidelines within the next two years. After the internship, the expectation is 30 hours of volunteer service and 10 hours of in-service education minimums. If you are interested in joining, Don Miller in the Logan County Extension Office will serve as the coordinator. His contact information is firstname.lastname@example.org or (217)732-8289.
August 24, 2010
All we have to do is look at a calendar, and we can see fall is coming at us rapidly. There are also many other signs, symptoms, and legends that predict the change in season and the severity of the winter.
The wooly bear caterpillar legend is one of the most often quoted. The banded wooly bear is black at both ends, and has orange and black stripes in the middle. The legend says the more stripes that are black in the middle, or the longer the black bands, the more severe the winter. Science says more stripes are dark dependent on moisture conditions in the area and the age of the caterpillar, so it is really the growing conditions until the time you see the caterpillar. There are also nine US species. The banded wooly bear is the larvae of the Isabella moth. Other moth larvae in the group have different colored caterpillars.
Of course, the first frost can be predicted by the singing of cicadas. "Six weeks from the first song of the dog day cicada comes the first frost." Boy I hope not. That would mean the end of August is going to be quite chilly. A yellow butterfly flying in your face also means a frost.
There are some more meaningful signs. The buckeye trees have lost most of their leaves, corn has been dented for three weeks, and ragweed season is here.
If you're one that usually suffers from the fall allergy season, you know the symptoms all to well. Many people blame goldenrod as the culprit, when it is mostly ragweed problems.
In our area, we have two types of ragweed. The most noticeable is giant ragweed. Giant ragweed, also called horseweed, can grow well over 10 feet tall. It is very noticeable as one of the few weeds that grows taller than our Illinois corn. The other type of ragweed is common ragweed. It is generally less than six feet tall, and not nearly as noticeable.
Ragweeds tend to bloom in late summer. The period can range from mid-August to mid-September. They put out a lot of pollen when they bloom. The amount of pollen is one problem, but the shape of the pollen is the other. The shape of the pollen is more jagged and sharp along the edges, making it more of an irritant than other types of pollen.
Add in the usual ragweed problems, alternating wet and dry conditions, and early leaf drop, and we have the recipe for an allergy sufferer's nightmare. There are also several leaf molds that are at work, and that compounds the allergy problem.
What can you do? One, try to eliminate ragweed in your particular area. Two, avoid the mid to late morning period in the great outdoors. This is when more pollen is released. Three, you can stay indoors (or office or car) with air conditioning. And, if your problems are particularly troublesome, talk to your doctor. There are prescriptions and over-the-counter medications that can help alleviate at least some of the symptoms.
This has probably been one of the worst years in history. This is almost a month earlier than normal. So take some comfort in the fact that next year will probably be better, and be reminded that fall is on the way. That first frost will make many allergy problems disappear.
August 10, 2010
This week I thought I would cover, in short form, many different topics. There seem to be many things going on at this time, but most are continuations of earlier problems. Hopefully you will at least be a little better informed after reading this week's offering.
Let's start with maple trees. Many have decided to shed all their leaves in response to the fungi, such as anthracnose, and the brutal beating they took from the wind earlier this year. Others have dropped leaves on portions of the tree, while retaining leaves on other parts. This is the result of the wind blasting. To check for possible recovery, inspect the buds on the tree and see if they are plump and are green inside. You can also scrape the bark on the ends of twigs with your fingernail. If the area under the bark is green, and buds are plump and green, there is still hope for next year.
Some area oak trees, particularly pin oaks, continue to show the signs of bacterial leaf scorch. This starts as spots on leaves which merge. The leaves then fall prematurely. The next phase is the dying of branches up the tree, followed in a couple of years by dead branch ends. Unfortunately there is no cure for this problem in the Midwest. There has just been a large scale research project done which indicates you may extend the life of these trees by a few years with early treatments of antibiotics. It requires something like oxytetracycline since the infection is from a bacteria. Early is best in both the stage of the disease, and timing in the year. Best results were about three weeks after full leaf expansion. Remember, this just prolongs the inevitable. It is not a cure.
We are at a possible time to control Zimmerman Pine Moth. Zimmerman pine moth is one of those "kind of borers." It generally affects only severely weakened trees, and goes just under the bark to girdle the cambium layer at a branch whorl. It seems like older Scotch, red, and Austrian pines are favorites when they begin to decline. There are other problems which cause the sap to leak out, and they include diseases and birds. Frequently, the damage from a severe infection of the pine moth leads to the branch, or top, breaking off in a wind storm. Permethrin is the insecticide of choice for the attempt to control the pine moth, and it should be applied as a broadcast spray concentrating on the branch junctions and main trunk.
Crabgrass continues to get worse, and may even compose most of some lawns at this time. Control is really not an option at this time, as it is an annual coming from seed every year. This means it will probably die within about a month anyway. Next spring, two applications of a preventative treatment with one around April 1 and another about June 1 would be the best plan. Mowing at a 2.5 to 3 inch height would also be beneficial. At least the absence of a preventative treatment would allow for putting down new seed this fall (August 15 to September 10).
Keep up with spray programs for apples until shortly before harvest. This will help control the sooty mold which looks like charcoal dust on apples. It does scrub off, but notice I said scrub and not rub. Sooty mold is usually worse on the yellow type apples, or at least more noticeable.
Also, the population of spiders, crickets, and other home invaders has grown by leaps and bounds the past week or so. This means to keep up the foundation treatments to provide a protective barrier against these insects. Permethrin or bifenthrin insecticides are the most commonly used now.
August 10, 2010
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. The timing of many of the treatments will begin in about a week, so now you'll have plenty of time to make your list and complete your shopping.
Keep mowing when the grass or weeds dictate mowing. The rule of thumb is to remove no more than a third of the leaf blade at any one time. This means that if your desired mowing height is 2 inches, you should be mowing when the grass gets 3 inches tall. No summer slump this year, due to all the rain. It figures that we mow every three days all summer long when gas is still relatively expensive.
Grubs are active. If the extreme heat keeps up, we'll be seeing the effects of grub damage this month. Grub problems are normally found first along walks, driveways, or patios. The insecticide must get to where the grubs are, so make sure to water the liquid formulations in as soon as they are applied. The two widely available products are GrubX (halofenozide) and Merit (imidacloprid). Remember the active grubs now are from the June bug, and we'll want to wait another two to three weeks on trying to apply grub treatments for the Japanese beetle grub. Carbaryl (Sevin) granules are an option for Japanese beetle grubs, but they don't work on the other species.
Yellow grass tops are visible in many areas. This tends to happen in very wet years when nitrogen is taken from the root area, and trees and shrubs grab available nutrients. In the past, treatments haven't had much effect in the current growing season. Next year you won't see the same problem, at least to start the season.
Fall seeding of grass should be done between August 15 and 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, these seeding dates also define ideal times 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 around September 1. 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. Preventative treatments may also be applied in the spring (around April 1 depending on soil temperatures) to kill the germinating seeds. As many have found out, a second treatment about June 1 is also necessary since the products only last six to eight weeks.
Last, but not least, is broadleaf weed control. Fall is a particularly good time to treat problem perennial weeds since they are sending food down to the roots to overwinter. A spray
about 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. Also, waiting this late in the season reduces drift potential for the neighbor's garden. Dicamba is particularly prone to vapor drifting, for up to two weeks, with hot, sunny conditions. It's hard to get a good weather forecast for two weeks, let alone the week we are in.
August 10, 2010
Another invasive plant, teasel, is easily noticed along highway and railroad right-of-way. The plant looks like a thistle, and has gone gangbusters since the spray programs have been curtailed due to budget restrictions. The plant behaves like a biennial in that it has a small rosette stage the first year, then bolts to the tall, flowering plant the second year. This life cycle is similar to another invasive plant: poison hemlock. The best controls listed are triclopyr and glyphosate (Roundup). The trichlopyr is a broadleaf only weed killer, and is often used to help with control of violets. The glyphosate will take out both broadleaves and grasses, so is most effectively used by wiping on a few isolated plants.