Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
June 22, 2011
A few beetles have shown up in the area. This makes them about a week earlier than normal. Whether these are local hatches or tag-a-longs from southern areas doesn't much matter. They are coming. Japanese beetle adults have a 1/2 to 3/4 inch long body with copper colored wing covers and a shiny metallic green head. A key characteristic is prominent white tufts of hair along their sides. They also have an overwhelming appetite for your favorite rose. Adults feed in herds on many deciduous trees, shrubs and vines such as linden, Japanese maple, sycamore, birch, elm, and grape. They generally do not feed on dogwood, forsythia, holly and lilac. Japanese beetle adults feed on flowers and fruits and skeletonize leaves by eating the leaf tissue between the veins. Feeding is normally in the upper portions of trees. Beetles prefer plants in direct sun, so heavily wooded areas are rarely attacked.
Adults can be with us until mid August. The life cycle is similar to a June bug, only it runs a few weeks later. After mating females lay eggs in turf which hatch into grubs in August. Grubs feed on plant roots until cold weather drives them deeper into the soil. Adults emerge in summer of the following year.
The bacterial control, milky spore sold as Doom or Grub Attack, is frequently recommended to control Japanese beetle grubs. In our area milky spore is generally not recommended, since it controls only Japanese beetle grubs. Also Japanese beetle grubs must already be infesting the turf for milky spore to work effectively. Pesticides commonly used for lawn grub control will also control Japanese beetle grubs. Controlling Japanese beetle grubs does not significantly reduce the number of adult beetles the following year. The beetles are good fliers and easily fly a couple miles in a single flight. Evidence suggests that adult beetles are attracted to previously damaged leaves. Therefore reducing feeding damage now can result in less feeding damage in the future.
Generally pesticide sprays of cabaryl sold as Sevin can reduce damage for up to two weeks, but four to seven days is more likely. Sevin is toxic to bees. Synthetic pyrethroids can also be effective, but tend to break down quickly with extreme heat. These would include permethrin and bifenthrin. The Japanese beetle repellent made from Neem has not been shown to be effective. Picking beetles off by hand every couple of days may be just as effective as spraying. When disturbed, the beetles fold their legs and drop to the ground. Covering plants with floating row covers can protect prized roses and ripening fruit. Japanese beetle traps are not recommended since they can actually increase damage by attracting more than they kill.
A number of birds such as grackles, cardinals and meadowlarks feed on adult beetles. Two native predator insects and a couple of introduced parasites may help to keep Japanese beetle populations in check. Protect natural enemies by keeping the use of conventional pesticides to a minimum. Although damage looks devastating, Japanese beetle feeding rarely kills plants. Therefore, confine control of beetles to shrubs and small trees near main building entrances and other important landscape locations where damage is obvious. Protecting a prize rose bush, or a newly transplanted linden tree is a good idea.
June 22, 2011
If you haven't sown pumpkins for fall decoration, usually around Father's Day is the correct timing. Vining pumpkins need at least 50 – 100 square feet per hill, with the larger pumpkins requiring the larger area. Hills should be five to six feet apart and rows of hills should be 10 – 15 feet apart. Each hill should have about four seeds per hill, planted about an inch deep. The miniature varieties such as the Jack-Be-Little are sometimes grown in rows with seeds planted every eight to twelve inches, then thinned to about two feet apart in the rows. Fall decoration pumpkins should be cut from the vine before the vine dries in order to have a good stem attached to the pumpkin, but after the color is acceptable.
June 17, 2011
With the warmer weather, it was bound to happen. The first Japanese beetles of the season were captured on June 16 in a pheromone trap north of Lincoln
Japanese beetle adults have a 1/2 to 3/4 inch long body with copper colored wing covers and a shiny metallic green head. A key characteristic is prominent white tufts of hair along their sides. They also have an overwhelming appetite for your favorite rose. Adults feed in herds on many deciduous trees, shrubs and vines such as linden, Japanese maple, sycamore, birch, elm, and grape. They generally do not feed on dogwood, forsythia, holly and lilac. Japanese beetle adults feed on flowers and fruits and skeletonize leaves by eating the leaf tissue between the veins. Feeding is normally in the upper portions of trees. Beetles prefer plants in direct sun, so heavily wooded areas are rarely attacked.
Adults can be with us until mid August. The life cycle is similar to a June bug, only it runs a few weeks later. After mating, females lay eggs in turf which hatch into grubs in August. Grubs feed on plant roots until cold weather drives them deeper into the soil. Adults emerge in summer of the following year.
The bacterial control, milky spore sold as Doom or Grub Attack, is frequently recommended to control Japanese beetle grubs. In our area milky spore is generally not recommended, since it controls only Japanese beetle grubs and not our predominate lawn grub, the annual white grub. Also Japanese beetle grubs must already be infesting the turf for milky spore to work effectively. Pesticides commonly used for lawn grub control will also control Japanese beetle grubs.
Controlling Japanese beetle grubs does not significantly reduce the number of adult beetles the following year. The beetles are good fliers, and easily fly a couple miles in a single flight. Evidence suggests that adult beetles are attracted to previously damaged leaves. Therefore reducing feeding damage now can result in less feeding damage in the future. Picking beetles off ornamental plants, or early chemical controls, will help prevent the pheromones from being released to attract others to the same area.
June 16, 2011
Insects are plentiful this year. I don't think we can blame it on the mild winter, but they have great systems of survival. One insect of note with the wet weather is the earwig. Earwigs tend to be in high organic areas, as they feed primarily on dead insects and plant material. However, they can and do eat live plant material such as marigolds, zinnias, strawberries, and others. They may be a prime suspect if you notice damage, but never see any insects during the day. Control can be obtained with insecticides such as bifenthrin or permethrin.
Leatherwing beetles, or soldier beetles, are now present where linden trees are pollinating. They look like pale lightning bugs, but don't have the light. These beetles are elongate, soft-bodied and about 1/2 inch long. Colors of soldier beetles vary from yellow to red with brown or black wings or trim. A common and easily-spotted species is the Pennsylvania leatherwing, which is yellow with one large black spot on each wing. Most larvae are carnivorous, feeding on insects in the soil. Larvae overwinter in damp soil and debris or under loose bark. The adults are also predators, eating caterpillars, eggs, aphids, and other soft-bodied insects. They will alternatively eat nectar and pollen if no insects are around. They do not damage plant foliage. Adults are often found on flowers such as goldenrod, where they lie in wait for prey, feed on pollen, and mate. Since soldier beetles are beneficial, it is inadvisable to kill them.
The last insect to discuss is the bagworm. Bagworms are notorious pests of evergreens such as spruce trees. June 15 is the traditional date for control. It has been recommended to wait an extra week this year to ensure egg hatch. The idea is to have all the eggs hatched before treatment, but not wait until the bagworms are almost mature. For control, the traditional standby has been Sevin, but the B.t. products such as Dipel and Thuricide have really taken their share of the market the past several years. The B.t. products have several good points including safety to mammals and toxicity to larger bagworms. Since they are bacteria that affect only the larvae of moths and butterflies, it does take a while for the bacteria to build up to the point where they can kill the bagworm. If you are in doubt about whether you have bagworms, check your trees and shrubs around June 15. You can actually see the small bags as the larvae build them. They become very noticeable at about 1/16 of an inch long. Treat bagworms early, since larger ones are more difficult to control. You can even mark your calendar for next year.
June 16, 2011
Apple and pear trees continue to have their problems. There is a large amount of tip dieback in some varieties, and this is probably fire blight. This would actually be the second bout for the year. Look for a shepherd's crook at the tip of the affected areas as a clue it is fire blight. Fire blight is a bacterial disease, therefore there is little chance for you to treat it. The common treatment in commercial operations is streptomycin, but it has to be applied before symptoms appear. Bordeaux mixture can also help prevent, and that means prevent and not cure, the disease in some years. Prune out disease cankers when dormant. This disease cost Illinois its pear industry.
June 10, 2011
Even though Logan County is not in the heart of the territory of the Periodical 13 year cicada, there may be spots experiencing the problem. Most of Sangamon County is in the expected zone, while the Chestnut and Latham areas of Logan County are the only areas indicated on a map for possible emergence. There are two types of cicadas. The first is the "dogday" cicada, which occurs in the heat of summer each year. The second is the periodical type that hatches in late May, based on soil temperatures, every 13 or 17 years. The 13 (Brood XIX) year brood is up this year, and numbers may be impressive in some areas. They have already created stirrings to the south and east. Prime areas would be heavily wooded for a period of many years. Numbers can average over 130,000 per acre.
The adult cicada is about an inch and a half long, dark in color, and has red or orange eyes. The female uses an ovipositor, like a saw, to make slits made in small twigs of trees. She then lays eggs in the slit. When the eggs hatch, the nymphs fall to the ground. They then tunnel in the ground where they find a tree root to suck sap from for 13 or 17 years. The root feeding activities are not the most damaging, but the egg laying slits can cause severe damage to young trees.
Young transplants up to two and a half inches in diameter can have their main trunk damaged to the point it will snap. On mature trees, there is little danger of the tree dieing from the damage, but many branch ends will break off in wind storms. The favored twig or trunk sizes are 3/16 of an inch to an inch and a half.
To protect young trees, or valuable small trees, a mechanical barrier is the most effective. Something like screen wire wrapped around the trunk will prevent damage. Insecticides will also kill many of the cicadas, but it only takes one female to do the damage. Sevin, permethrin or bifenthrin should show some effectiveness.
The other phenomenon that will occur is traditional predator numbers, such as cicada killer wasp numbers, will also greatly increase. These are extremely large wasps that paralyze the cicada, bury it in the ground, and lay eggs in it. The insecticides mentioned previously will also be effective against the wasps. Remember though, the wasps are actually beneficial. Control should only be done in very high traffic areas and children's play areas when the wasps become a hazard.
June 10, 2011
As anticipated many of the leaf diseases, such as anthracnose and apple scab, are causing problems. These problems include many leaves dropping from trees. Currently apples, crabapples, sycamores, maples, and many other good quality shade trees are affected. The maple group will accelerate even more in the near future, as they are just entering the worst of the phases.
What starts as the spots, eventually has more dead material in the leaf and leaf stem. At times, especially on apples and crabapples, the leaves then turn yellow. These dead areas cause the leaves to be weak, and weakly attached. With some wind, the leaves then fall to the ground.
While it may look like fall, most shade trees will then put out another set of leaves in four to six weeks. The apples and crabapples don't tend to initiate new leaves as easily, and may remain without leaves for a portion of the summer. The major problem is the loss of the food that these leaves would make for the tree.
Since treatment is not effective once you see the problem, a fertilizer program would be in order. Fertilize at the lawn rate of eight pounds of 12-12-12 or 13-13-13 per 1000 square feet (this would be the drip area in the case of trees). Then, just scatter the fertilizer on top of the ground. You may water if it doesn't rain for a day or two after the application.
June 3, 2011
Hollyhocks are one of the traditional, old-fashioned flowers often grown in our area. This year, they are definitely interesting. Even before the flowers open. Most area hollyhocks are infected with rust. Rust is usually a spring and fall disease problem, when it occurs.
Rust first shows up on the bottom of the lower leaves, and the top side of the leaves has some rather striking bright yellow to orange spots develop. Rust can attack all plant parts including leaves, stems, and leaf petioles. The rust disease spends the winter in old plant parts on the ground. Removal of the plant material will help reduce infection possibilities. Increasing air flow and reducing humidity will also help. Control is best accomplished by removing infected leaves at the first sign of the rust (on the bottom of the leaves). Chemical control may needed, and sprays containing sulfur are effective.
June 3, 2011
West Nile Virus (WNV) has, unfortunately, become a household phrase. WNV was first isolated in Uganda, Africa. It can harm humans, birds, and other animals. It is transmitted by infected mosquitoes, primarily the northern house mosquito. The mosquito becomes infected after biting wild birds that are the primary host of the virus. The mosquito is actually able to transmit the virus after 10-14 days after biting the infected bird.
The mosquito life cycle has four life stages (egg, larvae, pupa, and adult). The female mosquito lays eggs on water or moist soil. Most of the larvae hatch after 48 hours and the larvae and pupae live in the water. The females need a blood meal before they can lay eggs, so only the females bite. They bite every few days during their adult lives, which may last several weeks.
Preventing mosquitoes is a first step. Homeowners can best accomplish this by eliminating standing water. Tires and old containers are obvious places to start, drill holes in the bottom of recycling containers, clean clogged gutters, don't allow stagnant water in anything such as birdbaths, change landscape slopes to eliminate standing water, and use larvacides in standing water that can't be eliminated. B.t. Israeli is the strain that is effective against mosquito larvae – not the B.t. variety commonly used on trees and gardens! The mosquitoes have already begun hatching, so treatment time is at hand.
Also protect yourself from bites. Mosquitoes can travel up to three miles from their breeding sites! Make sure that screens and doors are tight, use proper outside lighting such as fluorescent lights, stay indoors at dawn and dusk when mosquitoes are most active, wear long-sleeved shirt and long pants when you must go outside, and use insect repellents properly applied. Exposed skin should be sparingly treated with a repellent containing up to 30% DEET (up to 10% for children), and make sure to treat thin clothing as well (since mosquitoes can bite through the thin clothing).
June 3, 2011
We are now in the middle of the correct planting time for the warm loving vegetables for our gardens. This would include lima beans, cucumber, eggplant, melons, peppers, summer squash, winter squash, and pumpkins. Pumpkins for use as fall ornamentals should be planted around Father's Day so they have less chance of rotting before fall display. Believe it or not, we're at the proper timing for fall garden plantings. That means potatoes, kale, and some others. Some of the planting dates overlap this time of year. That basically means plant it, but you can expect harvest to be closer to fall.