Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
June 30, 2008
Everyone who thought we had escaped the Japanese beetle attack this year may have to rethink that. The beetles are running a week or two behind schedule, due to the cool spring. A few beetles have shown up in the area. 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 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.
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 30, 2008
In keeping with the insect theme, potato leafhopper numbers have exploded this last week. This is the small wedge-shaped, light green insect that seems to just fog around security and patio lights. They are not only a nuisance, but they can cause damage to a wide variety of plants.
Potatoes are the first plant that comes to mind when we talk about potato leafhoppers (must be something about the name), but many other plants ranging from beans to trees can be affected. You may be wondering what kind of damage a few little leafhoppers can do, especially since they suck sap from plants and aren't that big in size.
Leafhoppers suck sap and then inject a toxin back into the plant. Along the same lines as humans getting a mosquito bite - it's the extra that's injected back in that causes the injury. Symptoms of leafhopper damage start as yellow "v" shaped areas on the tips of leaves. These areas turn brown or black and then fall out leaving a "v" shaped hole on the tip of the leaf. This is a symptom, but not the only injury. Large numbers of leafhoppers can kill potato and other plants.
Controls for leafhoppers are warranted with very low numbers. In alfalfa fields, it is recommended to treat when 2 leafhoppers are caught in a sweep net in alfalfa over a foot tall. Garden treatment options for potatoes include: Sevin and rotenone as common insecticide choices available to homeowners. Most trees and shrubs can be treated with Sevin, permethrin, or bifenthrin.
June 26, 2008
A lot has happened in a week with our trees. The maples continue to show increasing leaf drop. Sycamores have been hit with a vengeance, and leaves have been falling like rain for the last week. Other good quality hardwoods, such as ash, are also showing symptoms.
The symptoms are dead material between the leaf veins, along the leaf edges, or dead tips of leaves. There are also times when the disease affects buds and twigs. In the leaf stage, the disease only affects leaves currently out. If damage to leaves results in enough dropped leaves, the tree will shoot another set within four to six weeks. All we're out is the energy the tree spent in pushing out another set of leaves. Of course, we also had a freeze that caused the loss of leaves on many trees. What I'm getting at is trees have spent quite a bit of energy already this year. We need to do what we can to replace nutrients and keep moisture available.
Moisture will be needed to with keep those affected trees in a vigorous growing condition. Usual watering rates are an inch a week, and rainfall can supply part or all of that. Fertilizer applied to lawn area or trees is the other part of the equation. Fertilizer should be applied at the lawn rate (supply one pound each of nitrogen, phosphorus, and potassium per 1000 square foot of drip area), if you haven't fertilized the lawn area around the trees. This would translate to about 10 pounds of 10-10-10 fertilizer or eight pounds of 12-12-12 or 13-13-13 per 1000 square feet.Other leaf diseases are also quite evident. One the more common ones is apple scab. This disease affects apples and crabapples in much the same way as anthracnose does the shade trees. It starts as spots on leaves between the veins of the leaves, and ends with leaves dropping at a rapid rate. This is the reason for so many "naked" crabapple trees late in the summer. Traditional spray programs for production apples (used on the apples or crabapples) should prevent the problem. Samples of apple scab have been coming in for a week now, so expect some acceleration of the disease on susceptible varieties.
June 26, 2008
It is time to take action against the notorious oystershell scale, because the eggs are now hatching into young crawlers that are extremely susceptible to insecticide applications. However, as the scales mature later in the season, they are more difficult to control because they form an impenetrable protective covering. Oystershell scale has a wide host range, including ash, birch, dogwood, elm, hemlock, maple, poplar, privet, walnut, and willow.
Eggs hatch into young, creamy white to brown crawlers that are active from May through June. The crawlers locate a place to settle and then use their piercing–sucking mouthparts to remove plant fluids, which causes leaf yellowing, plant stunting, and possibly death. Branches or twigs totally encrusted with oystershell scale eventually die.Insecticides recommended for managing oystershell scale include acephate (Orthene), bifenthrin, carbaryl (Sevin), malathion, insecticidal soap, and horticultural (summer) oil. All these insecticides should be applied when the crawlers are most active, which increases their overall effectiveness in controlling oystershell scale populations. Repeat applications may be needed 10 to 12 days later, as the eggs don't all hatch at the same time. Lilacs and maples should also have a repeat spray in early August.
June 26, 2008
June 16, 2008
For those of us with linden trees, that are now pollinating, we probably have seen the soldier beetles. They look like pale lightning bugs, without the light. Following is some in-depth information on the beetles to give us a little clearer picture of what they do.
Soldier beetles, also known as leatherwings, get their name from the soft, cloth-like wing covers, which when brightly colored are reminiscent of uniforms. 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.
Soldier beetles resemble lightning bugs but do not have light-producing organs. Another group of beetles that may be confused with soldier beetles are the blister beetles, which are pests, but blister beetles have a square-shaped head and a very visible "neck."
Adult females lay their eggs in clusters in the soil. The larvae are velvety, covered with dense bristles, and have antenna-like projections on their head. Most larvae are carnivorous, feeding on insects in the soil. Larvae overwinter in damp soil and debris or 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. They may be a nuisance in the fall, if large numbers of larvae enter a house in search of a place to overwinter. They are also a major pest this time of year when populations congregate around those linden trees. Weather-stripping and caulking will help pest-proof a home. A vacuum cleaner will safely remove soldier beetles that are found inside.
June 16, 2008
Young bagworms are present at this time. Spray after eggs have all hatched (guessing this week) to control them. Sevin, Thuricide, or one of the pyrethroids will work.
Pruning evergreens is done about the end of June. This applies to both broadleaf and traditional evergreens. Pine, juniper, yew, arborvitae, spruce, holly, rhododendron, azalea, and other evergreens should all be pruned around the end of June. This keeps new growth from getting too rank this growing season, but still allows new growth that does occur to harden off before the cold month this fall and winter. Pruning can be done for shaping or size containment.
Check tomato plants for signs of septoria leaf blight. If you see brown areas between the veins and along tips of leaves, especially on the lower leaves, you may want to start a fungicide spray program. This is the disease that has caused leaves to drop off of plants the last couple of years, and it is present very early again this year. Fungicides such as mancozeb, maneb, or Daconil will have provide some control of the fungus.
Also on tomato plants, if you haven't mulched them yet you may want to do so. The mulch evens out soil temperature and moisture. This is a great assistance when preventing blossom end rot on the fruits as they begin to form. You may use straw, grass clippings, or any commercial mulch material. Apply about four inches deep and hopefully this will help prevent those leathery bottom tomatoes.
Keep spraying, or dusting, cucurbits and potatoes. Different things on each, but the potato leaf hopper populations have increased, and the beetles that transmit the wilts on cucurbits are present. Sevin and bifenthrin are the mainstays for these programs.
Japanese beetles will soon be emerging. Protect your favorite roses or apple tree with a cover spray of permethrin, bifenthrin, or Sevin liquid.Keep up foundation sprays to help control nuisance pests in the home. Crickets, millipedes, and ants are among those controlled to a great degree by spraying the foundation and adjacent foot or so of soil with permethrin or bifenthrin.
June 10, 2008
After some very severe infestations of bagworms the past several years, the calls have been coming in all year on the correct treatment times for bagworms this year. Year-in and year-out, the correct treatment time for bagworms is June 15.You can mark this date on your calendar for next year and be within a few days of the correct treatment time. With a very cool spring, a week later may be a possibility. The opposite is true for a very warm spring. The idea is to have all the eggs hatched before treatment, but not wait until the bagworms are almost mature.
The next problem is what to use. 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. The spring we have had is probably going to add a week to the timing, meaning the last week or so of June should be ideal.
Most people think that bagworms only affect evergreens. While evergreens may be their preferred host group, bagworms have a huge number of potential hosts. Through the years I have seen them on oak trees, grape vines, apples, and about any other growing thing you can think of. Make sure to check the tops of tall trees. An infestation may get started in a tall tree simply because you can't reach the top when applying a control. In that case, you'll have to use a taller ladder.
June 10, 2008
June 10, 2008
After several years of relatively few problems of junipers and arborvitae, we've had a resurgence in the shoot blights. The most common is phomopsis tip blight, which affects the new growth. New growth is susceptible until it loses its lighter color. Control consists of removing infected areas, and spraying new growth with protectant fungicides until it gets the dark green color. Symptoms are a "shepherd's crook" shape to the dead tips and the small black dots of the fungal fruiting bodiesKabatina and Cercospora blights affect older needles of evergreens. Kabatina blight is not as common, and it is not controlled by fungicides. Cercospora blight tends to infect the older needles on lower branches first. The appearance of branches is having only the new growth at the branch tips being green. Repeated applications of fungicides will have some effect on Cercospora. There are varieties resistant to these diseases, but you can't find one resistant to all three.
June 10, 2008
June 4, 2008
West Nile Virus (WNV) has quickly, and unfortunately, become a household phrase. With Illinois leading the nation in deaths from the virus, it behooves us all to take proper precautions. The excess moisture in much of the Midwest has led to one of the worst springs for mosquitoes in recent history. This is a more full-blown accounting of WNV.
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.
The first symptoms of WNV are often the deaths of susceptible bird species such as crows and blue jays. We have had bird deaths in the county many of the past summers, and. I'm also sure that this year will be no exception. The State Health Department is the agency in charge of testing birds for WNV.
Symptoms of WNV are rare in humans. A small percentage of people do develop fever, headaches, body aches, swollen lymph glands, and a body rash. Encephalitis develops in less than 1% of infected people, and this group can have headache, high fever, neck stiffness, tremors, and other symptoms.
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!
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).Elimination of mosquito breeding sites, treatment of larvae, and proper protection for people will go a long way in reducing the incidence of WNV in our area this summer. Further information on WNV may be found at http://www.urbanext.uiuc.edu/westnile/ .
June 4, 2008
It seems the leaf spot fungal diseases are present with a vengeance. Anthracnose and apple scab are very noticeable now. If you think your trees have escaped infection, hold a leaf up to the light to make sure. If you see light areas along the edges or between veins, you'll probably have the full-blown symptoms within a week.As there is no cure, keep the plants watered with an inch a week during dry spells. A little fertilizer also will help. Severe leaf drop early in the season will usually lead to another set of leaves being out in four to six weeks.