Eastern tent caterpillar, Malacosoma americanum (Fabricius), is a widespread defoliator of trees in the eastern U.S. Despite its name, the eastern tent caterpillar occurs as far west as the Rocky Mountains. Its favorite hosts are wild cherry, chokeberry, apple, and crabapple. The caterpillars will also construct web tents in a wide variety of trees including ash, oak, maple, cherry, peach, and plum. Their tents or webs are most prevalent in April, May, and early June.

The black, hairy caterpillars hatch from eggs in the spring from an over- wintering mass of eggs. Caterpillars usually select a fork or branch for the construction of a tent from which they go forth and feed on the newly opened leaves. As the caterpillars grow, so does the size of the tent. Damage to the tree can be severe because infested trees are forced to use their remaining stored reserves in the early spring to produce new leaves. The caterpillars leave the tent during the day to feed but return at night, and they feed for five or six weeks before the caterpillars are fully grown.

The fully-grown caterpillars are generally black with a white stripe down the back and a series of blue dots between yellow lines that run the length of the caterpillar. When they reach this stage, they leave the host-feeding tree and go to another location such as a fence, tree trunk, or some other protected space to spin a white cocoon in which they will transform into a reddish-brown moth that has two white strips running across each forewing. The adult moths emerge in late June or early July to mate and lay eggs for the following year.

Eastern tent caterpillars occur in abundance at cyclic intervals of about

10 years. As the population builds, so do natural enemies such as birds. In the meantime, damage can be reduced on small trees by getting rid of the egg masses during the winter or by clipping and destroying the tents and their occupants. Because larvae do not venture out of their tent during rainy, cool days, or at night, these are the best times to remove tents. For chemical control, most insecticides will not penetrate the web tent so you must break open the tent before applying the insecticide. Some recommended chemical controls include acephate, Bacillus thuringiensis kurstaki, and carbaryl. If chemical control is warranted, Bacillus thuringiensis kurstaki is the preferred insecticide because it selectively kills the caterpillar and not the natural enemies of other pests. Always read the label and follow all instructions, including allowable plants to be treated.

Many summertime lawn ills can be prevented with some attention now. The secret to a good lawn is to have it in the best condition possible before the stresses of summer begin. Grass death in the Midwest is usually due to diseases.

To avoid these diseases, the grass should be well rooted into the soil; have a minimum of thatch; be adequately, but not excessively, fertilized; and either properly watered or allowed to go dormant in dry weather.

Start by digging out a plug of turf and examining it for thatch. This is a brown-to-black layer of old roots and rhizomes above the clay soil. If the layer is more than 1/2 inch thick, core aerify.

A core aerification will make 3-inch deep holes every 2 inches or so throughout the lawn. The holes will penetrate the thatch mat, allowing better infiltration of water and nutrients to the grass roots.

If bare areas larger than 3 square inches exist, dig out the dead grass, thatch, and roots, and then loosen the soil. Sow a blend of three or four Kentucky bluegrasses and no more than 25 percent perennial ryegrass in these spots. Gently rake the seed into the soil and firm with the back of a shovel or a light oller. Moisten and cover with a light layer of straw.

Do not apply a complete lawn fertilizer to the entire lawn until mid-May.

Crabgrass preventer should be applied in early April. If you have done any re-seeding, be sure to use siduron-containing crabgrass control such as Tupersan, which kills some germinating annual grasses but won't do much damage to your new grass seedlings. Wait until May or September to apply weed control for broadleaf weeds.

Keep the grass mowed at 2 to 2½ inches tall, and mow often enough to remove only an inch or so at each mowing.

If the weather turns dry, you have the option of allowing the grass to go dormant or watering. If you opt to water, wait until the grass wilts; then, apply 1 inch of water early in the day. Put a tin can under the sprinkler so you know when you have an inch of water.

Do not water again until the grass wilts. Shallow watering or watering every night is disastrous to a lawn because it kills the deep roots and stimulates shallow rooting.

If you have a severe thatch problem or shallow rooting, diseases will sooner or later attack your grass. Regular core aerification and dethatching as often as you can afford it will eventually break down the barrier between the thatch and soil beneath, enabling the grass to root deep into the soil.

Chemical control of ring and patch diseases has met with little success. Where the diseases have become so severe that the lawn is essentially destroyed, the only remedy may be to remove the entire lawn, prepare a seedbed, and re-seed.

For more lawn care tips, download the Spring Lawn Care Guide at http://web.extension.uiuc.edu/regions/hort.

The peachtree borer is a common and often destructive tree fruit pest found where stone fruits such as peaches, nectarines, plums, cherry, and apricot are grown.

There are actually two species of peachtree borers, one known as the "lesser peachtree borer" and the other known simply as the "peachtree borer." These two species have slightly different life cycles and require different control approaches.

Damage by the lesser peachtree borer is caused by tunneling larvae feeding in the main limbs and upper trunk. It is mainly a problem in older trees. In contrast, the peachtree borer targets egg laying at the base of the tree—with larvae entry, feeding, and exit wounds located at the soil line of the trunk or just below ground. The peachtree borer prefers younger trees.

With both species, injury symptoms include quantities of gum or sap oozing from the bark wounds. The larvae feed inside the wood through the summer and fall, over-winter inside of the wood as larvae or pupae, and emerge as adults the next season to mate and repeat the cycle.

Understanding adult emergence timing and subsequent timing for egg laying is important for control.

The lesser peachtree borer adults begin to emerge in mid- to late May, with several generations occurring through the season, which makes season-long control necessary. The peachtree borer only has one generation and will begin emerging in early July.

Depending on over-winter development, initial emergence of the wasp-like adult moths for both species can be variable, and usually not all at once. Mating, egg laying, and new larval infestation can occur within two weeks after emergence. Protective sprays should be applied to limbs and trunks (not leaves) prior to larval tunneling.

If you regularly spray your trees with a combination insecticide/fungicide fruit tree spray mix, these cover sprays will provide some protection from borers, especially if trunks and limbs are covered along with fruit and leaves.

However, separate, directed limb and trunk sprays may be necessary. For lesser peachtree borer, begin supplemental sprays in late May to early June, and repeat sprays at 3- to 4-week intervals through earlySeptember. Sevin^TM, mixed at a strong rate of 3 tablespoons per gallon water, should be sprayed on the trunk and scaffold (main) limbs. If you are targeting the peachtree borer (for example protecting young trees), a trunk spray in late July, and again at the end of August, should be sufficient.

Without taking control measures, peaches, plums, cherries, and nectarines can be significantly weakened and even killed by these two types of peachtree borers.

More information about tree fruit pest and disease control is available in the U of I Home Yard and Garden Pest Guide, available through your local Extension office or online at PubsPlus, https://pubsplus.uiuc.edu

If you haven't yet visited the SI Gardening website, take a few minutes to browse at http://web.extension.uiuc.edu/regions/hort. This site contains printable fact sheets on all kinds of topics—from growing bulbs to lawn care to growing pecans. The site also contains information for commercial fruit and vegetable growers, as well as fact sheets on common insect problems in and around the home. You'll find a link to The Green Thumb newsletter, you can subscribe to the weekly SI Garden Column, and you can check out area gardening events in the News and Tips section.

If you don't have internet access, your local U of I Extension office can print any of the fact sheets for you.

Fire blight, caused by the bacterium Erwinia amylovora, is a common and potentially serious plant disease, specific to the family Rosaceae. It strikes apple and pear trees but can also affect other rose family members such as spirea, mountain ash, raspberries and blackberries, cinquefoil, quince, hawthorn, and cotoneaster.

The disease is also referred to as blossom blight, shoot blight, twig blight, spur blight, fruit blight, or rootstock blight—depending on the plant part that is infected.

Fire blight gets its name because infected trees appear as if they have been scorched with fire. Shoots infected with fire blight can be identified by the characteristic "shepherd's hook" on the tip.

Death can result if the infection is severe, especially on younger trees and trees grown on fire blight susceptible rootstocks. In most cases, fire blight will not kill an apple or pear tree, but trees can become unsightly and yields can be reduced.

Three conditions are necessary for the development of fire blight—the presence of the pathogen, moist conditions, and a high temperature. The fire blight bacteria over winters in cankers formed from the previous year and resumes growth in the spring when favorable conditions are reached. Fire blight enters the plant tissue through natural openings and wounds created by insects, storm damage, and mechanical injury. Favorable conditions include rain, heavy dews, or high humidity in combination with an optimum temperature range of 65^o to 86^oF. Without favorable conditions, infection does not proceed.

Highly Susceptible
Apple – Braeburn, Cortland, Fuji, Gala, Jonathon, Lodi, Rome Beauty, Winter Banana
Pear – Anjou, Bartlett, Bosc, Red Bartlett, Starkrimson

Moderately Susceptible
Apple—Empire, Golden Delicious, Granny Smith, Jerseymac, Jonafree, Jonagold, Jonamac, McIntosh, Mutsu, Spartan, Stayman
Pear—Maxine, Seckel

Moderately Resistant to Resistant
Apple—Red Delicious, Liberty, Enterprise, Prima, Priscilla, Pristine, Redfree, Winesap, William's Pride
Pear—Moonglow, Starkling Delicious

If a tree develops fire blight, what should be done? Fire blight can be unsightly if it's a heavy infection, and many growers feel the need to remove the infected plant parts. But, it is best to delay the removal of infected shoots until the dormant season to avoid spreading the infection to healthy shoots. In addition, summer pruning promotes new growth, which is more susceptible to fire blight. If pruning cannot be avoided, wait for dry weather when conditions are less conducive to infection spread. Always make the pruning cuts at least 6 inches below the last point of visible infection. Sterilize the pruning shears between each cut by dipping them in 1 part liquid bleach to 4 parts water.

Avoid over-fertilization of apple and pears because this practice also promotes lush green growth, which is highly susceptible to fire blight. Pears are generally more susceptible to fire blight than apples, and for this reason, fertilization is generally not recommended unless the tree demonstrates a nutritional need through reduced growth or yield.

Another line of defense against fire blight is chemical control. One option is Bordeaux mixture applied during the dormant stage to further reduce the inoculum level. Another option is the use of agricultural streptomycin labeled for apples and pears, like Ferti•lome Fire Blight Spray. Agricultural streptomycin can be applied during critical periods occurring between bloom and petal fall.