1. Ash Borer The adult form of this insect is a clear-winged, day-flying moth that resembles a wasp. The adults emerge in August or September and deposit eggs on the bark of the lower trunk. The larvae hatch out, then bore through the bark and feed within the branches and trunk of the tree until the following fall when they emerge as adults. 2. Dothistroma Needle Blight One of the most common fungal diseases of pines in Nebraska is Dothistroma needle blight. This disease is responsible for much of the premature needle drop that occurs in windbreaks and ornamental pine plantings. Twenty pine species are affected by this disease, but in the central and eastern United States the fungus is found most commonly and causes the greatest amount of damage on Austrian and Ponderosa pine. Scotch pine is usually not severely damaged. Symptoms of infection begin in the fall. Yellow or tan spots appear on needles of the current year's or older growth. These spots darken and become brown or reddish-brown then spread to form a band around the needle. These bands are often bordered by a yellow, chlorotic ring on each side. The fungus grows within these tissues, killing that portion of the needle beyond the lesion. 3. Zimmerman Pine Moth The larvae of this pest damages trees by tunneling just beneath the bark of the trunk and branches, most commonly on the trunk just below a branch. The tunnels they make can girdle the trunk or branches or physically weaken them so they are easily broken by wind or snow. Heavily infested trees are often deformed and are sometimes killed. 4. Iron Chlorosis In eastern Nebraska, it is common to see slow growing pin oak or silver maple trees with yellow leaves and possibly some branch die back. Many trees, shrubs, and other ornamental plantings in Nebraska suffer from this problem, called iron chlorosis. It is caused by poorly drained or compacted soils or by soils with a high calcium content, characterized by pH levels above 7.5. This high pH level causes iron, which is usually present in plentiful quantities, to be tied up in the soil and unavailable for the plants to pick up and use. 5. Spruce Spider Mite A tiny pest of spruces, hemlocks, arborvitae, junipers, and other conifers, the spruce spider mite is often most damaging in the cool weather of spring and fall. 6. Japanese Beetle The adult beetles feed on the leaves, flowers, and fruit of a wide range of landscape plants. The grubs feed on the roots of many plants and are often damaging to lawns. 7. Lacebug Usually found on the underside of leaves, lacebugs quickly cause damage that is apparent from the top of the plants. Lacebugs are difficult to control due to multiple generations each year. 8. Elm Leaf Beetle The larvae of this beetle consume the leaves of elms, leaving only veins of the foliage. The adult beetles are often a nuisance when they over-winter in buildings. 9. Aphid Aphids are sucking insects that build up to huge numbers on tender new shoots and leaves. A black stain known as "sooty mold" is a problem beneath infested trees.

1. Dutch Elm Disease (DED) This fungus disease affects the vascular system of the elm, causing a rapid wilting and failure to all American and European species of elm. Millions of elms throughout North America and Europe have died due to this disease. Today, many new treatments are available to combat DED. Treatments include a new biological control agent. Hybrid elms and several new selections of American elm that show resistance to the disease have been developed. 2. Anthracnose This fungus disease causes leaf, shoot, and bud blight on many deciduous trees including sycamore, dogwood, oak, and maple. Favored by cool, rainy weather in spring, anthracnose will weaken and can kill highly susceptible species like dogwood. Management of this disease includes fungicide treatments in spring and maintaining plant health through proper fertilization, mulching, and irrigation during droughts. 3. Bacterial Leaf Scorch A newly recognized disease, bacterial leaf scorch affects a wide range of plant species. Oaks, sycamores, and elms are especially at risk. Foliage browning (scorching) followed by defoliation occurs in mid to late summer. Branch dieback and subsequent decline occurs over a period of years. This eventually leads to the failure of the plant. Treatments are available to slow the decline and extend the life of the affected plant, but no cure or preventive measures are available yet. 4. Phytophthora Root Rot This fungus disease causes root rot and stem cankers on many landscape trees and shrubs. Phytophthora is most prevalent on clay soils that are poorly drained and on sites receiving excessive irrigation. Fungicide treatments are available to suppress this disease. Careful selection of plant species for sites prone to root rot and judicious irrigation are also keys to managing this disease. 5. Fireblight A bacterial disease, fireblight causes shoot blight and stem cankers on certain plants in the rose family. Pear, apple, and crabapple trees are affected. Highly susceptible species can be severely disfigured and even killed by this disease. In addition to preventive treatment to manage fireblight, many highly resistant apple, crabapple, and pear varieties are available. 6. Needlecast This fungus disease causes premature defoliation of spruce, Douglas fir, and pine. Chronic infections will devitalize trees, causing branch dieback, especially on the lower portions of the tree. Although treatments are available to suppress this disease, planting conifers in full sun with adequate spacing to allow development is the key to disease prevention. 7. Scab Scab is a foliage disease that produces raised, dark lesions on leaves, and premature defoliation of apples and crabapples. Applying fungicide treatments in spring, removing fallen leaves and planting resistant varieties are the key considerations in controlling this disease. 8. Powdery Mildew This foliage disease usually begins to appear in summer when the weather turns warm and humid. Dogwood, lilac, rose, and crape myrtle are among the species that are most susceptible to mildew. Thinning dense plants to improve light and air penetration along with preventive fungicide treatments help to suppress this disease. 9. Verticillium Wilt A soil-borne disease, verticillium causes wilting, decline, and failure of many species of landscape plants. Cultural practices including mulching, irrigation, and pruning aid in recovery of affected plants. The site must be replanted with a resistant variety if plantings are replaced. 10. Drought (Moisture Stress) This is a non-infectious disease which accounts for most plant losses. The past few years have been prone to drought conditions. Moisture stress is a particular concern for shallow-rooted plants such as dogwood or azalea. Recent transplants should be monitored. Judicious use of irrigation and proper mulching are critical for plants sensitive to moisture stress.