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Keeping landscape plants healthy and beautiful can be a challenge. Sherri Sanders UAEX White County Agent and colleagues developed this guide for identifying and managing Arkansas' most common #landscape problems caused by weeds, insects, and diseases. Download this guide for FREE by clicking the link. https://www.uaex.edu/publications/pdf/MP-468_2020.pdf
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Disease is a general term that can include fungal, bacterial and viral pathogens. All three of these pathogens can lay dormant until favorable conditions present themselves. This can be related to temperature, moisture or plant health. Many of the diseases we encounter in the South favor hot and humid conditions. It is important to identify whether you are dealing with fungal, bacterial or viral pathogens. The control for each of these is completely different. This a list of potential disease problems you may encounter in your garden. POWDERY MILDEW This disease can attack everything from trees and shrubs to vegetables. It appears as a gray-like powder on the tops of leaves. It is one of the only fungal disease problems that favors dry weather. It is most common in late spring and early fall. Powdery mildew can be controlled by spraying approved fungicides at 10 to 14 day intervals. FUSARIUM WILT This another fungal pathogen that attacks a broad range of plants, including ornamentals and vegetables. This fungus occurs in the soil and penetrates the roots of the plant, working its way into the vascular system. It begins to clog up the plants "plumbing" causing leaves to turn yellow and stems to wilt. Treatment is very difficult once the plant is infected. Vegetable plants normally will die and need to be removed. SEPTORIA LEAF SPOT AND SPOT ANTHRACNOSE These are two very common diseases that can be caused by either bacterial or fungal pathogens. Correct identification will be needed when selecting a control. Many times affected leaves can simply be plucked off and discarded. On larger shrubs and trees, the disease tends to be more of a cosmetic issue and the plant can normally survive. BACTERIAL WILT Bacterial wilts are caused by several different strands of bacteria and can affect vegetables, flowers, and other herbaceous plants. This disease can be transmitted through infected soil or through insects feeding on infected plants and transmitting to healthy plants. Bacteria cause a disruption in the vascular system of plants causing them to discolor, wilt, and eventually die. Once bacteria enter into the plant, it is almost impossible to control. Discard infected plants and keep damaging insects under control to help with the spread of disease. Fumigation or solarization of the soil my be an effective way to control the disease for future crops. FIRE BLIGHT This disease is actually a bacterium that is very host specific and affects members of the rose family. This includes pears, apples, crabapples, hawthorn, and Pyracantha. The disease is fed by insects feeding on the plants and is most active in late spring during warm, humid weather. Infected branches wilt and turn brown and then black as if scorched by fire. Spraying for this disease can be tricky depending upon the height of the plant or tree. Once infected, prune the damaged branches down several inches into the good wood. Remove the cut branches from the site. VIRUSES There are many viruses that can affect anything from ornamentals to fruit trees and vegetables. Viruses normally cause discoloration or mottling of leaves. Leaves and branches are often deformed and twisted and leaves may appear elongated or tiny. Insects, soil or moisture can carry or spread viruses. There are no effective controls so cutting damaged areas out and plant removal are the only remedies. DAMPING OFF This disease is caused by several species of fungi and is common in our Southern soils. It is one of the main causes of poor germination of vegetables and annual flowers. Seedlings are very susceptible when they first emerge. This disease is most prevalent in high-nitrogen soils that stay consistently wet. Plant seeds in well-amended and well-drained sites to minimize the chance of infection. Do not add high-nitrogen fertilizers until seedlings have grown several sets of leaves. Fungicide-coated seed can also discourage damping -off. PHYTOPHTHORA AND PYTHIUM ROOT ROT Both of these fungi thrive in wet, poorly drained soils. They can attack the roots and stems of plants causing them to rot and eventually die. Gardeners frequently mistake the wilting for drought stress. Often individual plant branches die first and then the overall plant turns yellow and eventually dies. Prevent this disease by planting only in well drained areas. Water plants only when necessary and allow soil to dry out between irrigations. This short list of disease problems are only a handful of what is actually out there, but these are definitely some of the most common ones you may encounter. Careful plant selection and good cultural practices will go along way toward keeping your plants healthy and avoiding these potential killers. Excert from
"THE BEATEN PATHOGEN" By Bob Westerfield Arkansas Gardener October 2015 Bagworms, Thyridopteryx ephemeraeformis, produce conspicuous spindle-shaped cocoons on trees and shrubs throughout the United States. Bagworms feed on over 128 plant species. The most commonly attacked plants are arborvitae, red cedar, and other juniper species. They will also feed on fir, maple, juneberry, buckeye, persimmon, ginkgo, honeylocust, larch, sweet gum, spruce, pine, sycamore, poplar, oak, locust, willow, and hemlock. Symptoms and Diagnosis The principle harm done by the insect is the destruction of foliage by the caterpillars. Plants usually are partially defoliated, weakened, and rendered unsightly. Complete defoliation can occur. The most notable sign of bagworm infestation is the presence of protective bags attached to a branch. The bags incorporate bits of twigs and leaves from the host plant. They are approximately 1 to 2 inches long and resemble Christmas tree ornaments hanging from the limbs. Life Cycle The adult female bagworm does not look like a moth and never leaves her bag. She is maggot-like in appearance, soft-bodied, and yellowish-white. A mated female lays between 500 and 1000 eggs within the bag, after which she dies. The eggs remain inside the bag throughout the winter until they hatch the following spring. There is one generation a year. From late May to mid-June, bagworm larvae (caterpillars) begin emerging from the bags. Almost immediately after emerging, a larva starts to produce its own protective bag. The bag is constructed such that the larva's head and legs are free. This construction allows the larvae to move about the plant as it feeds on the foliage. As the larva grows, it increases the size of its bag. The full-grown larvae are about one inch long. When a host plant becomes defoliated, the larvae will crawl off it with their bags and search for a new plant to feed upon. In mid-August, the mature larvae stop feeding and attach their bags to a twig. They close up the bag and pupate. By mid-September, the bagworm has completed its development, and adult males begin emerging from their bags. The male moth has a black, furry body and feathery antennae. The wings are almost transparent and have a span of about one inch. Integrated Pest Management Strategies 1. Handpick the bags. The most economical method of controlling bagworms is to handpick the bags and destroy them. Some birds and insect predators feed on larvae, so light infestations on large, healthy plants are usually controlled by natural means. On large plants, monitor infestations before resorting to chemical sprays. If the problem doesn't get worse, spraying is not required. 2. Use biological controls. In spring, as soon as eggs hatch and the young emerge, spray with Bacillus thuringiensis (Bt). Bt is a bacterium that causes the larvae to become sick, stop feeding, and later die. In St. Louis, the eggs hatch in late May to mid-June, or about the time the cigar tree, Catalpa speciosa, is in full bloom. 3. Use chemical controls. Because bagworms form protective bags very early, contact insecticides, while useful, are less effective than stomach poisons. For best control, spray when insects are young. Chemical controls become less effective as the bagworm matures. Chemical controls include acephate (Orthene), cyfluthrin and spinosad. Source: Missouri Botanical Garden
The Emerald Ash Borer (Agrilus planipennis or EAB) is responsible for the destruction of tens of millions of ash trees in 27 states. Native to Asia, it likely arrived in the United States hidden in wood packing materials. The first U.S. identification of Emerald Ash Borer was in southeastern Michigan in 2002. There are a variety of treatment options that can serve as a control measure for the EAB, but they are not a cure. Because pesticide regulations differ from State to State, homeowners should contact their State department of agriculture or local extension office for guidance.
What is at Risk:
What is the source:
Signs and Symptoms:
What you can do:
Source: USDA
Animal and Plant Inspection Service |
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