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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Pestalotiopsis is a type of needle blight fungal disease that is primarily found on arborvitae (Thuja). It is usually considered a secondary disease that attacks foliage that has been injured or weakened by unfavorable weather or growing conditions. The disease may kill the smaller twigs where the infected needles died.
Symptoms and Diagnosis The blight usually starts at the tip of the foliage and progresses towards the leaf base. Affected foliage color progresses from green to yellowish, then to a dark brown that looks almost black. Twig tips can also turn brown and have black, pimple-like, pinhead size, fungal fruiting structures dotting the surface. Usually, killed foliage is near the base of the plant where foliage is relatively dense. The plants may appear scorched.
Life Cycle Infections can occur at anytime of year. However, spring is the most likely time because favorable weather conditions exist and plants are showing stress from winter conditions. Integrated Pest Management Strategies 1. Avoid over crowding plants to allow for sufficient sunlight and air circulation. 2. Keep plants healthy with good cultural practices. Follow proper watering, fertilization practices and minimize any mechanical and snow/ice damage, etc. that could cause an entry point for the fungus.
3. Prune out dead foliage and twigs as soon as possible. 4. Application of fungicides should not be necessary. If necessary in certain circumstances (e.g. a nursery), copper fungicides are registered for this use as a preventative. Always read and follow product label directions before application to plants.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Ozone is the most damaging air pollutant to plants. The action of sunlight (ultraviolet radiation) on molecular oxygen and oxides of nitrogen spontaneously generates ozone. The organic compounds in automobile exhaust enhance ozone accumulation. Ozone can move across great distances to cause damage to plants far from its origin and is therefore classified as a non-pointsource pollutant.
Symptoms and Diagnosis The extent of damage depends on the concentration of ozone, the duration of exposure, and plant sensitivity. Acute damage to deciduous trees causes marginal leaf burn and dot-like, irregular-shaped lesions or spots that may be tan, white, or dark brown. Symptoms may spread over entire leaves. Another common symptom is bleaching of the upper leaf surface. Broad-leaved trees often exhibit these symptoms of stippling or red-purple or necrotic flecks on the upper leaf surface only.
Acute damage to conifers causes browning at the same point on all needles in a bundle (needle cluster). Other symptoms include chlorotic (yellow) mottling or necrotic (brown to black) banding, tip burn, dwarfing, and tufted appearance due to early defoliation of older needles. Damage from ozone can be confused with other problems and, if suspected, a more detailed reference material (such as Diseases of Trees & Shrubs by Sinclair, Lyon, & Anderson) should be consulted. Life Cycle Ozone builds up to phytotoxic levels in the atmosphere during warm, sunny weather when pollutants accumulate in stagnant air. Accumulation often occurs during atmospheric inversions in valleys and basins bounded by mountains.
Ozone may cause damage to plants far from the source of its precursors as masses of polluted air move overland. Ozone from natural sources (carried from the stratosphere or generated during electrical storms) alone is inconsequential for plant health, but may be added to that generated by humans. Integrated Pest Management Strategies 1. Maintain plant vigor. Plants that are in good health resist all type of injury better than weakened plants. Water during drought periods. Fertilize following a soil test report. Soil should be porous, well-draining, and not compacted.
2. Select plants. Select plants tolerant of air pollutants. 3. Reduce emissions. Reduce emissions from the source when possible.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Decline of trees and shrubs can be described in two ways–gradual and sudden. Sudden decline can cause the death of a plant anywhere from a month to a couple of years. Gradual decline generally occurs over several years. It can sometimes be difficult to distinguish between the two, not noticing the decline until too late.
The sudden death of trees and shrubs can be brought on by a single, primary cause that kills an otherwise healthy plant. This might be the case with an aggressive pathogen like Dutch elm disease or white pine blister rust. With gradual decline, no one particular disease causes the plant to die. Instead, conditions weaken the plant to the point that secondary organisms are able to invade the stressed plant. Dieback and decline diseases are caused by the successive action of primary stress factor(s) followed by organisms of secondary action that can successfully attack only weakened trees. One may attribute the plant’s decline to these secondary organisms, but an experienced professional knows the problem lies deeper.
Factors that lead to decline are many. This includes adverse weather conditions, such as rapid changes in winter temperatures and late spring and early fall frosts, flooding or changes in the water table, drought, bark damage from lawn mower injury or weed eaters, frost cracks, or animal feeding. Injury can also occur from lawn weed killers or other chemicals, accumulated salt injury from road salt, environmental pollution, soil fertility, or girdled or restricted root development. Finally, leaf loss from insects or diseases and damage from construction around the tree because of soil fill, root pruning, or soil compaction from heavy equipment can also be causes. Working singly or together over several years, these stresses can eventually result in tree or shrub death. A good example leading to gradual decline might be root decline where symptoms observed in the aboveground parts of the plant usually begin in the root system. When trees and shrubs are under stress, physiological changes occur in the roots, allowing fungi to infect the tissue.
Removal of the stress factors is required to save the declining plant. In many cases, action may come too late or may be impractical to carry out. Symptoms and Diagnosis Symptoms usually develop slowly and may not be noticed immediately. Trees and shrubs exhibit an overall loss of vigor. Early symptoms might include premature fall coloration of leaves, late leaf emergence in spring, production of foliage in clumps, decrease in twig growth, dieback, death of tissues between the leaf veins, and premature leaf drop. Later symptoms might include sprouting from the trunk, heavy seed crop production, dieback of larger limbs and branches, and foliage noticeably smaller and lighter green (chlorotic). The foliage over the entire plant may also look thinner in decline conditions. These visible symptoms may not occur until the plant is severely stressed. In the autumn, clusters of mushrooms may form at the base of infected trees. Wood-boring insects such as borers are also frequently associated with declining plants as they are attracted to weakened, stressed plants. Scale insects are also commonly found on stressed plants.
Integrated Pest Management Strategies 1. Location.Avoid placing plants in a stressful situation. Select species that are suited to the conditions of the planting location or modify the planting site to suit the requirements of the plant. This would include planting in a well-draining soil with the correct pH for the plant. Environmental conditions should also be considered, such as full sun for a sun-loving plant—not in the shade of another plant. Use warm weather plants in warm climates and moisture-loving plants in wet conditions. 2.Inspection. Prevention and early detection are the key to keeping trees and shrubs healthy. Inspect plants often and watch for symptoms of stress. 3. Planting. Do not crowd plants in restricted areas, such as close to sidewalks or streets, or place too many plants in an area that cannot support them. 4. On-going care. Water to reduce drought stress. Using a fertilizer like 5-10-5 that is high in phosphorus and low in nitrogen will stimulate root growth rather than shoot growth. Mulching over the root system will help prevent the loss of water, decrease compaction from rain, and keep the roots cool in the summer and warmer in the winter.
5. Pruning. Prune all dead and dying branches and no more than 10 to 20% of the remaining live branches at any one time. This should balance the foliage to the root system. If more pruning is necessary, complete this over 2–3 years. 6. Compaction. Compacted soil will cause a slow, sure death for many plants. Locate children’s play areas, dog runs, or car parking areas away from valuable trees and plantings. Core aerate compacted areas and around the drip line of trees. Change traffic patterns to reduce compacting the soil under trees. 7. Removal.Remove dead trees and shrubs and dispose of any infected material.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Kabatina blight is caused by the fungal organism Kabatina juniperi. It results in tip dieback of one year-old growth, causing death to terminal branch ends. It is a problem of junipers, cypress, and arborvitae in North America and Europe.
Symptoms and Diagnosis Kabatina symptoms occur in late winter or early spring, generally in February and March, when the terminal 2-6 inches of diseased growth turns a dull green or yellow brown and then red or yellow as the infection progresses. Damage can be confused with winter injury. This disease may also be confused with phomopsis tip blight as both may result in dead tips but symptom occurance is quite different for the two diseases. Phomopsis blight infection occurs in spring and results in the yellowing and death of new, succulent juvenile foliage. Once the needles are fully green and mature phomopsis is not capable of causing infection. Kabatina, however, can infect mature foliage in the fall, winter or the following spring.
Life Cycle The disease survives on infected plant debris as grayish lessions at the base of blighted portions of shoots. Fruiting bodies develop as small black "pimples," numerous in spring and diminish as the season progresses.The spores are moved by rain and irrigation and enter wounds or small opening caused by mechanical damage or insect feeding. The primary infection time is believed to be in fall although symptoms are not apparent until late winter or early spring. (Note: Symptoms of phomopsis tip blight occur in late spring as the new growth develops.)
Integrated Pest Mangement 1. Sanitation. Prune and destroy infected twigs and branches during dry weather. Avoid unnesessary wounding during wet weather which can provide entry points for the fungus. Damage is restricted to tips and doesn't cause death of the plant. 2. Good culture. Maintain adequate fertility for the plants but do not over fertilize. Avoid watering at night when the plants will remain wet all night long. 3. Fungicides. There are no fungicides currently registerd to control kabatina blight.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Dothistroma blight is a foliar disease of a number of pine species throughout the Midwest. Austrian pine is the primary host plant in Missouri. This blight is caused by the fungus Dothistroma pini, which infects and kills needles. The disease makes pines in landscapes unsightly and successive years of infection can result in decline and death of the tree.
Symptoms and Diagnosis The earliest observable symptoms are dark-green bands and tan spots or bands on the mature needles. The spots and bands later turn reddish-brown. The needles will begin to die back from the tip, but needle bases usually remain green. From the time symptoms are first noticed to the time of needle browning may take 2–3 weeks. Infected needles will drop prematurely. Infection typically is most severe in the lower crown of the tree, closer to the inoculum that spreads from infected needles that have fallen from the tree.
Life Cycle Dothistroma overwinters in infected needles. The infective spores are released during wet weather and dispersed by rain splash throughout the growing season. Because of the continual release of spores, infections can occur anytime from late April to late October. The fungus attacks the mature foliage; current season's needles are resistant until they are fully mature. Symptoms on newly infected tissue are especially obvious in early fall.
Integrated Pest Management Strategies 1. Live with the disease but monitor yearly. This disease is slow to spread. Annual spraying is not necessary in residential plantings. Wait and see how serious the problem becomes in one season. Serious infections can be prevented in the next growing season with the use of fungicides.
2. Plant resistant pines.Research on Austrian pine has determined that some populations are highly resistant to Dothistroma. Ask for these at your local garden center or nursery. Choose other nonsusceptible evergreens. 3. Apply fungicides. Adequate control of Dothistroma blight can be achieved with one or two sprays in late spring using a copper-based fungicides such as Bordeaux mixture. The first spray in early to mid-May protects mature foliage. A second spray in mid- June will protect the current season's needles which are resistant until they are fully grown. Other protectant fungicides include chlorothalonil (Daconil), Mancozeb and pentachloronitrobenzene.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Cytospora canker is caused by a fungus, Leucostoma kunzei (formerly known as Cytospora kunzei). In its perfect stage, it is known as Valsa kunzei. It is a destructive disease of many of the spruces, especially Colorado blue and Norway spruces, from the Midwest to New England. The disease is more common on trees over 15 years old and trees under stress and of low vigor. Trees with shallow roots, weakened by mechanical injury, insect, or weather stresses, and trees growing on unfavorable sites are most susceptible. The disease destroys the symmetry of spruce trees and in time may kill them. Infections on Colorado blue spruces are usually confined to branches. Branches and trunks are damaged on black, Engelmann, Norway, red, and white spruces. Cytospora cankers have also been found on Douglas fir, hemlock, larch, and balsam fir.
Symptoms and Diagnosis Dying of lower branches is usually the first symptom. The needles turn brown and after a few months drop off, and white or light blue patches of resin become obvious on the dead bark of larger branches. As the disease progresses over several years, higher branches also die. Dead areas called cankers are formed. The infected inner bark tissue and cambium are brown in contrast to the normal light color of healthy tissue, but the wood beneath the infected bark is not discolored. As cankers enlarge and girdle the stem, parts above the diseased area lose color, make little growth, wilt or wither, and die back from the tips. Infected branches often start growth later in the spring. The resin exuded from cankered branches is visible on dead bark after infected needles are cast. This is the most obvious symptom on infected branches.
Life Cycle The fungus overwinters in cankered bark. Spores from fruiting bodies formed in cankers are spread by rain, wind, insects, birds, and man. Infection occurs through wounds. The fungus grows and kills the bark, then expands until the entire branch is killed from the branch being girdled. Integrated Pest Management Strategies 1. Prune out diseased branches. Prune out all infected branches and burn or remove them from the site. Prune in late winter when it is sunny and the trees are dry. Dip pruning tools into a solution of 1–part bleach and 9–parts water between cuts to reduce spreading the disease. After pruning, oil blades to prevent rust.
2. Avoid injuries to bark and stems. Wounds can provide entry points for the pathogen, especially during wet periods. 3.Improve plant health. Water during dry periods and aerate the soil around the tree to relieve soil compaction and facilitate water and nutrient penetration. Fertilize to maintain vigor. 4. Maintain good air circulation. Chances of infection are greater on plants that are crowded together. Space plants out when planting to accommodate mature growth.
5. Fungicidal sprays are seldom effective and are not recommended. Once the tree is infected, the disease is difficult to control. Bordeaux mixture or other copper-containing fungicides may help slow the spread of the disease. The best time to apply fungicides has not been established. Consider using fungicidal sprays only if the tree is very valuable and you are willing to pay for regular sprayings. 6. Remove the infected tree and plant a different species or variety. Blue and Norway spruce are most susceptible to Cytospora canker.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Brown spot needle blight is a fungal disease of pines caused by Mycosphaerella dearnessii. It affects much pine in the Midwest including mugo, Japanese black, Virginia, eastern white pine, and most noticeably Scots pine. It is similar in appearance and can be confused with Dothistroma needle blight which is more commonly found on Austrian and ponderosa pine in the St. Louis area.
It generally starts on the lower branches and moves up the tree. It also favors the north side of the plant which is more humid. The blight is most damaging on small trees but over time can retard growth and weaken mature trees.
Symptoms and Diagnosis Dead needles, which turn brown or a burnt red-orange and then drop is characteristic of the disease. The loss of 2nd and 3rd needles is accelerated and branches may look bare except for small tufts of needles at the tips. Damage usually begins on lower branches first. Yellow to tan spots first appear in May to September on current year needles. Brown spots appear mid to late summer and coalescing into bands encircling the needles and causing death of parts beyond the band. The bands may occur at any location along the length of the needle. Resin may appear on the spots. By fall the spots may appear resin-soaked. By late summer/autumn yellow halos may surround brown bands and spots. Straw-colored lesions becoming light tan with a dark border may appear raised as surrounding, uninfected tissue dies. Dead needles drop in fall.
Life Cycle In late spring to early summer spores on dead needles initiate new infections through stomata on the needles. June-July is the most active infection period. In late summer, fruiting bodies called pycnidia form on infected needles in the tree and on the ground. The spores spread by splashing rain to new infection sites. Infection is favored by warm, humid conditions. Integrated Pest Management Strategies 1. Live with the disease. If damage is slight you may decide just to live with a few browning needles. The plant can easily survive light infections. 2. Sanitation. Remove and dispose of diseased needle on the tree if practical and most certainly those on the ground as these are the source of on-going infection.
3. Refrain from overhead watering. Since splashing water spreads the spores, limit overhead watering or do so only early in the day so the needles dry quickly. 4. Improve air circulation. High humidity and slow drying needles fosters infection so prune out dense foliage and evaluate nearby plants to see if pruning them might promote faster drying of the pine's needles. Provide ample spacing between plants.
5. Use fungicides. copper-based fungicides such as Bordeaux mixture are effective as a protectant. Other protectant fungicides include chlorothalonil (Daconil) and Mancozeb. Follow label directions for application. 6. Plant resistant pines or other plants. Consider replacing the pines with a species that is more resistant to the disease or an evergreen other than a pine, such as spruce, arborvitae, or juniper.
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Dummer. ゛☀
2017年09月18日
Dummer. ゛☀
Poison ivy, Toxicodendron radicans, is usually a vine twining on trees and occasionally an upright bush if there is no support. Each leaf is made up of three leaflets more or less notched at the edges. Two of the leaflets form a pair on opposite sides of the leafstalk, while the third leaflet stands by itself at the tip of the leafstalk. Small greenish flowers grow in bunches attached to the main stem close to the point where each leaf joins it. Later in the season, clusters of poisonous, berry-like drupes form. They are a dirty yellowish-white, waxy berry similar to mistletoe. The leaves are red in early spring becoming shiny green in summer and then turning red or orange in autumn.
Integrated Pest Management Strategies 1. Pull small plants. If only a few small plants are found, pull and dispose of the plants using rubber gloves and arm protection. Avoid touching the leaves. Dispose of the plants in a plastic bag so they will not be touched by others. All parts of the plant are toxic. NEVER BURN THE PLANTS. The fumes are as toxic as touching the plant and worse if inhaled.
2. Use herbicides. For small areas, poison ivy killers available in aerosol cans may be a good choice. They are effective and convenient but are too expensive for treating large areas. Another option is to use glyphosate (Roundup, Kleenup). Spray the leaves of actively growing plants taking care to protect nearby desirable plants from spray drift which can damage or kill them. Leaves can also be selectively "painted" with the solution using a brush or wiped on plants using a disposable cotton rag. Use rubber gloves approved for use with garden chemicals and avoid contact of the herbicide with skin and eyes.
A combination of 2,4-D and Banvel is also effective, but use 2,4-D with care as nearby plants may be sensitive to the drift. To kill the roots of large plants, cut the stem at soil level. Then paint the cut with undiluted 2,4-D. Mound soil over the treated stub. Amino triazole (Amitrol-T, Amino Triazole 90, and Weedazol) is also highly effective and safe to use. Available as a liquid or wettable powder, it should be applied during periods of rapid plant growth. Thorough coverage of the foliage is essential.
3.Use biological controls. Sheep and goats will eat poison ivy. Tether them in areas where you need poison ivy cleared. Not all municipalities or neighbors may welcome this control measure.
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Dummer. ゛☀
2017年09月17日
Dummer. ゛☀
Succulents don’t always fare well when exposed to the hot sun day in and day out. In nature, succulents often grow under or near a shrub or tree where they receive bright light but not constant direct sunlight. Don’t automatically plant your succulent smack-dab in the middle of the garden, where it receives endless hours of direct sunlight, especially during the summer. Instead, carefully select its growing location where your succulent will receive enough sunlight, but not too much.
1. Determine how much direct sunlight your succulent should receive each day. Consider whether your succulent plant requires only 4 hours of direct sunlight a day, which is the case with most succulents. Plan to provide succulents with afternoon shade in areas that are scorched by hot summer sun. 2. Plant your succulent on the east side of a building, tree or another structure that is exposed to morning sun if your plant should be protected from the afternoon sun. Plant it under a tree, if desired, that receives filtered sunlight throughout the day during the summer, which also protects it from the afternoon sun. Alternatively, plant your succulent in a sunnier location, such as on the west or south side of your home, if your climate is mild during the summer and is not afflicted with hot, scorching summer days.
3. Examine your succulent 2 to 4 weeks after planting and several times during the summer. Notice whether it is indented, or has a tan, yellow or red color on the side that faces the most sun, both of which indicate that your plant is receiving too much direct sunlight. Determine whether your succulent is not growing well, which could mean that it needs more sunlight, especially if you are providing it with proper water and fertilizer. 4. Transplant your succulent to a sunnier spot, or prune nearby trees and shrubs to increase sunlight exposure, if necessary. Alternatively, transplant your succulent to a shadier site, or plant a shrub or other plants near it to provide more shade if your plant is getting too much sunlight.
Tip Keep your succulent in a container for the first growing season so you can easily move it around until you find the best location. Slowly acclimate your succulent to its new growing location before planting it, especially if it was previously an indoor plant. Place it in the sun for 2 hours a day for 1 or 2 days. Increase the amount of time it spends in direct sunlight by one-half hour every day until it is exposed to the same amount of sunlight as it will get in its new location. Sketch your landscape and mark possible planting locations. Take a day to examine and record the amount of sunlight each area gets and what time of day.
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