动态第832页 - 绿手指 - 养花技巧、花生病了怎么办、花园打理和设计

2017年09月02日

If you think your yard is too small for oak trees, think again. Columnar oak trees (Quercus robur ‘Fastigiata’) offer the magnificent green lobed foliage and ridged bark that other oaks have, without taking up all that space. What are columnar oak trees? They are slow-growing, slender oaks with a tight, upright and narrow profile. Read on for more columnar oak information.[图片]What are Columnar Oak Trees? These unusual and attractive trees, also called upright English oak trees, were first found growing wild in a forest in Germany. These types of columnar oaks were propagated by grafting. Columnar oak tree growth is moderately slow and the trees grow up, not out. With these trees, you don’t have to worry about the spreading lateral branches you associate with other oaks. Columnar oak trees might grow to 60 feet tall, but the spread will remain about 15 feet. The dark green leaves turn brown or yellow in autumn and remain on the tree for months before they fall in winter. The trunk of the columnar oak is covered in dark brown bark, deeply ridged and very attractive. The tree has small acorns hanging on the branches most of the winter that attract squirrels.[图片]Columnar Oak Information These ‘fastigata’ types of columnar oaks are easy-care trees with outstanding ornamental qualities. Because the columnar oak tree growth direction is up, not out, they are useful in areas where you don’t have room for wide trees; the crown of the columnar oak remains tight and no branches break out of the crown and wander out from the trunk. Ideal columnar oak tree growth conditions include a sunny location. Plant these oaks in direct sun on well-drained acidic or slightly alkaline soil. They are extremely adaptable and very tolerant of urban conditions. They also tolerate drought and aerosol salt.[图片]Caring for Columnar Oak Trees You will find that caring for columnar oak trees is not difficult. The trees tolerate drought, but do best with occasional irrigation. These are good trees for cooler climates. They thrive in U.S. Department of Agriculture plant hardiness zones 4 or 5 through 8.

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2017年09月02日

Sudden oak death is a deadly disease of oak trees in coastal areas of California and Oregon. Once infected, trees can’t be saved. Find out how to protect oak trees in this article.[图片]What is Sudden Oak Death? The fungus that causes sudden oak death (Phytophthora ramorum) results in a quick death for tanoaks, California black oaks, and live oaks along the coast of California and Oregon. The fungus also infects the following landscape plants: Bay laurel Huckleberry California buckeye Rhododendron[图片]Here are the symptoms of sudden oak death: Cankers on the stems and branches. Leaves in the crown that turn pale green, then yellow, then brown. Cankers that bleed and ooze. In the alternative species, it causes non-fatal leaf spot or twig dieback instead of the bleeding cankers it causes in oaks. Sudden oak death can infect other species of oak, but those species don’t grow in habitats where the fungus is found, so for now, it isn’t a problem. Since P. ramorum has been identified in nursery stock in California, Oregon and Washington, there is a possibility of the disease spreading to other parts of the country.[图片]Sudden Oak Death Information This disease is always fatal in susceptible oak species and there is no cure. Sudden oak death treatment focuses on prevention and protection. Here are a few things you can do to protect your susceptible oaks: Allow 15 feet between the trunk of an oak tree and other susceptible species, such as bay laurel and rhododendron. Spray the fungicide Agri-fos to protect oak trees. This is a preventative spray, not a cure. Don’t plant new oak trees in areas with known infection.

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2017年09月02日

Water oaks are native to North America and found across the American South. These medium sized trees are ornamental shade trees and have an ease of care that makes them perfect in the landscape. Try growing water oak trees as street plants or primary shade trees, but be aware that these plants are short lived and can be assumed to survive 30 to 50 years. Read the article below for more water oak information.[图片]Water Oak Information Quercus nigra is a tolerant plant that can grow in partial shade or sun to full sun. These elegant trees are deciduous to semi-evergreen and an important part of ecosystems from New Jersey to Florida and west to Texas. Water oaks grow at a fantastic rate of up to 24 inches per year. Caring for a water oak is easy, but it is a weak wooded tree prone to many diseases and insect pests.[图片]Water oaks produce copious quantities of acorns, which are a favorite food of squirrels, raccoons, turkeys, pigs, ducks, quail and deer. Deer also browse young stems and twigs in winter. The trees tend to develop hollow stems, which are habitat for a host of insects and animals. In the wild, it is found in lowlands, flood plains and near rivers and streams. It has the capacity to thrive in compact or loose soil, provided there is adequate moisture. Water oaks may be short lived but their rapid growth makes them an excellent shade tree for decades. However, special water oak tree care when young is essential to produce a strong scaffold. Both pruning and staking may be necessary to help the tree develop a sturdy skeleton.[图片]Growing Water Oak Trees Water oaks are so adaptable they are often used as residential, reclamation or even drought zone trees. They may be planted in areas with pollution and poor air quality and the tree still thrives. The trees are reliably hardy in United States Department of Agriculture zones 6 to 9. Water oaks get 50 to 80 feet tall with a nice cone shaped crown. Bark ages to brownish black and thickly scaled. Male flowers are insignificant but female catkins appear in spring and become wide ½ inch long acorns. The leaves are oblong, spatulate and deeply tri-lobed or entire. Foliage may grow 2 to 4 inches long. These trees are extremely adaptable and, once established, caring for a water oak is reduced to handling any pest or disease issues and providing supplemental water during extremely dry periods.[图片]Water Oak Tree Care Water oaks must be trained when young to prevent the crotch from splitting due to poor collar formation and the weight of the side limbs. Young trees should be trained to a central trunk for best plant health. The rapid growth of the plant contributes to its weak wood, which is often hollow by its 40th year. Provide young trees with plenty of water to ensure good cell development and thick wood. Oaksare host to a number of pest and disease issues. Caterpillars, scale, galls, and borers are the insects of most concern.[图片]Oak wilt is the most serious disease but many fungal issues are often present. These might include powdery mildew, canker, leaf blight, anthracnose, and fungal leaf spot. A common deficiency in iron causes chlorosisand yellowing of the leaves. Most issues aren’t serious and can be combated by good cultural care.

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2017年09月02日

“Today’s mighty oak is just yesterday’s nut, that held its ground,” said author David Icke. Pin oak trees are mighty oaks that have held their ground as a fast growing, native shade tree in the eastern part of the United States for hundreds of years. Yes, that’s right, I did just use “fast growing” and “oak” in the same sentence. Not all oaks are as slow growing as we generally think they are. Continue reading to learn about pin oak growth rate and using pin oaks in landscapes.[图片]Pin Oak Information Native east of the Mississippi River and hardy in zones 4-8, Quercus palustris, or pin oak, is a large full, ovate shaped tree. With a growth rate of 24 inches or more per year, it is one of the faster growing oak trees. Tolerant of wet soils, pin oak trees usually grow 60-80 feet high and 25-40 feet wide – though in the right soil conditions (moist, rich, acidic soil), pin oaks have been known to grow over 100 feet tall. A member of the red oak family, pin oaks will not grow in areas of high elevation or on slopes. They are usually found in damp lowlands and near rivers, streams or lakes. Pin oak acorns are often dispersed far from the parent plant and germinated by spring flooding. These acorns, as well as the tree’s leaves, bark and flowers, are a valuable food source to squirrels, deer, rabbitsand various game and songbirds.[图片]Growing Pin Oaks in Landscapes During the summer, pin oak trees have dark green, glossy leaves that turn a deep red to bronze color in the fall, and hang on throughout winter. The beautiful foliage hangs from thick, dense branches. Having a rather ovate shape that turns more pyramidal with age, pin oaks’ lower branches hang down, while the middle branches reach out horizontally and the upper branches grow upright. These pendulous lower branches can make pin oak a not-so-good choice for street trees or small yards. What makes pin oak an excellent tree for large landscapes is its quick growth, beautiful fall color and winter interest. It also has the ability to provide dense shade, and its shallow fibrous roots make planting a pin oak tree easy. On young trees, the bark is smooth, with a red-gray color. As the tree ages, the bark becomes darker gray and deeply fissured.[图片]Pin oaks can develop iron chlorosis if soil pH is too high or alkaline, which causes leaves to turn yellow and drop prematurely. To correct this, use acidic or iron rich soil amendments or tree fertilizers. Other problems pin oaks can develop are: Gall Scale Bacterial leaf scorch Oak wilt Borers Gypsy moth infestations Call a professional arborist if you suspect any of these conditions with your pin oak.[图片]

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2017年09月02日

White oak trees (Quercus alba) are North American natives whose natural habitat extends from southern Canada down to Florida, over to Texas and up to Minnesota. They are gentle giants that can reach 100 feet in height and live for centuries. Their branches provide shade, their acorns feed wildlife, and their fall colors dazzle everyone who sees them. Keep reading to learn some white oak tree facts and how to include white oak trees in the landscape of your home.[图片]White Oak Tree Facts White oak trees get their name from the whitish color of the undersides of their leaves, distinguishing them from other oaks. They are hardy from USDA zone 3 through 9. They grow at a moderate rate, from 1 to 2 feet per year, reaching between 50 and 100 feet tall and 50 to 80 feet wide at maturity. These oak trees produce both male and female flowers. The male flowers, called catkins, are 4-inch long yellow clusters that hang down from the branches. The female flowers are smaller red spikes. Together, the flowers produce large acorns that reach over an inch long. The acorns are a favorite of a wide variety of native North American wildlife. In the fall, the leaves turn striking shades of red to deep burgundy. Especially on young trees, the leaves may stay in place all through the winter.[图片]White Oak Tree Growing Requirements White oak trees can be started from acorns sown in the fall and heavily mulched. Young seedlings can also be planted in the spring. White oak trees have a deep taproot, however, so transplanting after a certain age can be very difficult. White oak tree growing conditions are relatively forgiving. The trees like to have at least 4 hours of direct sunlight per day, though in the wild young trees will grow for years in the forest understory.[图片]White oaks like deep, moist, rich, slightly acidic soil. Because of their deep root system they can tolerate drought reasonably well once they are established. They do not, however, do well in poor, shallow or compacted soil. Plant the oak tree somewhere where the soil is deep and rich and the sunlight is unfiltered for the best results.

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2017年09月02日

Oak leaf gall mites are more of a problem for humans than for oak trees. These insects live inside the galls on oak leaves. If they leave the galls in search of other food, they can be a true nuisance. Their bites are itchy and painful. So exactly what are oak leaf mites? What is effective in treating for oak mites? If you want more information on how to get rid of oak mites, also called oak leaf itch mites, read on.[图片]What are Oak Leaf Mites? Oak tree gall mites are tiny parasites that attack gall larvae on oak leaves. When we say tiny, we mean tiny! You may not be able to spot one of these mites without a magnifying glass. The female and male oak tree gall mites mate. Once the females are fertilized, they enter the gall and paralyze the larvae with their venom. The female mites then feed on the larvae until their offspring emerge. An entire generation of oak mites can emerge in a single week, which means that the mite population can swell rapidly. Once the oak tree gall mites have eaten the gall larvae, they leave in search of other food. Even if they don’t run out of food, mites may leave the galls. They may fall from the tree or be blown off by a breeze. This usually happens late in the season when the mite population is very large. Some 300,000 mites can fall from each tree every day.[图片]Oak Mite Control Oak tree gall mites can enter a house through open windows or screens and bite people inside. More often, however, the mites bite people while working outdoors in the garden. The bites usually occur on the upper body or wherever clothing is loose. They are painful and itch a lot. People who are not aware of oak tree gall mites think they have been bitten by bed bugs. You might think that spraying the oak tree would be an effective oak mite control, but this is not the case. The oak tree gall mites actually live inside the galls. Since tree sprays do not penetrate the galls, the mites are safe from sprays.[图片]If you are wondering how to get rid of oak mites, there is no perfect solution. You can try to exercise oak mite control by using DEET, a commercially available mosquito and tick repellent. But in the end, you can only protect yourself best by being vigilant. Stay away from oak trees with galls toward the end of summer. And when you do go into the garden or near the trees, shower and wash your clothes in hot water when you come in from gardening.

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2017年09月02日

Mighty and majestic, the bur oak (Quercus macrocarpa) is a survivor. Its massive trunk and rough bark help it exist in a very broad natural range in a variety of habitats – from bottomlands to dry uplands. What is a bur oak? Read on for bur oak information and tips on bur oak care.[图片]What is a Bur Oak? Bur oaks, also called mossycup oak, are decidedly impressive oak trees native to North America. They grow in the wild in central and eastern sections of the continent. The common names comes from a mossy scale, or bur, on the acorn cup rim.[图片]Bur Oak Information Bur oak trees are medium to large sized trees. They are deciduous members of the white oak group and grow to heights between 60 and 150 feet tall (18 to 46 m.). If you are thinking of planting a bur oak, you’ll want to take height into account when selecting a site. Keep in mind that the trees also have broad, rounded crowns. Bur oak trees produce yellow catkin flowers in springtime, but they are not particularly showy. The acorns are oval with fringed cups, and offer a good food source for wildlife, including both birds and mammals. Don’t expect brilliant fall color in bur oak tree leaves. The green leaves turn a dull yellow-brown before they fall.[图片]Planting a Bur Oak Planting a bur oak is only a good idea for homeowners with very large backyards, given the size of the trees. The massive oak grows best in U.S Department of Agriculture zones 3 through 8. Be sure you site the tree with enough room to grow and in a permanent location. Bur oak information says that these native trees can live up to 300 years. If you do decide to start planting a bur oak, site the tree in full direct sun. Be sure the tree gets at least six hours of unfiltered sunlight every day. For best bur oak care, plant the tree in soil that is well drained and loamy. It will grow in either acidic or alkaline soil, and tolerates sandy, wet and clay soils too.[图片]And speaking of bur oak care, don’t forget to water the tree regularly, especially during its first year in your garden. Bur oak trees have some drought tolerance, but they will grow faster and healthier with moderate moisture. Note that bur oak trees tolerate city smoke and other air pollutants as well as compacted soil. They are often used as shade tree on U.S. city streets.

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2017年09月02日

Willow oak trees are very popular shade and specimen trees. Because they are fast growing and fill out with an attractive, branching shape, they are a frequent choice in parks and along wide streets. Keep reading to learn more about how to grow a willow oak and willow oak tree care.[图片]Willow Oak Information Willow oak trees (Quercus phellos) are native to the United States. They are hardy in USDA zones 5 or 6a through 9b, making their range the whole of the west coast, most of the east coast, and the entire south and southwest. The trees are fast growing. When they are young, they have a pyramidal shape, but as they mature their branches take on a wide, even spread. The lowest branches hang down somewhat toward the ground. The trees tend to reach a height of 60 to 75 feet (18-23 m.) with a spread of 40 to 50 feet (12-15 m.). The leaves, unlike other oak trees, are long, thin, and dark green, similar looking in appearance to willow trees. In the autumn, they turn yellow to bronze in color and eventually drop. The trees are monoecious and produce flowers (catkins) in the spring that can lead to some litter. The fruits are small acorns, no bigger than ½ an inch (1cm.) across.[图片]Willow Oak Tree Care Growing willow oak trees is easy and very rewarding. While they prefer moist, well-drained soil, they will thrive in almost any kind of soil and are wind, salt, and drought tolerant, making them popular in urban landscapes lining broad streets or filling in parking lot islands. They prefer full sun. They are, for the most part, resistant to both pests and diseases. Though they are drought tolerant, they will also perform well in soil that is perpetually wet. They’ve been used for decades as urban, street lining trees and have proven themselves to be up to the task.[图片]It should be noted that in smaller areas, it may be best to avoid the tree, as its height can eventually overpower the area.

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2017年09月02日

The neem tree (Azadirachta indica) has caught the attention of gardeners in recent years for the benefits of its oil, a safe and effective herbicide. However, that’s just the beginning of the story. This versatile plant, native to tropical India and Asia, is a valuable tree with many uses. Read on for neem tree information, including neem tree benefits and uses.[图片]Uses of Neem Tree Oil – Familiar primarily to organic gardeners in the United States, neem oil is made by pressing the oil-rich neem seeds. The oil is highly effective against a variety of pests, including: Aphids Mealybugs Fungus gnats Whiteflies It is also useful as a natural insect repellent and is often incorporated into shampoo, soap, lotion and other skin care products. Additionally, the oil makes a great fungicide for issues like powdery mildew, black spot and sooty mold.[图片]Bark – Neem bark isn’t widely used, although its anti-inflammatory and antiseptic properties make it a useful treatment for gum disease in mouthwash form. Traditionally, natives chewed the twigs, which served as effective, impromptu toothbrushes. The sticky bark resin is commonly used as glue. Flowers – Neem tree is widely appreciated for its sweet aroma, which honeybees love. The oil is also valued for its calming effect. Wood – Neem is a fast-growing tree that tolerates poor growing conditions and drought-prone soil. As a result, the wood is a critical source of clean-burning firewood in many frost-free regions of the world.[图片]Cake – “Cake” refers to the pulpy substance that is leftover after oil is extracted from the seeds. It is an effective fertilizer and mulch, often used to discourage diseases like mildew and rust. It is sometimes used as livestock fodder. Leaves – In paste form, neem leaves are used as a skin treatment, primarily for fungus, warts or chicken pox.[图片]How to Grow a Neem Tree Neem is a hardy tree that can tolerate temperatures up to 120 F. (50 C.). However, extended cool weather with temperatures below 35 F. (5 C.) will cause the tree to drop its leaves. The tree won’t tolerate colder temperatures, wet climates or prolonged drought. That being said, if you can locate fresh neem tree seeds, you can grow a tree indoors in a pot filled with good quality, well-drained potting soil. Outdoors, plant fresh neem seeds directly in the ground, or start them in trays or pots and transplant them outdoors at about three months. If you have access to mature trees, you can root the cuttings in late fall or early winter.[图片]Neem Tree Growth and Care Neem trees require plenty of bright sunlight. The trees benefit from regular moisture, but be careful not to overwater, as the tree won’t tolerate wet feet or poorly drained soil. Allow the soil to dry between every watering. Feed the tree about once a month in spring and summer, using a light application of any good quality, balanced fertilizer or a dilute solution of water-soluble fertilizer. You can also apply a diluted fish emulsion.

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2017年09月01日

Fruitless mulberry trees are popular landscaping trees. The reason that they are so popular is due to the fact that they are fast growing, have a lush canopy of dark green leaves and are tolerant of many urban conditions, plus, unlike their cousins the red and white mulberry tree, they do not make a mess with their fruit. Because of their popularity, many people become alarmed when the mulberry tree leaves start turning yellow. There are many reasons fruitless mulberry tree leaves turn yellow.[图片]Mulberry Leaf Spot Mulberry leaf spot is caused by a type of fungi that attacks the leaves of the tree. Fruitless mulberry trees are particularly susceptible to it. Mulberry leaf spot can be identified by the leaves growing somewhat malformed, yellowed and having black spots. Mulberry leaf spot can be treated with fungicide. Even without treatment, fruitless mulberry trees can normally survive this disease. The important thing to remember is that you will need to clean up and dispose of all the fallen leaves in the fall or winter. The mulberry leaf spot fungi over winter on the fallen leaves and in the spring, the rain will splash the fungi back onto the tree, which re-infects it for the next year. Removing and destroying the fallen leaves will help prevent this.[图片]Not Enough Water Fruitless mulberry trees grow rapidly and their root systems can grow to a massive size. What this means is that what may have been enough water one year will not be enough water the next. When the tree does not get enough water, the mulberry gets yellow leaves. A mulberry tree may be particularly prone to this during periods of drought when the leaves will be transpiring water faster than the roots can take it up.. The best course of action is too water the tree deeply about once a week. Watering deeply is better for the tree than multiple shallow waterings. A deep watering will get the water down into the root system so that more of the roots will be able to take water up at the same rate as the leaves transpire it.[图片]Cotton Root Rot Cotton root rot is another fungus that can cause a mulberry to have yellow leaves. Cotton root rot is characterized by yellowing leaves followed by wilting. The leaves will not fall off the plant though. Unfortunately, by the time the symptoms of cotton root rot are seen, the tree has most likely been damaged beyond repair and will most likely die within a year. Calling an arborist to look at the situation is advised due to the fact that cotton root rot will continue to spread in the soil and kill other surrounding plants and trees.[图片]Hopefully your mulberry tree will recover from whatever problem is causing the mulberry tree leaves to turn yellow. Fruitless mulberry trees are amazingly resilient and yours should bounce back in no time at all.

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