动态第843页 - 绿手指 - 养花技巧、花生病了怎么办、花园打理和设计

2017年08月30日

Dogwood trees are beautiful, iconic landscaping trees that come from the forest understory. Although they’re great for adding lots of curb appeal, they’ve got a few serious problems that can spoil the idyllic feel of your yard. It’s never good news when a tree gets sick, especially when it’s your stately dogwood tree. Dogwood tree blight, for example, is a fungal infection of dogwood trees that can turn these valuable visual assets into serious detriments. Read on to find out about dogwood tree blight and what you can do to help your plant through this rough time.[图片]Dogwood Anthracnose Information Dogwood blight, also known as dogwood anthracnose for the fungal pathogen that causes the disease, is a fairly new problem. It is believed to have started in the northeastern United States about 25 years ago, but has been spreading southward ever since. The early symptoms are similar to leaf spot diseases, with purple-bordered soft, wet spots appearing on leaves, especially around the margins. Once the disease spreads to leaf petioles and twigs, however, it becomes more obvious. Leaves attached to these infected areas will shrivel and turn black. In very advanced disease, lower branches may die, cankers may form on the limbs and trunk sprouts will increase in number.[图片]Controlling Dogwood Blight Dogwood blight control is difficult, but if you catch it early, you may be able to save the tree by cutting out all diseased tissues. That means all leaves, all twigs and all branches showing signs of infection must be removed and destroyed promptly. Small trees may be saved with a fungicide spray applied every 10 to 14 days as long as cool, moist weather persists. Prevention of dogwood blight is the best tool you’ve got to keep your landscaping trees healthy. Keeping your dogwood properly watered and fertilized is the first line of defense, two to four inches of mulch spread over the root zone will help maintain soil moisture. Removing spent leaves, pruning low branches, opening up a dense canopy and trimming water sprouts in the fall will create intolerable conditions for the fungus.[图片]If you’ve lost a tree to dogwood blight, consider replacing it with Oriental dogwood (Cornus kousa). It has a high tolerance to anthracnose. White dogwoods seem to be less susceptible to the infection than their pink counterparts; there are also new cultivars of the Appalachian dogwood series that are bred to be anthracnose resistant. Whatever you do, don’t transplant a wild dogwood into the landscape – this is how many infections started.

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2017年08月30日

Also known a swamp dogwood, silky dogwood is a mid-size shrub that grows wild along streams, ponds and other wetlands across much of the eastern half of the United States. In the home landscape, silky dogwood bushes work well in moist, naturalized areas and do a good job at stabilizing the soil in erosion-prone sites. Mature height generally ranges from 6 to 12 feet. Read on for additional silky dogwood information.[图片]Silky Dog Information Silky dogwood (Cornus amomum) is named for the silky gray hairs that cover the undersides of leaves and twigs, which turn purplish in spring and reddish-brown in autumn. It is from these silky hairs that make silky dogwood identification fairly easy. Clusters of tiny creamy white flowers bloom in late spring and early summer. The plant is often found in shade or semi-shade but tolerates moderate sunlight. Silky dogwood bushes may not be the best choice if your goal is a tidy, manicured garden, but the shrub’s rather unkempt, rounded appearance fits well into a natural setting. Birds love the pale blue fruit that shows up in late summer.[图片]Growing Silky Dogwood Shrubs A relative of dogwood trees, silky dogwood bushes are suitable for growing in USDA plant hardiness zones 5 through 8. The shrubs are adaptable plants that tolerate either dry or wet sites, but prefer moist, well-drained soil. Although silky dogwood withstands alkaline soil, the plant is better suited to slightly acidic conditions.[图片]Caring for Silky Dogwoods Water young shrubs regularly until the roots are well established. Once the shrubs are settled in, caring for silky dogwoods requires little effort. For example, you can water the shrub – or not. A 2- to 3-inch layer of mulch will keep the soil moist and cool. No fertilizer is required.[图片]Remove suckers if you want to limit growth, or allow the shrubs to grow unrestrained if you want to form a naturalized screen or thicket. Prune silky dogwood as needed into any size or shape you like, and be sure to remove dead or damaged growth.

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2017年08月30日

At maturity, it looks a bit like an elongated, bright red cherry and, in fact, its name references cherries, but it isn’t related to them at all. No, this isn’t a riddle. I’m talking about growing cornelian cherries. You may not be familiar with cornelian cherry cultivation and wonder what the heck is a cornelian cherry plant? Keep reading to find out how to grow cornelian cherry trees, uses for cornelian cherries and other interesting facts about the plant.[图片]What is a Cornelian Cherry Plant? Cornelian cherries (Cornus mas) are actually members of the dogwood family and native to areas of Eastern Europe and Western Asia (they even survive in Siberia!). They are shrub-like trees that can grow up to 15-25 feet in height if left unpruned. The plant can live and be fruitful for up to 100 years. They bloom early in the season, even prior to forsythia, and bloom for an extended period of time, carpeting the tree in a yellow haze of tiny blossoms. The bark of the tree is flaky, gray-brown to brown. Bright green glossy leaves turn purplish-red in the fall.[图片]Are Cornelian Cherries Edible? Yes, cornelian cherries are very edible. Although the plant is known primarily as an ornamental in the United States, ancient Greeks have been growing cornelian cherries for 7,000 years! The ensuing fruit is initially very tart and looks much like olives. In fact, the ancient Greeks pickled the fruit much like olives. There are actually a myriad of other uses for cornelian cherries such as for syrups, jellies, jams, pies and other baked goods. Russians even make it into a cornelian cherry wine or add it to vodka.[图片]How to Grow Cornelian Cherry Trees While historically significant, cornelian cherries have not been mass produced due to the elongated pit inside the fruit that is difficult to remove, as it is firmly entrenched in the pulp. More often, the trees are seen as ornamental specimens, popular and planted around the 1920’s. Cornelian cherry cultivation is suited to USDA zones 4-8. The trees do best in full sun to part shade and while they do well in a variety of soils, they prefer fertile, well-draining soil with a pH of 5.5-7.5. This adaptable plant is winter hardy to -25 to -30 degrees F. (-31 to -34 C.). The tree can be pruned and trained into a single stemmed tree if desired and is primarily insect and disease resistant with the exception of dogwood anthracnose.[图片]Cultivars include: ‘Aero elegantissima,’ with its variegated creamy-white leaves ‘Flava,’ with sweet, large, yellow fruit ‘Golden Glory,’ which bears large flowers and large fruit on its upright branching habit

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2017年08月30日

Crown canker is a fungal disease that attacks flowering dogwood trees. The disease, also known as collar rot, is caused by the pathogen Phytophthora cactorum. It can kill the trees it attacks or can leave them vulnerable to lethal attack by other pathogens. For more information on crown canker on dogwood trees, read on.[图片]Dogwood Tree Diseases Dogwood trees suffer from a variety of diseases and conditions, most of which result in only cosmetic damage. Some are caused by improper care, such as water stress, resulting from inadequate irrigation during dry periods. Other avoidable diseases include leafspot and sun scorch, which occur when this understory tree is planted in full sun. However, two dogwood tree diseases are potentially lethal to the trees. Both are canker diseases. One, dogwood anthracnose canker, kills leaves, twigs and branches, starting in the lowest branches. It often kills the tree within three to five years.[图片]The other deadly canker is known as crown canker of dogwood. Crown canker on dogwood trees is the most serious of the dogwood tree diseases in the eastern United States. It is caused by a canker that, over several years, girdles the tree and kills it. What are the first visible symptoms of crown canker on dogwood trees? You may not see the canker immediately on an infected tree. Look for undersized leaves of a lighter color than normal on a tree that appears stressed. Over time, twigs and branches die on one side of the tree as the disease spreads.[图片]Dogwood Crown Canker Treatment If you take steps to prevent dogwood tree bark problems, especially wounds, you are one step ahead of the game. Prevention of wounds is easier than dogwood crown canker treatment. As with many other canker diseases, crown canker of dogwood often enters through wounds on the base of the tree. Any dogwood tree bark problems that cause a break in the bark can allow in the disease. The most important step in dogwood crown canker treatment is prevention. Take care not to wound the tree with garden tools when you are transplanting it, or lawn mowers or weed whackers after it is planted. Insects or animals can also wound the tree bark and allow the disease to enter.[图片]Once the fungus has infected a large section of the dogwood’s base, you can do nothing to save the tree. However, if only a small area is diseased, you can try to stop its spread by cutting out the canker, removing all discolored bark and sapwood and some 5 cm of healthy bark. Use a sharp knife to perform this excision. Protect the new wound from infections by painting the area with orange shellac. Use an asphalt-base wound paint on the exposed heartwood. If the tree dies anyway, don’t replace it with another dogwood.

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2017年08月30日

If you’ve ever seen an elaborate Japanese pagoda, you know how the structure’s roof spreads out in symmetrical layers. The branches of pagoda dogwood are dense and layered too, and pagoda dogwood information says the trees get their common names from this branch structure. Despite its common name, the pagoda dogwood is actually an American native shrub. For more pagoda dogwood information, including tips for pagoda dogwood care, read on.[图片]Pagoda Dogwood Information Pagoda dogwood (Cornus alternifolia) is a large shrub or small tree for a garden or backyard. Native to the American East, the pagoda dogwood is hardy in U.S. Department of Agriculture plant hardiness zones 3 through 7. It is also an attractive plant. When you are growing pagoda dogwood trees, you’ll see that the branches are tiered and horizontal, turning up slightly at the tips. Pagoda dogwood information suggests that the blossoms are also a nice addition to a landscape. Although they are small, the creamy flowers are very fragrant and bloom in 2- to 3-inch groupings in late spring. These give way to berry-like drupes, the color of blueberries that appear on crimson stalks. The fruits mature in late summer. The long, oval leaves turn purple in autumn. This dogwood is of great benefit to wildlife. The flowers attract butterflies, and the dense foliage provides excellent nesting conditions for birds, while the drupes make meals for them too.[图片]Pagoda Dogwood Growing Conditions When you are growing pagodas, you’ll be particularly interested in tips about pagoda dogwood growing conditions. In fact, the trees have quite specific requirements. Ideal pagoda dogwood growing conditions include a sunny planting site that gets some shade during the heat of the afternoon. You’ll want to find a spot with moist, fertile soil. The soil should also be acidic and well drained. If you find a great planting location, growing pagoda dogwood trees requires less effort. That doesn’t mean that no pagoda dogwood care is required, however.[图片]Pagoda dogwood information suggests that these plants require regular irrigation. This is especially important in areas that do not get precipitation in the summer. It also helps your pagoda dogwood if you mulch the root area regularly. This locks in the moisture and also stabilizes the soil temperature.

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2017年08月30日

Dogwoods are beautiful trees with striking spring flowers. They are impressive trees to have around, but not every gardener has the space or the means to take care of a large tree. Other gardeners may not live in a zone warm enough to overwinter a dogwood outside. With some skill and attention, though, you can keep a dogwood tree in a container. Keep reading to learn more about caring for potted dogwood trees.[图片]Can I Grow Dogwood In a Container? Can I grow dogwood in a container? Technically, yes. It’s possible, but there are certain requirements to be met, and it’s not for the casual gardener. Dogwood trees have very dense, fast growing root systems that are less than ideal for container growing. They also need extremely well-draining soil, but at the same time the plants need lots of water, particularly in the first few years of life. Containers dry out quickly, so you’ll probably have to mulch heavily and water it every day or so.[图片]How to Grow Dogwoods in a Container When growing dogwood trees in pots, it’s important to give the roots plenty of room. This means you should opt for as big of a container as you can manage. Even so, you’ll want to remove the tree from its container to prune the roots back on occasion to keep it from becoming root bound. Again, container grown dogwoods will require plenty of moisture so you’ll have to water the tree frequently. You can also add a bit of mulch to the top of the soil, which should help it retain some of that moisture.[图片]Caring for potted dogwood trees in the winter is also tricky. The plants need cold temperatures in order to go dormant during the winter. If you want to bring it inside, it’s best to put it somewhere protected but unheated, like a shed or a garage.

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2017年08月30日

Evergreen dogwoods are beautiful tall trees grown for their fragrant flowers and remarkable fruit. Keep reading to learn more Cornus capitata information, including tips on evergreen dogwood care and how to grow an evergreen dogwood tree.[图片]Cornus Capitata Information Evergreen dogwood trees (Cornus capitata) are hardy down to USDA zone 8. They are native to east and Southeast Asia but can be grown in warm climates all over the world. They can grow as high as 50 feet (15 m.) in height, though they tend to top out between 20 and 40 feet (6-12 m.). In the summer, they produce very fragrant flowers, which are very small and surrounded by 4 to 6 bracts that are often mistaken for petals. The bracts come in shades of white, yellow, and pink. These flowers give way to very distinctive fruits that are actually dozens of tiny fruits fused together. These fruits are pink to red, about an inch in diameter (2.5 cm.) and round but bumpy. They are edible and sweet, but they can cause a litter problem if the tree is planted near a walkway. The leaves are dark and evergreen, though they are sometimes known to turn red to purple and partially drop in autumn.[图片]How to Grow an Evergreen Dogwood Tree Like many dogwood varieties, evergreen dogwood trees can thrive in both sun and shade. They do best in moist, clay to loam soil. They prefer acidity, but they can tolerate light alkalinity. They need a lot of water.[图片]The trees are monoecious, which means they can self-pollinate. It’s important to bear in mind, however, that they will not flower for 8 to 10 years if they are grown from seed. It’s best to start the trees from cuttings if you want to see flowers or fruit within the decade.

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2017年08月30日

Flowering dogwoods (Cornus florida) are deciduous trees native to the eastern half of the United States. These trees can add year-round beauty to the landscape. Let’s look at how to grow dogwood trees. Flowering dogwoods range in color from white to pink or red and generally bloom for about two to four weeks in early spring. They also add summer and fall color, with rich green foliage color in summer and reddish purple leaves during fall. This is oftentimes followed by brilliant red berries in winter. Proper dogwood care will bring these lovely trees to their height of beauty.[图片]How to Grow Dogwood Trees In their natural habitat, dogwoods are understory trees, which are generally surrounded or protected by other larger trees. Therefore, when caring for dogwood trees, this should be considered carefully before placement in the landscape. Locating these trees on the edge of wooded areas or in groups is oftentimes more suitable to their natural surroundings. They can also be used as a backdrop for azaleas or other spring-flowering shrubs. Flowering dogwoods can be grown in sun or shade; however, trees planted in partial shade generally perform better. Trees planted in full sun can be stressful, making them more susceptible to dogwood borers and heat stress. For care of flowering dogwood trees, dogwoods that are planted in full sun must also rely on frequent watering, especially during hot conditions. While dogwoods will grow in a variety of climates and soil conditions, they typically grow best in, and even prefer, well-drained, humus-rich soil that is slightly acidic.[图片]Planting Dogwood Care Bare root and burlap dogwood trees should be transplanted in late fall or early spring. Container grown trees can be transplanted anytime of the year, provided they are watered regularly after planting. A dogwood should be planted about two-thirds the depth of its root ball. The soil should be gently mounded around the sides of the root ball. Do not place soil directly over the top of the root ball, as this should be left slightly above ground level. It is acceptable to apply a layer of mulch to help conserve water; however, for good dogwood care, keep this a couple inches away from the trunk. Be sure to water the tree thoroughly after planting and on a regular basis until the tree establishes itself.[图片]Care of Flowering Dogwood Most dogwoods require supplemental water during summer and fall, especially during hot, dry spells. For care of flowering dogwood trees, regular watering once a week to a depth of 6 inches should suffice. However, adding a generous layer of mulch will help retain moisture, minimizing watering chores. Most established trees do not require fertilizer. However, if you do choose to fertilize young dogwoods, use only a small amount of slow-release fertilizer. Dogwood trees seldom need pruning; however, it may be necessary to remove dead or injured branches, suckers, and diseased or insect-infested parts on occasion. Shaping trees may also help keep them more attractive looking.[图片]Flowering dogwood trees are considered “bleeders,” which means they bleed sap, if pruned during late winter. Summer is an ideal time to take care of any pruning tasks that may be needed since these plants do not bleed sap during this time. Once established in the landscape, caring for dogwood trees is relatively easy. As long as they have been planted in the proper conditions and location, the overall care of flowering dogwoods is minimal.

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2017年08月30日

Cypress trees are fast-growing North American natives that deserve a prominent place in the landscape. Many gardeners don’t consider planting cypress because they believe it only grows in wet, boggy soil. While it’s true that their native environment is constantly wet, once they’re established, cypress trees grow well on dry land and can even withstand occasional drought. The two types of cypress trees found in the U.S. are bald cypress (Taxodium distichum) and pond cypress (T. distichum).[图片]Cypress Tree Info Cypress trees have a straight trunk that tapers at the base, giving it a soaring perspective. In cultivated landscapes, they grow 50 to 80 feet tall with a spread of 20 to 30 feet. These deciduous conifers have short needles with a feathery appearance. Most varieties have needles that turn brown in winter, but a few have lovely yellow or gold fall color. Bald cypress has a tendency to form “knees,” which are pieces of root that grow above the ground in odd and sometimes mysterious shapes. Knees are more common for trees grown in water, and the deeper the water, the taller the knees. Some knees reach a height of 6 feet. Although no one is sure about the function of knees, they may help the tree get oxygen when they are underwater. These projections are sometimes unwelcome in the home landscape because they make mowing difficult and they can trip passers-by.[图片]Where Cypress Trees Grow Both types of cypress trees grow well in areas with lots of water. Bald cypress grows naturally near springs, on lake banks, in swamps or in bodies of water that flow at a slow to moderate rate. In cultivated landscapes, you can grow them in almost any soil. Pond cypress prefers still water and doesn’t grow well on land. This variety is rarely used in home landscapes because it needs boggy soil that is low in both nutrients and oxygen. It grows naturally in Southeastern wetlands, including the Everglades.[图片]How to Care for Cypress Trees Growing cypress trees successfully depends on planting the in the right location. Choose a site with full sun or partial shade and rich, acid soil. Cypress trees are hardy is USDA zones 5 through 10. Drench the soil around the tree after planting and cover the root zone with 3 to 4 inches of organic mulch. Give the tree a good soaking every week for the first few months. Cypress trees need water most in spring when they enter a growth spurt and in fall just before they go dormant. They can withstand occasional drought once established, but it’s best to water them if you haven’t had a drenching rain for more than a month.[图片]Wait a year after planting before fertilizing a cypress tree for the first time. Cypress trees growing in a regularly fertilized lawn don’t generally need additional fertilizer once established. Otherwise, fertilize the tree every year or two with a balanced fertilizer or a thin layer of compost in fall. Spread a pound of balanced fertilizer for each inch of trunk diameter over an area approximately equal to the spread of the canopy.

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2017年08月30日

Rejuvenating a cypress tree necessarily means trimming, but you have to be careful how you wield those clippers. Cutting back cypress trees too drastically results in dead wood and unattractive trees. Read on for more information on pruning cypress trees.[图片]Can You Prune a Cypress? Cypress trees are narrow-leaf evergreens. Like other narrow-leaf evergreens, cypress do not develop new buds on the older wood. That means that cutting new shoots back to the branch may result in bare spots on the tree. On the other hand, cypress tree trimming is entirely feasible if you know what you are doing. Cypress are one of several species classified as “scale-leaf” needled evergreens. Unlike pine trees, with leaves that look like needles, cypress leaves appear more like scales. Both cypress and false-cypress are included in this category. Rejuvenating a cypress tree that is overgrown or unshapely involves trimming. Although excess pruning is destructive to a cypress, cutting back cypress trees at the right time and in the right way creates a better, stronger tree.[图片]Rejuvenating a Cypress Tree If you are thinking of rejuvenating a cypress tree, it is important to prune at the correct time of year. Dead, broken and diseased branches should be removed as soon as possible after you notice the damage. However, pruning to shape the tree or reduce its size must wait for the appropriate season. When you are rejuvenating a cypress tree that is overgrown, begin cypress tree trimming just before new growth begins in the springtime. You can pick up the pruners again in late spring or early summer if necessary to control growth or maintain an attractive tree shape.[图片]Tips on Cutting Back Cypress Trees The rule when pruning cypress trees is to work slowly and gently. Proceed branch by branch to determine what cuts are necessary. Cut back each overly-long branch to a branch fork with a green shoot growing from it. This is the most important rule for cutting back cypress trees: never cut all green shoots from any branch since the branch will not be able to grow more. Proceed from the underside of the branches, slanting the cuts up.[图片]When you are pruning cypress trees, aim for a natural look by pruning some branches deeper into the foliage than others. The tree should not look “pruned” when you are done.

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