动态第587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24日

START by finding the right pot. Most important: the pot must have a drainage hole. Second, it needs to accommodate the bulb. Choose one that's an inch or two wider than the diameter of the bulb. Check the depth, too. Ideally, you have room for an inch or two of soil below the bulb once it's been planted. Keep in mind that your amaryllis will be a bit top-heavy when it blooms, so a heavier pot is better. [图片]Use fresh potting soil and moisten it before planting the bulb. This makes it easier to work with. If the soil goes in dry, it's hard to get the bulb situated. Do not use regular garden soil; it will not drain properly and your bulb might rot. [图片]Position the bulb so the top third will remain above the soil surface. Leave an inch or so between the soil surface and the rim of the pot. This will make it easier to water the bulb thoroughly. Be sure to pack the soil around the bulb, giving the plant a good foundation for when it's in flower. [图片]Place the pot in a relatively cool, bright location. Direct sunlight is not essential. Water sparingly until you see about 2″ of new growth. In some cases, the flower stalk appears first; sometimes it's the strappy leaves. Either way is fine. Once the plant is in active growth, water regularly and turn the pot periodically to encourage the stalk to grow straight. Buds will appear and blooms will begin to open within five to eight weeks. To prolong the blooms, keep the pot away from heat and direct sunlight. Sometimes the long flower stems benefit from a little extra support. An amaryllis support stake does the job nicely.

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2017年09月24日

FEW bulbs are easier to grow than amaryllis — and few bloom with greater exuberance and beauty. Just plant the bulb in good potting soil. A support stake is handy for keeping the blooms upright, but little else is required: water regularly and provide bright, indirect light. Blooms will appear four to six weeks [图片]after planting If your amaryllis is not already potted, plant each amaryllis bulb in a heavy, 6-8" pot. Lightweight pots may tip over. Plant the bulb, pointed-end-up, in potting soil. Do not use soil from the garden because it will not drain properly. Pack the soil gently around the bulb so approximately one-third of the bulb remains above the soil line. Place the pot in a sunny location and water sparingly until you see about 2" of new growth. From then on, water regularly. As the plant grows, turn the pot periodically to encourage the stalk to grow straight. Within five to eight weeks, you will have an exciting and dramatic floral display. To prolong the blooms, keep the pot out of direct sunlight. [图片]For Bloom Next Year Amaryllis can be encouraged to blossom again the following year. It takes a little planning and extra care, but is quite simple and very rewarding. After the flowers have faded, cut the flower stalk to within 1" of the top of the bulb. Continue to water and feed the plant regularly with a liquid houseplant fertilizer. Amaryllis will grow a number of leaves during the spring and summer. This will help the plant produce energy for the following year's bloom. In mid-August, begin withholding water and let the foliage die back naturally as the pot dries out completely. Store the dormant bulb in a cool, dark and dry place for a minimum of eight weeks. About five to eight weeks before you want the amaryllis to flower again, repot the bulb in fresh potting soil and resume watering — sparingly at first. Once you see new growth, increase watering. You can expect another dramatic floral display within five to eight weeks. By following these basic care guidelines, you will be able to encourage your amaryllis to flower year after year.

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2017年09月24日

IF you want to grow flowers from seed, start with sweet peas. The large seeds are easy to manage and most varieties germinate readily. Plus, the resulting blooms are gorgeous and sweetly scented. [图片]Pick a range of varieties Sweet peas come in a huge array of colors and patterns. Most will grow to 5 or 6 feet, but there are shorter varieties "bush type" that are well-suited to containers. To extend the blooming season, choose a few different types. Read the seed packets to find varieties that bloom early (“short-day”) and late (“long day”). Although most sweet peas are annuals, you can also get perennial sweet peas (Lathyrus latifolia). [图片]Start early Sweet peas (Lathyrus odoratus) thrive in cool temperatures, so it's important to get them blooming early, before summer heat knocks them out. You can plant them outdoors as soon as the soil can be worked in spring. Chances are it will still be quite cold, but the seeds will be fine. Gardeners in the south can start sweet peas in late fall for bloom in late winter or early spring. Check with your cooperative extension for best practice in your area. To ensure the longest-possible season of bloom, start your peas indoors. Timing is based on the last frost date in your area. Once you have that date, back it up four to six weeks. That's when you plant. For instance, if your last frost date is May 15, you should plant in early to mid-April. Don't know the last frost date in your area? Check with your cooperative extension, or a good gardener in the neighborhood. [图片]Prepare the seed Whether you're planting indoors or out, it's a good idea to break or soften the hard seed coat before planting. You can do this by soaking the seeds overnight in water or nicking the brown coating with a nail clippers or a piece of sandpaper. If you start your seeds indoors, use biodegradable pots, such as Cowpots, homemade Paper Pots or peat pots. The seedlings resent root disturbance, so it's best to have a pot that can go in the ground right along with your transplants. [图片]Provide a trellis Plant the vines about 6″ apart in a sunny location, ideally with protection from intense, afternoon sun. Unless you've selected a bush-type, your peas will need strings or a trellis of some kind. Peas use tendrils to climb. They can grasp anything that's a quarter-inch or less. Anything bigger won't work. The best support is string, twine, or netting with a grid that's at least 2″ x 2″ . Netting with smaller openings — ½″ or 1″ — will not work well. Trellis netting, such as Nearly Invisible Netting or Biodegradable Netting, is ideal. Mulch the soil surface to help keep the roots cool. Water if rainfall is insufficient and fertilize every 15 days or so with liquid fertilizer. [图片]Pick frequently To keep your vine productive, cut flowers frequently and remove the faded blossoms. Once summer heat arrives, your vine might turn brown and die, which is normal. At that point, you can pull it out and replant with something else. Some varieties tolerate heat better than others, such as Starry Night and Cupani's Original, so check your seed packets.

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2017年09月24日

A comprehensive guide to orchid care THE beauty, complexity and incredible diversity of orchid flowers are unrivalled in the plant world. These exotic beauties comprise the largest family of flowering plants on earth, with over 30,000 different species, and at least 200,000 hybrids. Orchids can be found in the equatorial tropics, the arctic tundra, and everywhere in between. The reason for this diversity lies in the orchid’s amazing ability to adapt to its given environment. With so many different orchid varieties that thrive in so many different growing conditions, it is relatively easy to find an orchid that is well suited to the conditions that you can provide — whether it is a kitchen window or a full-size greenhouse. Most cultivated orchids are native to the tropics. In their natural habitat, they attach themselves to the bark of trees, or the surface of other plants. Their thick, white roots are specially adapted to absorb moisture and dissolved nutrients. Because these tropical orchids usually grow high in the trees, rather than on the forest floor, they are accustomed to good air circulation and plenty of light. They prefer a 12-hour day, all year-round, and require a high intensity of light — about the same as midsummer conditions in temperate regions. Are orchids difficult to grow? Many of them are. In fact, some are almost impossible to keep alive, much less bring into bloom—even for professional growers. But there are dozens of varieties of orchids, and hundreds of hybrids, that are perfectly happy growing on a sunny windowsill or under lights. For your best crack at success, start by choosing one of the less fussy varieties that is adapted to the type of growing conditions you can provide. Buy the most mature plant you can afford (young plants are much more difficult to please), and, if possible, buy it in bloom, so you’ll know what you’re striving for. [图片]How Orchids Grow Orchids are usually grouped into two broad categories that characterize their growth habits. Monopodial orchids have a single, upright stem, with leaves arranged opposite each other along the stem. The flower stem appears from the base of the uppermost leaves. Orchids with this growth habit include the phalaenopsis and vandas. The more common growth habit is sympodial. These orchids grow horizontally, sending out new shoots from the old rhizome. Leaves and flower scapes form at the top of the new shoots. Many sympodial orchids form pseudobulbs, which are swollen shoots that store water and nutrients to help the plant survive periods of prolonged drought. Sympodial orchids include cattleya, cymbidium, oncidium and dendrobium. Orchids can also be classified by their native habitat, which gives an indication of the temperature, moisture and light levels they prefer. Orchids native to the humid tropics, such as phalaenopsis and paphiopedilum, prefer daytime temperatures of 73° to 85°F, with 80 to 90 percent humidity. They are happiest in an east or southeast window where the light is not too intense. Warm-climate orchids, including cymbidiums and dendrobiums, are accustomed to an average temperature of 55° to 70°F, a steady supply of moisture, and good air circulation. They are generally happy in a south-facing window, though they may need a little shading during high summer. Cattleyas and some oncidiums grow where days are dry and relatively cool. They are able to tolerate a long dry season with temperatures of 80° or 90°F, followed by a distinct rainy season. Their need for light is high, so they should be placed in a sunny, south-facing window. High-altitude orchids, such as masdevallia and epidendrum, grow in the cloud forests where average temperatures are 60° to 70°F, and humidity is very high. These orchids prefer filtered light that is not too intense. [图片]Caring for Orchids With 30,000 different species of orchids, it is impossible to give general care and cultivation instructions. However, how an orchid looks can provide clues to its preferences for light, water, and growing medium. If the plant has few leaves, or leathery leaves (like most cattleyas and oncidiums), it's likely the plant needs a high-light environment. If the leaves are soft and limp (like some phalaenopsis and most paphiopedilum), the plants are probably very light-sensitive, and should not be placed in a sunny south-facing window. If the orchid has fat pseudobulbs, it should be watered sparingly, and should be grown on coarse chunks of bark or lava rock. If the orchid has no pseudobulbs, it may require more frequent watering, or should be grown in a more moisture-retentive growing medium, such as sphagnum moss. Light: As a general rule, orchids are light-hungry plants. For best results, they should get 12 to 14 hours of light each day, year-round. In a tropical environment, the duration and intensity of natural light does not vary as it does in temperate climates. For this reason, you may need to move your orchids around, and supplement with artificial light to keep them happy during the winter months. South- and east-facing windows are usually the best spot for orchids. West windows can be too hot, and northern ones are usually too dark. If you don’t have a good window location for your orchids, they will be perfectly happy growing under artificial lights. Orchids should be positioned no more than 6 to 8 inches away from a set of 4-foot fluorescent bulbs. Opinions vary as to the benefits of cool white, warm white, and grow light bulbs. The new full-spectrum bulbs are probably the best all-around choice. Some orchids with very high light requirements, such as vandas and cymbidiums, may need high-intensity discharge lighting in order to flower. For more information, read Growing Under Lights. Growing media: Terrestrial orchids, such as paphiopedilums and some cymbidiums, grow in soil. But most tropical orchids are epiphytes, which means that they grow in the air, rather than in soil. Their fleshy roots are covered with a layer of white cells called velamen, which acts as a sponge to absorb water. The coating also protects the roots from heat and moisture loss. An orchid growing medium must provide good air circulation and permit water to drain very quickly. It must also give the roots something secure to cling to. Depending on the type of orchid, they can be happy growing in peat moss, fir bark, dried fern roots, sphagnum moss, rock wool, perlite, cork nuggets, stones, coconut fiber, lava rock or a blend that combines several of these materials. Some epiphytic orchids can also be wired onto slabs of tree fern or cork. As a general rule, fir bark nuggets are the most popular growing medium. Watering: Most orchids can tolerate drought far better than they can tolerate excess moisture. Nothing kills an orchid faster than letting it sit in a water-logged pot. Without adequate air circulation, the plant will suffocate and die. As a very general rule, orchids should be watered once a week. The growing medium should be allowed to dry out between waterings, and excess water should not come in contact with the roots or the growing medium. After being re-potted, most orchids will not resume active growth for several months. Water very sparingly during this readjustment period.[图片]Humidity: Most tropical orchids prefer humidity levels of 60 to 80 percent. With the winter-time humidity level in most homes hovering closer to 30 percent, orchid growers often use a humidifier, or set their orchids in special humidity trays or gravel-filled trays. Some orchids also benefit from being misted. Fertilizer: Orchid-growing mediums provide very few nutrients, so orchids must be fertilized to sustain healthy growth. Use a liquid fertilizer, and dilute it more than you would for other plants. Fertilizer should only be applied when plants are in active growth. This means that most orchids should not be fertilized in midwinter, or right after they have been re-potted. Many growers use a 30-10-10 fertilizer, though others prefer 10-10-10 or 10-10-30. Misting your orchids with fish emulsion or seaweed extracts will provide micronutrients. Potting and re-potting: Orchids are usually happiest in a relatively small pot. Plastic pots are preferred because when it’s time to re-pot, the roots can be more easily detached, or the pots can simply be cut apart. To ensure good drainage, you can fill the bottom inch or two of the pot with foam “peanuts.” Suspend the orchid over the pot, and gradually fill the pot with fir bark chunks or whatever other growing medium you are using. The crown of the plant should be just a bit below the top of the pot. Sometimes it's helpful to use a bit of wire to secure the plant until its roots get established. Some orchids should be re-potted every year. Others may be happy in the same pot for seven or more years. As a general rule, don’t re-pot your orchid unless necessary. Orchids resent being disturbed. Re-pot if the growing medium has started to break down enough to reduce aeration; if the roots are creeping out well beyond the pot; or if new growth has unbalanced the plant.[图片]Propagation: Propagating orchids from seed is quite difficult. Unlike the seeds of other plants, orchid seeds do not contain nutritional storage tissues. To grow, the seed must land where it will find a particular kind of fungi that can penetrate its root system and convert nutrients into a usable form. To overcome the odds, an orchid seed capsule typically disburses millions of microscopic seeds, which can be carried hundreds of miles from the mother plant. To propagate orchids from seed, you must work in sterile conditions. The seeds must be grown in a gelatinous substance that contains nutrients and growth hormones. You must also be very patient. It takes months for the first leaves to develop, and, even then, they will only be visible with a magnifying glass. Roots appear even later. It will be at least three, and possibly as many as eight years before you see a bloom. It is far easier to propagate orchids by division. But remember that dividing a plant means forsaking blooms for at least a year. Also, the larger the orchid plant, the more flowers it will produce. Small divisions take many years to mature.

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2017年09月24日

WHEN it comes to orchids, phalaenopsis (moth orchids) are among the easiest to grow. Blooms last for several months and you can get them to rebloom without a lot of effort. Well, some folks can. I haven't had good luck getting another bloom, and I have the shelf of non-blooming phalaenopsis to prove it. Frankly, I'm a little bit embarrassed. How do I get my orchids to bloom again? In an effort to improve my success, I checked in with our orchid expert at Gardener's Supply, Anita Nadeau. She helps customers in the conservatory at our Williston, VT, store. Here are her tips for getting phalaenopsis to rebloom: [图片]Pay attention to watering and humidity. If you neglect your phalaenopsis, it will not reward you with blooms. The plants are probably growing in a free-draining blend of fir bark, so you need to water regularly. Don't let the roots dry out completely between waterings. Most homes are quite dry during the winter, but you can increase the humidity by setting the orchid pots on a tray of pebbles or a special humidity grid. Make sure the pots are not sitting in the water; they should be just above it. [图片]Fertilize regularly. A fertilizing routine is just as important as a watering routine. Anita recommends feeding orchids with water-soluble fertilizer that's formulated for orchids. Mix at the rate recommended on the package. [图片]Make sure plants get enough light—but not too much. Anita says, "When a healthy orchid does not flower, it is usually due to not enough light." Phalaenopsis thrive in bright light, but not direct sun. This means east- or west-facing windows are best. If you can't provide adequate natural light, orchids will also thrive under full-spectrum lights.+ [图片]Provide cool nights. Most orchids thrive best when there is a marked drop in temperature at night, usually about 10 to 15 degrees F. Phalaenopsis are more forgiving in this respect, but a reluctant plant can usually be coaxed into bloom more easily if it's grown where nights are cool.

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2017年09月24日

LIGHT: Abutilons bloom freely provided they receive 6-8 hours of direct sun. A south-facing window is usually ideal. TEMPERATURE: Day and night temperatures above 65°F are fine year round. Avoid putting plants in the path of cold drafts. WATERING: Water when the top ½ inch of the potting mix is dry to the touch. FERTILIZER: Feed every 2 weeks with a balanced, water-soluble fertilizer (such as 20-20-20) mixed at ½ strength. A fertilizer designed to promote blossoms (formula 10-30-20) may be used instead.. [图片]CONTINUING CARE: Abutilons are vigorous growers. To keep your plant compact and bushy, prune back long stems with pruning shears, cutting just beyond the point where a leaf joins a stem. Prune just enough to give a pleasing overall shape; if you remove too much growth, you may prevent the plant from setting flower buds. Repot your plant into a slightly larger pot in spring. PROBLEM: If pests appear, flush plant with water to wash them off; if they persist, spray with insecticidal soap. Growing Standards: A standard is a woody plant trained to a long, single stem. The stem is crowned with a round head of foliage and flowers. This arrangement is beautiful but also unnatural, requiring a bit of effort on the part of the gardener to prevent gravity and the unrepressed inclinations of the plant from undoing the horticulturist's handiwork. [图片]Staking a Standard: To keep your standard standing, put it out of reach of strong winds and support it with a stake that has a diameter at least as large as the stem's and long enough that when plunged into the pot or the ground it just reaches inside the head. Fasten the standard to the stake at several points with garden twine or green plastic tie tape looped in a figure-eight around stem and stake. Check the ties periodically during the growing season and loosen them if they constrict the outward growth of the stem. Pruning, fertilizing, and repotting: Maintain the shape of the head with selective pinching of the new shoots (overzealous pinching will prevent the formation of flower buds). Pinch each shoot between thumb and forefinger or cut with pruning shears. Do not shear the plant as though it were a hedge. Fertilize standards grown in pots as you would other pot-grown plants. If you find that a standard in a container dries out quickly after watering, the plant probably needs a larger pot. Lift it from its current pot, make four deep vertical cuts in the root ball, and place it in a new pot that is 2in wider and taller than the old one, filling in around the root ball with fresh potting mix. Water thoroughly after repotting. [图片]Overwintering a standard: Most standards require special care to overwinter. In cold winter climates, bring standards of Abutilon, Anisodontea, Fuchsia, Heliotrope, Lantana, and Rosemary indoors before frost and place them in an east- or west-facing window in a cool room. Water just enough to keep plants from drying out completely, and do not fertilize while plants are in this not-quite-dormant period. Set back outdoors in spring when nighttime temperatures remain consistently above 55°F.to bloom too early.

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2017年09月24日

Rabbits and other rodents may eat fleshy leaves or into the starchy core of a plant. These pests can be excluded by wire mesh fencing, which should be partially buried in the ground to discourage burrowing. [图片]The main pest is Agave Snout Weevil Scyphophorus acupunctatus, a glossy black beetle-like insect with a pointed snout, typically seen in late Spring and early Summer. The adult insects feed on sap from the leaves and may introduce harmful bacteria. However, the real damage is done by their larvae which infest the starchy core and roots of a mature plant leading to wilting leaves and collapse of the plant. The female weevil lays eggs on the base of lower leaves of a plant that is ready to bloom. The consequences for an Agave monoculture, such as for the production of Tequila, can be devastating. It is unlikely that this particular species of weevil will occur outside the native range of Agaves, but other types of bugs can sometimes be seen feeding on leaves (left). Although Agave Snout Weevil prefer the broader-leaved Agaves, any genera within the Agavaceae e.g. Beschorneria are at risk. [图片]Any snout weevils seen around a plant should be killed and a systemic insecticide applied. Prophylactic treatment with a systemic insecticide of an Agave collection within the native range of the weevil, may be advisable. Obviously this is impractical if any part of the plant is to be consumed or fermented. Once a plant has collapsed, it is too late for treatment. The infected plant should be removed and burned, along with any grubs that can be found. Watering nearby plants with a systemic inecticide may help to control the pest.

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2017年09月24日

While these notes focus on pests and diseases of cacti and succulents, incorrect cultural conditions are a major cause of poor growth or loss of house plants in general. The single commonest cultural problem is over-watering, with the roots left wet for excessively long periods resulting in rotting. Other growth problems are related to insufficient light and too low or high a temperature. Most cacti and succulents are expected to flower when they reach the mature size, or even before, and failure to flower may indicate unsatisfactory growing conditions. [图片]Over-watering This is probably the single most common cause of failure of succulent plants to thrive. The plant may appear to do well at first, its leaves plump up and new growth produced. However, the roots may be suffering in wet soil and begin to rot unseen. The plant still looks well as the few remaining roots are able to take up sufficient of the plentiful water. As the roots continue to die in the stagnant soil, a point is reached at which they are unable to supply sufficient water and the plant appears to be suffering from lack of water. If more water is supplied, the situation gets worse and the rot may spread upwards into the basal stems or plant body. Eventually the plant body is observed to be soft and discoloured, perhaps yellow or grayish, by which time it is usually too late to save it. The moral is, that if a plant appears to be failing to take up water, knock it out of its pot and examine the condition of the roots before supplying more water. Other reasons for loss of roots include pest damage and dormancy. Watering a succulent plant at the wrong time of year when it is dormant can cause rotting as effectively as can also happen if the roots have been eaten by insect pests. [图片]Under-watering If unsufficient water is provided for the prevailing temperature and stage in the growth cycle, leafy succulents stop growing and may shed their leaves and the apical tip of stems may die. This is followed by die-back or self-pruning of stems and branches. Cacti may shrink back into the potting mixture and possibly take on a reddish or purple hue because of production of coloured stress pigments. In some cases, shrinkage of a cactus during drought produces irreversible folds in the plant body which never fill out again. However, careful watering usually reverses the effects of drought on succulent plants. Small amounts of water should be given to water-starved plants at first, in case some of the roots have been lost. [图片]Poor light more about light and lighting Natural sunlight is the best way of illuminating your plants, many of which are native to arid hillsides under scorchingly bright sunlight. Succulent plants kept with insufficient light grow with pale or yellow sometimes stunted leaves and elongated relatively thin stems with long spaces between the leaf joints. This is known as etiolation. Cacti become soft and elongated with weak spination. The condition can generally be reversed by providing stronger light, although elongated growth in cacti will always remain as a record of the change in growing conditions. Succulent plants can often be pruned to restore their shape. Cacti and some succulents will not usually become etiolated in dark conditions if kept cool and absolutely dry, and some growers allow their plants to become dormant for winter storage. [图片]Scorch and heat damage Scorch can affect succulent plants if there is a sudden period of sunshine after the dark winter days, or even after a prolonged cloudy period during the summer. Sunken brown or white patches develop down one side of a plant where the tissues have effectively been "cooked" and the green chlorophyll destroyed. Sometimes a glasshouse plant loses all its green pigment through excessive heat alone, even though it may not have been in the direct sunlight. Scorching can be avoided by the timely application of shading to the greenhouse, improved ventilation and air circulation within the growing area to even out air temperatures. When moving plants into direct sunlight, or putting them outside for the summer, harden them off gradually in diffuse sunlight or put them under mesh shading for a few days to acclimatise. [图片]Cold damage Although many cacti and succulents are surprisingly cold-hardy if kept absolutely dry during the winter, some species from perpetually tropical climates (e.g. Madagascar) can suffer damage to the soft tissues at their growing points, and scarring and collapse of their stems leading to fungal attack and death of the tissues. The only solution is to maintain higher temperatures for susceptible plants. Some species such as Echincactus grusonii which are otherwise easy to grow, can develop unsightly brown marks which spoil a specimen plant, if temperatures are too low.

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Dummer. ゛☀

2017年09月24日

A range of fungal and bacterial diseases affect succulent plants, some of which can collapse and die very rapidly, once the disease has taken a hold. The world abounds with fungal spores, which are opportunists, waiting for the correct conditions for germination. Generally, fungi do not affect cactus and succulent plant collections because of the relatively dry conditions used by most growers. Damp conditions are a universal requirement for activation of fungal spores, and many of the problems with fungal infection of succulent plants arise from failure of excessive watering or condensation to evaporate, because of unexpected or seasonal cold weather. Damage from insect pests, which penetrate the plant's epidermis to feed on sap, may provide a route for entry of fungi into the nutrient-rich inner tissues. Hence, unexpected collapse of a plant is often the final symptom of a mealy bug infestation which has gone unnoticed. On the other hand, some fungi provide their own mechanisms for penetrating the epidermis. [图片]Seedlings are especially susceptible to fungal attack of the lower stem which causes damping off. Once the seedling has wilted, it is usually too late to save it and preventative measure are a better option. Aloe rust is a fungus that causes round brown or black spots on leaves of Aloes and Gasterias. It is of some importance in commercial cultivation of Aloe vera. The black colour is caused by oxidation of phenolic substances in the sap which seals of the affected area. Once formed, the black spots are permanent and can be unsightly, but do not usually spread. Fungi can be discouraged by spraying with a systemic fungicide, but prevention is the best option. Do not allow water to lie on the leaves for long and avoid excess damp in cool weather. Arrange for plenty of air circulation and sunlight. [图片]Black or Sooty Mold A ubiquitous fungus which is often seen on plants covered with honeydew from whitefly, mealy bugs etc or on plants with nectar-producing glands such as certain Ferocacti. Generally, sooty mould is more unsightly than harmful on otherwise healthy plants. However, it will attack seedlings following mechanical damage or excessively wet conditions and other weak or damaged plants. [图片]Basal Stem Rot Cold or damp conditions may lead to rotting of stems, often just around the soil level where damp soil may be in prolonged contact with the plants stem. The rotten tissues may go black or reddish brown depending on the plant and organism attacking it. If the stem is cut well above the rotten part, it may be possible to re-root or graft the healthy tissues and save the plant. Many people support the basal stems of difficult plants with a layer of grit above the potting medium, so that there will be little water retention against the stem in this critical region. A range of brown or gray spots spots on leaves and corky brown marks on stems of are undoubtably due to fungal attack following damage or prolonged contact with drops of water. Others may reflect poor cultural conditions or the natural development of corky or woody stems as the plant matures. In many cases, fungal attack and poor culture are linked. Improving ventilation, temperature control, watering and application of fertiliser may help to prevent all sorts of problems. Growers of Asclepiads will be familiar with black spots developing on the stem which spread and develop into sunken patches of dead tissues. This fungal infection can spread to the whole plant unless the affected part is removed promptly or treated with fungicide. Usually this happens after overal-liberal water, perhaps where water droplets fail to evaporate because of unexpectedly cold conditions. [图片]Control of Fungal Diseases Once a plant has collapsed or the stems have started to become soft and rotten it is often too late to save it. However, an attempt may be made to save part of a valuable plant by cutting away the infected tissues with a clean knife, sterilised with methylated spirits. A wide margin of apparently sound tissue should be removed as the infection will almost certainly have spread further than is apparent. The remainder can be painted or dipped in a systemic fungicide such as Nimrod T or dusted with sulphur and rooted as a cutting or grafted onto a compatible stock. [图片]Botrytis or damping off This common cause of early loss of seedlings can be avoided by lightly spraying the potting mix with a systemic fungicide such as Benlate or Nimrod T. Spraying with a copper sulfate solution is a traditional remedy, but copper fungicides may accumulate in the soil with potential copper toxicity to plants. Any seedlings that become infected should be removed promptly before more spores are produced, the remaining seedlings sprayed with fungicide and surface moisture alllowed to evaporate.

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Dummer. ゛☀

2017年09月24日

Quarantine When new succulent plants are aquired, it is a good idea to keep them separate from the rest of the collection for a few weeks so that obvious pests can be spotted. This allows time for eggs of pests to hatch and the progeny dealt with. A good way to do this is to maintain a "quarantine" window ledge separate from other plants. Many growers repot newly aquired plants into their favourite growing medium, and this is a good occasion to examine the general condition of the roots and check for pests such as root mealy bugs. It may seem over-cautious, but many people like to treat their new plant with systemic insecticide while re-potting. This doubtless helps to avoid introduction of new pests into the collection. Repotting with "sterilised" compost which has been heated sufficiently to kill insects, larvae and eggs is a good idea. [图片]Inspection A regular check on the condition of your succulent plants, perhaps while you are watering them, will help you to spot the early signs of pests and diseases which are best treated early before serious damage is done to the plants, or before they can spread through the collection. However, never assume that just one plant in a collection is affected. Pests may well have spread to other specimens nearby, even if you can not see them. Ants "farm" mealy bugs for their honeydew secretions and may help to spread them through the collection. [图片]Also watch how well individual plants are growing. Poor growth, a sudden change in condition or a limp plant which fails to take up water can be a warning sign of damaged roots caused by e.g. root mealy bugs, vine weevil, or roots rotting as a result of over-watering. [图片]HygieneCleanliness in the greenhouse is an important measure in preventing outbreaks of pests and diseases. Always remove dead leaves and flowers as soon as possible. Some growers like to remove flower stalks of e.g. Adromischus before they flower and drip nectar on the plants, potentiating moulds. Leaf litter provides an ideal hiding place for pests. If wet by watering, dead plant material is a breeding ground for fungi and production of their spores. Tidy up debris in the green house left from re-potting and propagation. Treatment of the ground under the staging, walkways and areas of paving with a disinfectant solution e.g. Jeyes Fluid is a smelly but effective traditional way of discouraging pests and diseases.

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