动态第774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14日

Downy Mildew on Impatiens There's been an increase in downy mildew affecting Impatiens plants recently. The particular mildew affecting impatiens is Plasmopara abducens. It spreads rapidly, under the right conditions, and once infected, there is no cure. However, there are some preventative measures you can take. But first, here's some background to help you understand the disease.[图片]What is Downy Mildew? Downy mildew diseases are caused by oomycetes or water molds. They are fungus-like, but more closely related to algae. There are 2 types of downy mildew spores. One type, zoospores, can be splashed up by water or spread by the wind. The other type, oospores, reside inside the plant tissue and can spread rapidly and over-winter. At this point, there is no evidence that this particular mildew affecting impatiens is doing that, but why take chances.[图片]Downy mildew is more prevalent in the spring and fall when the cool, wet or humid weather provides ideal conditions. Which Impatiens Varieties are Affected? According to an e-Grow Alert by Nora Catlin, Floriculture Specialist, Cornell Cooperative Extension of Suffolk County, the following types of Impatiens are susceptible to downy mildew. All Impatiens waller IANA, including the double and mini types. These are the most common bedding impatiens sold in garden centers. (I. waller IANA hybrids, like the Fusion® series, are less prone, but still susceptible) Balsam Impatiens / Garden Balsam (I. balsam in a) These are taller plants than common Impatiens, with elongated, pointed leaves. Jewel Weed (I. capers is) and Yellow Jewel Weed (I. pallidum). Generally considered weeds, but if they are in the area, they can spread the disease to your landscape Impatiens.[图片]Impatiens Not Affected Himalayan balsam / policeman’s helmet (Impatiens glanduliferous), a wild and sometimes invasive species that can reach heights of 6 - 10 ft. (2 - 3 m), is tolerant of the disease but can act as a host. New Guinea impatiens (Impatiens hawkers) and its hybrids, like SunPatiens®, have so far shown resistance. There may be more plants affected or that act as hosts, but this is the information so far. Symptoms of Downy Mildew on Impatiens Early symptoms can be hard to spot and might be mistaken for a nutrient problem. Leaves stippled or chlorotic (yellowing) and looking like they need fertilizer. Floppy or downward curling leaves.[图片]Sometimes white fuzzy spots will form on the undersides of the leaves. These are spores and usually appear in cool, damp weather. (See photo on page 2.) As the disease progresses the plants may stop growing and look stunted, drop their leaves or completely collapse. What to Do about Downy Mildew on Impatiens Although there is no cure for Impatiens already infected with downy mildew, there are some steps you can take keep it from spreading. Prevention Avoiding downy mildew entirely can be very difficult, because so much is weather dependent. High humidity and cool, damp weather cannot always be avoided. But there are a few growing conditions you can provide, so as not to make matters worse. Provide good air circulation. Don't overcrowd your plants.[图片]Water from below, trying not to wet the leaves when watering and water early in the day. Remove any suspect plants immediately. Cultural management is your best bet. Once a plant is infected, there is no cure. If you want to try controlling the spread of the disease with a preventative fungicide, neem and copper sprays are recommended for homeowners. Will it Over-Winter and Re-infect Plants? So far, there is no sign that it infects seed, although other mildews do - so there is a chance. Some mildews can also over-winter in plant tissues. Although that does not seem to be happening with this downy mildew, don't take a chance by composting affected plants. If downy mildew becomes a major problem in your garden, you should consider not planting them for a year or two. Shade plant alternatives to impatiens include New Guinea impatiens, begonias, and coleus.[图片]Additional resources: Downy Mildew of Impatiens – Some (But Not All) Questions Answered Cornell Cooperative Extension of Suffolk County

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2017年09月14日

Whiteflies are tiny, heart-shaped flies that rest in very large numbers on the undersides of leaves. When the plant is disturbed or brushed up against, the flies will fly out in a great, sudden cloud. These annoying insects aren't only a nasty surprise for plant owners—who find themselves engulfed in swarms of flies—their nymphs and various larval stages attach to the plant's soft tissues and feed on the plant.[图片]Like other sucking insects, they also secrete honeydew, which raises the risk of fungal diseases and attracting still other pests. Whiteflies are nothing if not prolific. They hatch from tiny, cone-shaped eggs into small scale-like insects that can travel along the plant's stems. The scales molt into nymphs, which then go through several more growth stages before going into a brief resting stage then emerging as adult flies. During almost every step of their development, they continue to feed on the plant. The whole lifecycle takes about 30 days, but this varies depending on the temperature. In warmer weather, they reproduce more quickly, and in colder weather, their growth cycle is slowed.[图片]Whiteflies are a common problem in greenhouses, warm climates, and indoors. They cannot tolerate cold weather, but an indoor whitefly infestation can quickly spiral out of control. It's best to treat whiteflies at the first sign of infection. How to Get Rid of Whiteflies Like most pests, the best control for whiteflies is defensive. Healthy, vigorous plants are less susceptible to infestation than weak, underpotted, and stressed plants. As a general rule, make sure your plants are healthy, and you're less likely to attract these annoying critters in the first place.[图片]If you see whiteflies on your indoor plants, there are several control options: Vacuum them away. Being careful not to damage the plant, you can use your vacuum cleaner's hose attachment to hoover up adult whiteflies. Make sure that any newly hatched whiteflies can't escape from your vacuum bag! Sticky tape. The same sticky tape that works for houseflies can be used for whiteflies. Hang it from the infected plant if possible and follow label directions. Insecticidal soap. Insecticidal soaps are available on the market (such as Safer's Insecticidal Soap), or you can make your own by using a dish detergent such as Ivory Liquid. Try to find a product free of perfumes and additives that might harm plants. Mix the soap in a weak concentration with water (starting a 1 teaspoon per gallon and increasing as necessary). Spray on plants. These will help control the population but are unlikely to wipe them out.[图片]Neem oil. Neem oil is derived from the neem tree. Use according to label instructions. In addition to its insecticidal properties, neem is also a fungicide and has systemic benefits (meaning the plant absorbs it so it can control insects it doesn't directly contact). According to the Environmental Protection Association, neem is safe for use on vegetables and food plants as well as ornamentals. Like insecticidal soap, neem is useful for controlling whitefly populations but might not eliminate the problem.[图片]Kitchen insect spray. This all-purpose insect spray was developed by the editors of Organic Gardening magazine and came to me by way of Rodale's Organic Gardener's Handbook of Natural Insect and Disease Control. To make a batch, combine 1 garlic bulb, 1 small onion, and 1 teaspoon of cayenne pepper in a food processor or blender and process into a paste. Mix into 1 quart of water and steep for 1 hour. Strain through a cheesecloth and add 1 tablespoon of liquid dish soap. Mix well. The mixture can be stored for up to 1 week in the refrigerator.

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2017年09月14日

Soap sprays are some of the oldest insecticides used by gardeners in the old days; gardeners used to boil water with Fels Naptha soap to create an effective soap insecticide. Over time, these "old fashioned" remedies fell out of favor as they were replaced by much stronger and more toxic chemicals. Today, however, as the interest in organic and less chemical intensive gardening continues to grow, insecticidal soap sprays have made a major comeback.[图片]You can find these products in virtually every garden center or, if you find the right ingredients, you can make your own. How Do They Work? Insecticidal soap works through several mechanisms. The soap itself penetrates insects' cuticles, which causes cell collapse and desiccation. In other words, it dries them out. They also operate by suffocating insects such as scale insects. In general, soap sprays are effective for soft-bodied insects including mealybugs and aphids. To varying degrees, soap sprays are also effective against chiggers, earwigs, fleas, mites, scales, and thrips. They are not effective, however, on chewing insects such as caterpillars and beetles.[图片]Although soap sprays are less toxic to gardeners and non-pest animals, they can still be potentially damaging to some plants, especially if an oil has been added to the spray. Before the widespread use of any spray, test it on a small section of the plant first and wait at least 24 hours to see if there are any negative effects. Look for signs like spotting, wrinkling, and browning on leaves. If you see any negative signs, discontinue use of the product. Plants that are susceptible to damage from soap sprays include beans, cucumbers, ferns, gardenias, and peas. How to Use Soap Sprays Soap sprays can be purchased or made at home. Be careful, however, because there is a difference between detergents and soaps. Clear dishwashing detergents are not the same as soaps and should not be used in soap sprays. Instead, look for brands like Ivory Snow, Ivory Liquid, Dr. Bronner's, or Shaklee's Basic H. Do not use any product with additives like fragrance.[图片]To make your soap spray, start with the weakest solution possible, mixing between 1 teaspoon and 3 or 4 tablespoons of soap per gallon of water and using it immediately. When you spray, soak both the tops and bottom of leaves and directly spray any visible insects. The spray needs to make direct contact with the pest insect to be effective. There is some debate whether or not you should use oil to enhance the effectiveness of your spray. Technically, oil is not necessary for the soap to work. However, adding oil will enhance the effectiveness of your spray and increase its shelf-life. To make an easy at-home spray base, Rodale's recommends mixing 1 tablespoon of soap with 1 cup of cooking oil and emulsifying by shaking vigorously. When it comes time to spray, mix 1 to 2.5 teaspoons of this base to every 1 cup of water and spray immediately. Soap sprays can also be enhanced with additives to control fungus and chewing insects.[图片]You can safely add bacullus thuringiensis (BT), copper fungicide, or pyrethrin to the mix, depending on your needs. If you prefer to buy an insecticidal soap, there are some effective commercial products on the market labeled insecticidal soap, many including supplemental ingredients. As with home-made spray, test this on a few leaves before applying to the whole plant.

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2017年09月14日

Homemade remedies are a longstanding tradition among organic gardeners, who have had to be creative in finding ways to battle insects and diseases without the help of synthetic chemicals. In the case of fighting aphids, two homemade sprays have proven very effective in controlling aphid infestations. Organic gardeners have been using tomato leaf spray or garlic oil spray to battle aphids for generations.[图片]While knowing how to make and use them is important, it's equally important to understand why they work. Tomato Leaf Spray Tomato plants, as members of the nightshade family, contain toxic compounds called alkaloids in their leaves. When the leaves of tomato plants are chopped, they release their alkaloids. When the alkaloids are suspended and diluted with water, they make an easy to use spray that is toxic to aphids, but still safe around plants and humans.[图片]How to Make Tomato Leaf Spray Simply chop one or two cups of tomato leaves and soak them in two cups of water. Let it steep overnight. Strain out the leaves using cheesecloth or a fine strainer; then add another one to two cups of water to the liquid and add it to a spray bottle.[图片]Applying Tomato Leaf Spray Use the mixture by spraying the stems and foliage of the infested plant, paying particular attention to the undersides of leaves since that is where aphids most commonly congregate. One word of caution, while this spray is very safe for humans, some people are allergic to members of the nightshade family. If you are one of them, use care in making and applying this spray.[图片]Garlic Oil Spray Organic gardeners have long relied on garlic as part of their pest-fighting arsenal. Garlic contains sulfur, which, besides being toxic to pests, is also an antibacterial and antifungal agent. The dish soap in this mixture also breaks down the bodies of soft-bodied pests, such as aphids.[图片]How to Make Garlic Oil Spray To make garlic oil spray, mince or finely chop three to four cloves of garlic, and add them to two teaspoons of mineral oil. Let this mixture sit for 24 hours. Strain out the garlic pieces, and add the remaining liquid to one pint of water. Add one teaspoon of liquid dish soap. This mixture can be stored and diluted as needed.[图片]Applying Garlic Oil Spray Before using this spray test it by spraying an inconspicuous part of the plant. If there are no signs of yellowing or other leaf damage after a day or two, it is safe to use. If there is leaf damage, dilute the mixture with more water and try the test again. Once you have determined that it won't harm your plant, spray the entire plant, paying particular attention to the undersides of leaves.[图片]A word of caution about this spray, garlic oil is a non-selective insecticide. It will kill beneficial insects (such as ladybugs, who are natural predators of aphids) just as easily as it kills the bad guys. It's best to keep as many beneficial insects around as possible. This spray should only be used if you haven't seen any beneficial bugs in your garden. The tomato leaf recipe, above, won't harm beneficial bugs, so you should use that if you're lucky enough to have some in your garden.

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2017年09月14日

Creeping Charlie, or "ground ivy" is an aromatic, perennial, evergreen creeper of the mint family that thrives particularly in moist, shady areas, although it will also take some sun. Native to Europe and known by the botanical name, Glechoma hederacea, it has naturalized in North America, where it has become a hard-to-kill weed common in lawns. Its range in the U.S. includes every state except for three states in the southern portion of the Rocky Mountains.[图片]Part of the reason why the plant is invasive and why it is so hard to kill creeping Charlie is the variety of ways it has to spread. It spreads both by seeding and by rooting at the nodes that stud its little vines (which means you can spread it via mowing without even realizing it, unless you mow with a bag attachment). It can also spread by rhizomes, a fact to keep in mind when you're trying to dig it out. Leaving behind just a fragment of rhizome results in the birth of a new plant.[图片]Killing Creeping Charlie Naturally, With Chemicals People often wonder how to get rid of creeping Charlie (although, at the end of the article, you will read about its benefits, as well as some of the history behind this interesting weed). So let's take a look at both some chemical and natural ways of controlling it. First of all, you may have heard of the well-known home remedy for killing creeping Charlie that involves using a solution with Borax, so let's deal with it briefly here. This method has fallen out of favor, because, unless you use scientific precision in mixing the solution and applying it evenly onto the creeping Charlie plants, you can end up with a case of boron toxicity in your soil. But for those who are curious, Iowa State University's Richard Jauron says to Dissolve 10 ounces of Borax into 4 ounces of warm water. Then make a further dilution by mixing this solution into 2 1/2 gallons of water (this amount would provide coverage for an area of 1,000 square feet).[图片]Assuming you're not willing to risk boron toxicity, let's look at some other ways to kill creeping Charlie, both naturally and with chemicals. One factor that may help you decide on your control method is just how badly the weed has taken over the area in question. If the invasion is really bad, you may opt for a method that kills everything in the area, after which you would simply begin afresh from square one (whether it be starting a new lawn or starting a new garden). If you do not mind using chemicals, you could spray a glyphosate-based herbicide, such as Roundup, onto a lawn in such cases. Wait about a week before reseeding a lawn after using glyphosate.[图片]Many gardeners prefer weed control without chemicals. At the very least, you should be looking for natural ways to kill creeping Charlie in garden areas. If the weed has totally taken over your garden beds, consider the following ways to kill creeping Charlie naturally (you can also use these methods on a weed-infested lawn that you've given up on, if you wish to avoid chemicals): Smothering with newspapers. Smothering with tarps, as you would in eradicating Japanese knotweed. But what if the infestation isn't too bad? How can you get rid of small patches of creeping Charlie, removing it in a very targeted way that allows you to keep your current lawn or garden bed (instead of having to begin all over)? For chemical control on the lawn, seek a selective broadleaf herbicide intended for use in killing creeping Charlie. Apply it around the time of the first frost in fall. Consult the label on the product to make sure the herbicide is effective against this particular weed (triclopyr, for example, is an active ingredient in some of the herbicides to which creeping Charlie is not resistant). While you're reading the label, also check: That it's meant for use on the type of grass that you grow.[图片]When and how to apply. Safety precautions to take. For natural control (in either lawn or garden), good old-fashioned weeding (hand-pulling) is your best choice. The problem with hand-pulling, though, is that you have to be determined to stick with it. It's not a magic bullet: The weed most likely will return after the first hand-pulling, because the tiniest piece of rhizome left behind will eventually shoot up as a new plant. Keep an eye on the area so that you can catch any new shoot that comes up as soon as possible and remove it. It's hard work, but you will eventually wear the weed down. An Herb With a Tale to Tell: History, Benefits With all of the effort it takes to kill creeping Charlie, you may be surprised to learn that it was intentionally brought to North America by European settlers. Once you learn about the history of creeping Charlie's uses, some of that surprise should wear off, though. But before you hear that story, let's back up. You need to know a bit more information about the traits of this fascinating weed.[图片]Creeping Charlie has a square stem that varies in length from a few inches to 2 feet. The color of its leaves also varies, from dark green to purple. The funnel-shaped flowers have a bluish-purple color, and the plant spreads to form a dense mat over the ground, making it something of a wild groundcover. A somewhat slower-growing type of creeping Charlie with two-toned leaves and suited to planting zones 4-9 is sold at some garden centers. Grow it in a container garden (which will check its spread) on a deck or patio, and give it full sun to discourage its leaves from reverting back to their natural green color.[图片]The plant's uses for treating ailments have been known since at least the days of ancient Greece and Rome. The famous Greco-Roman doctor, Galen, for instance, recommended it for inflamed eyes, and English herbalist, John Gerard (1545-1607) recommended creeping Charlie for ringing in the ears. Never is it wise, however, to eat any plant, medicinal or otherwise, without first becoming informed about its properties. If you are not an expert in such matters, you may be unaware that it is only a particular part of the plant that can safely be used, whether as an herbal remedy, a food, or a drink. Common Names, How It Differs From Creeping Jenny, and Whether It's Poisonous It wasn't only as a healing herb that the plant was prized, traditionally. The Saxons used creeping Charlie to clarify their beers, in the same way that hops vine is now used. In fact, an alternate common name for the plant is "gill" (or "gill-over-the-ground"), which comes from the French word that means "to ferment beer" (guiller).[图片]Sometimes, this weed is also referred to as "creeping Jenny," but that nickname is more commonly reserved for Lysimachia nummularia. Novices may think the two weeds look alike, but, if you take a closer look, you can easily tell the two apart: Creeping Jenny's leaf does not have the scalloped edges that creeping Charlie's does. Yet another common name for this perennial lawn weed is "catsfoot" (its leaf is more or less the shape and size of a kitten's paw). But don't let the innocent-sounding name fool you: Cats, dogs, and various other animals can get sick by eating large amounts of creeping Charlie. So can humans. According to the University of Illinois Extension, there are compounds in creeping Charlie that are poisonous, being harmful to "the liver, gastrointestinal tract and kidneys."[图片]When a plant has this many nicknames, you can be pretty sure of two things: It's widespread, and people have interacted with it in a number of ways over a long period of time. Creeping Charlie, the despised lawn weed, the invasive alien that we spend so much time battling, is just such a plant. Do you enjoy the fragrance of a freshly mown lawn? Most people do. Well, wait until you have mown a patch of lawn that has some creeping Charlie growing in it. You haven't smelled anything yet until you've experienced the aroma of freshly mown creeping Charlie. Truly one of the joys of summer, smelling the aroma of these fragrant plants almost makes the boring chore of mowing the lawn worthwhile.

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2017年09月14日

Botrytis blight is a cruel disease for flower gardeners, because it frequently strikes garden plants in their prime, destroying blossoms just as they are ready to open. Botrytis, also called grey mold, is a fungal disease, and gardeners can recognize it when they see these symptoms in plants: Spotting or discoloration on leaves Wilting or decaying leaves and shoots Leaf drop Fuzzy grayish brown growth on flowers and foliage Flower buds that fail to open Rotting flower buds Damping off disease of seedlings Botrytis thrives in high humidity and cool weather, so gardeners will see signs of grey mold most often on spring flowers.[图片]Flowers Affected by Botrytis In the outdoor flower garden, marigolds, impatiens, peonies and roses are the most likely plants to show signs of botrytis. In the greenhouse, several flowers are susceptible to this fungus, especially cyclamen, geraniums, and poinsettia. Seedlings that often succumb to damping off disease caused by botrytis fungi include pansies, petunias, and snapdragons.[图片]Organic Sprays for Botrytis Sulfur powders and sprays are effective at controlling fungal diseases like botrytis in the flower garden. Apply sprays early in the morning or evening to avoid harming bees or beneficial insects. A less common, but very effective organic treatment against foliage diseases in the flower garden is the bacterium Bacillus subtilis, sold under the trade name Serenade. Many gardeners report that the fragrance of this spray is less offensive compared to other organic or conventional fungicide sprays.[图片]Cultural Control of Botrytis When you notice the first signs of botrytis in the flower garden, get out the clippers. Remove all affected foliage and flowers, and destroy the plant matter. Sanitize clippers with an alcohol wipe after pruning diseased plants to prevent spreading the fungi to healthy plants. It’s also important to keep the ground around plants free of decaying leaves, which act like a nursery for fungal spores. Although you can’t do anything about humid conditions in your area, you can help plants cope with excessive moisture. Use drip irrigation, which delivers water to the root zone where it's needed and keeps leaves dry. Avoid overhead watering, which can splash disease-carrying soil onto leaves. Water in the morning to allow the sun's rays to quickly evaporate any moisture on leaves. Follow proper plant spacing guidelines, to enhance air circulation. Prune the interior of dense plants to increase air movement that carries away disease spores.[图片]Greenhouse Botrytis Management The principles of botrytis management in the greenhouse are similar to those in the garden, but greenhouse gardeners can control the greenhouse environment more than the outdoors. Use fans of adequate size and number for the greenhouse size. You should aim for a relative humidity below 80%, and completely changing the air three one to three times an hour should help to achieve this. Your greenhouse retailer can help you calculate fans needed according to the cubic feet of your greenhouse. Raise the temperature of the greenhouse at sunset to dry condensation on leaves. This is especially important in the winter. Isolate plants showing signs of botrytis from the greenhouse population. Destroy the plants on inexpensive specimens that you can easily replace; this prevents widespread, more costly outbreaks.[图片]Conventional Control of Botrytis Severe botrytis outbreaks may require fungicide applications to achieve control of the disease. Botrytis can become resistant to chemicals, so switching it up occasionally may achieve better control. Gardeners should look for fungicides that contain one of these active ingredients: Chlorothalonil Fenhexamid Fludioxonil Myclobutanil[图片]Botrytis Resistant Flowers to Grow Unfortunately, horticulturists haven’t developed any completely botrytis-resistant flower species. 'Fantasy Blue' petunias and 'Tidal Wave Pink' petunias are two varieties that are more resistant to flower blight than older petunia varieties. Peony lovers may have more luck with tree peonies and intersectional hybrids than with P. lactiflora garden peonies. Gardeners must continue to battle this tenacious fungal flower disease by practicing good garden and greenhouse hygiene and cultural practices.

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2017年09月14日

Spotting Spider Tree Mites in the Garden Spider tree mites are among the most commonly found pests in gardens. Hundreds of different species are categorized as spider mites, which are members of the Tetranychidae family. These critters can damage plants by sucking on the tissues, mainly in the leaves. The mites often cluster on the undersides of the leaves.[图片]Eight-legged arachnids, they belong to the same class as spiders and are closely related to ticks. Like spiders, they will produce webbing on the plant. Spider mites come in a wide variety of colors, including red, yellow, green and brown. Some even change colors throughout the year, while others are translucent. Use the tips that follow to identify signs of an infestation, the common trees spider mites target and the different ways to control them.[图片]Signs of a Spider Mite Infestation Spider tree mites leave visible signs of damage to trees. If your leaves develop yellow, orange, brown or gray spots, an infestation may be at work. Other signs of infestation include the following: Leaf drop Webbing covering the plant Visual confirmation of the presence of mites Common Tree and Shrub Hosts[图片]While any tree or shrub may fall prey to spider mites, some often serve as hosts. They include: Broadleaf evergreens Elms Evergreens Fruit trees Honeylocust Maples Mountain ash Oaks Roses[图片]Try Biological Controls First Several different insects and arachnids are natural predators of spider mites. Encourage these helpers by limiting the use of chemicals in the garden. Natural predators include: Big-eyed bugs (Geocoris spp.) Gall midge (Feltiella acari Suga) Lacewings (Chrysopa spp.) Minute pirate bugs (Orius app) Predatory mites (Phytoseiidae Family) Predatory thrips (Scolothrips spp.) Spider mite destroyer (Stethorus app. - a genus of lady beetle)[图片]Organic Controls Horticultural oils and insecticidal soaps are organic methods for controlling spider mites. For example, oil from the neem tree (Azadirachta indica) can be used as an organic miticide. The timing of when you apply these oils depends on the product used, so consult with someone at your local garden center, nursery or extension center to figure out the right one for your situation. Combining a couple of tablespoons of natural soap in a quart of water provides an inexpensive and safe way to attack spider mites. Don't add extra soap, as too much may cause leaf damage. For an added punch, include garlic or cayenne.[图片]Water as a Control Spider mites attack plants that are suffering from drought, so proper watering is essential to help ward off these invaders. Water is also useful in controlling spider mite infestations on houseplants, where it is harder to bring in natural predators and the use of chemicals is undesirable. Use a faucet or hose to knock off mites and webbing, making sure to hit both sides of the leaves. You could also set it in a bathtub to help make this process less messy, if indoors.

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Dummer. ゛☀

2017年09月14日

Ick. I hate spider mites. They are a plague, particularly on the container gardens that I try to overwinter inside. I have had them infest several fruit trees, including, Meyer lemon, lime, kumquat and orange. It could be that all these trees became infested because of their close proximity to each other. However, once one plant gets spider mites they can infest all of your plants pretty quickly.[图片]Unfortunately, it's very hard to get rid of spider mites and sometimes, you just have to pitch plants that get them. Be careful, if you do have to get rid of plants that are infested, do not compost them. Sadly the best way to get rid of them is to either throw them way out in the woods, or put them in plastic bags and put them in the garbage. Identifying a Spider Mite Infestation - Spider mites are tiny - smaller than the head of a pin - so it's hard to see them. To identify an infestation, you can check to see if there is webbing on your plants particularly at the intersection of branches. Another, sign, after the spider mites have infested a plant, is to see leaves that are spotted or speckled looking. Spider mights can range in color from red to light brown, yellow to green.[图片]Getting Rid of Spider Mites - Like most plant pests, you a have much better chance dealing with spider mites before you have an all out infestation. The more mites, the more eggs and the harder it is to control them. My first line of defense, with almost any insect problem in my containers (though spider mites aren't actually classified as an insect, but as an arachnid), is to spray them with a hose, trying to knock as many insects off as possible--making sure to spray the underside of the leaves as well as the tops. Once the plant is dry, I try an insecticidal soap spray. With large plants, it's hard to get good coverage all over the entire plant, including the undersides of leaves, but do the best you can. I like to use insecticidal soap instead of a pesticide because it doesn't harm beneficial insects and is listed as ok for organic gardening. After insecticidal soap, I try neem oil or a neem oil combination. A disadvantage of neem oil is some people don't like the smell and it can be sticky and get on walls and furniture. Another thing to try is a pyrethrin insecticide, which is somewhat more toxic than the neem oil and insecticidal soap, but is still considered "natural" pesticide because it is made from chrysanthemums.[图片]Be Persistent - Chances are you will have to keep spraying your spider mite infested plant every seven to ten days in order to interrupt the cycle of eggs hatching. Also, make sure to spray the soil as well as the entire plant. When to Give Up - To be honest, there is no absolute answer to this unless your plant is completely dead--even then, plants can surprise you and bounce back. I have battled spider mites through the winter and then have taken plants that looked like they were at death's door, cut them back severely in the spring, and then put them outside. Some of the plants rebounded gorgeously, thriving throughout the summer. However, on bringing them back inside, the mites returned with a vengeance. But I have a hard time giving up on beloved plants, so I tend to keep them limping along, way past when it is practical.[图片]How to Prevent Spider Mites from Attacking Your Plants - Prevention is always the preferred option when it comes to mites. Before you buy a plant, look for the tell-tale signs of spotted leaves or webbing. If you see any indication of mites, don't buy the plant or any plants nearby. Also, mites like dry and dusty conditions, so keep your plants hydrated and healthy, and a level of humidity in the air, so the conditions will be inhospitable to mites.

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Dummer. ゛☀

2017年09月14日

Hopefully, your trees and shrubs will never be attacked by beetles. They bore into the plant, destroying the nutrient transport system and weakening the overall health. If the infestation is serious enough, death may occur. They are very hard to control, but here are some ways to get rid of beetles:[图片]Choose Trees and Shrubs Wisely and Keep Them Healthy This may seem very obvious, but it's best if you take steps to try not to have a beetle infestation at all. This begins by choosing trees and shrubs that are adapted to growing in your area; species that are poorly adapted will struggle and have health issues. Make sure it is planted properly and watered well to help limit the amount of stress the tree goes through. If you keep the plant healthy, it has a much better chance of not being attacked, and a better chance of surviving if it is. Keep the tree or shrub free of cuts and breaks. Do not do your pruning when beetles are known to be in the area. Don't leave newly cut firewood nearby, as this will provide a place for the beetles to breed.[图片]Different beetles attack different kinds of trees and shrubs, so don't plant the kinds affected if there have been known infestations in the area. You can also try species known to have some resistance. Hire a Licensed Pesticide Applicator to Apply Appropriate Pesticides It is difficult to control beetles using chemical means unless the beetle attacks are detected very early. The pesticides used are also very expensive and not usually available to homeowners. However, if you have valuable trees that you would like to try to save, call in a licensed pesticide applicator. They may be able to save trees by spraying the trunks when the adults are flying. Trees and shrubs that were attacked in the past but no longer have beetles should not be sprayed.[图片]Neither should you spray species that are not affected by the type of beetle present. Trees that are highly infested cannot be saved by pesticides. Prune Away Affected Branches If the beetle problem is noticed early enough, you can prune off any branches that have been attacked. However, you should be careful when doing this, as new pruning wounds may attract more beetles. Learn the months when the adult beetles are flying and try to avoid pruning during those times.[图片]Cut Down Affected Trees and Shrubs Sadly, cutting down the affected trees or shrubs is the only sure-fire way of controlling beetles in most cases. Usually, by the time the problem is noticed, the infestation is too widespread to be controlled. Pesticides are not able to wipe out large beetle populations, nor pruning if the whole plant is affected.[图片]If you have many susceptible trees together, thinning them out can help improve the chances of the remaining trees' survival. Cut down the affected tree or shrub entirely and destroy the wood. The pieces should be chipped or burned to destroy any beetle larvae. Be sure to move it far away from your remaining trees and shrubs or the beetles may find a new home.

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Dummer. ゛☀

2017年09月14日

The imported Viburnum Leaf Beetle (VLB), a native of both Europe and Asia, was first spotted in North America in 1978, in the Ottawa-Hull region of Canada. Since then, it has been making its way south from Canada into the U.S. Viburnums have always been considered exceptionally pest free landscape plants, but this new pest is challenging that assumption. The VLB is a close relative of the more common elm leaf beetle and can very quickly strip the leaves from viburnums plants.[图片]Both the larva and the adult beetle feed on viburnum leaves, skeletonizing them in a relatively short time. Initial infestations will not kill the plants, but defoliation for 2 - 3 consecutive years can be fatal. What Does the Viburnum Leaf Beetle Look Like? Viburnum leaf beetles are rather bland looking for an exotic pest and can be easily missed. The adults are about a 1/4 inch long (4.5 to 6.5 mm) and a dull brown, as are the tiny eggs. The larvae are a greenish-yellow, somewhat blending in with the foliage. They grow to about ½ inch long. Invasive.org has some great pictures of the various stages of the viburnum leaf beetle, which will help with identification.[图片]Does the Viburnum Leaf Beetle Feed On All types of Viburnum? Currently, the VLB has three favorite varieties of viburnum plants: European highbush cranberry (Viburnum opulus) Wayfaringtree viburnum (Viburnum lantana) Rafinesque viburnum (Viburnum rafinesquianum) Viburnum Leaf Beetle Lifecycle The beetles overwinter as eggs deposited in the branches. They hatch in May and the larvae then feeds on the new leaves. Since the newly emerged larvae are so small, the first signs of injury may be missed, as the damage can appear as holes no larger than pin holes. Within a month, skeletonizing will be hard to miss.[图片]It takes about 8-10 weeks for the VLB to go from egg to adult. Sometime in June, the larvae will make their way to the ground, where they will pupate in the soil. The adult VLB emerges in the latter part of July and continues feeding on viburnums. The female VLB can lay eggs from late summer to the first frost, sometimes as many as 500 eggs per season. She chews holes in the new growth of viburnum and lays eggs in each hole. The holes are then covered with a mix of chewed twig and excrement, making them harder to notice. However, the holes will be made in a straight line on the underside of the twig.[图片]How to Control Viburnum Leaf Beetle Damage The best protection against VLB is to plant resistant varieties. These include some of the most popular landscape viburnums, including: Doublefile viburnum (Viburnum plicatum) Korean Spice viburnum (Viburnum carlesii) Leatherleaf viburnum (Viburnum rhytidophyllum) Cornell’s VLB Citizen Science lists those most resistant and varieties to avoid or monitor closely.[图片]If you already have viburnums in your landscape, keep a close watch. In the early spring, before the eggs hatch in May, closely examine the small twigs from the previous year’s growth for egg laying holes and scars. Warmer temperatures will cause the holes to swell and the caps may fall off. You will need to prune out and destroy all infested wood before the eggs hatch. A the new leaves begin to open, check both sides of the leaves for larvae and again prune and destroy infested plant parts. Chemical pesticides are most effective when applied while the larvae are young. Adults tend to fly away or drop to the ground when disturbed. Check with your local Extension Service for recommended pesticides.

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