动态第943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17日

Cacti are among the best known warm-weather plants, so you may be surprised to hear about freeze damage to cactus. But even in summer toasty regions of Arizona, temperatures can dip down to below 32 degrees Fahrenheit (0 C.) in winter. This can result in freeze damage to cactus. If you find your cactus damaged after a cold snap, you’ll want to know how to care for a frozen cactus. Can a frozen cactus be saved? How do you start reviving a frozen cactus? Read on for tips in assisting a cactus damaged by cold. [图片]Recognizing a Cactus Damaged by Cold When you have a cactus damaged by cold, how can you tell? The first sign of freeze damage to cactus plants is softened tissue. This tissue often turns white, initially. However, in time the damaged areas of the plant turn black and decay. Finally, the freeze damaged parts of the succulent will fall off. [图片]How to Care for a Frozen Cactus When you see your cactus tips or trunks turn from green to white to purple, don’t take any action. The odds are good that the cactus will heal itself. But when those tips turn from green to white to black, you will need to prune. Wait until a sunny day later in the spring season to be sure that the cold weather has passed. Then snip off the black parts. This means that you cut off the arm tips or even remove the “head” of the cactus if it is black. Cut at a joint if the cactus is jointed. Don’t hesitate to act once the cactus parts have blackened. The black portions are dead and rotting. Failure to remove them can spread decay and kill the entire cactus. Assuming things go according to plan, your pruning will help in reviving a frozen cactus. In a few months, the chopped section will sprout some new growth. It won’t look exactly the same, but the parts of the cactus damaged by cold will be gone.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

Prickly pear cacti, also known as Opuntia, are lovely cactus plants that can be planted in an outdoor desert garden or kept as a houseplant. Unfortunately, there are several common diseases that can attack these beautiful plants. One of the most serious diseases that affects prickly pear is cactus sunscald. [图片]What is Cactus Sunscald? So, what is cactus sunscald? Despite the name, cactus sunscald disease is not a result of sun exposure. It is actually a disease caused by the fungus Hendersonia opuntiae. This fungus infects the cladodes, or cactus pads, which are the thickened, flattened, green stems of Opuntia cacti. Cactus sunscald disease first causes discoloration and cracking in a localized area of one cladode, then gradually spreads. This eventually causes the entire cactus to rot. [图片]Signs of Cactus Sunscald Disease Cactus sunscald is common, so it is important to recognize the signs. The problems begin when a small, circular, greyish-brown spot appears on one of the cactus pads. The discolored area may also be cracked. The infected area will later expand across the cladode, and the outer portion may turn reddish-brown. Finally, the entire cactus will rot. Once cactus sunscald begins to attack a cactus, other fungi may also take advantage of the infection and begin growing in the damaged area. Mycosphaerella fungi can also cause a similar disease, also known as sunscald or scorch, on prickly pear cacti. This disease causes similar symptoms and will also eventually kill the cactus. Sunburn on cactus can appear similar to cactus sunscald, but the affected area will appear yellowish or white and will not appear to be gradually spreading from a small original area. Sunburn can be prevented by shielding the cactus from intense sun. As long as the sunburn is not severe, it will not kill the plant. [图片]Cactus Sunscald Treatment Unfortunately, treating cactus sunscald is difficult or impossible. There is no cure, and infected plants usually cannot be saved. If you have more than one Opuntia cactus, focus on preventing the disease from spreading to the healthy plants. The first step it to recognize the disease and to distinguish it from a sunburn. If your cactus does have sunscald, you should remove and dispose of the infected cactus as soon as possible to prevent the disease from spreading to healthy plants.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

Succulents, like all plants, are susceptible to pest infestations. Sometimes, the pests are readily visible and at other times difficult to see, but their damage is obvious. An example of this is succulent mite damage. Mites that affect succulents, of which there are many, are difficult to see with the naked eye but their damage is there for the world to see. Read on to find out about mites on succulent plants and succulent mite control. [图片]Mites That Affect Succulents Due to the dizzying array of succulents to choose from, many people are so fascinated by them they become virtual succulent hoarders. Collecting succulents is a great hobby but the one downside may be if the collection becomes pest infested. Pest and diseases especially afflict large collections and can be difficult to control in its entirety. Mealybugs, scale, whitefly, various weevils and a few varieties of mitesare examples of pests that attack succulents. Most pests can be controlled with systemic or contact insecticides, insecticidal soaps and sometimes natural predators. How about mites? [图片]Succulent Mite Control Spider mites damage both cacti and succulents by sucking the plant’s juices. The first sign you have spider mites on succulent plants will be webbing and small brown spots on young growth. These tiny “insects” are not really insects at all but are more closely related to spiders. They look like dust when viewed by the naked eye. Red spider mites are actually reddish-brown in color and thrive in hot, dry conditions. They dislike humidity, so misting and overhead watering can reduce their incidence. These red spider mites should not be confused with harmless, much larger red mite, which is a harmless predator mite. To thoroughly rid the plant of these mites, use a miticideaccording to the manufacturer’s directions. There is also a predator that can be used as a biological control, Phytoseiulus persimilis. This predator requires temperatures over 70 F. (21 C.) and it’s also difficult to maintain a balance between predator and prey. Spider mites are not the only mites responsible for afflicting succulents. Mites that feed on aloe also attack other species such as Haworthia and Gasteri, and are called eriophyid mites. Unlike spider mites, which have four sets of legs, these mites have two sets of legs. As this mite feeds, it injects a chemical into the tissue that results in galling or other abnormal growth. In the case of aloe plants, aloe succulent mite damage is irreversible and the plant must be discarded. Place infected plants in a plastic bag or incinerate to prevent contamination of other plants. If infestation is minimal, treat the plant with a miticide according to manufacturer’s instructions. Frost hardy aloes can be exposed to freezing temperatures, which will kill the mites. Another mite, the two-spotted mite, feeds primarily on yucca. Under a microscope, this mite is pink, yellow-green or red with two dark spots on its body. These mites have eight legs but no wings or antennae. Tell-tale signs of the presence of the two-spotted mite are tan or gray stippling of foliage. As the infestation progresses, again, a fine webbing can be seen on the undersides of leaves. If the infestation is severe, the plant will die. Insecticidal soap and keeping the plant area high in humidity by misting will retard the mite population. Also, chemical control with the aid of products known as acaricides will help. To really get a handle on the mites, inspect the succulents frequently so you can take action before the infestation gets out of hand. Keep the plants healthy with the proper amount of water, fertilizer and light. Remove any dead or dying succulent parts and dispose of truly ailing plants immediately.

...显示更多

1

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

Recently, cacti and other succulents in fancy little glass terrariums have become a hot ticket item. Even big box stores have jumped on the bandwagon. You can go to almost any Walmart, Home Depot, etc. and purchase a cool little terrarium filled with a mix of live cacti and succulents. The problem with this, however, is they took a really cool idea and then figured out how to cheaply mass produce them. No thought is put into proper drainage of these terrariums or each plant’s specific growing needs. To ensure that they’ll stick together through shipping and stocking, pebbles or sand are glued into place around the plants. They are basically made to look nice, just long enough for them to be sold. By the time you purchase them, they could have been severely neglected, watered improperly and sitting on death’s doorstep because of Dreschlera fungus or other rot diseases. Continue reading to learn if you can save a rotting cactus. [图片]Causes of Stem Rot on Cactus Dreschlera fungus is commonly known as cactus stem rot. The first signs and symptoms of Dreschlera cactus stem rot that you may notice are yellow to dark brown or black spots on the cactus. However, these spots are just what you see on the surface. Damage on the inside of the plant could be much more severe. Stem rot on cactus plants usually begins near the bottom of the plant, then works its way up and throughout the plant. Dreschlera fungus is spread by spores that often infect plant tissues that are already damaged or weakened. Symptoms can progress to a complete rotting of the bottom of the plant, causing the top to tip over or the center of the plant may sink in upon itself, or the whole plant may suddenly look like a shrunken mummy of a cactus. Cactus stem rot can kill a plant in as little as four days. Some common factors that contribute to stem rot on cactus plants are over watering or improper drainage, too much shade or humidity and damaged plant tissues from insects, pets, humans, etc. [图片]Rotting Cactus Treatment Once a cactus plant has rotted so severely that the top has tipped over, has sunken in on itself or looks like a shriveled mummy, it is too late to save it. If it is only showing some small spots of rot, there are a few things you can try to save a rotting cactus plant. First off, the plant should be removed from other plants, placed in a sort of quarantine and forced into a mock drought. You can simulate drought by placing the plant in sand, not watering it at all and using bright heat lamps. Sometimes, this is enough to kill small patches of Dreschlera fungus. You can also try to wash away fungal spots with q-tips or a small brush and disinfectant soap. Simply, scrub away the yellow to black fungal spots. Fungal spots can also be cut out, but you will need to cut widely around the spots because healthy looking tissues around the spots may already be infected. If you choose to try either of these methods, be sure to sanitize your tools, brushes or q-tips in rubbing alcohol or bleach and water between each scrub or cut. Immediately after scrubbing or cutting, spray the whole plant with copper fungicide, the fungicide Captan, or a bleach and water solution.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

When you think of cacti and other succulents, you probably think of dry, sandy, desert conditions. It’s hard to imagine that fungal and bacterial rots could grow in such dry conditions. Actually, cacti are susceptible to a number of rot diseases, just like any other plant. While oftentimes cactus rot diseases are caused by too much water and humidity, this article will specifically discuss Erwinia soft rot in cactus plants. [图片]Erwinia Soft Rot in Cactus Erwinia carotovora bacterium is a bacteria caused soft rot of cactus. Bacterial soft rots affect many other plants besides cacti and succulents. In fact, soft rot contributes to major crop failure of many vegetables. Plants with calcium deficiencies are specifically at risk. Erwinia carotovora is also known as Pectobacterium carotovia. Erwinia soft rot in cactus plants is caused by bacteria entering wounds or natural openings of the plant. Wounds can be from insect damage, pet damage, accidentally knocking the plant with gardening tools, etc. On cactus plants, it will take at least a week for a wound to scab over, depending, of course, on the size of the wound. In humid, wet weather, cactus rot diseases can spread very quickly. The ideal temperatures for soft rot development are between 70-80 degrees F. (21-27 C.) with high humidity. Soft rot can affect any part of the cactus plant, including roots that have been damaged by transplanting, insects or other pests. [图片]Treating Rotting Cactus Plants Soft rot of cactus plants can be spread to other plants by insects, dirty gardening tools and moving of garden debris. It is important to always keep the garden free of possibly diseased garden debris and to thoroughly sanitize your garden tools between each use. Also, if a cactus plant develops a wound anywhere on it and from anything, treat the wound immediately with copper fungicide or a solution of bleach and water. Cactus plants with soft rot may first appear to have watery looking scabs on them. Then the plant tissues will turn brown to black in these spots. You may notice a foul smelling seepage or discharge from these areas as well. There is no cure for rotting cactus plants once it is showing these symptoms. The best way to handle Erwinia soft rot in cactus plants is to take preventative measures to avoid it. Clean wounds immediately and thoroughly, keep the plant dry and out of humidity and once a year feed the cactus plant a fertilizer with a boost of calcium.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

Gardeners must be ever vigilant when it comes to diseases on their plants. Often, a speedy diagnosis can help prevent more damage. This is the case with scab of cactus. What is cactus scab? Read on to learn more. [图片]What is Cactus Scab? Cactus scab is particularly common on prickly pear cactus but can affect many other varieties. It is a form of edema, where something has stimulated an abnormal increase in the size of the cells. This results in strange patches on the skin of the plant. It occurs in many other plants too, such as: Tomatoes Cucumbers Potatoes Begonia Violets Cabbage Cracks, discoloration, dry scabby lesions? Identifying the issue is quite easy, although the appearance can be mistaken for sunscaldor spider mite attacks. Initial signs of scab of cactus are pale yellow spots on the skin of the plant. These become irregular, corky or rusty. Hence, the name corky scab. The whole effect looks like the cactus has a patch of eczema. Essentially, the cells in the epidermis are breaking and opening up, resulting in almost wound-like lesions. The oldest parts of the plant are usually the first to show signs, with young shoots rarely being affected until they mature. Some plants experience just a few patches, while others can become covered in them. [图片]What Causes Corky Scab on Cactus? It is believed to be caused by poor cultivation methods and, once noted, can be halted before it damages any more of the plant. Corky scab on cactus is primarily an aesthetic disease, but it can have economic impact in commercial growing. Luckily, the problem is easy to prevent by changing cultural methods. As one of the more common diseases of cactus, corky scab is thought to be the result of overwatering, low temperatures and poor ventilation. It is most common in areas where there is abundant, warm water in soil and cool, moist temperatures. Other situations thought to stimulate the disease are high light, injury to the plant, chemicals and poor drainage. Since most of these conditions can be controlled, cactus scab treatment relies upon changing the cultural situation and methods. Outdoor plants may need to be moved to a location where more control over wind, temperature and ambient humidity are possible. [图片]Cactus Scab Treatment There are no sprays, drenches or systemic preparations for cactus scab treatment. Avoid irrigating in cool, moist weather and ensure good drainage is occurring. Never let a cactus sit on a saucer in water. If plants are indoors or in a greenhouse, increase ventilation. Increase the temperature of the area in which the plant is being grown. Avoid fertilizing in fall and winter, and do not use a formula with a high nitrogen content. Keep light bright but not above 14,000 foot candles, or lumens. If necessary, repot the plant into fresh cactus mixture. Generally, going back to good cactus cultivation and ensuring good light, watering practices and diminishing humidity will prevent any further corking and see your plant back on the road to optimum health.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

If you have prickly pear or cholla cacti in your landscape, you’ve probably been confronted with a cottony white mass on the surface of the plants. If you were to remove the mass and crush it on a piece of paper, the result would be a smear of vibrant red, a tell-tale sign of the presence of cochineal scale bugs. What is a cochineal scale and how can you treat cochineal scale? Let’s learn more. [图片]What is Cochineal Scale? Cochineal scale (Dactylopious spp.) bugs are commonly found on cactus of the Opuntia genera of cacti. It is an insect native to the New World, which was used by the Aztecs for dying and painting. Spanish conquistadors took dried cochineal scale powder back to their homeland where it became a sought after red dye until the 1850’s. Cochineal dye was replaced in popularity by aniline dyes but is still commercially produced in Mexico and India where it is still used to color food, drinks, cosmetics and paints. [图片]Cochineal Scale on Cactus These small insects suck on cacti leaves. Cochineal scale on cactus is initially a nuisance but, in extreme infestations, can weaken and kill the plant. The cottony, waxy mass is produced to shelter the female insects and their eggs. When the eggs hatch, the nymphs feed on the plant for three weeks, moving all around the plant. After their three weeks of feeding, the nymphs settle down to spin the cottony mass that shelters them from predators. [图片]How to Treat Cochineal Scale If the infestation of scale is minimal, cochineal scale treatment consists simply of a spray of water. Blast the affected area with hose under pressure. This will expose and weaken the scale bugs, which can then be treated with an insecticidal soap or a mix of ½ teaspoon of dish soap to a gallon of water. If the problem persists, prune off the worst pads at the joints and discard them. If the cactus seems to be heavily infested, you may have to go with a chemical cochineal scale treatment. Apply a combination of insecticide, dormant oil spray and/or insecticidal soap. Malathion and triazide combined with Neem oil or Volck dormant oil spray should do the trick. Apply according to the manufacturer’s directions. Do not spray on hot, sunny days, as the plant is likely to burn from the dormant oil. If the weather is too hot to use dormant oil, use pesticide mixed with dish soap. Cochineal scale is spread around by sticking to birds’ feet, so you need to inspect the plant frequently. Spray the cactus well, paying attention to joints. Spray again in 7 days and then again 14 days after the first application. You’ll know if the scale is being killed off when the white cottony tufts turn gray and squeezing them doesn’t result in a red smear. If scale is still alive after 14-30 days, reapply as above.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

Fungal issues plague almost every form of plant. The sheer number of fungal organisms is staggering and most survive dormant for long periods of time. Fungal lesions on cactus may be caused by any number of fungal types, but the important things to note are what causes them to colonize and how to prevent their damage. In this way, the gardener is armed with knowledge on how to treat fungus on cactus should any disease symptoms develop. Some fungal diseases simply cause cosmetic damage while others can develop into rots that completely eat the cactus from the inside out. [图片]Types of Fungal Damage in Cactus The vast amount of cacti species can only be outcompeted by the huge quantity of fungal varieties. Fungus spots on cactus pads are common, as in the case of Phyllosticta pad spot. It is often quite impossible to diagnose which fungal organism is causing the spots, but often that is unimportant since treatments are generally the same. A few fungi types damage the roots and eventually the whole plant, so once their visual damage is seen, it is too late for the plant. Simple topical fungal spots are much easier to combat and are usually not life threatening to the cactus provided steps are taken to control the offending fungus. Lesions on cacti may present in many different ways. They may be round, irregular, raised, flat and any other shape. Many are discolored but, again, the tones can range from yellow to brown and all the way to black. Some are corky, while others are weepy. These may ooze brown, rusty or black fluid, evidence of severe infection. The cacti most frequently plagued by fungal lesions are Opuntia and Agave. Fungal lesions on cactus usually start as water spots or slight discolorations on the plant’s epidermis. Over time, as the fungi mature and spread, the symptoms can broaden and even eat into the cambium as the surface skin cracks and allows the pathogen to enter. [图片]Causes of Fungal Lesions on Cactus Outdoor cactus can come in contact with fungal spores in various ways. Spores may be blown in from wind, in soil or contracted from splashing water. Plants with consistently wet pads or stems are the worst affected. Conditions where rain or high humidity combine with warm temperatures promote the formation of fungal lesions. Fungus spots on cactus pads are more prevalent in the springtime. They are also enhanced by overhead watering and in areas where humidity is high. Greenhouse specimens may be particularly susceptible unless there is adequate ventilation. Condensation adds to the ambient humidity and promotes spore growth. Soil is another contributing factor. Many soils harbor fungal spores, which can persist for years until the right set of conditions occur. Even purchased potting soil may be contaminated with fungal spores. [图片]How to Treat Fungus on Cactus Once there is a fungus affecting your cactus, it can be difficult to stop. If damage isn’t severe, a fungicide spray can usually help. If the plant is rife with lesions, it may be best to find some uninfected healthy material and start a new plant with a cutting. Use a sterile knife to take the cutting and dust it with sulfur to kill any possible adhering spores. Controlling cultural conditions with plenty of heat, under stem watering, sterile potting medium and ventilation will halt many fungal outbreaks. Another way to save a plant is to cut out the infected tissue. This doesn’t work with all fungi, but it may be effective at times. Again, sterilize your cutting implement and remove more tissue than appears to be affected to ensure all the pathogen is removed. Keep the area dry as it calluses and watch carefully for signs of reinfection.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

Nematodes are tiny, microscopic roundworms that live in the soil and feed on plants. While some are nitrogen fixing and actually beneficial, others can cause serious damage and open up pathways in plants for harmful bacteria and disease. Root knot nematodes are very common among most cactus species. Keep reading to learn more about how to detect cactus root nematodes and the best methods for managing nematodes in cactus roots. [图片]Cactus Root Knot Nematodes Nematodes feed on plant roots by digging into the root’s cell walls with a sharp, pointed feeding tool called a sytlet. The puncture wound created by the stylet is usually more of a problem than the presence of the nematode itself, because it creates an opening that allows bacteria and fungi to enter easily into the plant, infecting it from within. Root knot nematodes are a specific kind of nematodes that feed on roots and usually create telltale fleshy masses, or “galls” on the roots. These galls make it difficult for the cactus to draw up water and nutrients properly. Since the galls form underground, it’s necessary to look for aboveground signs that your cactus is infected. The lack of adequate water and nutrients can make for a plant that’s yellowed, shriveled and stunted looking. [图片]Treating Nematodes of Cactus The best method for root knot nematode control is prevention. If you’re planting your cacti in containers, always use new, sterile potting medium and clean any used containers thoroughly. If cactus root knot nematodes are already in your soil, it’s possible to treat with nematicides. These chemicals usually come in either granular or liquid form, and can be applied in a few different ways. Always follow the application instructions on the label exactly. It’s easier on the plant to treat soil before planting, but you can treat the soil around your established cactus this way as well.

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px

Dummer. ゛☀

2017年08月17日

...显示更多

0

文章

😀 😁 😂 😄 😆 😉 😊 😋 😎 😍 😘 🙂 😐 😏 😣 😯 😪 😫 😌 😜 😒 😔 😖 😤 😭 😱 😳 😵 😠

* 仅支持 .JPG .JPEG .PNG .GIF

* 图片尺寸不得小于300*300px