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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
Diseases in plants can be very difficult to diagnose due to the nearly infinite numbers of pathogens. Phytoplasma disease in plants are generally seen as “yellows,” a form of disease common in many plant species. What is phytoplasma disease? Well, first you need to understand the phytoplasma life cycle and how they are spread. New studies indicate that phytoplasma effects on plants can mimic damage shown by psyllid insects or leaf roll virus. Phytoplasma Life Cycle Phytoplasmas infect plants and insects. They are spread by insects through their feeding activities which inject the pathogen into the phloem of the plants.
The pathogen causes a host of symptoms, most of which are all potentially damaging to plant health. Phytoplasma live in the phloem cells of a plant and usually, but not always, cause disease symptoms. These tiny pests are actually bacteria with no cell wall or nucleus. As such, they have no way to store necessary compounds and must steal these from their host. Phytoplasma are parasitic in this way. Phytoplasma infect insect vectors and replicate within their host. In a plant, they are limited to the phloem where they replicate intracellularly. Phytoplasma cause changes in their insect and plant hosts. The changes in the plants are defined as diseases. There are 30 recognized insect species which transmit the disease to various plant species. Symptoms of Phytoplasma Phtoplasma disease in plants can take on several different symptoms. The most common phytoplasma effects on plants resemble the common “yellows” and can affect over 200 plant species, both monocots and dicots.
The insect vectors are often leafhoppers and cause such diseases as: Aster yellows Peach yellows Grapevine yellows Lime and peanut witches’ brooms Soybean purple stem Blueberry stunt The primary visible effect are yellowing leaves, stunted and rolled foliage and unripened shoots and fruits. Other symptoms of phytoplasma infection might be stunted plants, a “witches’ broom” appearance on terminal new bud growth, stunted roots, aerial tubers and even die back of entire portions of the plant. Over time, the disease can cause death in plants. Managing Phytoplasma Disease in Plants Controlling phytoplasma diseases usually begins with controlling insect vectors. This starts with good weed removal practices and clearing brush that can host insect vectors. Bacteria in one plant can also spread to other plants, so often removal of an infected plant is necessary to contain the contagion.
Symptoms appear in mid- to late summer. It can take 10 to 40 days for plants to exhibit infection after the insect has fed on it. Controlling leafhoppers and other host insects can help control the spread of the disease. Dry weather seems to increase leafhopper activity, so it is important to keep the plant watered. Good cultural care and practices will increase plant resistance and spread.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
Have you ever seen a tree, such as spruce, with healthy looking needles at the tips of the branches, but no needles at all as you look further down the branch? This is caused by needle cast disease. Find out more in this article. What is Needle Cast Disease? Needle cast diseases cause spruce trees to “cast off” their older needles and keep only the young needles at the tips of the branches. The tree becomes unattractive and may look as though it is dying, but don’t despair. Rhizosphaera and Stigmina, the two most common needle cast diseases of spruce trees, are treatable. You can have your tree looking lush and beautiful again within a few years by following a program of needle cast treatment. Stigmina and Rhizosphaera Needle Cast in Trees These diseases primarily affect blue spruce. If you have seen trees affected by needle cast disease in the area, avoid planting this highly susceptible tree.
Instead, consider planting Norway spruce, which is resistant. White spruce and other conifers, like pine and fir, are also susceptible. The first step is to get a reliable diagnosis. Experts recommend that you send a few diseased needles to a diagnostic laboratory where they can run tests to identify the problem. If you feel comfortable trying to identify the disease at home, here’s what to look for: Trees with Stigmina or Rizosphaera needle cast fungus have a distinctive appearance. The branches have green, healthy needles at the tips and diseased and dying needles toward the trunk.
The damage begins on lower branches and moves up the tree. Trees affected by needle cast disease have needles that turn yellowish in summer, gradually changing to purplish brown in late winter and spring. If you look at the needles with a hand lens, you’ll see rows of small black dots. These dots are the fruiting bodies of the fungus, and they are diagnostic of the disease. Rows of white dots are normal. Treat the tree by spraying with a fungicide twice in the spring and then once every four weeks during wet weather. Alternate between sprays with different active ingredients.
Copper and chlorothalonil are two active ingredients that are proven effective against the diseases. Keep in mind that these sprays are highly toxic to plants, animals and people. Follow the safety precautions on the label to the letter. Wear the recommended protective clothing, and read all instructions regarding mixing and applying the fungicide before you begin. Large trees are difficult to treat without help from a tree service.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
What is volutella blight on plants? Also known as leaf and stem blight, volutella blight is a destructive disease that affects pachysandra plants and boxwood shrubs. Early diagnosis and vigilant plant care are the keys to volutella blight control. Read on to learn about treating volutella blight. Volutella Blight Symptoms Initial symptoms, which appear in early spring, frequently resemble winter injury. Volutella blight symptoms begin with delayed emergence of new growth and patches of wilted, discolored, yellow, red or bronze leaves that gradually increase in size before turning black and falling from the plant.
Greenish-brown, water-soaked cankers girdle the stems, causing the plant to shrivel and wilt as the cankers turn dark black or brown. Pinkish fungal spores often appear during humid weather. Volutella Blight Treatment Prune damaged growth.
Wipe cutting tools with bleach solution or rubbing alcohol between each cut to prevent spread of disease. Shake or rake the plant to remove infected leaves, then destroy the debris. Although fungicide sprays won’t cure volutella blight, application of lime sulfur or copper sprays may help in case of severe infestations. Spray plants just before growth appears in spring, and then continue throughout the growing season as directed on the label. Plants may benefit from an additional volutella blight treatment in autumn to protect late summer growth. Remove plants if the blight is overly severe.
Replace them with more disease-resistant shrubs or ground covers. Volutella Blight Control and Prevention To prevent volutella blight, keep plants healthy and minimize stress with regular trimming, which improves air circulation and increases penetration of sunlight. Trim plants during dry weather. Water plants in the morning so the foliage has plenty of time to dry before temperatures drop later in the day, as volutella blight is more prevalent in wet, humid conditions. Avoid heavy mulch, which may keep the growing environment overly damp. Treat insect infestations as they appear, and clean beds and rake plant debris in autumn.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
Gardeners know that any manner of disease can befall their prized plants. In the case of Armillaria root rot, fungi are the underlying cause and the disease can be fatal. Armillaria root rot symptoms can by sly, starting out slowly with slowed growth and culminating with wood rot and mortality. Recognizing the disease and implementing a process of Armillaria root rot control can slow the disease. More information can be found by reading the article below. What is Armillaria Root Rot? Armillaria affects many ornamental and edible plants. What is Armillaria root rot? The disease is found through temperate and tropical regions of the world. Symptoms can be difficult to identify because the fungus responsible for the disease attacks roots deep in the soil. Once the disease has started to progress, it can be difficult or even impossible to arrest its effects. Armillaria stems from its mycelium harbored in the earth. The disease can persist for many years before above-ground symptoms emerge.
Typical Armillaria root rot symptoms can vary from species to species, making the disease even more difficult to nip in the bud. Additionally, the fungus spreads in groves or stands of trees from plant to plant through rhizomorphs, very similar to root rhizomes. It can also spread when mechanical soil movement occurs and transfers diseased wood chips. This makes the disease that much more insidious and challenging to manage. Armillaria Root Rot Symptoms One of the first symptoms of the disease is usually wilted, limp foliage. Leaves or needles yellow and fall, while upper limbs experience die-back. Definite diagnosis of the disease may involve cutting into the cambium of the affected tree.
The fungus appears in cambium as whitish in color and has a distinctly mushroom-like odor. Affected conifers may develop a bumper crop of cones, known as stress cones, and any sick tree is prone to attack by other disease and insect pests. Among the more interesting Armillaria root rot facts, is its natural presence in soil and symbiotic relationship with affected trees. Plants under environmental stress, other disease issues and in incorrect sites will be more quickly symptomatic than trees in excellent health. Armillaria root rot control depends upon early recognition of symptoms and superior cultural care of diseased plants. Treatment for Armillaria Root Rot Sadly, there is no absolute treatment for Armillaria root rot. The disease can be managed by consistent removal of dead trees and infected stumps.
Armillaria requires consistent moisture to survive, and in citrus groves, excavation around the root crown has been an effective deterrent but not an ultimate cure. Providing excellent care to trees has been shown to increase vigor and health, thereby reducing the plant’s symptoms. In large scale forests, affected stands are often removed and replanted with species that are naturally resistant to the disease. Occasionally, chemical fumigants are applied, reducing the spread of the disease. This practice isn’t practical for the home gardener, so cultural management, removal of infected plant material and good sanitation seem to be the best options in the home landscape.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
Cedar hawthorn rust is a serious disease of hawthorn and juniper trees. There is no cure for the disease, but you can prevent its spread. Find out how to control cedar hawthorn rust in this article. What is Cedar Hawthorn Rust? Caused by a fungus called Gymnosporangium globosum, Cedar hawthorn rust disease is a disfiguring condition of hawthornsand junipers. Although it rarely kills trees, the trees never recover from the damage. You can prune out the worst of it, but once it affects the entire tree, your only choices are to learn to live with it or take the tree down.
In addition to the rust-colored spots on the leaves, hawthorns may have rusty-looking “fingers” projecting from the fruit. The leaves may yellow and drop from the tree. Junipers develop woody galls that also have rusty fingers. If you recognize and treat the disease early, you may be able to enjoy your tree for several more years.
Cedar Hawthorn Rust Treatment When a tree has visible symptoms of cedar hawthorn rust, it is too late to save the tree. Focus on slowing its progress and preventing it from spreading to other trees in the surrounding area. The fungal spores that infect additional trees are blown about on the wind, so most new infections occur within a few hundred feet of an infected tree. That said, spores have been known to travel a few miles. It’s best to err on the side of caution when deciding whether or not to use preventative treatment on a tree. The two-part life cycle of cedar hawthorn rust disease involves both hawthorns and junipers. Infected hawthorns develop reddish-brown spots (rust) on the leaves and junipers have galls with fingers extending from them. Remove the galls in winter to help prevent spread and never plant junipers near hawthorns.
Although you can’t cure an infected tree, you can prune out infected parts of the tree to improve its health and appearance. Remove entire branches wherever possible. This not only benefits the infected tree, but also reduces the number of spores capable of spreading the infection. Moisture around hawthorn and juniper trees encourages the fungus. Reduce moisture by making sure air circulates freely around the tree. You may be able to accomplish this through pruning. When watering the tree, direct the spray toward the soil rather than the branches. Protect trees from infection by spraying in spring and early summer with an approved fungicide. Both chlorothalonil and mancozeb are registered for use against cedar rust disease on hawthorns. Follow the label instructions and spray the tree until the fungicide drips from the branches. Spray junipers with a Bordeaux mixture every two weeks beginning in midsummer.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
What is algal leaf spot and what do you do about it? Read on to learn about symptoms of algal leaf spot and tips on algal leaf spot control. What is Algal Leaf Spot? Algal leaf spot disease, also known as green scurf, is caused by Cephaleuros virescens, a type of parasitic algae. Algal leaf spot disease spores, which are spread by rain, create a big problem for more than 200 plant species, especially plants growing in warm, humid climates. Susceptible plants include those that have leathery leaves such as:Magnolia Camellia Boxwood Crepe myrtle Azalea Bougainvillea Wisteria Rhododendron Viburnum.
Recognizing Symptoms of Algal Leaf Spot Algal leaf spot disease is marked by rough, net-like orange, brown, gray or green blotches on the leaves, each measuring about ½ inch in diameter or less. However, blotches that grow together take on the appearance of larger blotches. Although the disease affects primarily foliage, it sometimes impacts branches and twigs, causing a stunted appearance with reddish-brown or pale green lesions.
Algal Leaf Spot Control Algal leaf spot disease is rarely deadly and the problems are mostly cosmetic. Unless the outbreak is severe, non-chemical strategies for treating algal leaf spot are usually adequate: Keep plants as healthy as possible, as well-managed plants are less susceptible to disease. Maintain proper soil drainage and water, and fertilize as needed. Prune plants to improve air circulation and access to sunlight.
Trim around the plants to reduce the humidity level, including overhanging trees that create too much shade. Rake up and dispose of leaves and debris under and around the affected plant. Discard of infected debris carefully to prevent spread of the disease. Keep in mind that the algae can survive on fallen leaves during the winter months. Water at the base of the plant. Avoid wetting the leaves as much as possible. Apply a Bordeaux mixture or copper-based fungicide if the plant is seriously infected. Repeat every two weeks during cool, damp weather.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
One of the more common diseases of lima beans is called pod blight of lima beans. Pod blight in lima bean plants can cause serious losses in yield.
What causes this lima bean disease and what methods of control are there for lime bean blight? Symptoms of Pod Blight in Lima Bean Plants Symptoms of pod blight of lima beans first manifests as irregular, brown eruptions on fallen petioles in mid-season, and on pods and stems close to maturity. These small, raised pustules are called pycnidia and in wet seasons may cover the entire plant. The upper portions of the plant may yellow and die. Seeds that have become infected may look completely normal or will crack, shrivel and become moldy. Infected seeds often do not germinate. Symptoms of this lima bean disease may be confused with those of anthracnose, as both of these diseases of lima beans occur late in the season.
Conditions Favorable for Lima Bean Blight Pod blight is caused by the fungus Diaporthe phaseolorum, which overwinters in infested crop detritus and in infected seeds. Spores are transferred to plants via wind or splashed water. Thus, although infection can occur throughout the season, this fungus thrives in wet, warm conditions. Pod Blight Control Since the disease overwinters in crop detritus, practice good garden sanitation and clear the beds of any lingering crop debris. Remove any weeds that may also harbor the disease.
Only use seed that is grown in the western United States and use a high quality disease free seed. Do not save seed from the previous year if the disease was evident in the crop. Rotate the crop with non-host crops on a 2 year rotation. Using a copper-type fungicide on a regular basis will help control the disease.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
Fungus happens. Even the most experienced and dedicated gardeners will experience fungal disease on plants at some point. Fungus can affect plants in any climate and hardiness zone because, like plants, certain fungal spores grow better in different climates.
Even new disease resistant varieties can suffer from these issues. As gardeners, we can choose to spend a fortune on different chemicals that can have residual effects to treat different symptoms or we can use a natural based product that has been used by growers and breeders for hundreds of years.
What is Lime Sulfur? Lime sulfur is a mixture of calcium hydroxide and sulfur. In horticultural dormant sprays, lime sulfur is usually mixed with an oil, like mineral oil, to make it stick to plant surfaces. These horticultural oil sprays contain a high concentration of lime sulfur that is only safe to use on plants that are dormant because the sulfur can burn leaf tissues. Lime sulfur can also be mixed in much weaker concentration with water for use when plants have leafed out. Even in lower concentrations and diluted with water, it is important not to spray lime sulfur on plants during hot, sunny days, as the sulfur can cause sunscald on plants. With warnings like this, you may wonder is lime sulfur safe? When used properly, lime sulfur is a safe and effective treatment of fungal diseases such as: Powdery mildew Anthracnose Black spot Blights Black rot As a horticultural dormant spray, lime sulfur is safe to use even on fruits that include: Raspberries Blackberries Blueberries Apples Peaches Pears Plums Cherries Lime sulfur is also used to treat fungal diseases of ornamental plants like: Roses Dogwoods Ninebark Phlox Rudbeckia.
How and to Use Lime Sulfur Fungal disease spores can overwinter in cracks or fissures on plants or in soil and garden debris. For this reason, lime sulfur is used in high concentrates mixed with oil as a horticultural dormant spray. When to use lime sulfur this way is in late winter or early spring before the plant begins to leaf out. It is also a good idea to spray the soil around plants that have been previously infected or are prone to infection. For perennials or plants that are showing new signs of fungal diseases, lime sulfur can be mixed with water and sprayed on plants anytime except for hot, sunny days. The mixing ratio is 1 tsp. per gallon of water. Spray all surfaces of the plant thoroughly. Allow the mixture to sit on the plants for 15-20 minutes. Then thoroughly rinse the plants with just clear water. Occasionally, you will notice the bottom portion of tree trunks covered with white latex paint. Sometimes, this contains a diluted mixture of lime sulfur.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
Just like people, plants are known to feel under the weather now and then. One of the more common signs of ailment is yellowing leaves. When you see leaves turning yellow, it’s time to put your Sherlock hat on and do some sleuthing to find the possible cause and solution. Among the reasons why plant leaves are yellow are environmental conditions, cultural reasons, pests or disease, and even the medium in which the plant grows.
Common Reasons for Leaves Turning Yellow There are many conditions that affect plant growth. Plants are susceptible to temperature variations, sensitive to chemicals and excesses of nutrient, require specific soil compositions and pH levels, have varying lighting needs, are prey to certain pests and diseases, and many other factors influence their health. Yellowing leaves on plants can be a sign of any of these out of balance or even certain nutritional or chemical influences. Plants don’t have facial expressions so they, therefore, can’t express discomfort or displeasure the way we can. What they can do is show dissatisfaction with a condition by signaling with their leaves. So when you find out why plant leaves turn yellow, you can start triaging your ill plant and nurse it back to health. Yellowing leaves on plants may often be a sign of too little or too much water or nutrients which can affect plant performance. Your plant may also be located in too much light where it is scorching, or too little light where it is fading due to an inability to photosynthesize properly. Yellowing also occurs due to blatant physical damage. Age is another cause when plant leaves are yellow. It is quite usual for many types of plants to lose the older leaves as the new ones arrive. Older foliage will turn yellow and often wither before it drops off. Winter dormancy is another condition with which most are familiar that makes yellow plant leaves. Of course, yellow plant leaves may not be the only hue experienced, as autumnal displays of red, orange, bronze and rust are common sights.
Why Plant Leaves Turn Yellow in Containers Because of the closed environment in container plants, the conditions must be carefully controlled. There is a limited amount of space, area to store moisture, nutrient in the medium, and lighting and temperature must be considered for each species of potted plant. Our houseplants often have leaves turning yellow due to nutrient deficiency or excess salt in the soil from too much fertilizer. It may be necessary to change the soil or leach it with large amounts of water to correct the balance. Of course, changing the soil can trigger a condition called transplant shock, which also causes yellowing and dropping leaves. Indoor plants are often tropical in nature and something as simple as changing the plant’s location can produce yellowing leaves on plants which drop off the specimen. This is often due to stress but can also indicate low light or exposure to a draft. The pH may also be too high, causing a condition called chlorosis. It is a good idea to use a pH meter in potted plants to ensure the correct growing conditions. Overhead watering is yet another cause for yellow “water spots” on plants like gloxinia, African violet and several other species of plants with slightly furred foliage. When Plant Leaves are Yellow from Pests or Disease Pinpointing the causes of yellowed leaves can be quite difficult due to all the potential causes. One thing we haven’t gone over are pests and disease. Sucking insects attack plants inside and outside. These encompass: Mites Aphids Mealybugs Thrips Scale Whiteflies Many of these insects are too tiny to see with the naked eye and are identified by the plant’s response to their feeding activity. The insects are robbing the plant of its sap, which is the life blood of the plant.
The plant’s response is a reduction in overall health including stippled and yellowing leaves. Leaves may crinkle at the edges and fall off. In most cases, repeatedly washing the plant to remove the insects or using a horticultural soap or neem oil can combat these little pirates. Root diseases are often found in root bound plants or in soils with poor drainage. Any attack on roots can limit the ability of the plant to uptake moisture and nutrients, severely affecting its health. Roots may simply rot away, leaving the plant with minimal ways to sustain themselves. Withering, fading leaves are a common sight when roots are under attack by root rot disease or even root nematodes. As you can see, there are many causes for yellowing foliage. It is best to familiarize yourself with your plant’s specific needs so you can consider each cultural condition carefully and unearth possible causes. It takes patience, but your plants will love you for it.
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Dummer. ゛☀
2017年08月07日
Dummer. ゛☀
he Aristolochiacea family of plants are commonly known as Birthworts. They are a small family which occur in tropical and Mediterranean regions.
Aristolochia baetica is very similar to Aristochia sempiverens which occurs in parts of Italy, North Africa and parts of the eastern Mediterranean region. Aristolochia baetica has darker flowers which are more purple in colour, and the leaves of the plant are a blue-green colour.
The plants of the Aristolochiaceae family attract their pollinators (flies) by exuding a strong smell from their flowers which are typically saxaphone-shaped. When the flies crawl down into the flowers, they are trapped by the hairs that surround the 'mouth' and remain, crawling around, inside the flower overnight. By the following morning the hairs have withered and the flies, now covered with pollen, are able to escape and move on to other flowers and so complete the pollination cycle.
Aristolochia baetica is very common in the Algarve in Portugal, and can be found on roadsides and other waste ground where the plants scramble over shrubs and rough stone walls. It flowers from June to August.
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