|“|| Freshly harvested maple sapling. Needs to be cured before it can be used for crafting and repair.
Can be used for crafting and repair after air-drying indoors for 6 days. In-game description
|“||Small maple sapling that has been cured. Can be used for crafting and repair. In-game description||”|
- Overview Edit
- Verticillium wilt
- Verticillium Wilt Treatment: What Is Verticillium Wilt And How To Fix It
- What is Verticillium Wilt?
- Control of Verticillium Wilt
- Verticillium Wilt – A Serious Disease of Trees and Shrubs
- Verticillium Wilt on Trees and Shrubs
- What Plants Are Resistant To Verticillium Wilt? – Knowledgebase Question
- A verticillium cure that works
- Verticillium Wilt
- Symptoms & Disease Cycle
- Maple (Acer spp.)-Verticillium Wilt
A maple sapling is a plant-based material that can be harvested and cured. The cured sapling can then, with the proper tools, be crafted into a survival bow at a workbench. Contrary to the in-game description, the sapling cannot be used for repairs. Both green and cured maple saplings will always be at 100% condition.
Maple saplings are found out in forested and, occasionally, more open landscapes. They usually come in ones and twos, but are normally not found in very close proximity to birch saplings.
Green saplings can be harvested with a hatchet or a hacksaw, adding 1 x green maple sapling to the inventory. After being harvested, a small root stalk remains where the sapling once stood.
To cure the young maple, place it in the open inside a building or moderately deep cave and wait. Progress can be checked by looking at the sapling while close. The curing process advances at approximately 0.8% per hour.
Cured maple saplings stack in the inventory.
|Materials v • d • e|
|Gunsmithing||Bullet • Can of gunpowder • Dusting sulfur • Rifle shell casing • Revolver shell casing • Scrap lead • Stump remover|
|Miscellaneous||Arrow shaft • Arrowhead • Cloth • Scrap metal|
Verticillium wilt is a serious fungal disease that causes injury or death to many plants, including trees, shrubs, ground covers, vines, fruits and vegetables, and herbaceous ornamentals. It is a disease of the xylem, or water-conducting tissues, in the plant. Commonly infected woody plants include maple, smoke-tree, catalpa, and magnolia, among others.
Verticillium wilt is caused by a soil fungus called Verticillium dahliae. Another species, Verticillium albo-atrum, is less common. This fungus lives in soil as small, darkened structures called microsclerotia. These microsclerotia may lie dormant in the soil for years. When the roots of susceptible plants grow close to the microsclerotia, the fungus germinates and infects the roots of the plants through wounds or natural openings. The fungus spreads into the branches through the plant’s vascular system and simultaneously causes the plant cells to “plug” themselves. Once the xylem is infected, it becomes so plugged that water can no longer reach the leaves. Verticillium can also be spread to plants through wounds on branches or trunks.
One or more branches, usually on one side of the tree, wilt suddenly. Sometimes the leaves turn yellow before they wilt, or leaf margins turn brown and appear scorched. In some instances, there is a slower decline in new twig growth, or dead twigs and branches appear. On maples and tulip trees, elongated dead areas of bark, called cankers, may appear on diseased branches or trunks. In Illinois, these symptoms usually occur in July, but can be seen as early as May or as late as October.
Internally, diseased trees may exhibit discolored sapwood in the recent annual rings. In maples, Verticillium produces greenish streaks; in smoke-tree, the streaking is yellow-green. In other woody plants, the discoloration is brown. In some trees and on younger twigs, discoloration does not occur or is found several feet below the point where leaves are actually wilting. This makes identification difficult.
There seem to be two forms of the disease, one in which plants die slowly over several years and another where they die rapidly within a few weeks. Trees that show minor branch wilt one year may show more the next year or may not show symptoms again for several years. There is some evidence that unbalanced fertilization (too much or too little nitrogen, for example) exacerbates this disease.
The appearance of streaking helps to identify the disease but does not guarantee that the tree has Verticillium. Sometimes other factors or diseases cause discoloration of sapwood. Only laboratory examination can positively diagnose the disease.
For laboratory identification, select twigs that are about 1/2-inch in diameter and approximately eight inches long. The twig must be from a branch that is actively wilting, but not yet dead. Wrap the samples in wax paper or other material that will keep the sample from drying out. Mail the sample (overnight, if possible) with your name, address, and a history of the problem to the University of Illinois Plant Clinic. Phone 217-333-0519
There is a charge per sample.
Verticillium wilt is difficult to control because it persists in the soil indefinitely. Infected trees that are not yet dead sometimes “outgrow” the fungus. Dead branches should be pruned out to help overall plant vigor. The disease can be transmitted on pruning tools. It is recommended that tools be sterilized by dipping them in a diluted cleanser, such as Lysol, Pinesol, or household bleach, between cuts and between trees.
To avoid stress, trees should be planted in sites that are favorable to their growth. Water thoroughly during dry periods. Use a three- to fourinch layer of organic mulch to retain moisture and prevent soil temperature fluctuation. Fertilize properly and avoid injuries to the roots, trunk, and branches. Severely infected trees should be removed and replaced with plants that are not susceptible to Verticillium. Trees that are not known to be susceptible include: arborvitae, baldcypress, beech, birch, boxwood, crabapple, ginkgo, hackberry, hawthorn, hazelnut, hickory, holly, honey locust, hornbeam, ironwood, Katsura tree, mulberry, oak, pine, serviceberry, spruce, sweetgum, walnut, willow, and yew.
At this time, there is no known chemical control for this disease.
Verticillium Wilt Treatment: What Is Verticillium Wilt And How To Fix It
Leaves that curl, wilt, discolor and die may mean that a plant is suffering from verticillium wilt. You may first notice these symptoms in spring or fall when temperatures are mild. Read on to find out how to distinguish verticillium wilt from other plant diseases and what to do about it.
What is Verticillium Wilt?
Verticillium wilt is a fungal disease that lives in the soil. It invades susceptible plants through their roots and spreads through the plant’s vascular system. The list of plants affected by verticillium wilt is extensive and includes trees, shrubs, and garden annuals and perennials. It can also affect fruit and vegetable crops.
Verticillium wilt symptoms mimic those of other plant diseases and environmental problems, and this makes it hard to diagnose. The leaves wilt and curl, and turn yellow or red. They eventually turn brown and drop off. Stems and branches die back. It’s not unusual to see these symptoms on one
side of the plant while the other side appears unaffected.
As the disease travels up a tree or shrub’s vascular system, it leaves dark discolorations. If you peel back the bark, you’ll see dark streaks on the wood. If you cut through a branch and look at the cross section, you’ll see rings of dark color. These discolorations in the wood can help you tell the difference between verticillium wilt and other plant diseases.
Control of Verticillium Wilt
Verticillium wilt can’t be cured once it enters the plant. It’s best to remove and destroy small, easily replaced plants. The disease remains in the soil after you remove the plant, so don’t plant another susceptible species in the same area.
Verticillium wilt treatment for trees and shrubs focuses on giving the plant the best possible care to build up its resistance. Water the plant regularly, and when possible, provide afternoon shade. Fertilize on schedule, using a low-nitrogen, high-phosphorus fertilizer. Prune off dead and dying branches.
You can often get rid of the verticillium wilt fungus in the soil by solarization. Soil solarization heats up the top 6 inches or so of soil to temperatures high enough to kill the fungus. Prepare the soil by tilling or digging and then wetting it down. Cover the area with a clear plastic tarp and bury the edges under a few inches of soil to hold it in place and keep the heat in. It takes three to five weeks of bright sunlight and warm temperatures for the soil to heat up enough to kill the fungus.
Verticillium wilt is a devastating and incurable disease, but with special care and attention, you can preserve the plant and enjoy it for several more years.
Whether you are caring for a lush vegetable garden or a flowerbed for pollinators, verticillium wilt is a threat. The best way to deal with this dreaded plant disease is avoiding it, but before you can protect your plants, you must first understand this deadly plant nemesis.
What Is Verticillium Wilt?
Verticillium wilt is fungal disease affecting over 350 host plants found throughout the world. It’s caused by the soil-dwelling Verticillium dahliae and Verticillium. albo-atrum. This fungus grows into plant roots and stems, depriving plants of necessary nutrients for proper growth and clogging plants’ water transport systems. It’s is most active in cooler weather but may also affect plants in warmer weather due to previous damage.
Signs of Verticillium Wilt in Plants
Plants affected by this fungus show certain signs, including faded yellow or green leaves that wilt and die. The lower leaves show signs before upper plant leaves. Very young or non-woody plants may die quickly. However, signs of disease can differ by plant type. Here are some signs of verticillium wilt on commonly grown plants.
Common Susceptible Food Crops
Tomatoes and cucumbers are often staples in many home gardens, and unfortunately susceptible to verticillium fungi. Signs of disease for both plants includes wilting of older plant leaves and stunted growth. You may notice a brown v-shaped pattern on affected leaves as well. The only cure is to remove affected plants. You can help to prevent future infections with crop rotation, planting tomatoes in well-drained soil, and choosing resistant varieties.
Strawberries are a favorite summer fruit. They too are often victims of verticillium fungi living in your soil. Affected plants leaves have brown edges and veins, mainly lower plant leaves. These leaves often die. Plants also produce few new leaves. You’ll need to dig out and destroy infected plants, and like tomatoes and cucumbers, choose disease-resistant varieties to ensure healthy growth.
Common Susceptible Flowers
Roses are very common ornamental plants, but also susceptible to this fungus. Sick plants develop drying canes, and new leaves are stunted and yellow. The plants may die if swift action isn’t taken. Trim out infected canes at soon as signs develop. Once too many canes are affected and the plant is dying, the only solution is to uproot the plant.
Chrysanthemums are an excellent addition to a sustainable garden, but they too can be infected with verticillium fungi. The disease shows signs at the base of the plant first with leaves that turn yellow and die. The plant will also produce very few if any, blooms.
Dahlia blooms are always a great addition to your garden but can also be affected by verticillium fungi. The plant’s lower leaves turn yellow, its blooms droop, and you may also notice dark brown areas on plant stems. In most cases, you’ll need to remove sick plants and trim any decayed areas from stored tubers to prevent disease.
Avoiding Verticillium Wilt
There is no cure for this disease, so your best chance of a healthy garden is preventing the fungi from living in your soil. You can achieve this by utilizing good gardening practices.
Proper watering and fertilization is essential to growing healthy plants. Making sure soil has plenty of nitrogen and good drainage is a good start. Also avoid overwatering plants!
Rotation also helps. Rotate your susceptible plants using a four-year cycle.
Solarization is another possible solution. In sunny, warm areas you can cover your garden area with a tarp and allow the heat to build up and kill the fungi.
If you know your soil is contaminated, you can choose from a variety of plants that are naturally immune to this disease. Some examples include beans, asparagus, corn, lettuce, onions, peas, sweet potatoes, and carrots.
These quick tips can help you in growing healthy plants that are free of this dreaded fungus. If you do find yourself struggling with this disease, we’ve put together a comprehensive list of plants that are susceptible, immune, and resistant to Verticillium Wilt.
Verticillium Wilt – A Serious Disease of Trees and Shrubs
This maple leaf is exhibiting signs of Verticillium wilt.
By Christine Engelbrecht
Extension Plant Pathologist
Iowa State University
The green, leafy branches of a maple or ash tree can provide much-needed refuge from the sun during the hot days of summer. Verticillium wilt, a common but often overlooked disease, can destroy that beautiful shade by causing these trees to wilt and die, sometimes within a few weeks or months.
Verticillium wilt is a fungal disease that affects over 300 species of plants, including many common trees and shrubs. In Iowa, it is most commonly seen on maple, ash, and catalpa trees, although it is also frequently found on smoke tree, viburnum, lilac, cherry, plum and several other trees and shrubs.
Verticillium wilt is caused by a fungus that lives in the tiny tubes (xylem) that carry water through the tree. The fungus essentially blocks these tubes, preventing water flow and causing the plant to wilt. The fungus also produces toxins that poison the plant.
The disease can occur either acutely or chronically. In acute infections, a branch or a section of several branches of the tree may wilt and turn brown rather suddenly. Often other branches soon follow, until most or all of the branches are wilted. Leaves may also turn yellow between the veins, or may drop prematurely. Branches may die back. Acute infections occur when the fungus is living in the newest wood (the sapwood).
In chronic infections, leaves may be smaller than usual or yellow, often with brown edges. The tree may grow poorly and may produce abnormally large seed crops. The tree does not wilt or die quickly, but declines slowly over time. Chronic infections occur when the fungus is living in older wood.
The Verticillium fungus lives in the soil and infects plants through the roots, often entering through wounds, such as wounds that naturally occur as the roots grow through the soil. The fungus survives in the soil as a thread-like body called a mycelium and as microscopic, dark, resistant structures called microsclerotia. These microsclerotia can survive in soil or dead plant material for up to ten years. For this reason, it is virtually impossible to eradicate the fungus from the soil.
The Verticillium fungus is abundant in many soils, and we do not know why it can lay dormant for many years before suddenly attacking a tree that has been growing in a spot for a long time. It is possible that stresses to the tree, such as a drought or living in poor soil, can make it more susceptible to infection.
There are no treatments available to remove the fungus from the soil where it survives. Management relies on keeping trees in good vigor. Trees with recent wilt symptoms may be able to section off (compartmentalize) the infection themselves and recover.
There is no need to quickly remove infected trees, as the fungus lives in the soil and does not spread through the wind. Dead branches should be pruned out to prevent infection by other fungi and to improve the appearance of trees with chronic infections.
Since the fungus lives in the soil, trees that have died from Verticillium wilt should be replaced with resistant species. Luckily, many species of trees and shrubs are unaffected by Verticillium wilt. These include all conifers, crabapple, beech, ginkgo, hackberry, hawthorn, hickory, white oak and poplar, among others. When a tree dies from Verticillium wilt, replacing it with one of these resistant species can help to ensure a steady source of summer shade.
A high resolution version of the photo is available 62405VerticilliumLeaf.jpg
Verticillium Wilt on Trees and Shrubs
Description & Symptoms
Verticillium wilt is a soil-borne fungal disease that plugs the vascular system of woody plants. Symptoms include wilting leaves, often along a single branch. In acute cases, leaves curl and wilt, and the branch dies. Scattered dieback of branches may occur over several years. In chronic cases, branches survive but growth is slow and leaves are small and sparse. Both acute and chronic symptoms can appear on the same plant. The sapwood of an infected branch may contain dark streaks. To check for this symptom, cut a cross-section of a thumb-sized branch and look for darkened tissue immediately under the bark.
Timing & Life Cycle
Once taken up by a plant, spores germinate and grow inside the xylem (water-conducting tissue), blocking the movement of water beyond the growth. Fungal spores live in the soil and enter plants through the roots. Infection occurs most frequently in cool to warm weather. Incidence of disease subsides during hot weather. The fungus survives in the soil for many years.
With careful watering and pruning, most plants survive verticillium wilt. Severely infected plants with widespread wilting and branch dieback may not survive.
Treatment & Solutions
The verticillium wilt fungus cannot be eradicated from the soil, and fungicidal treatment of infected plants is ineffective. Wilted branches should be pruned out. Severely infected trees and shrubs should be removed. Pruners must be disinfected between cuts with a mild bleach/water solution to avoid spreading the disease to healthy tissue. Avoid overfertilizing plants as succulent, new growth is particularly susceptible to infection. Use resistant plants when replacing a tree killed by verticillium wilt.
For a list of trees that are less susceptible to verticillium wilt, call the Plant Information hotline at (847) 835-0972.
What Plants Are Resistant To Verticillium Wilt? – Knowledgebase Question
Verticillium wilt is caused by a fungi which attacks the vascular systems of plants. The wilt fungi remains in the soil if there are suitable hosts. Plant debris and some commonly encountered organic matter can sustain the life of the fungal spores until another suitable host is planted in the same soil. Here’s a partial list of plants that are generally resistant to verticillium:
Amur Cork-tree (Phellodendron)
Bald cypress (Taxodium)
Burning bush (Euonymus alatus)
Concolor fir (Abies)
Cotoneaster (some species)
Chinese elm (Ulmus)
Flowering quince (Chaenomeles)
Goldenrain tree (Koelreuteria)
Hophornbeam, American (Ostrya)
Hornbeam, European (Carpinus)
Kentucky coffee tree (Gymnocladus)
Kousa dogwood (Cornus)
Northern bayberry (Myrica)
Oregon grape holly (Mahonia)
Pagoda-tree, Japanese (Sophora)
Persian parrotia (Parrotia)
Rubber tree (Eucommia)
Silver bell (Halesia)
Smoke bush (Cotinus) Verticillium wilt infrequent
Spirea (Spiraea) Leaf spot,
Sour gum, tupelo (Nyssa)
Sweet pepperbush (Clethra)
Turkish hazel (Corylus)
Yellow wood (Cladrastis) Verticillium wilt, infrequent
Witch hazel (Hamamellis)
Japanese zelkova (Zelkova)
Hope this list helps you find a suitable replacement for your Dodonea.
A verticillium cure that works
Verticillium Wilt is a disease that affects more than 300 species of plants, including cotton, tomatoes, potatoes, eggplants and peppers. It is caused by two types of fungus; Verticillium Dahliae and Verticillium Albo-Atrum.
Verticillium Albo-Atrum is a plant pathogen most severe in temperate regions with cooler soils. Verticillium Dahliae can thrive in a wider range of soils and is therefore more common.
Signs and Symptoms
Verticillium Wilt is most often seen from spring to autumn. It infects plants through the roots and grows up through their water-conducting tissues. It eventually causes wilt due to stress. Furthermore, the Verticillium Dahliae and Verticillium Albo-Atrum fungi cause dieback.
Common symptoms of the fungal infection include yellowing and shriveling lower leaves and the wilting of part or all of the affected plants. The disease also creates brown or black streaks in tissue under bark. These symptoms are magnified during warm weather; plants may recover slightly in cooler, wetter conditions.
Trees with Verticillium Wilt may experience dieback in some limbs but not the entire tree; dead branches may indicate infection in previous years.
Verticillium Wilt can often kill the plants it affects.
Treatment and Prevention
It is imperative not to spread soil contaminated by Verticillium Wilt as the disease is distributed through earth. Outbreaks can be controlled in part by removing weeds and infected plants, including as much of the roots as possible. Heavy watering is also effective in the treatment of the affliction.
The spread of Verticillium Dahliae and Verticillium Albo-Atrum can be culled by applying Oxidate. While often used as a pre-plant dip or foliar treatment, it is also an effective soil drench. TerraClean can also be applied through drip irrigation to eliminate soil-born pathogens.
It is wise to avoid replanting with susceptible plants. Grassing for 15 years is a possibility, as is replanting with crops resistant to the fungi.
Verticillium wilt is caused by two species, Verticillium dahliae and V. albo-atrum. However, V. dahliae is responsible for the majority of infections on woody ornamentals in southern New England.
Various trees and shrubs are susceptible to Verticillium wilt in the region. The most common hosts in landscape settings include: maple (Acer), elm (Ulmus), smoketree (Cotinus), ash (Fraxinus), tulip poplar (Liriodendron), Viburnum, redbud (Cercis), Catalpa, Magnolia, Kentucky coffee tree (Gymnocladus dioicus) and Russian olive (Elaeagnus angustifolia).
Symptoms & Disease Cycle
Infections from Verticillium originate in the soil, when the fungus invades the root system of susceptible plants. Once the fungus becomes established in the vascular system, it is transported throughout the canopy. Verticillium also grows through ray cells to penetrate deep into the secondary xylem. Symptoms can appear rapidly after infection and the most commonly observed symptoms of Verticillium wilt include marginal leaf scorch, leaf wilting, vascular staining and branch dieback. Because there is a disruption of water and mineral transport to the affected branches and leaves, the symptoms appear similar to those caused by root disease, abiotic root damage (e.g. severing, crushing or compaction), drought stress and stem/branch cankering. Acute foliar symptoms can range from wilting, drying, marginal/interveinal browning and premature shedding on a single branch or one side of the tree’s canopy. These symptoms can appear at any time during the growing season. In addition, there are chronic symptoms that resemble a tree in decline, such as: stunted growth, marginal leaf scorch, undersized and sparse foliage, heavy seed production and branch dieback. The vascular staining that results from the disease is the best diagnostic symptom that can be used to determine if additional testing to confirm the pathogen is necessary. However, keep in mind that staining is not always present on infected trees and shrubs. Vascular staining is often olive-green in color but may range from yellow to brown, depending on the host. Because of the pathogen’s ability to move through ray cells, staining may be present deep in the xylem tissue and not in the outer vascular tissue just under the bark (where vascular staining caused by Dutch elm disease is often observed).
One of the most interesting features of Verticillium is its ability to produce microsclerotia. These are very small, black-colored resting structures that resemble a small seed. Once Verticillium has caused disease, microsclerotia are produced within a variety of dead plant parts, including roots, stems and leaves. They allow the pathogen to overwinter in dead plant tissues and when produced in the soil, allow the fungus to persist for many years at the site. When infected leaves and stems fall to the ground, the fungus can also grow into the soil to overwinter. Contact between neighboring, healthy roots and dead, diseased roots can allow Verticillium to spread locally. Overland spread can occur when infected leaves are dispersed away from an infected tree by wind. In addition, Verticillium can infect several resistant weedy plants and create new microsclerotia without ever causing any above-ground symptoms. Therefore, once the fungus is established at a site it can remain there indefinitely.
Verticillium is widespread in forest and landscape settings, yet disease incidence remains relatively low in most cases, signifying that many plants are able to resist the pathogen when attacked. The impact of Verticillium wilt depends on the inherent susceptibility of the tree/shrub, environmental stress (especially drought and root damage) and the virulence of the pathogen. Maintaining high tree vigor is essential, since the tree’s natural defense response may be able to compartmentalize the infection. For recently transplanted trees and shrubs, provide regular irrigation during extended dry periods, fertilize as needed and maintain an adequate mulch layer over as much of the root zone as possible. These activities do not have direct impacts on the pathogen itself, but they serve to enhance the tree’s ability to resist infections. Reduce inoculum and improve the appearance of infected trees and shrubs by removing dead shoots and branches. Keep in mind, however, that pruning does not eliminate Verticillium from the plant since infections first establish from the roots. Because of the soilborne nature of the fungus and its establishment within the roots, fungicides often have little to no effect. Use of resistant or immune trees and shrubs as replacement for those infected with Verticillium wilt is often the only viable strategy in landscape settings. A selected list of resistant trees and shrubs include: apple/crabapple (Malus), beech (Fagus), birch (Betula), boxwood (Buxus), dogwood (Cornus), hackberry (Celtis), hawthorn (Crataegus), hickory (Carya), holly (Ilex), honeylocust (Gleditsia triacanthos), katsura (Cercidiphyllum), linden (Tilia), mountain-ash (Sorbus), oak (Quercus), pear (Pyrus), aspen/poplar (Populus), sycamore/planetree (Platanus), sweetgum (Liquidambar) and walnut (Juglans). All conifers are also resistant or immune to Verticillium wilt. Resistance does not imply immunity; therefore some of the plants listed here may be susceptible to infection.
Maple (Acer spp.)-Verticillium Wilt
Verticillium Wilt in the Pacific Northwest
Cause Samples with Verticillium wilt have dominated the maple problem diagnoses sent to the OSU Plant Clinic. Verticillium dahliae, a soilborne fungus that is almost impossible to eradicate once established in the soil. There are over 300 plant species susceptible to this fungus. It forms microsclerotia that germinate in response to exudates from roots that are growing nearby. Mycelia from the microsclerotia infect the roots. The fungus grows into the xylem where it colonizes the plant through mycelial growth and conidial production. Fluid movement in the xylem passively transports the conidia. Once in the xylem, this fungus partially blocks water movement and produces toxins that result in wilt symptoms. The cambium may die, resulting in an elongate canker, which can be colonized by other pathogens such as Nectria sp. and Cytospora sp. Current-season sapwood may not be infected, and symptoms may not reappear; or infection may occur without foliar symptoms. This may result in branch dieback or bud failure in spring.
After diseased plant parts die, microsclerotia form inside the tissue. Once the infected tissue decays, microsclerotia are released and can survive several years in soil. Many weeds are susceptible and can help the fungus survive and disperse. Plant-parasitic nematodes also can increase Verticillium wilt incidence and severity. Other diseases, such as bacterial dieback, can also increase in incidence and severity on trees with Verticillium wilt. The Norway maple cultivars Jade Glen and Parkway are tolerant and have few symptoms.
Symptoms Leaves on one side of the tree or on just an individual branch suddenly wilt and die. Leaves are yellowish and smaller than normal. Leaf scorch can also occur at leaf margins. Leaves die and fall or hang on dead branches. Later, other limbs wilt and die. Greenish streaks or bands that follow the grain can be found in sapwood but perhaps not in the earliest stages of infection. In cross sections of the stem, vascular discoloration will appear in rings or arcs. Vascular discoloration is more likely to be found in larger branches and trunks. Infected trees may die within a few weeks or live for years.
Sampling Send soil samples to any of various private and public laboratories to assay for Verticillium propagules. Nurseries may wish to test individual core samples to determine the distribution in a particular field. The presence of any microsclerotia in the soil should be interpreted as a potential disease risk.
- Prune off and burn affected limbs preferably before leaves fall and thus before new inoculum is incorporated into the ground.
- Clean pruning equipment after use.
- Do not track soil from infested areas into clean areas. Clean boots, equipment, and tools before leaving an infested area.
- Keep nitrogenous fertilizers to a minimum-enough only to produce normal, not succulent, growth.
- If the tree dies and/or is removed, replace it with a nonsusceptible host such as any conifer, birch, dogwood, or sycamore.
- Avoid planting maple in fields with a history of Verticillium wilt. Avoid fields previously planted to potato or tomato; however, former peppermint fields may be lower risk.
- A preplant soil test for Verticillium propagules will help determine a planting site.
- Incorporating freshly mown Italian ryegrass followed by covering the soil with plastic for 3 months in the late summer was effective in the Netherlands at reducing disease incidence in a nursery crop of Norway maple planted 6 months later. Effect was observed up to 4 years after planting.
- Preplant fumigation.
- A few chemicals are registered for tree injection as a preventative treatment. Do not inject trees less than 2 inches in diameter or that are suffering from various stresses.
- Fungisol for spring application only.
Note Although Phyton 27 is registered as a spray it is not recommended based on a single trial where it was ineffective when used before or after infection.
Q After my Japanese maple died, I had it removed and I replanted another Japanese maple in the same location. Now one side of this new tree has clusters of brown, dead leaves. What’s happening to my expensive maples?
A Japanese maples are very susceptible to a soil-borne disease called Verticillium wilt. The brown, dead foliage you observe may be because of infection by the Verticillium dahliae fungus.
The fungus enters the plant through the roots and, over time, systemically clogs or restricts the flow of water in the xylem, the tree’s water transport system.
Japanese maples and other hosts of Verticillium wilt respond to the presence of the fungus by compartmentalizing it to keep it from spreading. Symptoms subside when the tree is successful in doing so; however, if the fungus breaks through the barriers, the infection grows and the symptoms reappear.
The reduced vigor of infected trees can be seen in the sparse canopies of undersized, off-color, curled and dry leaves. When branch die back with partial or total defoliation on one side of the tree, the symptom is called “flagging.”
Another diagnostic indicator of Verticillium wilt is the grayish green or olive green streaking in the sapwood, usually seen near the base of larger, affected branches. An infected Japanese maple will exhibit more pronounced symptoms if stressed by drought, waterlogged soil or soil compaction.
Mature trees can take years to die and may recover if conditions favor plant growth rather than the spread of disease. Do not rush to remove a symptomatic tree. Although there is no cure for Verticillium wilt, your Japanese maple may continue to perform if you offer it some environmental manipulation.
As Verticillium spreads more quickly in weaker plants, follow these sound cultural practices:
Disease incidence is influenced by cultural care and environmental conditions, so homeowners who choose to beautify their gardens with Japanese maples must take precautions against the establishment and spread of Verticillium wilt.
Chantal Guillemin is a Contra Costa Master Gardener.
The Master Gardener programs are UC Cooperative Extension, county-based volunteer organizations dedicated to providing research-based gardening information to home gardeners. They love sharing information and answering questions.
Contra Costa Master Gardeners, 925-646-6586, 9 a.m.-noon, Mondays-Thursdays. http://ccmg.ucdavis.edu
Alameda County Master Gardeners, 510-639-1371 or 925-960-9420. http://acmg.ucdavis.edu
Santa Clara Master Gardeners, 408-282-3105, 9:30 a.m. -12:30 p.m. Mondays-Fridays. http://mastergardeners.org/scc.html
Solano County Master Gardeners, 707-784-1321. http://cesolano.ucdavis.edu/Master_Gardener
San Mateo/San Francisco Master Gardeners, 650-726-9059, ext. 107, 9 a.m.-4 p.m. Mondays-Thursdays. http://ucanr.org/sites/MGsSMSF
California Master Gardener website: http://camastergardeners.ucdavis.edu