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Cherry Cotton Root Rot Info: How To Treat A Cherry Tree With Root Rot

Cherry Cotton Root Rot Info: How To Treat A Cherry Tree With Root Rot


By: Darcy Larum, Landscape Designer

Few diseases are as destructive as Phymatotrichum root rot, which can attack and kill over 2,000 species of plants. Fortunately, with its affinity for hot, dry climates and calcareous, slightly alkaline clay soil, this root rot is limited to certain regions. In the Southwest United States, the disease can cause significant damage to fruit crops, such as sweet cherry trees. Continue reading for more cherry cotton rot info.

What is Cherry Phymatotrichum Rot?

Cherry root rot, also known as cherry cotton root rot, cherry phymatotrichum root rot, or simply cotton root rot, is caused by the fungal organism Phymatotrichum omnivorum. This disease is soil borne and spread by water, root contact, transplants or infected tools.

Infected plants will have rotted or decaying root structures, with visible brown to bronze colored woolly strands of fungus. A cherry tree with root rot will develop yellowing or browning foliage, starting with the plant crown and working down the tree. Then, suddenly, the cherry tree foliage will wilt and drop. Developing fruit will also drop. Within three days of infection, a cherry tree may die from phymatotrichum cotton root rot.

By the time the symptoms of cotton root rot on a cherry are visible, the plant’s roots will have been severely rotted away. Once the disease is present in the soil, susceptible plants should not be planted in the area. Depending on conditions, the disease can spread in the soil, infecting other areas by stowing away on transplants or garden tools.

Inspect transplants and do not plant them if they look questionable. Also, keep your gardening tools properly sanitized to avoid the spread of diseases.

Treating Cotton Root Rot on Cherry Trees

In studies, fungicides and soil fumigation have not been successful in treating cotton root rot on cherry or other plants. However, plant breeders have developed newer varieties of plants that show resistance to this devastating disease.

Crop rotations of three or more years with resistant plants, such as grasses, can help control the spread of phymatotrichum root rot. As can deeply tilling infected soils.

Amending the soil to reduce the chalk and clay, and also to improve moisture retention, will help prevent the growth of phymatotrichum. Mixing in garden gypsum, compost, humus and other organic materials can help correct the soil imbalances in which these fungal diseases thrive.

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Cottonwood Tree Facts

Learn about growing cottonwood trees, known for their ample shade and cotton-like seeds.

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Photo by: Shutterstock/Doug Matthews

A towering native, a cottonwood tree soars and spreads, growing more than 100 feet tall and almost as wide. It’s a cherished shade tree, often planted in parks. In the wild, cottonwood grows along rivers, ponds and other bodies of water. It also thrives in floodplains and dry riverbeds, where infrequent rains transform dry land into waterways.

Historically, cottonwood earned its place as a landscape tree because it grows rapidly, adding up to 6 feet a year. It's also a favorite for shade, with the large spread helping to cast cooling shade over homes and streets. There’s a cottonwood for nearly any region, with different hardy types in Zones 2 through 9.

Cottonwood Tree Fall Color

Eastern cottonwood trees offer fabulous fall color, with leaves shifting through shades of orange to gold.

Photo by: Julie Martens Forney


What Is Cherry Phymatotrichum Rot - Treating Cotton Root Rot On Cherry Trees - garden

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Tree decay fungi - Identification and Significance

The Kingdom of fungi is vast, fungi play vital roles in many ecosystems and are crucial to the lifecycles of many plant species on this planet. Connections between fungi and trees are often critical in determining tree vitality and stability.

Fungi can be put into three groups distinguished by how they feed:

Symbiotic or Mycorrhizal fungi live in association with many vascular plants' root systems, and a beneficial exchange takes place between the two. The fungi will have almost constant access to the trees carbohydrate stores, in return benefiting the trees ability to absorb water and minerals with its structure of highly absorbent mycelium, effectively expanding the root system of the host plant
One of the most notable relationships we have of this kind is that of the Fly Agaric (Amanita muscaria) with the Silver Birch (Betula pendula)

Saprophytic fungi live on dead organic matter. This group of fungi will usually only take advantage of dieback caused by a separate factor, e.g. drought, rather than being the cause of decline themselves. While their role in the woodland ecosystem is every bit as important as that of the symbiotic, they are not so good to see on amenity trees. They may not kill trees but can ultimately cause mechanical failure.
A common and easily distinguishable saprophytic fungus is the Birch Polypore (Piptoporus betulinus)

Parasitic fungi live off or at the expense of their live host plant, often resulting in the demise of this host. In general these fungi will only target already unhealthy or stressed plants. No bad thing in the woodland ecosystem as it makes way for regeneration, but again not good for amenity trees.
While parasitic fungi on the whole blend in with everything else happening around us, from time to time they have had catastrophic consequences. There can be no better memorable example than the near end of elm trees due to Dutch elm disease in the 1970’s. This was thanks to the microscopic Ophiostoma novo-ulmi fungus.
The most prevalent of the parasitic fungi that also happens to be noticeably saprophytic is Honey Fungus (Armillaria mellea)

The fungi in these three groups each have very different implications and in some cases, end results for their hosts. To follow is a list that we will try to add to on a regular basis.
You will find the fungi listed by order of the month they are seen, starting late summer when most fungi will begin to fruit and finishing with the perennial brackets.

List of Common Tree Decay Fungi

Including Habitat, Common Fruiting Season, Strategy, and Significance

Chicken of the woods (Laetiporus sulphureus)

Description: Notable annual from its early stages as a bright yellow knobble on the trunk growing to a group of uneven shelf like brackets from 10-60cm across. The soft, thick yellow flesh will darken to orange before drying and hardening to white in a period of a few weeks, then persist sometimes until the following year. Spores exuded from pores giving a white spore print.

(Photograph taken in August)

Habitat: Common on willow (as photo), oak, yew, cherry and sweet chestnut anywhere from the base of the trunk up to about 15ft

Season: Summer to autumn

Strategy: Saprophytic, causing a brown cubical rot of the heartwood

Significance: Affected wood at risk of brittle fracture

Notes: Edible when young and fresh

Fly Agaric (Amanita muscaria)

Description: Notable annual, appearing first as a cracked white sphere before flattening to 8-20cm across by which time the fleshy cap will be bright red covered in distinctive white warts. These will be washed off by rain leaving a smooth fading skin. Fleshy white stem 8-20cm. Spores exuded from gills giving a white spore print

Habitat: Generally with birch and pine trees, occasionally others

Strategy: Mycorrhizal

Significance: Beneficial to host species. Can help prevent colonization of parasitic species such as Armillaria

Notes: Common. Poisonous, hallucinogenic. Photograph taken October

Oak Bracket (Inonotus dryadeus)

Description: Annual bracket ranging from 10-70cm across. Pale when young, usually with droplets of clear to brownish liquid that seep from tubes on top. The flesh is reddish brown, hard and fibrous. The bracket will darken after several weeks, before turning black and cracked but remaining on the tree for a year or more. Spores exuded from pores leaving an off-white spore print

Habitat: The base of trunks of oaks

Season: All year though most often late summer

Strategy: Parasitic and saprophytic to oak trees causing triangular white rot, starting with decay of lignin around roots and base
Significance: Eventual ductile fracture at point of decay

Notes: Locally common. Not edible. Photograph taken September

Birch Polypore (Piptoporus betulinus)

Description: Annual bracket ranging from 10-10cm across. Roughly spherical and pale when young, expanding to a semi-circular pale brown bracket and persisting for a year or more, by which time usually found blackened. The flesh is white and rubbery. Spores exuded from pores leaving a white spore print

Habitat: Usually dead birch trunks and branches, but occasionally found on living hosts.

Strategy: Parasitic causing brown cubicle rot. Persisting as a saprophyte once the tree has died.
Significance: Brittle fracture at point of decay, and usually the demise of a birch tree.
Notes: Enters wounds in healthy trees or may be present and dormant within vascular system from seed, but usually only becomes active when trees are stressed or in decline Very common. Not edible. Photograph taken February

Porcelain fungus (Oudemansiella mucida)

Description: Grows in groups. Young greyish bell shaped cap will flatten and whiten to 3-10cm across, slimy on top. Scaly grey stem 3-10cm long, white and lined above the membranous ring. Flesh is white. Spores exuded from white gills leaving a white spore print

Habitat: Generally high up on beech, dead trunk or branches

Season: Late summer to late autumn

Strategy: Saprophytic, white rot localised to dead wood
Significance: Ductile fracture leading to eventual failure of affected parts
Notes: Common. Edible once gluten is removed. Photograph taken October

Inonotus hispidus

Description: Annual bracket ranging from 6-25cm across. Red to brown and velvet-like on top and usually growing independently. The bracket will blacken with age and finally drop off within the year, remaining on the ground below the tree for a long time. Spores exuded from red to brown pores
Habitat: Commonly between 10-20ft on the trunks of ash, but sometimes seen on walnut, apple and London plane
Season: Summer, but evident on the tree or below it usually all year
Strategy: Parasitic causing simultaneous white rot
Significance: Brittle fracture at point of decay. The likelihood of standing wood being created is fantastic for biodiversity
Notes: Common. Not edible. Photograph taken October

Shaggy Pholiota (Pholiota squarrosa)

Description: Annual that appears at first as a dense cluster of convex shaggy dark yellow caps before individually flattening out to 5-15cm across and becoming paler in colour. The shaggy appearance is retained due to its covering of red-brown upturned scales. The stem is smooth and pale above the membranous ring but shaggy similar to the cap beneath, becoming darker towards the base. Flesh is tough and pale yellow. Spores are exuded from gills that are yellow at first before turning brown with age. Rust brown spore print
Habitat: The base of many deciduous trees (willow in photo) and occasionally conifers
Season: Autumn to winter
Strategy: Parasitic causing a simultaneous white rot
Significance: Brittle fracture at point of decay, usually the base of the tree
Notes: Locally common. Not edible. Photograph taken November

Oyster Mushroom (Pleurotus ostreatus)

Description: Annual first appearing as a cluster of grey shell-shaped caps before flattening to 4-20cm across sometimes becoming wavy and splitting at the margin. Top will become more brown and paler with age. Lateral but often absent stem. Lilac spores are exuded from white gills, becoming yellow with age

Habitat: The trunks of many broad-leafed trees, standing or fallen. Common also on stumps. Horse chestnut pictured

Strategy: Saprophytic causing a simultaneous white rot

Significance: Can lead to brittle fracture, especially when associated with already dead wood. Decay may be more localised on a healthy tree

Notes: Common. Edible. Photograph taken January

Artist’s Fungus (Ganoderma applanatum)

Description: Perennial bracket ranging from 10-60cm across, found singularly and in groups. Rather flat and semicircular in shape. Very hard, concentrically ringed on top with a grey-brown cracked crust. Flesh is cinnamon brown. White pores beneath will bruise brown giving this fungus its common name, historically having been used as a tablet. Spore print brown

Habitat: The trunks of many broad-leafed trees, hornbeam pictured

Strategy: Parasitic causing an intensive white rot. Persisting as saprophytic after trees demise

Significance: Demise of host and/or brittle fracture of main trunk at point of decay

Notes: Locally common. Not edible. Photograph taken January

The yellow flat-footed fly (Agathomyia wankowiczii) lays its eggs inside G. applanatum causing galls on the underside of the bracket. By no means always seen, but you can be sure it is G. applanatum you are looking at if you see these galls as this is the only known case of galls on a bracket in Britain!

Ganoderma adspersum syn. G. australe

Description: Perennial bracket ranging from 10-60cm across. Often thicker than G. applanatum but otherwise superficially very similar. Very hard, concentrically ringed on top with a red-brown cracked crust. Flesh is dark brown. Cocoa brown spores are exuded from white pores, and though they are on the underside of the bracket, spores usually end up on top of it and above it thanks to electrostaticity

Habitat: The base of trunks of many broad-leafed trees, sycamore pictured

Strategy: Parasitic causing an intensive white rot. Persisting as saprophytic after trees demise

Significance: Demise of host and/or brittle fracture of main trunk at point of decay

Notes: Locally common. Not edible. Photograph taken January. Difficult to distinguish from G. applanatum

Many-zoned Polypore (Coriolus versicolor)

Description: Annual? Bracket 4-10cm across found in crowded groups, often in the hundreds. Young specimens have a velvety upper surface but this becomes smooth and leather like with age. Concentric rings of varied colours: black, green, grey, blue, brown or red. Flesh is with and tough. Spores exuded from pores leaving a straw-yellow spore print

Habitat: Dead wood, ash pictured

Strategy: Saprophytic

Significance: Eventual structural failure at point of decay

Notes: Very common. Not edible though does contain Polysaccharide-K an immune system boosting agent, thus used in the medical industry. Photograph taken December

Description: Annual? Bracket 4-10cm across found singly or in small groups. The top is concentrically ringed off white to brown and covered in fine grey hairs, surface greying with age. Flesh is white and tough. Spores exuded from pores leaving an off-white spore print

Habitat: Dead wood, ash pictured

Strategy: Saprophytic

Significance: Possible structural failure, but most often found on wood that is already lying on the ground

Notes: Locally common. Not edible. Photograph taken January

King Alfred’s Cakes (Daldinia concentrica)

Description: Perennial rounded fruit body 2-10cm across. Usually found in groups. Brown when young but soon aging black. If cut open shiny grey to purple concentric rings can be seen. Black spores

Habitat: Most often dead ash as pictured but occasionally beech

Strategy: Saprophytic causing white rot

Significance: Possible structural failure. A sure sign of dead wood on ash

Notes: Common. Not edible but a good fire lighter when dry. Photograph taken January

Coral Spot Fungus (Nectria cinnabarina)

Description: Annual? Two types: red flask shaped fruit body 1-2mm across and similar pink pustules, sexual and asexual respectively. Found in massed groups. Pink spores

Habitat: Dead wood, horse chestnut pictured

Strategy: Saprophytic

Significance: Eventual structural failure at point of decay

Notes: Common. Not edible. Photograph taken December

Dutch Elm Disease (Ophiostoma novo-ulmi)

Description: Ophiostoma novo-ulmi is a microscopic ascomycete fungus, thus no fruit body is visible to the naked eye. However, tell tail signs of its presence are sudden die back in elm trees and the feeding galleries of the elm bark beetle (Scolytus scolytus) found under the bark (see photo). It is these beetles that carry the fungus’ spores from tree to tree

Significance: Demise of elm trees

Notes: Common. Not edible. Photograph taken December showing beetle galleries

Jew’s Ear (Auricularia auricular-judae)

Description: Annual ear-shaped bracket 3-8cm across, often grouped. Jelly like when fresh but drying hard with age. Red-brown outer surface covered in tiny grey hairs often with vein like protrusions. Shiny smooth inner surface, more grey-brown in colour and often wrinkled. White spores

Habitat: Dead branches, most commonly of elder. Sycamore pictured

Season: Usually autumn but found all year

Strategy: Saprophytic

Significance: Eventual structural failure at point of decay

Notes: Very common. Edible. Photograph taken January

Honey fungus (Armillaria mellea)

Description: Annual appearing at first as a dense cluster of convex yellow to brown caps that will individually flatten to 3-15cm across becoming depressed in the center and wavy at the rim. Dark scales often seen towards the center. 6-15cm stem swollen at the base, white to begin with but becoming brown with age, a thick white membranous ring towards the top. Flesh is white. Very pale brown spores exuded from gills that are white at first but darkening to pinkish-brown with age

Rhizomorphs or bootlaces (see photo) can be found year round under infected bark, on roots and in the soil. These are thick black thread like bundles of hyphae that can give means for the fungi to travel fairly large distances through the soil

Habitat: Roots, trunks and stumps of most tree species. Fruit bodies pictured on birch and rhizomorphs on oak

Season: Summer to early winter

Strategy: Parasitic causing an intensive white rot

Significance: Death of tree and brittle fracture at base. Considered to be one of the most dangerous parasites known to trees

Notes: Common. Edible if cooked. Photographs taken November and January respectively

Velvet Shank (Flammulina velutipes)

Description: Annual appearing at first as a dense cluster of convex yellow caps that will individually flatten to 2-10cm, dark towards the centre and wavy at the rim. Smooth and slimy. Tough stem, 3-10cm in length yellow at top, darkening to black towards the base and darkening completely with age. Thin yellow flesh. White spores exuded from pale yellow gills

Habitat: Dead wood, trunks and branches. Commonly elm or horse chestnut as pictured.

Strategy: Saprophytic

Significance: Possible structural failure at point of decay

Notes: Common. Edible. Photograph taken December. Unusually, this fruit body can withstand being frozen and thawing continuing to produce spores

Lentinellus cochleatus

Description: Annual found in groups. Irregular funnel like cap 2-6cm across reddish-brown and darkening towards center and often split. Central stem 2-5cm similar colour to cap but darkening towards the base. White spores exuded from pale pink decurrent gills

Strategy: Saprophytic

Significance: Wood decay, habitat creation

Notes: Locally common. Edible. Photograph taken December

Clustered Bonnet (Mycena inclinata)

Description: Annual growing in dense tufts. Rounded cap expands to a bell shape of 2-3cm across, pale brown on top but darker towards the center and ribbed in appearance. 5-10cm stem that is darker towards the base, where it is covered in a fine white down of mycelium. Thin white flesh. White spores exuded from white adnate gills that darken to pink with age

Habitat: Old stumps, commonly oak

Strategy: Saprophytic

Significance: Wood decay, nutrient recycling

Notes: Locally common. Not edible. Photograph taken October

Candle-snuff Fungus (Xylaria hypoxylon)

Description: Annual usually in groups. Upright fruit body 1-7cm tall. Fairly rounded and hairy at the bottom but flattening and branching out towards the top where it is powdered white

Habitat: Dead wood, birch pictured

Strategy: Saprophytic

Significance: Wood decay, nutrient recycling

Notes: Common. Not edible. Photograph taken January

Brittle Cinder (Kretzschmaria deusta =Ustulina deusta)

Description: Annual forming a flat but wavy, grey cushion like fruit body that is white at the edges. Aging black and becoming very brittle but remaining on the tree. Black spores.

Habitat: The base or roots of many deciduous trees. Ash pictured

Season: Spring to summer

Strategy: Parasitic causing simultaneous white rot

Significance: Likely brittle fracture at base or roots

Notes: Common. Not edible. Photograph taken January. “This is a particularly dangerous decay fungus” – David Lonsdale ‘Principles of Tree Hazard Assessment and Management’ 1999. There are usually no warning signs and can be very difficult to detect

Hoof Fungus (Fomes fomentarius)

Description: Perennial bracket ranging from 5-50cm across. Hoof like in appearance with its horn like crust and concentric grey zones. Hard and woody to touch. The flesh is hard, fibrous and cinnamon brown. Found as either a single fruit body or with several on the same stem. Lemon-yellow spores exuded from grey-brown pores

Habitat: The stems of birch, beech and sycamore. Beech pictured

Season: All year, sporulating early summer

Strategy: Parasitic causing simultaneous white rot

Significance: Possible fracture at point of decay

Notes: Uncommon. Not edible. Can be used for tinder. Photograph taken February

A huge cavity in a mature Ash with

poor growth response and a full crown

A large Polyporus squamosus bracket on common host Ash

Coriolus versicolor covering a large


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Verticillium fungi target the roots of hundreds of species, many of them annual vegetables such as tomatoes (Lycopersicon esculentum), rhubarb (Rheum rhaponticum) or pumpkins (Curcubita pepo). The fungus enters feeder roots with other nutrients, then travels throughout the stems and foliage of the plant. It leaves withered, or necrotic, leaves behind, beginning from the plant’s bottom. As the plant dies, the fungus colonizes adjoining plants. Verticillium overwinters in decaying plant matter for up to 15 years, so one infected plant can re-infect an entire garden..