Butt rot is a disease of plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s, mostly tree

Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

s, caused by fungi

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

. The fungus attacks the moist, poorly protected undersurface of tree trunk's thickest part (the "butt" above the root, as opposed to "top"), where the end of the stem

Plant stem

A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...

 makes contact with the soil

Soil

Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

. It may affect the roots as well, causing a disease known as root rot

Root rot

Root rot is a condition found in both indoor and outdoor plants, although more common in indoor plants with poor drainage. As the name states, the roots of the plant rot. Usually, this is a result of overwatering. In houseplants, it is a very common problem, and is slightly less common in outdoor...

. It then moves up into the interior of the plant, producing a roughly conical column of dead, rotted plant matter, up to one and a half meters long in severe cases. Such an infection is likely to impair the transport properties of the xylem

Xylem

Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...

 tissue found at the center of the stem. It also reduces the stem's structural properties and makes the plant more vulnerable to toppling. One particularly virulent species of fungus associated with butt rot is Serpula himantioides.

External links

• Root and Butt Rots of Oaks - North Carolina State University