Disease symptom characterized by the dropping out of small, round fragments of leaves, making them look as if riddled by shot.
An abscission layer forms around the necrotic spot allowing the diseased tissue to drop out.
Jay W. Pscheidt, 2010.
The manifestation of disease by the presence of structures of the causal agent.
Refers to many fungi able to survive in the soil as saprophytes. Also called "soil inhabitant."
a disease control practice in which soil is covered with plastic sheeting and exposed to sunlight, thereby heating the soil and inhibiting or killing soilborne plant pathogens.
A compact aggregation of spores and/or sporophores growing out to the surface of the host.
A single-celled, wall-less, spiral, filamentous organism associated with corn stunt and citrus stubborn disease.
A sporangium-bearing hypha.
A fruiting body that produces asexual spores within a more or less spherical wall.
Single sporangium of Phytophthora sp. on ginseng leaf.
Photo by Melodie Putnam, 1997.
Reproductive body of fungi and other lower plants, containing one or more cells; a bacterial cell modified to survive an adverse environment.
A cushion-shaped spore-producing body of a fungus.
Bright pink to coral-red fruiting bodies (sporodochia) of Nectria sp. break through the apple bark in the cankered area.
OSU Plant Clinic Image, 2014.
Capable of forming spores.
The process of producing spores.
Any agent or chemical that destroys all living organisms in a substance such as soil.
a distinct form of an organism or virus within a species, differs from other forms of the species biologically, physically, or chemically.
An elongated lesion with irregular sides.
A compacted mass of hyphae that supports sexual fruiting bodies.
Note the black stroma within this sunken eastern filbert blight canker.
Photo by Jay W. Pscheidt, 1990.
An unthrifty plant reduced in size and vigor due to unfavorable environmental conditions.
Slender, tubular mouthparts in plant-parasitic nematodes or aphids.
to convert into cork tissue.
The substance or object on which an organism lives and from which it gets nourishment.
Injury to aboveground plant parts (leaves, bark, flowers, and fruit) caused by excessive exposure to solar radiation. Associated with high temperatures but not necessarily lack of soil moisture.
Rhododendron sunburn resulting in chlorotic areas near the leaf midribs and some necrosis.
Photo courtesy Jim Green.
Plant tissues are injured when freezing temperatures precede or follow daytime warming by the sun. Can also be considered winter injury or called southwest injury.
The sum of the qualities of a plant and causal agent that allows the development of the causal agent.
External or internal physical characteristics of disease expressed by the host plant.
Pertaining to a disease in which an infection leads to general spread throughout the plant body. Also, a chemical that spreads internally through a plant.
Sexual stage of a fungus.
Thick-walled resting spore produced by some fungi, notably rusts and smuts, that germinates to form a basidium.
Teliospores (developed and developing) with paraphyses. Also shown are three urediniospores.
Photo by Peter R. Bristow
The vegetative body of the lower plant that has not differentiated into stems and leaves.
the tightly intertwined layer of plant litter (lawns and turf) from accumulations of undecomposed or partially decomposed plant residues.
Ability of the plant to endure the development of the parasite without showing marked symptoms of disease.
a plant epidermal hair, of which several types exist.
A bladderlike intrusion of the protoplasm from a parenchymatous cell through a pit into the lumen of a xylem cell.
One or more races of a pathogen that are characterized by the limitation of their host range to a certain genus or genera. Also, a group of closely related plants of common origin and similar characteristics within a species (see also Cultivar).
a cylinder of meristematic cells (lateral meristem) that produces secondary phloem to the outside and secondary xylem (wood) to the inside of a branch or trunk of a woody plant.
An agent, such as an insect, nematode, or fungus, that may transmit a pathogen.
Symptom of a virus disease in which regions along the veins are darker green than the tissue between the veins.
A state or condition in which normally white or colored tissues, such as flower petals, become green.
Coneflower (Echinacea spp.)-Aster Yellows
OSU Plant Clinic image, 2015.
An infectious nucleic acid without a protein coat that causes hop stunt, potato spindle tuber, or chrysanthemum stunt.
Strong ability to produce disease.
Capable of transmitting a virus.