USDA Forest Service

Forest Health Protection, Southern Region


USDA Forest Service
Forest Health Protection
Region 8
1720 Peachtree Road, NW
Room 816 N
Atlanta, GA 30309

Phone: (404) 347-7478
Fax: (404) 347-1880

United States Department of Agriculture Forest Service.

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  • Abdomen - The third and rearmost region of the insect body.
  • Aecium (pl. aecia) - One of the reproductive structures in the life cycle of a rust fungus. Aecia normally appear as blisters on the host plant.
  • Aeciospores - Spores produced in an aecium.
  • Alternate host - Host in the life cycle of a rust fungus on which the pycnial and aecial stages are formed.
  • Ascospores - Spores produced in a saclike structure (the ascus). This structure is typical of a large group of fungi, the Ascomycetes.
  • Basidiospore - A spore borne on the outside of the reproductive structure called a basidium. This structure is typical of the group of fungi called the Basidiomycetes.
  • Cambium - A layer, one- or two-celled thick, between the xylem and phloem in higher plants. The cambium produces both of these tissues, resulting in diameter growth.
  • Canker - A localized necrotic lesion of the cambium.
  • Chlorosis (adj. chlorotic) - The loss of green pigment in a plant due to the plants inability to produce chlorophyll.
  • Conk - A fruiting body of a wood decay fungus that bears basidia.
  • Dormant - Having growth, development, or other biological activity suspended; resting, inactive.
  • Dorsal - Of or relating to the back; belonging to or situated on or near the upper surface.
  • Epicormic - Growing from a dormant bud that has been exposed to light and air.
  • Frass - Solid larval excrement, as left by defoliators; wood fragments made by a wood-boring insect, usually mixed with excrement.
  • Fruiting Bodies - Any structure formed of mycelia that contains spore bearing cells.
  • Fungus (pl. fungi) - A nongreen plant with a vegetative body formed of tubular filamentous cells (hyphae). Fungi reproduce by spores.
  • Generation - Period of time required to complete the life cycle of an insect.
  • Gouting - Tumorlike swellings on boles, branches, or twigs, caused by feeding of sucking insects.
  • Haustorium (pl. haustoria) - A specialized structure of a pathogen that is capable of direct penetration into, and nutrient absorption from, a host plant.
  • Head - The first region of the insect body. Eyes, mouth parts, and antennae (where present) are attached in this region.
  • Honeydew - A sweetish secretion produced by sucking insects, particularly aphids and scales.
  • Host - A plant which provides nutrition for an invading parasite.
  • Host Range - The various plants which a pathogen can infect.
  • Infection - The establishment of a feeding relationship between a host and a parasite.
  • Infection Court - Point of entry and establishment of a pathogen in the host organism.
  • Instar - The life stages of an insect larva between molts.
  • Larva (pl. larvae) - A young insect differing fundamentally in form from the adult (compare to nymph).
  • Metamorphosis - Series of changes through which an insect passes in developing from egg to adult.
  • Mycelium - A mass of fungal filamentous cells. It forms the vegetative body of the fungal plant.
  • Mycoplasma - A group of microscopic organisms intermediate between bacteria and viruses.
  • Necrotic - Dead.
  • Nymph - Young stage of insect which does not fundamentally differ in form from the adult (compare to larva).
  • Parasite - An organism that lives on or in, and obtains its food from, another organism (host).
  • Parthenogenesis - Reproduction without male fertilization.
  • Pathogen - An agent that causes disease.
  • Perithecium (pl. perithecia) - A closed bulb- or ball-shaped fruiting body with a pore through which ascospores are extruded, usually in a gelatinous paste.
  • Primary host - The host of a rust fungus on which the telial stage of the fungus is produced.
  • Prothorax - Firstthoracicsegment bearing the first pair of legs but no wings.
  • Pupa (pl. pupae) - The intermediate life stage between the larva and the adult.
  • Pupate - To become a pupa; to pass through a pupal state.
  • Resinosis - Exudation of pitch from a wound or infection on a conifer.
  • Resistance - The ability of a host to slow the development of a disease.
  • Resistance Breeding - The selection and deliberate propagation of those individuals in the population which display resistance to a specific pest.
  • Rhizomorph - A thick strand of mycelium in which the hyphae have lost their individuality; similar in appearance to a small root.
  • Saprophyte - Any organism which feeds on dead organic matter.
  • Segment - A subdivision of an animal body or appendage.
  • Sooty Mold - A dark or black velvety coating of mycelium of various fungi growing in insect honeydew on the leaves, fruit, or other exposed parts of plants.
  • Spores - The reproductive unit of fungi. Spores function in the same way that seeds do for higher plants.
  • Sporodochium (pl. sporodochia) - A cushion-shaped vegetative structure covered with spore bearing cells.
  • Stroma (pl. stromata) - A compact vegetative structure on, or within which, fruiting bodies are formed.
  • Telium (pl. telia) - Specialized fruiting structure of a rust fungus which produces teliospores. Generally, telia appear as hairlike filaments on the underside of leaves of the host.
  • Teliospores - In a rust fungus life cycle these resting spores are the normal overwintering spore form. They germinate in the spring and generate basidiospores.
  • Thorax (Adj. thoracic) - The second (middle) region of the insect body. The six true legs are normally attached in this region.
  • Thoracic legs - True legs located on the second region of the insect body.
  • Uredium (pl. uredia) - One of the five reproductive tissues in the complete rust life cycle. This tissue gives rise to a large number of spores on a continuous basis for an extended period of time.
  • Urediospores - Spores produced in a uredium.
  • Vector - Any organism that transmits a disease-causing organism.
  • Ventral - Of or relating to the belly; belonging to or situated on or near the lower surface.
  • Windthrow - The uprooting or overturning of trees by the wind.



USDA Forest Service - Forest Health Protection, Southern Region
Last Modified: Monday, 16 December 2013 at 14:18:29 CST

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