Glossary

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Abiotic- Nonliving disease agent.

Ascospore- A spore produced in the sexual or perfect state of an ascomycete fungus.

Asexual- Imperfect state of a fungus.

Biotic- Living agent of a disease.

Blight- Rapid death or dieback.

Blotch- Large, irregular necrotic area on a leaf caused by a pathogen or insect.

Broom- An abnormally dense mass of tree branches.

Bt (Bacillus thuringiensis)- A bacterium used as biological disease agent to control larvae of some insect species.

Canker- A localized dead portion of the cambium and bark of branches and stem of a tree.

Chlorosis - Yellowing of foliage.

Chrysalis- The pupal stage of a butterfly.

Conidia- Asexual fungus spores.

Dieback- Progressive death of branches from the tip downward.

Disease- Unfavorable change in the function or form of a plant that adversely affects its health.

Egg niche- Cavity in plant tissue made by an adult insect to hold eggs.

Flag- A single dead branch with dead foliage remaining.

Frass- Insect excrement or mixture of destroyed plant tissue and excrenebt.

Fruit body- A reproductive structure of a fungus that produces spores.

Gall- Swelling of plant tissues caused by certain fungi, bacteria, viruses, insects, mites, or nematodes.

Gallery- A tunnel made in plant tissue by an insect larva.

Girdle - Damage that completely encircles a tree stem, often killing the portion above.

Hyphae- The filaments of a mycelium.

Inoculum- Spores, mycelium, or other propagules of a pathogen that can infect a plant, causing disease.

Larva- The feeding stage of certain insects that emerge from the egg stage; often called caterpillar, maggot, slug, or grub.

Lesion- An injury or wound on a plant.

Mycelium- Mass of hyphae that forms the fungus body.

Necrosis- Death of plant cells resulting in a darkening of the tissues.

Pathogen- An organism that causes disease.

Pupa- Quiescent stage of an insect following the larval stage; may be in a cocoon.

Serpentine mine- Snake-like burrow inside leaf caused by an insect larva.

Signs- Visible evidence of a pathogen or insect.

Skeletonizing- Insect feeding on leaf tissues, removing most interveinal tissue but leaving most of the veins intact.

Spore- Reproductive structure of a fungus.

Stools- Poplar plants grown in nursery propagation beds. Shoots are harvested annually for producing hardwood cuttings, forming what are commonly referred to as stools.

Symptom-  Visible response of a plant to a pathogen or an insect.

Tubercle- A small, solid pimple or button on caterpillars often covered with hair.

Wood shavings- Woody slivers cut by larvae when constructing galleries.