Glossary

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Submicroscopic, infectious agent, too small to be seen with a compound microscope, that multiplies only in living cells.
A virus consists of nucleic acid (DNA or RNA) surrounded by a protein coat.

the concentration of a virus.

Describing plants or lesions that appear wet and dark and are usually sunken and translucent.

Water-soaked

Lack of freshness and turgor and drooping of leaves from lack of water; a vascular disease that interrupts the plant's normal uptake and distribution of water.

Water-soaked

Damage by freezing or below freezing
temperatures when plants are dormant. See also frost injury.

Abnormal, brush-like development of many weak shoots.

Witches' Broom

The yellow color of plant parts resulting from the excessive proportion of yellow pigments, in turn produced by the underdevelopment or partial destruction of the green pigments.

A disease characterized by yellowing and stunting of affected parts (caused by fungi, virus, bacteria, or deficiency of essential elements).

Fungus spore with flagella, able to move in water.

A fungal resting spore produced by the fusion of equal gametes.