Glossary

 

---

 To the reader: If you come across another term in this WIKI that needs explanation, please let us know.

 

Alternaria-- A specific genus of fungus particularly a problem when plant surfaces are wet for prolonged periods.

 

 

Anthracnose-- A symptom of certain plant diseases that appears as a necrotic and sunken lesion on a stem, leaf, fruit or flower.

 

 

Adventitious-- Arising from a point not normally the usual location and usually in abnormal numbers.  For instance, adventitious roots may arise along stems or other above-ground plant parts.

 

 

Botrytis-- A specific genus of fungus that usually colonizes weakened or senescing tissue-- epecially tissue high in sugars.  It can also be pathogenic.

 

 

Canker-- A plant wound containing necrotic tissue that is usually sunken beneath the surface of the stem of a woody plant.  The plant may be partially successful at walling off the disease.   

 

 

Chlorosis--  A yellowing of green leaves due to the loss of chlorophyll or one or several components of the chlorophyll.

 

 

Cotyledon-- Literally, "seed leaves," they contain the energy necessary to sustain seedling growth until the first true leaves begin photosynthesis.

 

 

Curculio-- A beetle with a long, curved proboscis that causes various types of injury to fruits, nuts, and berries.

 

 

Cytospora-- A specific genus of fungus that causes a serious canker and possibly complete girdling of plant stems or trunks.

 

 

Delicata-- A specific genus or class of squashes.

 

 

Desiccation-- A moisture loss causing a drying out of plant tissue.  It could be caused by drought, wind, frost, herbicides, or excess soluble salt (fertilizer) levels.

 

 

Downy mildew-- A specific type of mildew characterized by white (or gray) velvety mold growth, unlike the white talcum powder-like growth (spores) of Powdery mildew.

 

 

Early Blight-- A disease caused by the Alternaria fungus-- especially common to cururbit and solanaceous crops-- causing leaf and stem lesion or fruit rots.

 

 

Edema-- A swelling of plant cells which results in rupturing and scabbing over, leaving a blister-like wound.  It could be caused by excess water uptake or other types of injury.

 

 

Epinasty-- An uncontrolled twisting and distortion of plant stem and leaf growth.  It could be caused by growth regulator herbicides or by viruses.

 

 

Excision--  Literally, cutting out.  It can be a method of surgically removing diseased tissue in hopes that the tree will heal over or compartmentalize the wound.

 

 

Fusarium wilt--  A wilt disease caused specifically by root damage or vascular plugging from one of the many species of Fusarium fungus.

 

 

Gall-- A swelling on any part of a plant caused by either insects, mites, fungi, or bacteria.  The gall, always unique to the causal agent, is normally a means of reproduction of the agent.

 

 

Glomerella-- A genus of fungus that causes the disease called bitter rot of apple.

 

 

Leaf roll-- A physiologic response of plant leaves usually caused by excessive moisture or turgor pressure.  It is not related to, and may even be almost the opposite of wilting. 

 

 

Lesion-- A disease-caused wound on any part of a plant that leaves a spot with well-defined boundaries.

 

 

Necrotic-- The characteristic of having dead tissue on a plant part

 

 

Necrosis-- Death of plant cells, which can either be a possible site of secondary disease infection, or may be compartmentalized (walled off) by the plant.

 

 

Oviposition site-- Literally, egg-laying site.  The site on the plant is sometimes characterized by unique punctures or scars.

 

 

Petiole-- The small stalk that attaches the blade of a leaf to the stem or branch of a plant. 

 

 

Psyllids--  Small sucking insects in the insect order Homoptera.  Sometimes called jumping plantlice, certain ones secret white waxy threads from their bodies; some spread viruses.

 

 

Phylloxera-- Small sucking insects in the insect order Homoptera.  Some may be covered with a white powder; several kinds cause galls on plants.

 

 

Physiologic-- Usually referring to a problem caused by factors affecting the plant system (egs. environmental conditions), rather than a problem caused by a pest or a pathogen.

 

 

Phytophthora-- A specific genus of fungus that usually lives and moves in the water film in soil, thus being referred to as a "water mold."  It may cause root rots or above-ground rots of fruits or stems.

 

 

Phytotoxicity-- Literally, plant toxicity or plant death, it is often referred to as "burning."  For example, insecticidal soap may cause phytotoxicity to plant leaves if applied when the weather is too hot.

 

 

Pythium--  A specific genus of fungus that usually lives and moves in the water film in soil, thus being referred to as a "water mold."  It usually causes root rots.

 

 

Pycnidia-- Structures of a fungus which produce the reproductive spores of that fungus.  They can be seen with the naked eye as small dots within necrotic tissue.

 

 

Russeting-- A physical description of slightly raised, tan- colored cells that appear after normal cells scab over following certain humid weather conditions, spray injury, or disease infestation. 

 

 

Scorch--  A description of plant injury characterized by an appearance of being subjected to the heat from a bonfire or blow torch.  Scorch is usually rapid, leaving leaves brown and crispy.

 

 

Septoria-- A specific genus of fungus that usually results in leaf spots or lesions.

 

 

Soluble salts-- Salts present in soils, artificial media, or hydroponic solutions, which serve as plant nutrients, but at excessive concentrations, can burn plant parts-- especially roots.  High soluble salts can be the result of excessive or repetitive use of fertilizers and can even come from excessive use of manures and certain types of compost.

 

 

Stunting-- A "holding back" of normal plant growth due to root damage, stem girdling, vascular malfunction, water or nutrient deficiencies, or any number of other physiologic or pathologic problems.

 

 

Triazine-- A specific family of chemical herbicides commonly used in agriculture that inhibit the process of photosynthesis.  Sub-lethal symptoms of injury are characterized by chlorosis-- showing up first between the veins of the leaves.