BBIO203: Non-infectious Agents of Plant Diseases

A complete set of vocabulary flashcards covering non-infectious plant disease agents, environmental causes, mineral deficiencies, and air pollutants based on the lecture notes.

Non-infectious diseases

Plant diseases that occur in the absence of a pathogen and cannot be transmitted from a diseased plant to a healthy plant.

Freezing injury

Plant damage occurring in areas with temperatures below $0^\circ\text{C}$, caused by the formation of ice crystals within and between cells that damage cell membranes and kill cells.

Chilling injury

Plant damage occurring at low temperatures slightly above freezing, characterized by pitting and a water-soaked appearance, commonly affecting tropical fruits and vegetables.

Sunscald disease

A disease caused by prolonged exposure to high temperature and sunlight, resulting in wilting and death of young leaves, as well as light-colored, blistered, or water-soaked areas on affected fruits.

Heat necrosis of potato

A high-temperature disease showing yellow or brown discoloration in the vascular system of affected tubers planted in hot, dry, light soil.

Blackheart disease of potato

A disorder caused by insufficient oxygen levels in internal potato tissues, typically occurring in waterlogged soil or poorly aerated high-temperature storage, leading to tissue suffocation and blackening.

Etiolation

A condition resulting from lack of sufficient light, characterized by retarded chlorophyll formation, pale green leaves, long internodes, thin and tall spindly growth, and susceptibility to lodging.

Air pollutant

Any factor mediated by the atmosphere that causes an unwanted effect on plants.

Ethylene

An essential plant hormone that, when present in high concentrations or at the wrong stage of plant development (sourced from vehicle exhaust, burning fuel/coal, or ripening fruit), causes premature senescence, etiolation, stunting, flower drop, sepal necrosis, and leaf malformations.

Nitrogen oxides

Air pollutants emitted from internal combustion engines and furnaces that cause plant bleaching, bronzing, and irregular brown or white lesions along leaf margins and between veins.

Peroxyacetyl nitrates (PANs)

Air pollutants from automobile exhaust that enter leaves through stomata at concentrations as low as $0.01$ to $0.02\,\text{ppm}$, plasmolyzing spongy parenchyma and lower epidermal cells to produce silver leaf disease.

Silver leaf disease

Plant injury caused by peroxyacetyl nitrates (PANs) where collapsed parenchyma and epidermal cells are replaced by air pockets, causing bronzing, silvering, and glazing on leaf surfaces.

Ozone

An atmospheric pollutant that enters stomata and injures palisade cells at concentrations of $0.1$ to $0.3\,\text{ppm}$, resulting in white necrotic flecks, mottling, chlorosis, stunting, and premature defoliation.

Macroelements

Mineral elements required by plants in larger amounts for normal growth, specifically Nitrogen, Phosphorus, Potassium, Calcium, Sulfur, and Magnesium.

Microelements

Mineral elements required by plants in smaller amounts, listed in the text as Iron, Manganese, Sulfur, Copper, Molybdenum, and Chlorine.

Nitrogen deficiency

A nutrient deficiency affecting protein and nucleic acid synthesis, causing chlorotic leaves, dwarfing, premature leaf fall, and poor seed and fruit production.

Phosphorus deficiency

A nutrient deficiency manifesting as subnormal root systems, small, erect, necrotic leaves, and reddish or purplish tints on cereal leaves.

Potassium deficiency

A deficiency affecting photosynthesis and respiration, showing chlorotic leaf tips starting on older leaves, scorched leaf margins, bronzing, and reddish-brown tissue death.

Iron deficiency

A deficiency affecting cytochrome function and chlorophyll synthesis, characterized by general chlorosis with leaves turning almost colorless, leaf mottling, and twig die-back.

Manganese deficiency

A deficiency in an enzyme activator for photosynthesis and metabolism, causing wide yellowish areas between green veins, scattered necrotic spots on young leaves, crinkled margins, dwarfing, and premature death.

Sulfur deficiency

A nutrient deficiency characterized by yellowing of leaves and die-back, distinguished from nitrogen deficiency because older leaves do not show chlorosis.

Boron deficiency

A deficiency affecting sugar transport and cell growth, resulting in stunting, distortion and death of growing root/shoot tips, brittle foliage, leaf tip yellowing, hollow heart, and heat-blast.

Copper deficiency

A deficiency in photosynthesis and enzyme function causing die-back of leaf tips, wilting, stunting, distortion, and head melanosis in crops like wheat.

Zinc deficiency

A deficiency causing interveinal chlorosis (with green veins retained near leaf bases), leaf mottling, necrosis, defoliation, twig die-back, and abnormal shortening of growing parts.

Molybdenum deficiency

A deficiency affecting nitrogen metabolism electron transport, leading to undeveloped leaf blades with bare midribs, limp cereals, interveinal chlorosis, stunting, and failure of nitrogen fixation in pasture legumes.

Calcium deficiency

A deficiency affecting cell wall and membrane structural integrity, resulting in collapsed mesophyll tissues, dead growing points, poor root development, and blossom end rot.

Blossom end rot (BER)

A disorder in tomatoes and peppers caused by calcium deficiency and irregular soil moisture, leading to tissue collapse at the bottom of the fruit.

Magnesium deficiency

A deficiency of a core chlorophyll component that produces interveinal chlorosis starting on older leaves, extending along leaf lengths, and leading to necrotic lesions.

Juglone

A naturally occurring toxic chemical compound formed by black walnut trees that is toxic to plants such as potato, apple, and tomato.

Amygdalin

A compound produced by peach roots that breaks down into toxic hydrogen sulfide and benzaldehyde, preventing new peach trees from establishing in old peach orchards.