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Environmental Factors that cause Noninfectious Plant Diseases


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What are characteristics of noninfectious (abiotic) disease?
Caused by the lack of or excess of a factor
Occurs in the absence of pathogens and cannot be transmitted from diseased to healthy plants
Affect plants in all stages of growth
Symptoms vary
Why is there confusion on the etiology of stress vs nonstress diseases?
often symptoms of several noninfectious diseases are too indistinct and closely resemble those caused by several viruses, mollicutes and many root pathogens
Describe the symptoms of high/low temps.
High-- sunscald, can kill seedlings
Low-- damage young leaves, twigs and meristematic tips; kills buds, flowers and young fruit
Describe the symptoms of moisture.
Poor drainage or flooding
Lack of vigor, wilting, leaves pale green, death
Increase in anaerobic microorganisms form nitrites that are toxic
Fibrous roots decay
Toxic metals can be taken up
Describe the symptoms of inadequate oxygen.
Root rots
Occur in center of fleshy fruits or veggies-- oxidize normal plant constituents into melanin
Describe the symptoms of light.
etiolation, sunscald
Describe the symptoms of air pollution.
necrosis, reduction in growth, prolong exposure weakens plants & prediposes them to attack, more susceptible in low temps
Describe the symptoms of ozone.
enters stomata, killing cells
Where does acid rain come from, what two acids are involved, how does it get into the plant, and what part of the plant does it affect?
Caused by combustion of fossil fuels and the smelting of sulfide ores that are released into the atmosphere and form nitric and sulfuric acid falling to the ground in rain, snow and fog
Give an example of a macro and micronutritional deficiency and the disease symptoms.
P-- purplish leaves
Fe-- young leaves chlorotic but main veins green
What soil minerals can be toxic to plants.
Cu, Mn, Zn
Why does herbicide injury occur?
not the right crop
not the right time
not the correct dosage
not the correct environmental conditions

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