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DIAGNOSING PLANT DAMAGE: SUMMARY
  MG Manual Reference
Ch. 3, pg. 3

I. DEFINE THE PROBLEM (Determine that a “real” problem exists):
A. PLANT IDENTIFICATION and CHARACTERISTICS. Establish what the “normal” plant would look like at this time of year. Describe the “abnormality”: Symptoms & Signs.
B. EXAMINE THE ENTIRE PLANT AND ITS COMMUNITY. Determine the primary problem and part of the plant where initial damage occurred.
II. LOOK FOR PATTERNS: On more than one plant? On more than one plant species?
A. NONUNIFORM DAMAGE PATTERN (scattered damage on one or only a few plant species) is indicative of LIVING FACTORS (pathogens, insects, etc.).
B. UNIFORM DAMAGE PATTERN over a large area (i.e. damage patterns on several plant species) and uniform pattern on the individual plant and plant parts indicates NONLIVING FACTORS (mechanical, physical, or chemical factors).
III. DELINEATE TIME-DEVELOPMENT OF DAMAGE PATTERN:
A. Progressive spread of the damage on a plant, onto other plants, or over an area with time indicates damage caused by LIVING ORGANISMS.
B. Damage occurs, does not spread to other plants or parts of the affected plant. Clear line of demarcation between damaged and non-damaged tissues. These clues indicate NONLIVING DAMAGING FACTORS.
IV. DETERMINE CAUSES OF THE PLANT DAMAGE. Ask questions and gather information
A. DISTINGUISHING AMONG LIVING FACTORS
1. Symptoms and signs of PATHOGENS.
2. Symptoms and signs of INSECTS, MITES, and OTHER ANIMALS.
B. DISTINGUISHING AMONG NONLIVING FACTORS
1. MECHANICAL FACTORS
2. PHYSICAL FACTORS
a. Temperature extremes
b. Light extremes
c. Oxygen and moisture extremes
3. CHEMICAL FACTORS
a. Analyzing damage patterns in fields and other plantings.
b. Injury patterns on individual plants.
c. Pesticide-pollutant phytotoxicities - damage patterns.
d. Nutritional disorders -key to nutritional disorders.
C. REFERENCES (check reports of damaging factors on identified plant); may need LABORATORY ANALYSES to narrow range of probable causes.
V. SYNTHESIS OF INFORMATION TO DETERMINE PROBABLE CAUSES.



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