AGRICULTURAL CROP DISEASE MANAGEMENT CATEGORY 1C
STUDY GUIDE TEST 2025/2026 QUESTIONS WITH SOLUTIONS
GRADED A+
✔✔What could cause phytotoxicity? - ✔✔Off target drift to other plants, excessive
pesticide rates, mixing of chemicals, excessive hot and dry weather following
application
✔✔Pesticide drift - ✔✔movement of pesticides from the target host to a nontarget plant
✔✔Biggest weather condition for pesticide drift - ✔✔winds greater than 5-10 mph
✔✔When is wind speed generally lower? - ✔✔Just before sunrise and just after sunset
✔✔What is the best way to avoid pesticide drift? - ✔✔Larger droplet size
✔✔T/F: Sclerotia are bacterial structures that help the pathogen survive adverse
conditions - ✔✔False, it is a fungal structure
✔✔T/F: Noninfectious disorders can spread from plant to plant by vectors - ✔✔False
✔✔T/F: Many pathogens can survive in the soil or on crop debris - ✔✔True
✔✔T/F: Diseases often occur in patterns within a field - ✔✔False
✔✔T/F: Some of the worst plant disease epidemics have been caused by pathogens
introduced from abroad - ✔✔True
✔✔T/F: Sprayers should be recalibrated after any modification to nozzles, pressure, or
speed. - ✔✔True
✔✔T/F: Certain environmental conditions may cause phytotoxicity or increase its
intensity - ✔✔True
✔✔T/F: Systemic fungicides need a minimum of 24 hours on the plant surface before a
rain event - ✔✔False, minimum 3 hours
✔✔ plant disease - ✔✔any abnormal condition that damages a plant and alters its
appearance or function
✔✔How plant disease vs injury occurs? - ✔✔Plant disease is a process and changes
happen over time vs injury occurs instantly
, ✔✔symptoms - ✔✔visible effects of a plant disease on the host plant; symptoms are not
the disease itself; detectable changes in color, shape, or functions of plant
✔✔pathogen - ✔✔parasitic organism that causes disease
✔✔Examples of symptoms - ✔✔leaf spots, leaf blight, yellowing of plant tissue, stunting,
wilting, death of plant tissue
✔✔Signs of plant disease - ✔✔Different from symptoms, signs are the physical
evidence of the disease
✔✔Examples of signs - ✔✔fungal fruiting bodies, bacterial ooze, nematode cysts
✔✔What are the three components of the plant disease triangle? - ✔✔Susceptible host
plant, pathogen, and favorable environment
✔✔Why is favorable environment needed in for plant diseases? - ✔✔Susceptible plants
can be exposed to large amounts of a pathogen but will not develop the disease if the
environment isn't right for that pathogen.
✔✔Two most important environmental factors that affect disease development? -
✔✔temperature and moisture
✔✔What other environmental factors may affect disease development? - ✔✔Relative
humidity, soil pH, soil texture, light, and nutrient status
✔✔What human affected factors can also have significant effects on disease
development? - ✔✔compaction, tillage practices, planting depth, seed bed prep, and
residue management
✔✔How does the "disease triangle" work? - ✔✔All three factors are needed for disease
development so disease can be prevented by altering any one of the three factors (or
sides of the triangle)
✔✔Give an example of altering the host plant factor of the disease triangle. -
✔✔Choosing disease resistant varieties.
✔✔Give an example of altering the pathogen factor of the disease triangle. -
✔✔Removing debris and weeds, rotating crops, controlling insects that carry
pathogens, using fungicides to kill pathogen
✔✔Give an example of altering the environment factor of the disease triangle. -
✔✔Changing row spacing, avoiding overhead irrigation
STUDY GUIDE TEST 2025/2026 QUESTIONS WITH SOLUTIONS
GRADED A+
✔✔What could cause phytotoxicity? - ✔✔Off target drift to other plants, excessive
pesticide rates, mixing of chemicals, excessive hot and dry weather following
application
✔✔Pesticide drift - ✔✔movement of pesticides from the target host to a nontarget plant
✔✔Biggest weather condition for pesticide drift - ✔✔winds greater than 5-10 mph
✔✔When is wind speed generally lower? - ✔✔Just before sunrise and just after sunset
✔✔What is the best way to avoid pesticide drift? - ✔✔Larger droplet size
✔✔T/F: Sclerotia are bacterial structures that help the pathogen survive adverse
conditions - ✔✔False, it is a fungal structure
✔✔T/F: Noninfectious disorders can spread from plant to plant by vectors - ✔✔False
✔✔T/F: Many pathogens can survive in the soil or on crop debris - ✔✔True
✔✔T/F: Diseases often occur in patterns within a field - ✔✔False
✔✔T/F: Some of the worst plant disease epidemics have been caused by pathogens
introduced from abroad - ✔✔True
✔✔T/F: Sprayers should be recalibrated after any modification to nozzles, pressure, or
speed. - ✔✔True
✔✔T/F: Certain environmental conditions may cause phytotoxicity or increase its
intensity - ✔✔True
✔✔T/F: Systemic fungicides need a minimum of 24 hours on the plant surface before a
rain event - ✔✔False, minimum 3 hours
✔✔ plant disease - ✔✔any abnormal condition that damages a plant and alters its
appearance or function
✔✔How plant disease vs injury occurs? - ✔✔Plant disease is a process and changes
happen over time vs injury occurs instantly
, ✔✔symptoms - ✔✔visible effects of a plant disease on the host plant; symptoms are not
the disease itself; detectable changes in color, shape, or functions of plant
✔✔pathogen - ✔✔parasitic organism that causes disease
✔✔Examples of symptoms - ✔✔leaf spots, leaf blight, yellowing of plant tissue, stunting,
wilting, death of plant tissue
✔✔Signs of plant disease - ✔✔Different from symptoms, signs are the physical
evidence of the disease
✔✔Examples of signs - ✔✔fungal fruiting bodies, bacterial ooze, nematode cysts
✔✔What are the three components of the plant disease triangle? - ✔✔Susceptible host
plant, pathogen, and favorable environment
✔✔Why is favorable environment needed in for plant diseases? - ✔✔Susceptible plants
can be exposed to large amounts of a pathogen but will not develop the disease if the
environment isn't right for that pathogen.
✔✔Two most important environmental factors that affect disease development? -
✔✔temperature and moisture
✔✔What other environmental factors may affect disease development? - ✔✔Relative
humidity, soil pH, soil texture, light, and nutrient status
✔✔What human affected factors can also have significant effects on disease
development? - ✔✔compaction, tillage practices, planting depth, seed bed prep, and
residue management
✔✔How does the "disease triangle" work? - ✔✔All three factors are needed for disease
development so disease can be prevented by altering any one of the three factors (or
sides of the triangle)
✔✔Give an example of altering the host plant factor of the disease triangle. -
✔✔Choosing disease resistant varieties.
✔✔Give an example of altering the pathogen factor of the disease triangle. -
✔✔Removing debris and weeds, rotating crops, controlling insects that carry
pathogens, using fungicides to kill pathogen
✔✔Give an example of altering the environment factor of the disease triangle. -
✔✔Changing row spacing, avoiding overhead irrigation
