Manipulations of the Environment Flashcards
What is the MacroEnvironment?
The earth
What is the microenvironment?
Local conditions
Greenhouses
What factors of the disease triangle can human practices effect?
Host,
Pathogen,
Environment
What two environmental factors are most important?
Moisture
Temperature
List six environmental factors that effect disease development.
Moisture Temperature Air composition and aeration Soil reaction Light quality Physical and temporal barriers
Is flooding an abiotic pathogen?
Yes
Are abiotic pathogens considered indirect effects?
No
Are abiotic pathogens considered direct effects?
Yes
What is the most important environmental requisite for disease development?
Moisture
What three forms does moisture occur for disease development?
free moisture on plant surfaces (water film)
relative humidity in the air
soil moisture
Does high moisture favor all plant diseases?
No
Does high moisture favor most plant diseases?
Yes
What environmental advantage is associated with use of furrow irrigation in comparison to overhead pivot irrigation?
eliminates free moisture on plant surfaces (water film)
What is the number one disease on cereal?
Cercospora
What environmental advantage is associated with use of pivot irrigation in comparison to furrow irrigation?
most soilborne diseases will be more severe
Spreading of soilborne pathogens
Less soil moisture content
Give an example of soilborne diseases made worse through furrow irrigation.
Southern blight of tomato
Bacterial soft rot of cabbage
Are plants more productive with high or low relative humidity?
Low
List four ways to reduce relative humidity in the greenhouse.
Do not wet leaves when irrigating plants
Avoid standing water in the greenhouse
Cover irrigated soil with plastic film to reduce evaporation.
Increase space between plants
What causes sun scald in cucumber?
Combination of high temperatures and sunlight
What is the second most important environmental factor for disease development?
Temperature
Is a plant’s disease resistance influenced by temperature?
Yes.
How can temperature be moderated by cultural practices?
Time of planting Plowing and disking Raise seed beds Shading Ventilation Burning Irrigation
Does plowing and disking increase or decrease soil temperature?
Increase
Does raising the seed bed increase or decrease soil temperature?
Increase
Does shading increase or decrease soil temperature?
Decrease
Does Ventilation increase or decrease soil temperature?
Decrease
How does burning decrease the risk of pathogen?
Kill or reduce pathogen inoculums
Does irrigation increase or decrease soil temperature?
Decrease
Does plowing and increasing soil temperature promote growth of soilborne diseases?
No, it suppresses soilborne diseases.
Does reducing oxygen and increasing carbon dioxide increase or decrease risk of disease?
decreases risk
Is southern blight favored more by alkaline or acidic soils?
Acidic
What element lowers soil pH?
Sulfur
What element raises soil pH?
Lime
Does animal waste increase soil organic matter?
Yes
Does increasing soil organic matter decrease risk of diseases developing?
Yes
Do some diseases require UV light to reproduce?
Yes
Does covering the ground with plastic film reduce risk of soilborne diseases?
Yes
What do screenhouses protect plants from?
insect-transmitted diseases
What does a buffer zone or trenching control?
Nematodes
Explain Interplanting
using tall and short plants to create a wall/barrier that aphids will not go through.
What does interplanting protect the plants from?
Insect-transmitted diseases
Is distance from inoculum a direct barrier or indirect barrier?
Indirect
Is shallow plating a way to escape pathogens?
Yes
List three ways to avoid replant problems in fruit trees.
Change the fruit variety
Replace the soil
Soil fumigation
Define allelopathy.
chemical and biological inhibition of one species of crops by another
