Manipulations of the Environment

Question 1

What is the MacroEnvironment?

Answer 1

The earth

Question 2

What is the microenvironment?

Answer 2

Local conditions

Greenhouses

Question 3

What factors of the disease triangle can human practices effect?

Answer 3

Host,
Pathogen,
Environment

Question 4

What two environmental factors are most important?

Answer 4

Moisture

Temperature

Question 5

List six environmental factors that effect disease development.

Answer 5

Moisture
Temperature
Air composition and aeration
Soil reaction
Light quality
Physical and temporal barriers

Question 6

Is flooding an abiotic pathogen?

Answer 6

Yes

Question 7

Are abiotic pathogens considered indirect effects?

Answer 7

No

Question 8

Are abiotic pathogens considered direct effects?

Answer 8

Yes

Question 9

What is the most important environmental requisite for disease development?

Answer 9

Moisture

Question 10

What three forms does moisture occur for disease development?

Answer 10

free moisture on plant surfaces (water film)
relative humidity in the air
soil moisture

Question 11

Does high moisture favor all plant diseases?

Answer 11

No

Question 12

Does high moisture favor most plant diseases?

Answer 12

Yes

Question 13

What environmental advantage is associated with use of furrow irrigation in comparison to overhead pivot irrigation?

Answer 13

eliminates free moisture on plant surfaces (water film)

Question 14

What is the number one disease on cereal?

Answer 14

Cercospora

Question 15

What environmental advantage is associated with use of pivot irrigation in comparison to furrow irrigation?

Answer 15

most soilborne diseases will be more severe
Spreading of soilborne pathogens
Less soil moisture content

Question 16

Give an example of soilborne diseases made worse through furrow irrigation.

Answer 16

Southern blight of tomato

Bacterial soft rot of cabbage

Question 17

Are plants more productive with high or low relative humidity?

Answer 17

Low

Question 18

List four ways to reduce relative humidity in the greenhouse.

Answer 18

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

Question 19

What causes sun scald in cucumber?

Answer 19

Combination of high temperatures and sunlight

Question 20

What is the second most important environmental factor for disease development?

Answer 20

Temperature

Question 21

Is a plant’s disease resistance influenced by temperature?

Answer 21

Yes.

Question 22

How can temperature be moderated by cultural practices?

Answer 22

Time of planting 
Plowing and disking
Raise seed beds
Shading
Ventilation
Burning 
Irrigation

Question 23

Does plowing and disking increase or decrease soil temperature?

Answer 23

Increase

Question 24

Does raising the seed bed increase or decrease soil temperature?

Answer 24

Increase

Question 25

Does shading increase or decrease soil temperature?

Answer 25

Decrease

Question 26

Does Ventilation increase or decrease soil temperature?

Answer 26

Decrease

Question 27

How does burning decrease the risk of pathogen?

Answer 27

Kill or reduce pathogen inoculums

Question 28

Does irrigation increase or decrease soil temperature?

Answer 28

Decrease

Question 29

Does plowing and increasing soil temperature promote growth of soilborne diseases?

Answer 29

No, it suppresses soilborne diseases.

Question 30

Does reducing oxygen and increasing carbon dioxide increase or decrease risk of disease?

Answer 30

decreases risk

Question 31

Is southern blight favored more by alkaline or acidic soils?

Answer 31

Acidic

Question 32

What element lowers soil pH?

Answer 32

Sulfur

Question 33

What element raises soil pH?

Answer 33

Lime

Question 34

Does animal waste increase soil organic matter?

Answer 34

Yes

Question 35

Does increasing soil organic matter decrease risk of diseases developing?

Answer 35

Yes

Question 36

Do some diseases require UV light to reproduce?

Answer 36

Yes

Question 37

Does covering the ground with plastic film reduce risk of soilborne diseases?

Answer 37

Yes

Question 38

What do screenhouses protect plants from?

Answer 38

insect-transmitted diseases

Question 39

What does a buffer zone or trenching control?

Answer 39

Nematodes

Question 40

Explain Interplanting

Answer 40

using tall and short plants to create a wall/barrier that aphids will not go through.

Question 41

What does interplanting protect the plants from?

Answer 41

Insect-transmitted diseases

Question 42

Is distance from inoculum a direct barrier or indirect barrier?

Answer 42

Indirect

Question 43

Is shallow plating a way to escape pathogens?

Answer 43

Yes

Question 44

List three ways to avoid replant problems in fruit trees.

Answer 44

Change the fruit variety Replace the soil Soil fumigation

Question 45

Define allelopathy.

Answer 45

chemical and biological inhibition of one species of crops by another