Pests and Diseases

Question 1

What effect do plant pets and disease have on our crop plants?

Answer 1

Reduce yield potential and Reduce end use quality

Question 2

Reduce yield potential.

Answer 2

 Reducing plant stands and killing plants.
 Reduce photosynthesis, destroy leaf foliage.
 Damage destroys root systems.
 Feed of the plant

Question 3

Reduce end use quality.

Answer 3

 Visual appearance.
 Particularly with fruits and tuber rots.
 Also related to seeds.
 Impact export potential.

Question 4

What types of pest and disease affect crop plants?

Answer 4

o Air borne fungi
o Soil borne fungi
o Bacteria
o Viruses
o Eelworms
o Insects
o Other, including mammals

Question 5

What three conditions are necessary to have a disease infect a crop plant?

Answer 5

o Suitable environment.
o Susceptible host plant.
o Pathogen

Question 6

What is the difference between vertical and horizontal disease resistance?

Answer 6

o Vertical resistance is controlled by a single resistance gene and usually
confers immunity to non-virulent path types.
o Horizontal resistance is controlled by many resistance genes, is not
usually absolute, and is more durable than vertical resistance.

Question 7

How does weed infestation negatively affect crop plants?

Answer 7

• Yield loss as they compete for: Interceptable light, Water, Nutrients.
• Harbor Pests:
• Over winter insects, host to diseases and cause infection.
• Weed seed contamination.

Question 8

Annual weeds:

Answer 8

 Complete life cycle in one year. Relatively easy to control. Seeds
can remain dormant for many years.
 Summer annuals (warm season) germinant in spring and grow
through summer.
 Winter annuals (cool season) germinate in fall, live through winter,
produce seed in spring

Question 9

Biennial weeds:

Answer 9

 Germinant in the spring of one year, live vegetatively through
winter and flower the following spring

Question 10

Perennial weeds:

Answer 10

 Most difficult to control when established.
 Warm season weeds
 Cool season weeds

Question 11

Why is it important to rotate herbicides with a different mode of action?

Answer 11

o Repeated use of herbicides fr4om the same mode of action will encourage
the development of herbicide resistant weed species.

Question 12

Group 1

Answer 12

grasses, disrupts fatty acid synthesis leading to membrane degenerate

Question 13

Group 2

Answer 13

broadleaf, disrupts synthesis of branched amino acids, inhibits DNA synthesis

Question 14

Group 3

Answer 14

broadleaf and some grasses, interfers with cell division

Question 15

Group 4

Answer 15

broadleaf, upsets plant growth regulator and increases auxins

Question 16

Group 5, 6, and 7

Answer 16

broadleaf and some grasses, disrupts photosynthesis

Question 17

Group 9

Answer 17

broad spectrum, disrupts

the shikimic acid pathway