1. Managing Diseases, Good Bugs and Bad Bugs
NC STATE UNIVERSITY
Managing Diseases, Good Bugs and Bad Bugs
Frank Louws, Louise Romanow; Rosemary Hallberg 1

4. Successful Diagnosis comes with Knowledge and Experience
Disease: impairment of the normal state of the plant being a response to environmental factors, infective agents, inherent defects of the plant, or combinations
Diagnosis: a systematized knowledge …to determine the nature and principles concerning the causation of disease
Modified from R.G. Grogan The science and art of plant-disease diagnosis. Ann. Rev. Phytopathol. 19:

5. Grower Knowledge/Experience
Site Selection
Environmental control
Cultural control
Crop Selection
Growing system
Genetic resistance
Sanitation
Therapeutics
Biological control

6. I A. Know Your Biology: The Disease Triangle
ENVIRONMENT
PATHOGEN
Amount of
Disease
HOST

7. I B. Know Your Biology: Common Sources of Plant Pathogens
SOIL INVADERS
SOIL INHABITANTS
FREE RIDERS
Napoleon “Know Your Enemy”
From: G.N. Agrios Plant Pathology. 5th edition. Elsevier AP.

8. II. DIAGNOSIS CAN BE DIFFICULT:
From: G.N. Agrios Plant Pathology. 5th edition. Elsevier AP.

9. A Natural variation Viral disease Nutritional disorder
Spider mite injury
C. Warfield

11. Grower Knowledge/Experience
Site Selection
Environmental control
Cultural control
Crop Selection
Growing system
Genetic resistance
Sanitation
Therapeutics
Biological control

12. STRATEGIES TO MANAGE DISEASES:
CROP ROTATIONS:
The length of crop rotation needed depends on the disease.
(SOIL INVBADERS) A disease like early blight of tomato can be reduced by following a 3-yr rotation plan. Very important for nematodes.
(SOIL INHABITANTS) Many soil-borne diseases require 5 or more years (sometimes without effect).
Downy mildew of squash and pumpkins is not affected by rotation.

13. Develop a 3-5 year plan Rotation Groups Group 1 Cucurbit Family
Brassica Family
Group 3
Solanaceous Family
Group 4
Beet Root Family
Group 5
Pea and Bean Family
Group 6
Onion Family
Group 7
Other
Watermelon
Cabbage
Pepper (all types)
Beets
Beans
Onions
Sweet corn
Cucumber
Cauliflower
Tomato
Swiss chard
English peas
Shallots
Sweetpotato 
Squash
Broccoli
Eggplant
Spinach
Snow peas
Garlic
Cantaloupe
Brussels sprouts
Irish potato
Southern peas
Leek
Pumpkin
Mustard
Gourds
Turnips
Collards
Develop a 3-5 year plan

14. Grower Knowledge/Experience
Site Selection
Environmental control
Cultural control
Crop Selection
Growing system
Genetic resistance
Sanitation
Therapeutics
Biological control

15. Cultural Control

17. Grower Knowledge/Experience
Site Selection
Environmental control
Cultural control
Crop Selection
Growing system
Genetic resistance
Sanitation
Therapeutics
Biological control

18. Sanitation

19. Buy certified propagation material

20. Grower Knowledge/Experience
Site Selection
Environmental control
Cultural control
Crop Selection
Growing system
Genetic resistance
Sanitation
Therapeutics
Biological control

21. Therapeutics

22. Grower Knowledge/Experience
Site Selection
Environmental control
Cultural control
Crop Selection
Growing system
Genetic resistance
Sanitation
Therapeutics
Biological control

23. Genetic Resistance
Vegetable Grafting
To Graft
Or Not
VFNT

24. AN INTEGRATED APPROACH
DISEASE MANAGEMENT:
AN INTEGRATED APPROACH