Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004

Outline of topics: (pp. 258-275 in text)

I. Nematodes

II. Non-pathogenic causes of plant disease

III. Principles of pest management

IV. Methods of pest management

V. Decision-making steps in pest management

VI. IPM and pesticide use

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 2

Nematodes can live parasitically on plants.

Plant-parasitic nematodes live in the soil and are microscopic.

Infected roots can develop galls, and tubers and roots may be malformed. Pathogens can enter wound sites.

Root knotting nematodes inhibit nutrient and water uptake.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 3

In Kentucky, a major nematode problem exits in soybean production.

Soybean Cyst Nematode (SCN) can greatly reduce yields of soybeans.

Fumigation or chemical drenching of the soil, and using resistant cultivars can be used to combat SCN.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 4

Adverse environmental conditions can damage plants and are considered to be ‘diseases’.

Temperature extremes hurt plant growth.

Moisture stress also is harmful (droughts or flooding).

Air pollution damages many crops.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 5

Nutrient deficiency or toxicity can harm plants.

Herbicide damage to plants can also occur.

(Damage can come from wrong rate, wrong chemical, or drift from another area).

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 6

Successful agricultural pest management uses the following strategies:

1. Exclusion - prevent pest from coming in. (Quarantines are an example)

2. Eradication - control and eliminate pest

3. Protection - preemptive pest control

4. Resistance - use of resistant cultivars5. No action - not all pests are economic pests

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 7

Preventing pest attack:

1. Use adapted cultivars - healthy plants are more resistant.

2. Use resistant cultivars

3. Plant high-quality seed - to avoid noxious weeds and diseases.

4. Prepare seedbed or growing medium properly.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 8

Preventing pest attack:

5. Plant at the best time.

6. Provide adequate nutrition and water.

7. Observe good sanitation.

8. Remove weeds.

9. Avoid microclimates that favor pests - high humidity, poor aeration, high temperature.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 9

Important information for pest management:

Pest Density - by counting, bioassays, amount of damage observed.

Expected crop damage - how much is the damage threshold?

Economic injury = the level of pest density where value of crop yield loss prevented is equal to the cost of implementing control measures.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 10

Action threshold = pest population density at which a treatment must be implemented to avoid economic injury.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 11

Methods of pest management:

Biological pest management - using natural defenses

1. Parasitism - wasps for hornworms, alfalfa weevils

2. Predator-Prey relationships

3. Structural features - cuticle, pubescence.

4. Chemicals - using plant extracts (nicotine, pyrethroids)

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 12

Biological pest management - con’t.

5. Phytoallexins - produced by plants in response to damage

6. Repellents - onions, garlic, marigolds

7. Trap crops

8. Biocontrol - use one organism to suppress another

9. Microbial sprays - Bt=Bacillus thurengiensis

10. Use of resistant cultivars.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 13

Cultural pest management

1. Crop Rotation - reduces pest buildup.

2. Sanitation

3. Use of resistant cultivars

4. Mulching

5. Host eradication

6. Planting time - early plantings can avoid pests

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 13

Cultural pest management, con’t.

7. Soil reaction - adjusting pH to control pests

liming controls some fungi,

lowering pH reduces scab on potato

8. Drainage - improve aeration

9. Wider spacing - improve air circulation to reduce humidity around plants

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 14

Legislative pest management:

Plant quarantines can prevent new pests from coming in.

Plant Quarantine Act of 1912 - laws to control movement of plant material

Certification programs - seed regulations

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 15

Physical/Mechanical pest management:

1. Mechanical traps

2. Handpicking

3. Barriers

4. Tillage

5. Heat treatment - solarization of fields, pasteurization

6. Radiation - gamma radiation for produce shelf-life.

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 17

Chemical pest management:

Using any chemical pesticide, in whatever formulation, that can control pests.

Decision-making steps for pesticide use:

1. Detection - early detection is a key to pest control

2. Identification - correct ID is crucial

3. Biology and habits - know lifecycle of pest

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 18

Decision-making steps for pesticide use:

4. Economic importance - what is the threshold?

5. Choice of method of control

6. Application

7. Evaluation

8. Record keeping

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 19

Integrated Pest Management (IPM) Strategies

1. Identify pests and beneficial organisms

2. Know biology of the pest and environment

3. Determine the tolerable pest population threshold

4. Select best method of pest management

5. Use least toxic methods

6. Develop pest-monitoring schedule

7. Evaluate program and make adjustments

Pests, Other Plant Maladies, and IPM PLS 386 Sept. 3, 2004 p. 20

US Pesticide Use

In 1965 - 215 billion pounds of active ingredients

1982 - 572 billion pounds

1995 - 565 billion pounds

Most pesticides are used for corn (most acres)

Herbicides - 57% of total, 2/3 cost of all pesticides

Insecticides - 13%