Exam 3 begins here

1. Exam 3 begins here

2. Recall: Three components interact to produce different biocontrol approaches Emphasize effect of cropping system on NE Cropping System Natural Enemy Ideal NE lacks persistence, emphasize introduction Emphasize the NE-Pest Interaction Pest Complex

3. Types of Biological Control • Classical – Use of NE taken from native home of a foreign pest. Release once. • Inoculative – Release occasionally. Builds up, controls pest, then dies out & must be re-introduced. • Augmentative – Add to existing population as needed. • Inundative – Flood area with NE. Not persistent. Similar to pesticides. • Competitive Exclusion – Mostly applies to use of hypovirulent pathogen strains out competing virulent strain. • Conservation – Avoid harming existing NE complex. • Suppressive Soils – In some soils, pest (usually a pathogen) does not cause much damage.

4. BC type and three components Conservation, Suppressive Soils Cropping System Natural Enemy Classical Augmentation Inoculative, Competitive Exclusion Pest Complex

5. Points on Inoculative vs. Inundative Releases

6. Points on NE Conservation • Judicious pesticide use • Reduce other mortality caused by other management activity • Control secondary enemies • Manipulate host plant attributes • Provide NE’s ecological requirements • Genetic enhancement of NE

7. Points on Suppressive Soils • Factor responsible often not identified but is biological (lost on sterilization). • Have 3 main effects on plant pathogens • Pathogen may not persist • Pathogen establishes but doesn’t cause disease • Initial disease declines with continued monoculture • Ways to Achieve Suppressive Soils • Soil amendments to alter microbial communities • Green manures for fungal pathogens • Adding chitin for nematode control • Crop rotations/intercropping – Some crops encourage pest-antagonistic microflora.

8. Biocontrol Conclusion • Read to examples of biocontrols in the text • Evaluation of NE effectiveness • Necessary to use biocontrols in decisions • May be based on: • Statistical correlations from field observations • Numerous types of controlled experimentations • Requires that NE’s be monitored along with pest (cf. spider mite examples cited earlier)

9. Pesticides

10. Pesticides • Pesticides Defined: Any substance or mixture of substances, intended for preventing, destroying, or mitigating any pest, or intended for use as a plant growth regulator, defoliant or desiccant. (FIFRA) • Technically includes biocontrols and plants bred for pest resistance. Common usage excludes these.

11. Pesticide Classification Pesticides are commonly classified several ways: • Chemical class -- Increasingly diverse • Target Organism • Mode of Action • Application timing or usage

12. Pesticides Classified by Target

13. Target classification may also specify growth stages • Ovicides – Eggs • Larvicides – Larvae • Adulticides -- Adults

14. Mode of Action Examples • Broad Spectrum -- Kills broad range of pests, usually refers to insecticides, fungicides, and bactericides • Contact Poison -- Kills by contacting pest • Disinfectant (Eradicant) -- Effective against pathogen that has already infected the crop • Germination Inhibitor -- Inhibits germination of weed seeds, fungus spores, bacterial spores. • Nonselective -- Kills broad range of pests and/or crop plants, usually used in reference to herbicides • Nerve Poison -- Interferes with nervous system function • Protectants -- Protects crop if applied before pathogens infect the crop • Repellents -- Repels pest from crop or interferes with pest’s ability to locate crop • Systemic -- Absorbed and translocated throughout the plant to provide protection • Stomach Poison -- Kills after ingestion by an animal

15. Classification by Timing Annual Crops • Seed Treatment -- Pesticide coats or is absorbed into the seed. • Pre-Plant -- Pesticide applied any time before planting • At-Planting -- Pesticide applied during the planting operation • In-Furrow -- In the planting row, direct contact with crop seed • Side-Dress -- Next to the row, no direct contact with crop seed • Broadcast -- Distributed over the soil surface. • Pre-Emergent -- Before the crop has emerged from the ground • Post-Emergent -- After the crop has emerged from the ground • Lay-By -- Final operation before harvest sequence Perennial Crops • Dormant -- Applied during winter dormancy • Bud Break -- Applied as dormancy is broken Harvest-Related Timing • Pre-Harvest -- Just before crop is harvested • Post-Harvest -- After crop is harvested

16. Benefits of Pesticides in IPM • Inexpensive • Greater control confidence • Effective and rapid • Therapeutic • Management efficiency • Can enable other management practices

17. Costs of Pesticides in IPM • Greater human health threat • Greater environmental cost • Detrimental effects on non-target species • Those useful in the CPS • Those useful outside the CPS • Those with no established uses • Interferes with other aspects of IPM • Secondary pests • Re-entry Intervals & scouting • Limits other control options • Less sustainable

18. Role of Pesticides in IPM • Pest complex – Some require pesticides • Multiple, simultaneous species in same group • At least one species that causes excessive damage at low density • Important species new/poorly understood • Key pest(s) lacking control alternatives • Key pest(s) especially vulnerable to pesticide placement/timing

19. Pesticide Strategy Vs. Tactic As a group, pesticides may be therapeutic or preventative, broad or narrow spectrum, fast or slow acting, long or short lived, etc. As individuals, each pesticide occupies one point on this multidimensional continuum. The key is to consider each individual pesticide as a separate tactic in an overall IPM plan.

20. The Selectivity Concept • Key concept in pesticide usage in IPM • Pesticides often classified as “selective” or “non-selective” • Meaning of these terms in common usage is context-dependent (weeds vs. insects) • More formally, there are two types of selectivity – Physiological and Ecological

21. Physiological Selectivity • Relative toxicity of pesticides under controlled application conditions • Species-specific susceptibility to a pesticide. • Measured as a ratio of LD50’s of non-target/target species (cf. table handout) • Assumes all individuals & species equally dosed. • Three general methods: • Residues (cf. handout) • Topical application to individuals • Before/after assessment of field populations

22. Ecological Selectivity • Differential mortality based on pesticide use • Formulation (e.g. granules result in more mortality on soil pests than on foliar NE’s) • Placement (e.g. spot sprays, seed treatments, wicks, in-furrow). • Timing (e.g. pre vs. post-emergent applications, diurnal timing for bees) • Dosage – Reduced dosage usually used in conjunction with one of those above

23. Uses of Selectivity in IPM • Mammalian toxicity of decreasing significance except in urban/structural IPM • Insecticides – Physiological selectivity favored (target & non-target intermingled) • Herbicides – Historically favored ecological selectivity • Bactericides/Fungicides – Non-selective pesticides usually favored.

24. Types of Pesticides Your book identifies two kinds (pp. 250 – 257) • Traditional Toxic Chemicals • Inorganic • Organic (Synthetic) • Biopesticides (= Biorational Pesticides) • Living Systems (Microbial pesticides) • Fermentation Products • Botanical Pesticides • Transgenic (Plant Incorporated Pesticides) – cover under host plant resistance

25. What are Reduced Risk Pesticides? • Any pesticide that meets any of the following criteria: • Reduce human health risk • Reduce risk to non-target organisms • Reduce environmental contamination • Enhance IPM adoption • All ingredients of a pesticide must meet these criteria • Can include traditional or biorational • Reduced risk pesticides have greatly reduced regulatory burdens: incentive to manufacturers & farmers

26. Growth in the use of Reduced Risk Pesticides in California: 1990 - 1998 Tons Applied (Thousands) Acres Treated (Thousands)

27. Pay particular attention to the following sections: An exam question is likely from each of these • Chemical Relationships: pp 262 – 264 • Modes of Action: pp 264 – 266 • Application Technology: 270 – 280 • Pesticide Label: 303 - 306

28. Pesticide Interactions Book has these three categories, mostly discussed as antagonistic interactions. • Formulation Incompatibility • Altered Crop Tolerance • Alteration of Efficacy

29. More Thoughts on Interactions • Additive Effects – Most Common: • Different pesticides with the same formulation but targeting different pests. • Synergistic Effects – pesticides used in combination are more effective than when used alone: Two types: • Biochemical • Ecological • Antagonistic Interactions • Formulation–based = “Incompatibility” • Biological = “Pesticide Antagonism”

30. Resistance, Resurgence, and Replacement Chapter 12 – pp. 314 – 335 Three different ecological responses of pests to pesticides in this chapter: • Resistance – Pest susceptibility to pesticide decreases over time. • Resurgence – Pest population increases dramatically following pesticide • Replacement – One pest is replaced by another. We’ll take them in reverse order

31. Pest Replacement • Mostly a problem with arthropods and weeds • Tends to be more reversible with arthropods • Note Fig. 12-7

32. Read Chapter 17 by Next Wednesday Host-Plant Resistance and Other Genetic Manipulations of Crops and Pests pp. 443 – 469 Do not confuse plant resistance to pests with pest resistance to pesticides. They are different.

33. Resurgence • Mostly documented with insect pests • Mostly associated with indirect, secondary/minor pests for several reasons. • Key pests are watched too closely to resurge • Direct pests are mainly late-season pests & there isn’t time to resurge • Pest must be held at least partially in check by some agent that is affected by the pesticide • Note Fig. 12-6 in book.

34. Pest Resurgence Pest (8) Natural Enemy

35. Pest Resurgence Pest Natural Enemy

36. Pest Resurgence pest pest

37. Pest Resurgence Note: 14 pests/leaf

38. Four processes contribute to resurgence • Reduced Biological Control (Secondary) – most common with insects • Reduced Competition – most common with weeds (mono vs. dicots) • Direct Stimulation of Pest – usually due to sub-acute doses • Improved Crop Growth

39. Resistance • Mostly a problem with pesticides (so far) but applies to all management tactics. Ex: • Biological Control – Rabbits & virus, Bt • Cultural Control – corn rootworms & rotation • Host Plant Resistance – many examples • Most serious, general problem in IPM • Arises because all management actions are selection pressures • Problem is rapidly getting worse

41. Read about Kentucky’s Herbicide Resistant Weeds Here

42. Resistance is best understood as a process Initially, a small proportion of population has a resistant mechanism by chance.

43. The Resistance Process These individuals survive at a higher rate than others

44. Resistance as a process Resistant individuals increase in frequency

45. Resistance as a process Eventually, the pesticide or other management tactic causes too little control to be effective.

46. The process has three general stages, each with its own Management Strategy Abandon Pesticide/Management Tactic Manage or Reverse Prevention Need to monitor resistance

47. Impact of Resistance • Overall agricultural productivity (during build phase) • Increased pesticide usage • Increased damage • Environmental impact • Increased pesticide usage • Increased use of non-renewable resources • Increased acreage • Pest management flexibility • Loss of pesticide tactic • Constraint on new pesticides

48. Causes of Resistance Independent of Pesticide • Genetic Factors • Ecological Factors • Severity of Selective Pressure

49. 1. Genetic Causes of Resistance • Genetic Factors • Relative dominance – More dominant is bad • Linkage to phenotype – Fewer genes is bad • Initial resistant pop – Prior exposure • Broad diversity & diversity-maintenance • Low diversity associated with foreign pests • Sexual reproduction • Haplo-diploidy

50. 2. Ecological Causes of Resistance • Population Isolation • More isolated develop resistance more rapidly • Less isolated allow resistance to spread more rapidly • Narrow host range – more selective pressure • Intrinsic population factors • Voltinism • Generation time • Fecundity • Behavioral factors