Pesticides

1. Pesticides October 30, 2013

2. The Trail of Death • In 1838 a band of over 800 Potawatomi Indians were forcibly removed from their homeland in Northern Indiana and marched to eastern Kansas. Many died along the trail during the two month trek. This mournful caravan traveled this road on September 14, 1838 and camped near Williamsport.

3. Pests • Most insects, and their relatives (mites, millipedes) and other small organisms (nematodes and mollusks) are notfield crop pests • Insect pest presence is a reason for concern, but may not necessarily justify the use of an insecticide • It is important to know which insects can cause crop damage and when they need controlling

4. Effective Pest Management • Plant response occurs when • insect population is large enough • the crop is vulnerable • The potential for pest damage (significant yield reduction) is related to the pest infestation • Size • Timing • So, knowledge of insect pests is important in any insect pest management program

5. Insect Pests • Alfalfa • Alfalfa Weevil • Potato Leafhopper • Corn • Army worm • Black cutworm • Corn rootworm • European corn borer • Soybeans • Bean Leaf Beetle • Japanese Beetle • Two-Spotted Spider Mite

6. Weeds • Reduce crop yields • Interfere with production • Lower crop quality • Impede harvest • Can harbor other crop pests (e.g., plant disease agents and insect pests) • Limit cropping practices choices (e.g., rotation and tillage systems) • Can injure or poison livestock

7. Weed Identification • Accurate weed identification is critical to a successful weed management program • Pesticide applicators need to know what weeds are present to choose the proper control • Most weeds should be controlled at the seedling stage

8. Weed Classification • Classification – structure & life cycles are the basis for the two primary classification systems • Structure • Monocot - plant produces one seed leaf at emergence and the growing point remains beneath the soil surface • Dicot – plant produces two seed leaves at emergence and the growing point is above ground

9. Weed Classifications • Life cycle – all plants have four developmental stages: • Seedling • Vegetative • Reproductive • Maturity

10. Plant life cycles • Annuals – complete life cycle in one growing season • Biennial – complete life cycle in two growing seasons • Perennial • Plants live longer than two growing seasons • Some live indefinitely • Some perennials reproduce primarily by seed and some spread vegetatively

11. Herbicide Treatment • Treatment terminology • Foliage-applied (post-emergence application) • Applied on growing plants after leaves have emerged • Soil-applied – Preplant (pre-emergence) • Applied after planting but before the weeds and crop emergences • Requires incorporation (by irrigation, rainfall, or cultivation)

12. Soil-applied Herbicides • The major obstacle to success is the difficulty in bringing the herbicide into contact with the emerging weed seedlings • Understand herbicide characteristics • Solubility • Determines the rate the herbicide will leach from the soil • Herbicides that dissolve easily in water are more likely to leach out of the root zone (than oil-soluble herbicides) • Herbicide adsorption • Determines the strength of the chemical bond between the herbicide and soil particles • Strongly adsorbed herbicides are not readily available for weak uptake by plants

13. Soil-applied Herbicides • Herbicide persistence • Length of time the herbicide remains active • Dependent on the herbicide chemistry • Soil characteristics • Herbicides prone to adsorption bind to organic matter in the soil • Soil-applied herbicides leach more rapidly in course-textured soils • Soil microbes • Breakdown many soil-applied herbicides • Warm, moist conditions and high OM enhance microbe activity

14. Soil-applied Herbicides • Soil moisture • Active weed growth and herbicide uptake require adequate soil moisture • Rainfall • Provides movement into deeper layers of soil where weeds may be germinating • Excessive rainfall can leach herbicides too deeply into the soil, reducing weed control and increasing the possibility of groundwater contamination • Soil temperature • Increased temperatures generate active plant growth (requirement for successful weed control with herbicides) • Increases microbe activity (can break down herbicide)

15. Foliage-applied Herbicides • Applicator selects the herbicide (or combination) for a specific problem • Scouting and applying within four to six weeks after emergence should not hurt yields • The challenge is to get the herbicide through the leaf cuticle (waxy layer) and into the weed

16. Foliage-applied Herbicides • Objective: to get enough herbicide through the cuticle to control the weed • Herbicides sprayed on leaves may: • Volatize • Remain on the leaf surface • Penetrate the cuticle but not enter the plant • Penetrate the cuticle and move into the xylem (water and nutrient system) • Penetrate the cuticle and move into the phloem (sugar moving system) • Water-based spray solutions tend to bead up and bounce or wash off so spray adjuvants can help by spreading the spray over the leaf surface, sticking the spray to the leaf, and/or degrading the cuticle

17. Foliage-applied Herbicides • Spray adjuvants for post-emergence herbicides • Surfactants (reduce surface tension) • Oil-based (reduce spray drop surface tension and increase herbicide penetration) • Nitrogen fertilizer adjuvants improve herbicide performance on some weed species but it is unclear how they work

18. Minimizing Spray Drift: Application • Knowledgeable herbicide applicators • Correct herbicide • Applied at the right time • Applied in the proper amount • Weather conditions that can cause spray drift • Too wet • Too dry • Too windy

19. Spray Drift Factors • Wind speed and direction • Air stability • Relative humidity and temperature • Nozzle type • Spray pressure • Nozzle spray angle • Boom height • Drift control agents

20. Vapor Drift • Vapor drift is not the same as spray drift • Vapor drift occurs when a chemical vaporizes (changes to a gas) and air currents carry the vapors to another site where damage can occur • The potential for vapor drift depends largely on air temperature and the product formulation

21. Drift Control Practices • Maximize droplet size and minimize the time the droplets are in the air by: • Spraying only when conditions are right • Selecting the most appropriate nozzle type and size for each application • Keeping the boom close to the target surface by using wide-angle nozzles • Adjusting the boom for maximum performance • Using high carrier rates, when practical, and follow all label instructions • Use drift control agents

22. Maintaining a Safe (Pesticide) Workplace • Goals: • Protect yourself and any employees • Maintain good relations with neighbors • Safeguard the environment • The Worker Protection Standard (WPS) requires employers to protect workers in the production of agricultural crops • In areas treated with pesticides • Employees who handle pesticides

23. Worker Protection Standard • Commercial Pesticide Handler Employers • People who hire pesticide handlers or are self-employed as handlers • WPS guidelines include: • Requirements for information exchange • Restrictions • Specific instructions for handlers • Equipment safety • Personal protective equipment

24. Bulk Storage Regulations • The Office of the Indiana Chemist (OISC) regulates the bulk storage of pesticides and fertilizers on the basis of storage capacity • Guidelines apply to primary, secondary, and, in some cases, operational (load pad) storage

25. Commercial Pesticide Applicator Certification • Legally required of individuals who • Apply either general-use or restricted-use pesticides to another person’s property for $$$ • Apply either general-use or restricted-use pesticides for area-wide mosquito control • Apply restricted-use pesticides on the property of an employer as a function of their job • Apply restricted-use pesticides as an employee of a state or local government agency • There are 14 categories of commercial pesticide applicators in Indiana

26. Handling Pesticides Safely • All pesticides are designed to disrupt essential metabolic processes of the target pest • Pesticides that affect a pest in a unique manner (e.g. growth) have little effect on humans • Pesticides that are toxic to pests with systems similar to humans (such as the nervous system) pose a greater potential hazard to humans • Toxicity signal words Caution – slightly toxic Warning – moderately toxic Danger – highly toxic

27. Toxicity • Acute toxicity – immediate negative effects • Chronic toxicity – can result in delayed/long-term health effects which may include: • Damage to organs (esp. the liver) and nervous system • Cancer • Changes or alterations to the reproductive system

28. Pesticide Exposure & Hazard • Exposure - pesticides can enter the body through • Dermal – through the skin or eyes • Inhaled – respiratory • Oral - ingestion • Hazard (risk) = toxicity x exposure • Prevent exposure by minimizing hazards

29. Hazard Prevention • Select the safest formulation (usually granular or microencapsulated) • Use pesticides with reduced concentrations of active ingredients • Mix only enough to complete the work needed • Select application method to minimize personal contact • Purchase only what is needed

30. Hazard Prevention • Wear protective clothing as stipulated on the label • Avoid direct contact with the pesticide at all times • Use pesticides only in well-ventilated areas • Be cognizant of others around you during application and consider their safety • Dispose of pesticide containers properly

31. Hazard Prevention • Be attentive to reentry intervals specified on the label • Always keep pesticides in their original, labeled pesticide containers • Avoid pesticide drift • Avoid conditions what might lead to ground and surface water contamination

32. Pesticide Applicator Certification • Assigned Reading: Pesticide Applicator Certification (PPP-25) • Background for requirements, reasoning, authority, and training information • Pesticide Applicator testing • Sign up at: www.oisc.purdue.edu/ • Monthly Exams Offered at Purdue University - Free • Register with the state chemist office (765.494.1594) • Present a government issued photo I.D.

33. Pesticide Safety Tips for the Workplace and Farm • PPP-61, linked to ASM 336 homepage • Prevent Off-site Movement • Safe and Proper Storage of Pesticides and Containers • Be Prepared for Emergency Situations • Make the Workplace Safer • Practicing Professionalism in the Field