PesticidesOctober 30, 2013
In 1838 a band of over 800 Potawatomi Indians were forcibly removed from their homeland in Northern Indiana and marched to eastern Kansas.
The Trail of Death
Many died along the trail during the two month trek. This mournful caravan traveled this road on September 14, 1838 and camped near Williamsport.
Most insects, and their relatives (mites, millipedes) and other small organisms (nematodes and mollusks) are not field 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
Pests
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
Effective Pest Management
Corn◦ Army worm◦ Black cutworm◦ Corn rootworm◦ European corn borer
Soybeans◦ Bean Leaf Beetle◦ Japanese Beetle◦ Two-Spotted Spider
Mite
Alfalfa◦ Alfalfa Weevil◦ Potato Leafhopper
Insect Pests
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
Weeds
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
Weed Identification
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
Weed Classification
Life cycle – all plants have four developmental stages: ◦ Seedling◦ Vegetative◦ Reproductive◦ Maturity
Weed Classifications
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
Plant life cycles
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)
Herbicide Treatment
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
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
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)
Soil-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
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
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
Foliage-applied Herbicides
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
Minimizing Spray Drift: Application
Wind speed and direction Air stability Relative humidity and temperature Nozzle type Spray pressure Nozzle spray angle Boom height Drift control agents
Spray Drift Factors
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
Vapor Drift
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
Drift Control Practices
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
Maintaining a Safe (Pesticide)
Workplace
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
Worker Protection Standard
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
Bulk Storage Regulations
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
Commercial Pesticide Applicator Certification
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 toxicWarning – moderately toxic
Danger – highly toxic
Handling Pesticides Safely
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
Toxicity
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
Pesticide Exposure & Hazard
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
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
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
Hazard Prevention
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.
Pesticide Applicator Certification
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
Pesticide Safety Tips for the Workplace and Farm