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