Application Technology : Introduction

Table of Contents

1. Introduction
2. Developments in New Equipment
3. Sprayers for Home Use
4. Field Sprayers
5. Air-Blast or Mist Sprayers
6. Wiper Applicators for Selective Weed Control
7. Other topics in Application Technology
   • Care and Use of Equipment
   • Sprayer Calibration
   • Determining Amount of Herbicide Needed
   • Materials, Mixing and Mixtures
8. Related Links

Introduction

Herbicide application should be a precision operation. Recent advances in equipment and control systems can make the job relatively simple and precise.

Pesticides applied incorrectly may result in wasted pesticide, poor or no control, damage to crops (possibly the neighbour's) or environmental contamination. Every effort must be made to apply chemicals properly to help eliminate these undesirable effects.

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Developments in New Equipment

In building sprayers that accurately apply herbicides, equipment manufacturers work closely with the crop protection industry. New concepts, such as closed-injection-type systems with herbicide concentrate carried separately from the water carrier, are now in use. Electronic rate controllers provide more accurate spray application by utilizing speed sensors, flow controllers and microprocessors to maintain the desired application rate. This technology has also included radar to accurately sense true ground speed of the sprayer Rate controllers are common among the professional applicators.

The industry is currently working towards the closed-injection system. Work continues in the area of drift reduction using air assists and electrostatic methods.

Nozzle manufacturers have brought to the market air-induction nozzles that significantly reduce spray drift. These nozzles are made by a number of companies and are available in a range of sizes. Operating these nozzles within their working pressure range is crucial to ensure designed spray angle development and proper air induction into the nozzle. Before buying a certain brand of air induction spray tips, make sure your sprayer pump can produce sufficient pressure to operate these tips under all conditions. Check with the nozzle manufacturers for operating pressures required.

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Sprayers for Home Use

A 9-14 L backpack, hand-held or compressed-air garden sprayer is satisfactory for use on lawns and around the home. A nozzle tip that produces a fairly coarse spray will help reduce spray drift. Care should be taken to keep the pressure relatively low; high pressures produce more fine spray droplets, which can drift in light winds to susceptible plants. The sprayer should be reserved for use only with herbicides and should not be used to apply insecticides or fungicides.

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Field Sprayers

The most common sprayer used in herbicide application is the boom-type sprayer. This sprayer applies a uniform amount of spray solution across the width of the boom.
The main requirements for field spraying are:

• a uniform pressure across the whole boom
• all nozzles have the same output and a good spray pattern
• a uniform forward speed in actual field conditions
• a stable boom height to ensure proper overlap of the nozzle-tip patterns

Most commercially built sprayers can be adapted and used safely to apply liquid fertilizers. Extra agitation may be required. Ensure that the sprayer components being used are compatible with the fertilizer formulation and follow the manufacturer's recommendations.

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Air-Blast or Mist Sprayers

These machines should never be used to apply herbicides, especially hormone-type herbicides such as 2,4-D. The danger of causing herbicidal damage at a great distance from the treated area is very great.

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Wiper Applicators for Selective Weed Control

Wiper applicators (rope-wick, roller applicator or similar device) have been extensively used with glyphosate (Roundup). Check product labels for use of this application technique with other herbicides. Product labels list the crops for which this technique is registered. The main criteria for using wiper applicators are:

• contact enough of the target plant to get herbicidal effectiveness
• keep the wick application above the crop to avoid crop injury.

Travel speeds should be 4-10 km/hr for wick application. Two passes in opposite directions may be beneficial, especially in heavy weed infestations and where higher vehicle speed is contemplated. Care must be taken not to contact sucker growth in orchards, vineyards and shelterbelts. This may result in crop injury. Follow manufacturer's directions.

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Related Links

• Weeds in Ontario
• Problem Weed Control in Field Crops
• Integrated Pest Management (IPM)
• Pesticide Application and Safety
• Pesticide Companies and Agents
• OMAFRA Sprayer Calibration Calculator
• Search the PMRA website
• OMAFRA Publication 505: Ontario Weeds
• OMAFRA Publication 75: Guide To Weed Control

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