Safe Use of Aquatic Herbicides

Reeves Petroff

MSU Pesticide Education Specialist

http://mtpesticides.org

Types Of Aquatic Weed Growth

Aquatic Plant Control Methods

• Prevention

• Manual or mechanical removal

• Manipulate water levels

• Shade, dyes

• Install liners

• Use biological controls

• Use chemical controls

Pesticides

PESTICIDES

A pesticide is any chemical that is used to control pests.

PISCICIDES ?

INSECTICIDES

ALGICIDES

RODENTICIDES

HERBICIDES

Kills fish

General and Restricted Use Pesticides

GENERAL-USE PESTICIDES

• Less likely to harm the user or the environment when used according label instructions.

• Almost anyone can buy and apply general-use pesticides.

• 2,4-D, Roundup, Rodeo.

RESTRICTED-USE PESTICIDES (RUP)

• Can harm the environment or the applicator when not used as directed.

• Licensing and certification are required for purchase and use.

• Magnacide H, Hydrothol, Aquathol, T Chem Aquatic Weedkiller

HERBICIDES Most commonly used method. Caution is needed.

Fish Kills Potable water intakes

$$$ Short term Dead weeds stimulate future weed growth

A PESTICIDE FORMULATION IS MADE UP OF ONE OR MORE CHEMICALS:

(a.i.)

Sonar AS

Using Herbicides Correctly

1. Pesticides must be registered by the U.S. EPA and MDA before they can be sold or applied in Montana.

2. Pesticide labels provide necessary information to pesticide users.

3. Pesticides must be used according to label instructions.

A Legal document

PESTICIDE LABELS ARE

Uses inconsistent with the Pesticide Label

It is illegal to use a pesticide in any way not permitted by the labeling. Off-site Improper equipment settings Improper rate (lack of calibration) No safety gear worn when the label says

you must!

Pesticide Labels You may not use

higher dosages higher concentrations more frequent applications

Pesticide Labels

apply a pesticide at any dosage, concentration, or frequency less than that listed on the labeling

apply a pesticide against any target pest not listed on the label as long as the the application is to a plant, animal, or site that is listed,

You can….

use any appropriate equipmentor method of application that is not prohibited by the labeling

– mix a pesticide or pesticides with a fertilizer if the mixture is not prohibited by the labeling

– mix two of more pesticides, if all of the dosages are at or below the recommended rate

Pesticide LabelsAllowed uses not mentioned in the labeling

Before you purchase the product

Before you mix and apply the product

Before you dispose of the container

Is it approved for use?

Will the pesticide will control the pest or pests?

Can the pesticide can be applied safely and legally? Application conditions

Where can the pesticide be applied? - Sites-

Special equipment setup?

BEFORE YOU BUY A PESTICIDE

Any use restrictions.

Compare different pesticide labels,

Different products may control the same pest.

Select approved products that control the pests and are less toxic and/or less expensive.

BEFORE YOU MIX

Protective equipment you should use. Compatibility of the pesticide with other products

or additives. Amount of the pesticide to use. Product rate? Mixing procedure.

BEFORE YOU APPLY

Safety measures. PPE required? Procedures to follow to minimize harm to

people, animals, plants or the environment. How to apply the pesticide. When to apply the pesticide

Susceptible life stageREI?

BEFORE YOU DISPOSE OR STORE Where and how to store the pesticide.

Pesticide label information intact?

How to decontaminate and dispose of the pesticide container.

Where and how to dispose of surplus pesticides.

Nature of the Problem

Few aquatic herbicides Many restrictions Lots of risks Multiple interests and

viewpoints

SUGGESTED PRECAUTIONS Registered?

EPA? Montana? Buy from a local dealer.

Where do irrigation canals and ditches end?

Acrolein & xylene can kill fish & other aquatics?

Can the treated water be held? Acrolein - 6 day waiting period – release into

state waters Xylene – 10 ppm – state waters

SUGGESTED PRECAUTIONS

Inspect and repair leaky flow through structures.

Patrol or secure diversion structures to prevent accidental or deliberate opening.

Make sure bulk containers and nurse tanks are properly labeled

SUGGESTED PRECAUTIONS

Follow label mixing and application directions. Labeled site? Equipment calibrated? Proper mixing equipment? Correct product rate? Label Personal Protective Equipment

(PPE)

SUGGESTED PRECAUTIONS

Know the pest! Biology and life cycle Application timing Labeled?

SUGGESTED PRECAUTIONS

DREADED CALCULATIONS

Canals and Ditches CFS

W x D x V FT x FT x FT/sec 450 GPM = 1 CFS

PPMV 1 gal in 1,000,000

gal

Ponds and Lakes Acre-foot 43,560 ft2 x 1 foot deep

= 43,560 ft3

% active ingredient (a.i.) expressed as a decimal

Converting a.i. To formulated product

Converting ppm to pounds (x 2.72)

10 feet wide, 4 feet deep, flow rate 1.5 feet per sec. (fps)ant 740 ppm in the water applied over a 30 minute period.  How much xylene do you apply in 1/2 hour?

Gal. (per CFS) = 450 GPM x ppmv x CFS x time (min.) 1,000,000 599.4 gal. = 740 ppmv x 450 GPM x 60 CFS x 30 min. Xylene in 1,000,000 30 min

• 1,000 CFS irrigation canal • Rate of 2 gallon per CFS over an 8 hour period.  • What is the concentration in ppmv

ppmv = 1,000,000 x dosage rate . 450 GPM x time applied (min.) PPMV = 1,000,000 ppm x 2 gallons =  9.26 ppmv       450 gpm x 480 minutes**         

** 8 hours x 60 minutes in one hour = 480 minutes

• 200 feet by 150 feet with an average depth of 6 feet. 

• copper sulfate crystal at 25 percent copper iron (0.25)

• want maximum rate of 1 ppm copper ion in water. 

• How much copper sulfate crystal do you apply?

Volume of pond in acre feet = 200 x 150 x 6  180,000 ft3 43,560 ft3 = 4.13 acre-feet

Find the total pounds of the formulation that is required.4.13 acre-feet x 2.72 (convert PPM to pounds) x 1 PPM (as required by the label) = 11.23 pounds of active ingredient (a.i.) required.

Convert percentage to a decimal: 25% copper iron content = 0.25

Convert a.i. to pounds of the formulated product. 11.23 pounds a.i. 0.25 = 44.92 pounds of the formulated product is needed.

11.23 X 100 = 44.92 25

The End