Monterey Thistledown

Monterey Thistledown

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Product Overview

Monterey Thistledown is a highly effective herbicide for selective, post-emergence control of broadleaf weeds in rangeland and permanent grass pastures. This herbicide provides control for pesky species such as Canada Thistle, Musk Thistle, Yellow Starthistle, Knapweed and Kudzu. It can also be applied on grazed areas and non-crop land areas such as equipment pathways, industrial manufacturing, storage sites and rights-of-way, including roadsides electrical lines and railroads. Sold in 8-oz bottles.

Features and Specs

Active Ingredient: Clopyralid, monoethanolamine salt 40.9%
Target pests: Canada Thistle, Musk Thistle, Yellow Starthistle, Knapweed and Kudzu.
For use in: For use in rangeland, permanent grass pastures, grazed areas non-crop land areas such as equipment pathways, industrial manufacturing, storage sites and right-of-way, including roadsides electrical lines and railroads.
Pet safe: Yes, if followed as directed on the label.
Shipping Weight: 0.72 lbs
Manufacturer: Monterey Lawn & Garden (Mfg. Number: LG 5482)
EPA Registration: 228-491-54705



Do not apply this product in a way that will contact workers or other persons, either directly or through drift. Only protected handlers may be in the area during application. For any requirements specific to your state or tribe, consult the agency responsible for pesticide regulation.

Sprayer Clean-Out:

To avoid injury to desirable plants, equipment used to apply this product should be thoroughly cleaned before reusing to apply any other chemicals.

1. Rinse and flush application equipment thoroughly at least 3 times with water after use. Dispose of rinse water by application to treatment area or in non-cropland area away from water supplies.
2. During the second rinse, add 1.28 fl. oz. of household ammonia for every 1 gallon of water. Circulate the solution through the entire system so that all internal surfaces are contacted (15-20 minutes). Let the solution stand for several hours, preferably overnight.
3. Flush the solution out of the spray tank.
4. Rinse the system twice with clean water, recirculating and draining each time.
5. Remove nozzles and screens and clean separately.

(Including but not limited to Ranchette Pastures)

Use this product to control susceptible broadleaf weeds areas or established forage grasses in permanent grass pastures. Best results on most weeds are obtained when weeds are small and actively growing.

There are no grazing restrictions following this product’s applications when used at labeled rates.

Additional Broadleaf Weeds Controlled:

In addition to the list of broadleaf weeds listed below, this product controls kudzu in non-crop areas.

Application Rates

Apply this product at a rate of 1/8 to 1/2 fl. oz. per 1,000 sq. ft. in 2 gallons of water when weeds are young and actively growing. This product may be applied as described below for control of spotted and diffuse knapweed, Canada thistle, musk thistle, Yellow Starthistle and suppression of Russian Knapweed. Use the lower labeled application rate for young, actively growing weeds. The higher rate should be used under less favorable conditions, or on dense weed stands and/or larger weeds.


Application Timing

For the control of kudzu, apply this product between late June and early October, as long as the kudzu is actively growing and not under drought stress. The ideal time to apply this product is during vigorous growth and just prior to or during flowering. For best results on control of all other labeled weed species, apply this product when weeds are small and actively growing. Extreme growing conditions such as drought or near freezing temperatures prior to, at, and following time of application may reduce weed control. Only weeds that have emerged at the time of application will be affected. Wet foliage at the time of application may decrease control. The treatment with this product will be rainfast within 2 hours after application.

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Questions & Answers

Have a question about this product?
How long is the wait until you can replant after spraying Monterey Thistledown?

I work retail and a customer wants to replant trees and shrubs after use.


You should wait until at least the following season to plant desirable ornamentals in an area where Monterey Thistledown has been applied. We recommend this be at least 3 months after application. Please refer to the product label for complete application instructions.

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