Guide to Weed Control in Potatoes

If there is a problem in the current season, managing that pest in another crop in a following year, if at all possible, may be the best management practice. Certain weeds such as wild buckwheat, Canada thistle and perennial sow thistle are examples of such problem pests.

The table below shows herbicides registered for use on potatoes in Canada. Note that some herbicides are not registered for use on potatoes in the United States and should not be used on consumable product destined for export. Most processing companies have their own list of approved chemicals that may be used on their respective contracted acres.

The information in Table 1 is based on available product information. The “S” indicates suppression only, whereas “P” indicates partial control. The weed species that are controlled will vary with the rate of product applied.

For details on rates, varietal restrictions, additional weeds controlled, re-cropping restrictions, timing and mixing instructions, please refer to the product label.

Table 1. Herbicides registered for use on potatoes

Weeds controlled

Herbicide

Common name

PHI (pre-harvest interval)

Barnyard Grass

Green Foxtail

Kochia

Lamb’s quarters

Mustards

Quack- grass

Redroot Pigweed

Canada Thistle

Smartweeds

Volunteer Cereals

Wild Buckwheat

Wild Oats

Clethodim

Select

60

–

–

S

–

–

Centurion

60

–

–

S

–

–

Arrow 240

60

–

–

S

–

–

Chlorthal*

Dacthal W-75

–

–

–

–

–

–

Diclofop-methyl*

Hoe-Grass 284*

60

–

–

–

Diquat

Reglone

14

Non-selective for green vegetation – vine kill

EPTC

Eptam 8E

45

–

–

–

–

–

–

–

Fenoxaprop-f-ethyl*

Excel Super

35

–

–

–

–

Fluazifop-p-butyl*

Venture L

90

–

–

–

–

–

Glyphosate

Wide range of products (e.g. Roundup)

–

–

–

–

–

–

–

–

–

–

–

–

Metribuzin

Sencor (various)

60

–

–

–

–

Lexone

60

–

–

–

–

Paraquat

Gramoxone

30

Kills top growth of most weeds

Rimsulfuron

Prism

30

–

–

S

–

–

–

Sethoxydim

Poast Ultra

80

–

–

–

–

–

S-Metolachlor

Dual II Magnum

–

–

S

Linuron

Linuron

–

–

–

–

–

–

–

–

–

Lorox

P

–

–

–

–

–

–

–

Glufosinate Ammonium

Liberty

14 - 21

–

–

–

–

–

S

–

S

–

–

–

–