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Maize - Weeds and herbicides
Weed management
Weeds compete for nutrients and water that can contribute to crop stress if not properly managed. Weeds may also create harvest problems and increase the cost of marketing. Crop rotations, planting into weed-free seedbeds, inter-row cultivations and herbicides are all techniques used for weed control. To avoid significant yield loss, weeds need to be controlled within 4-5 weeks of planting.
Herbicides may be applied at pre-plant, pre-emergence, post-plant or post-emergence. Before using herbicides, always read the label. Do not use the herbicides Dual® or Primextra® (Dual + Atrazine) with waxy maize varieties.
Herbicides in maize
The tables below include examples of commonly used herbicides in Queensland maize crops. Comprehensive information on registered agricultural chemicals is available on DPI&F's Infopest CD-ROM (which can be purchased singly or as an annual subscription) or from the Australian Pesticides and Veterinary Medicines Authority website.
Always refer to the container label for current registrations and safety information. These details may be subject to change.
| Herbicide | Mode of action group (1) | Weed type |
| atrazine |
C |
Annual grasses susceptible to atrazine (e.g. barnyard grass, crowsfoot grass) and broadleaf weeds |
| metolachlor (Dual®) |
K |
Annual grasses tolerant to atrazine (e.g. digitaria, brachiaria, green panics, Mossman river grass, urochloa) |
| atrazine + metolachlor (Primextra®) |
K,C |
Annual grasses and some broadleaf weeds (refer to label) |
| EPTC (Eptam®) |
E |
Nutgrass, couch, annual grasses |
IMPORTANT: Check rates, weeds controlled and application and safety guidelines on the label.
|
Active |
Mode of action group (1) |
Trade name examples |
|
atrazine |
C |
various trade names |
|
pendimethalin |
D |
Stomp® |
|
metolachlor |
K |
Dual® |
|
Dual® + atrazine |
K+C |
Primextra® |
|
linuron |
C |
various trade names |
|
flumetsulem |
B |
Broadstrike |
|
propachlor |
K |
Ramrod® |
|
MCPA formulation |
picloram + 2,4-D amine | atrazine | flumetsulem | Dicamba not in CQ |
fluroxypyr | Tordon 75D | Tordon 75D + atrazine | |
| Mode of action group(1) | I | I | C | B | I | I | I | C+I |
| Amaranth | R | R | R | R | R | |||
| Annual ground cherry | S | R | R | R | R | |||
| Anoda weed | S | |||||||
| Apple of Peru | R | R | ||||||
| Bathurst burr | R | R | R | R | ||||
| Bellvine | R | R | R | |||||
| Billygoat weed | R | |||||||
| Blackberry nightshade | R | R | R | |||||
| Black pigweed | R | R | R | R | R | |||
| Bladder ketmia | R | R | S | R | ||||
| Caltrop | R | R | R | R | ||||
| Cobbler's peg | R | R | R | |||||
| Common morning glory | R | |||||||
| Fat hen | R | R | R | R | ||||
| Jute | R | |||||||
| Mexican poppy | R | R | ||||||
| Mintweed | R (sodium salt) |
R | R | R | R | R | ||
| Noogoora burr | R | R | R | R | R | R | ||
| Paddy melon | R | R | ||||||
| Potato weed | R | R | R | |||||
| Red pigweed | R | R | R | R | ||||
| Sesbania pea | R | R | R | R | ||||
| Siratro | R | |||||||
| Spiny emex | R | R | ||||||
| Stinking roger | R | |||||||
| Sunflowers | R | R | R | R | ||||
| Thornapples | R | R | S | R | R | R | ||
| Turnip | R | R | R | |||||
| Wandering jew | R | R | ||||||
| Wild gooseberry | S | R | R | |||||
| Wild radish | R (sodium salt) |
R | R |
R-registered
S-suppression
These tables are intended as a guide only. Registrations may differ between individual products and change over time. Check the label in all cases before using.
(1) Some weeds have already developed herbicide resistance in the northern grains region. To prevent resistance developing on your property, rotate herbicides between these different herbicide groups and with other methods of weed control.
Note: Dicamba is not registered in central Queensland - even the lowest application rate for this product can cause crop damage. Check the withholding periods of all chemicals in relation to silage cutting and harvesting. Check residual effects on future crops.
Author: Michael Hughes
Page maintained by Judy Shepherd
Last reviewed 30 November 2006
URL: http://www.dpi.qld.gov.au/cps/rde/xchg/dpi/hs.xsl/cps/rde/dpi/hs.xsl/26_3678_ENA_HTML.htm