A guide to protecting your maize crop and maximising your yeilds


Targeted, early weed and pest control is essential when growing maize. Most hybrid varieties are endowed with high yield potential but are poor competitors against weeds or pests. To give your crop every chance of success planning is essential.

Nufarm has developed a six step plan to help you maximise the yield potential of your crop.

The benefits of early weed control:

  • It eliminates competition for light, nutrients and moisture, giving your crop the opportunity to establish.
  • It protects the palatability and nutritional potential of your crop.
  • It substantially curtails opportunities for pests to establish themselves in your crop.

Step 1 - Start early where perennial weeds are a problem

In autumn select the paddock early and control hard to kill perennial weeds (especially couch, Mercer grass, paspalum, Kikuyu, Californian thistle, browntop etc) with WeedMaster® TS540. Spray in autumn to maximise WeedMaster translocation and effectiveness, then sow an annual crop (ryegrass or cereal) for some high quality grazing or silage.

Step 2 - A pre-plant clean-up saves time

In spring, before establishing the crop, spray with WeedMaster TS540 to kill the existing vegetation. This clean-up and the use of WeedMaster TS540 provides the following benefits:

  • WeedMaster TS540 is rainfast in just 20 minutes when used in a tank-mix with Pulse Penetrant. Therefore, it is less vulnerable to spring showers and you avoid the cost of a re-spray due to rain.
  • WeedMaster TS540 controls perennial weeds to minimise competition in the maize crop.
  • Reduce the tillage required to reproduce an excellent seedbed, saving time and money, because plant root breakdown has already been achieved by WeedMaster TS540
  • Keeps the paddock in production longer beforehand, because an extensive cultivation or fallow period is NOT required for the new crop.

Application rates for

WeedMaster TS540

Annual ryegrass and cereals
1.9 - 2.5L/ha
Perennial ryegrass and Californian thistle
Couch and paspalum
2.5 - 3.8L/ha
Browntop, Kikuyu and Mercer grass

Tips to maximise WeedMaster performance

For maximum absorption you need 5 - 10cm of actively growing leaf. Preferably spray first then graze or cut later.

Add Pulse® Penetrant at 100ml/100L of water to:

  • Improve penetration and uptake of WeedMaster.
  • Ensure control of perennial ryegrass in spring.
  • To aid the rainfastness of WeedMaster TS540 (20 minutes versus 2 hours without Pulse)

Step 3 - Pre-emergence weed control is key

Controlling weeds early with a pre-emergence herbicide is crucial in maximising maize yields. FAR trial results show that waiting to control weeds until as little as 4 weeks after emergence can reduce maize yields by at least 10 - 20 %.

Other risks of relying solely on a post-emergence herbicide include:

  • Larger weeds are typically more difficult to control.
  • Delay in application of post-emergence herbicides due to weather may result in even further yield losses.
  • Post-emergence herbicides may only control certain weeds or control only broadleaf weeds and not grass weeds or vice versa.

Remember Weed Competition = Yield Loss

Pre-emergence Weed Control Options


controls annual weeds before they emerge and compete in the crop, by applying Roustabout to the bare soil. Roustabout is a high strength formulation which is applied soon after planting and within seven days of final cultivation.


  • Provides up to 10 weeks pre-emergence weed control, a critical factor for maximum yield.
  • Controls a broad spectrum annual grasses and broadleaf weeds.
  • Is effective in a wide range of soils and climates.
  • Doesn't rely on incorporation although incorporation may be beneficial where dry conditions are expected to continue.
  • For best practice, tank-mix with Nu-Trazine 900DF or Flowable Atrazine 500 to enhance broadleaf weed control.

Nu-Trazine™ 900DF

If a high infestation of broadleaf weeds (especially willow weed or fathen) is expected, tank-mix Nu-Trazine 900DF with Roustabout.

Nu-Trazine 900DF offers the following benefits:

  • Highly effective for pre-emergence or post-emergence broadleaf weed control.
  • High strength granular formulation of atrazine, so there is less to handle and it is safer to use.
  • More compatible with other herbicides.
The ability to tank-mix Nu-Trazine 900DF and Roustabout offers the flexibility to vary the rate of either herbicide according to conditions, which is not possible with ready-mixed products.

Flowable Atrazine 500

Flowable Atrazine 500 is a highly effective herbicide used for both pre and post-emergence broadleaf weed control. Weeds controlled include: fathen (excluding triazine resistant fathen), black nightshade, willow weed, amaranth spp. and apple of Peru.

Either Nu-Trazine 900DF or Flowable Atrazine should be tanked mixed with Roustabout for pre-emergence use and with either Kamba, Primiera, Emblem Flo and or Latro for post-emergence use. (Please check product labels carefully for tank-mix directions and rates)

Step 4 - Post-emergence weed control

Trials show pre-emergence weed control in maize out-yields post-emergence weed control, due to the removal of weed competition. Therefore pre-emergence weed control should remain the foundation of a successful maize weed control programme.

However, post-emergence herbicides may be required in a range of situations, and it is important that they are chosen wisely. The weeds present and crop height will dictate which post-emergence herbicides or tank -mix will offer the most suitable solution.

Broadleaf Post-Emergence Weed Control Options:

Kamba® 500

Kamba 500 is a unique high strength dicamba formulation.
  • Controls broadleaf weeds such as Californian thistles, bindweed, fathen and docks.
  • Kamba 500 is a high strength formulation so there is less product to handle.


Primiera is an easy to use, selective post-emergence herbicide for weed control in maize with a flexible application period.

Primiera offers:
  • Outstanding broadleaf weed control including atrazine resistant fathen, hemlock, volunteer potatoes and oxalis.
  • Soil and foliar activity.
  • Excellent crop safety and potential yield gains.
  • Provides suppression of certain annual grasses.

Emblem® Flo

A fast acting liquid contact herbicide with no residual activity, providing excellent control of many seedling broadleaf weeds including triazine or dicamba resistant weeds.

  • Emblem Flo controls a wide range of broadleaf weeds.
  • Emblem Flo is suitable for use in sweetcorn crops (refer to the label for crop specific directions).
  • If you apply Emblem at the early post-emergence stage it can be tanked-mixed with Nu-Trazine 900DF or Flowable Atrazine 500 for increased weed control and residual activity.

Do you have a specific broadleaf weed issue?


  • Targets Californian thistles, yarrow, Bathurst bur and volunteer potatoes.
  • Apply at 500ml - 1L/ha after the three leaf expanded stage but before crop closure.

Valdo® 800WG

  • If buttercup, mallow, mayweed or spurrey are a major issue in your crop consider Valdo 800WG
  • Apply at 30 - 65g/ha at the fourth leaf stage (approximately 90mm plant height).
  • Valdo can be tank-mixed with Latro 750WG where grass weeds are also a problem.

Are grass weeds an issue?

Latro® 750WG

Latro is a water dispersible granule that is ideal for post-emergence control where perennial grasses are the main target. Latro also controls annual grasses and certain broadleaf weeds.

Benefits include:

  • Controls perennial grass weeds including couch, Mercer grass and Kikuyu.
  • Latro also controls summer grasses and barnyard grass "escapes".
  • Easy to mix granular formulation.

Is Nutgrass a problem?


Sempra is the only registered product available to control purple nutsedge (nutgrass) in maize. It can be tank-mixed with Kamba 500 to provide general broadleaf weed control.

Sempra should be applied at 65 - 130g/ha when there is a minimum of 10cm of new nutsedge growth and prior to canopy closure of the crop (Use the higher rates for dense infestations).

Step 5 - Watch for pests

Check maize crops regularly (every few days) in the first few weeks after emergence for evidence of cutworm, slugs and snails.

Sheriff® 100

Sheriff 100 contains 100g/L alpha-cypermethrin in the form of an emulsifiable concentrate. Sheriff 100 is used to control greasy cutworm, armyworm and corn earworm.


SlugOut is highly effective for controlling crop-destroying slugs and snails. SlugOut's unique dust-free granules give excellent coverage per square metre, ensuring effective control of slugs and snails when planting new crops, or as a spot treatment on emerged or established crops.

Step 6 - Post-harvest clean up

Take the opportunity to clean up post-harvest by spraying with WeedMaster, particularly if hard to control perennial weeds are present. This is the essential last step when establishing perennial pasture.
Click to download Top of the Crop brochure (3.27MB)

Click here for more information on Pulse Penetrant

Click here for more information on Flowable Atrazine 500

Click here for more information on Kamba 500
Click here for more information on Primiera
Click here for more information on Emblem Flo

Click here for more information on Archer
Click here for more infoarmation on Valdo 800WG

Click here for more information on Latro 750WG

Click here for more information on SlugOut