Successful spring weed control – timing is everything

Successful spring weed control – timing is everything

1 November 2015

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It may seem a bit early to be thinking about summer flowering weeds, but from now through to December is in fact the ideal time on most farms to spray these unwelcome visitors.

That’s because by the time you can see them flowering, it’s often too late to control them properly.

Right now, weeds like Californian thistle, pennyroyal, water pepper, willow weed, buttercup, fleabane, hedge mustard and daisy are germinating or have already germinated under existing pasture covers where they are usually out of sight, and out of mind.

Once pastures are grazed, however, these weed seedlings and small plants are then exposed to sunlight and their growth takes off rapidly as a result. Most of them are strongly invasive, and if they are not removed promptly, they not only reduce the amount of quality pasture dry matter (DM) that can be grown this season, but will also limit pasture productivity in future seasons.

The good news is that the period between germination and flowering of these weeds is the optimum time to eradicate them from your paddocks. They are growing fast, but they are still susceptible to herbicide.

Depending on your location and seasonal conditions, this window of opportunity will be from October to mid December. Many spring germinating weeds are in flower by late December, which is often when people realise they have a problem. However this is too late for consistent levels of weed control.

Typically the best results come from spraying after the main germination but before any flower stalks have developed. Californian thistles are the exception to this rule, as these are best sprayed at hard-ball stage.

Correct spray timing makes all the difference. Unfortunately spring weeds do not usually germinate evenly all at once; instead germination can be staggered during spring, so a good goal is to try and kill most of the weeds present without letting any plants which germinated early get too big for effective control.

Thistrol® Plus, Valdo® 800WG, Baton® and Bonza® are key tools in getting on top of spring weeds before they get on top of your pastures. Different weeds can require different herbicide treatments, however, so it always pays to check which species are present on your farm before deciding which product(s) to use, and at which rates.

To get the best out of your spray application, graze paddocks before spraying to expose the target weeds, and to reduce clover leaf area which in turn minimises clover damage. Let the paddock freshen for two to three days, and aim to spray as soon as possible thereafter, weather permitting. Wait until the grazing withhold period is finished before grazing, to allow herbicides to move through the weed plants.

Successful spring weed control

For more advice on smart, successful control of spring weeds this season, call into your local Fonterra Farm Source store or have a word with your Technical Sales Representative today.

®Baton and Thistrol are registered trademarks of Nufarm Australia Limited. Valdo and Bonza are registered trademarks of Nufarm Limited.

Article supplied by Nufarm