Successful spring weed control: timing is everything

Successful spring weed control: timing is everything

1 October 2021

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.

By the time you can see weeds 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, out of sight, and out of mind.

Once pastures are grazed, however, these seedlings and small plants are then exposed to sunlight and their growth takes off rapidly as a result.

Most are strongly invasive, and if not removed promptly, they not only reduce the amount of quality pasture dry matter (DM) that can be grown this season, but also limit pasture productivity in future seasons.

Generally, animals do not like to eat weeds, and avoid grazing too close to some species, leading to further loss of pasture productivity.

Many spring-germinating weed species can only be effectively controlled when they are newly emerged and most vulnerable to application of effective broadleaf herbicide such as Baton® 800WSG. Spraying weeds while they are still small is also more cost-effective.

Useful herbicide options for this job include Baton® 800WSG and Valdo® 800WG. They are specifically designed to kill broadleaf weeds while the plants are still small.

Baton is a selective phenoxy herbicide that controls many broadleaf weeds, including ragwort, thistles, pennyroyal and wild carrot in pasture, without major damage to clover.

Depending on the weed species present, Baton can be tank-mixed with Valdo. This clover-friendly flumetsulam herbicide is particularly useful for improving control of buttercups and brassica weeds such as hedge mustard and wild turnip.

Correct spray timing makes all the difference. Unfortunately, spring weeds do not usually germinate evenly all at once, with germination sometimes staggered during spring. 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.

Typically, the best results come from spraying after the main weed germination but before any flower stalks have developed. Californian thistles are the exception to this rule, as these are best sprayed just before flower buds open.

Graze paddocks before spraying to expose target weeds, and reduce clover leaf area to minimise clover damage.

Let the paddock freshen for two-three days and try to spray as soon as possible thereafter (weather permitting).

Pasture cannot be grazed for 14 days post application to allow the herbicide to move through the weed plants.

For more advice on using Baton and Valdo to control spring weeds, talk to your local Technical Sales Rep or visit your Farm Source Store.

® Baton is a registered trademark of Nufarm Australia Limited.
® Valdo is a registered trademark of Nufarm Limited.

Article supplied by Nufarm.