Broad leaf weed control essential for pasture productivity

Broad leaf weed control essential for pasture productivity

12 September 2018

Spring-germinating weeds in established pasture could be a big issue on many dairy farms this season, especially those which have now experienced two wet winters and early springs in a row.

These conditions often result in paddocks becoming bare and open, with plenty of space available for weeds to become well-established.

Most paddocks contain high levels of weed seed in the soil, but thick and healthy pasture usually prevents these germinating in large numbers.

When pasture plant populations drop, however, weeds are quick to take advantage. Weeds which germinate or emerge in spring, such as Californian thistle, pennyroyal, willow weed, storksbill, dandelion, hedge mustard, dock, nettles and wild turnip, are fast-growing and can colonise bare patches of ground surprisingly quickly.

If these weeds are not removed promptly, they can significantly reduce the amount of quality pasture dry matter (DM) grown this season.

Many are invasive and can create ongoing problems for the future.

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

A further consideration is spring-germinating weed species can only be effectively controlled in spring, when newly emerged and most vulnerable to an application of effective broadleaf herbicide such as Baton.

Spraying weeds while they are still small is more cost-effective and removes them from pasture before they become large enough to compromise grass and clover DM yield.

Because it can be difficult to spot and correctly identify weed seedlings when they are very small, it’s a good idea to inspect pastures closely and seek advice from your Farm Source TSR if you are not sure which weeds are present.

As a phenoxy herbicide Baton provides an ideal means of control for spring-germinating weeds, because it is effective against a very wide spectrum of seedling weed species.

It is an advanced formulation containing 800g/kg 2,4-D as the dimethylamine salt. This means it can be formulated as water-soluble granules, has low odour, is non-volatile and causes less damage to valuable clovers.

Baton applied in spring will have some effect on clover growth but clover normally recovers well and any suppression is more than balanced by the benefits of less weed competition.

Correct timing is essential. Weed germination can be staggered throughout spring, so the aim is to kill the bulk of the weed population without letting early-germinating weeds get too big for effective control. Optimum timing is typically after the main germination but before any flower stalk development. Most spring-germinating weeds flower by late December which is too late for consistent control.

Graze paddocks before spraying to expose target weeds and reduce clover leaf area to minimise clover damage. Let the paddock freshen for two to three days. Try to spray as soon as possible thereafter (weather permitting).

Wait 10 to 14 days before the paddock is grazed again to allow Baton to move through the weed plants.

For more information, talk to your local Farm Source team.

Article supplied by Nufarm