Weeds compete with desirable plants for nutrients and water and if left unchecked can significantly reduce the productivity of a forage crop, and even lead to total crop failure. Forage crops are at their most vulnerable during establishment when the ability of the crop to compete with weeds is minimal.
Weed control prior to, and at sowing, (or seeding) is the most effective and cheapest way to deal with weeds. Doing this can reduce competition during the critical establishment phase and reduce the need for costly selective herbicide application after the crop has been sown.
Identifying target weeds
Different weeds have differing commercial impacts. It is important to focus on those weeds that pose the greatest commercial threat to the business and the business objectives of the enterprise eg weeds that are toxic to livestock or will potentially outcompete the forage crop should be the target of a weed control program.
The first step is to identify the kinds of weeds in the paddock where the forage crop is to be sown and to categorise these as either grasses or broadleaf weeds. Woody weeds may also pose a problem and may require specific control methods.
Weed control can be achieved through the use of herbicides, strategic grazing or a combination of both.
Herbicides specifically targeting broadleaf weeds or grasses may be used or a knock down herbicide employed for the general control of broadleaf weeds and grasses. A range of additives that improve the effectiveness or aid the uptake of herbicides are available and specialist advice from an agronomist or consultant should be sought when deciding upon the best control option for a particular situation.
Plants tend to have varying sensitivity to herbicides depending on their growth phase and this can be critical when planning control. Producers should react quickly following a rain event or cultivation to ensure that time critical control opportunities are not missed.
Strategic grazing can also be used as an effective weed control method. Spray-grazing is one useful technique, however, producers must always be careful to abide by grazing withholding periods (WHP) and export grazing intervals (EGI) if considering spray-grazing.
Goats are particularly proficient when it comes to weed control, particularly for various hard-to-kill woody weeds.