Published on 28/04/2023
If they are not well controlled, tough invaders like docks, thistles and chickweed can permanently and significantly damage your wonderful new pasture before your cows even have a chance to graze it.
Complete loss of pasture is rare. But it is easy to under-estimate the immediate and ongoing impact of early weed competition on the quality, com-position, yield and persistence of your newly re-grassed paddocks.
“The moment you have weed seedlings challenging the clover and grass you have competition for light, space, moisture and nutrients. That’s when part of your new pasture never becomes new pasture, because it becomes weeds instead,” says Nufarm technical specialist Paul Addison.
With attention to detail, however, and the right new grass spray programme, you can banish weeds before they do too much harm. The first step is the most important, Paul says.
“The closer you watch those newly sown paddocks in the first weeks after sowing, the better your chance of spotting weed seedlings as they emerge. It is easy to get fooled from a distance by what looks like a nice green haze of germinating grass and clover. Most times there are species in there you definitely don’t want, and the only way to see them is to get right up close.”
Some weed species look similar, so get help if you have any doubts. A quick, easy way to do this is to take a photo on your phone and send it to your spray contractor or agronomist. Then get organised to apply broadleaf herbicide before the first full grazing. This is the most effective time to control rogue seedlings, Paul says.
Tribal Gold is an ideal option at this time. If you want a broader weed spectrum and/or need to control hard-to-kill weeds like chickweed, shepherd’s purse and buttercup, this is the herbicide to turn to.
Thistrol Plus has a narrower weed spectrum and is also very effective before the first full grazing. Valdo 800WG can be added if required to extend the range of weeds controlled.
Dictate 480 can also be useful for early weed control in new pastures, and is more effective on weeds like storksbill, chamomile and stinking mayweed.
Whatever option is right for you, it is well worth getting in early, Paul says.
“Before the first full grazing, weeds are still small and vulnerable, which makes them easier and most cost-effective to control with herbicide. Also, at this stage they haven’t had a lot of time to compromise the establishment of your young grass and clover.”
Tips for first-rate paddock prep
Even before sowing new pasture, you should set up successful establishment by effectively spraying out the previous crop before autumn sowing. Paul Addison says two of the most common pit-falls when spraying out for autumn sowing are not using the right rate of glyphosate and not using a companion herbicide when one is needed.
“The main thing farmers or their contractors should do before they spray out is check what weeds are present in paddocks ear-marked for autumn sowing. A high-performance glyphosate like Crucial and Pulse Penetrant will kill grass and many broadleaf weeds. But glyphosate does not necessarily do a good job against some broadleaf species, such as clovers, yarrow, dock and buttercup,” Paul says.
Controlling these broadleaf weeds could require a specialised herbicide strategy. For example, tank mixing Crucial with an appropriate partner like Nail 600EC can be a good option. If the main challenge in paddocks to be sown with new pasture is ‘just’ grass weeds – browntop, couch, mercer grass or paspalum – it is worth doing a thorough job of spraying out.
“If they are present when new grass seed goes in the ground this season, grass weeds will stay there for the life of that pasture, undermining the investment in seed, fertiliser and paddock preparation every day,” Paul says.
“Late summer is when such weeds start to move reserves down to their roots to prepare for win-ter. So, if you apply the right herbicide, the plants ‘own internal transport system will carry it where it needs to be for an effective kill,” Paul says.
Crucial plus Pulse Penetrant is a good option for such weeds as medic, chickweed, cleavers, mallow, fathen, fumitory, hawksbeard, nettles, prairie grass, oxtongue, speedwell, wireweed and shepherd’s purse. This combination offers good adhesion, rapid uptake and excellent translocation through the plant tissue. It also has a performance guarantee of15 minutes rainfastness. Paddocks sprayed with Crucial can be cultivated or drilled just one day after application for annual weeds, and three days for perennial weeds.
Article supplied by Nufarm