Published on 23/04/2020
Taking time now with your customers to plan a grassweed control strategy will pay dividends over the coming months. In recent years, controlling grassweeds has become more challenging. Grasses are expanding their geographical range, their populations are increasing and herbicide resistance is spreading. The perfect grassweed storm!
But help is on the way. Autumn 2019 saw the introduction of Sakura® in New Zealand, which provided farmers with a new, very effective, group K, root acting grassweed herbicide. And with a different mode of action against ryegrass, it enabled the strengthening of resistance management for a grassweed where resistance to several herbicides is intensifying.
Pre-emergence grassweed control is so important. These weeds compete aggressively for space, water and nutrients and early removal results in healthier, higher yielding crops. And small weeds are easier to control. They have smaller roots ystems and less leaves, meaning recovery for the weed from a herbicide is harder. Also, if weeds show a level of resistance to herbicides, then, quite often, small weeds can be at least partially controlled.
But grassweeds germinate over a long period of time, so it is usually the case that a programme of Sakura applied pre-emergence followed by an effective post-emergence herbicide such as Othello® OD will be required. Sakura is a pre-emergence grassweed herbicide that controls all types of ryegrass, hair-grass, smooth brome and meadow grass. It also provides very useful suppression of ripgut brome and wild oats. Overall, Sakura performed very well in autumn 2019 with many satisfied farmers but, as always with any new herbicide, there were lessons to be learned.
As a specific grassweed herbicide, Sakura was targeted at paddocks with difficult grassweed problems, often paddocks which had grown a ryegrass seed crop. But these challenges helped the Bayer field team learn how to get the best from Sakura. One important lesson was that keeping weed seeds near the surface, using minimal cultivation or a direct drilling approach, ensured a very large proportion of the seed germinated. This enabled Sakura, which principally acts via root uptake, to control them.
Another important lesson was that deciding what programme to follow will require paddock walking.
In most autumns there will be adequate moisture to move Sakura to the rooting zone of weed seeds, thereby allowing it to control emerging weeds. This is why Bayer recommends that Sakura should be applied immediately after planting. Then a follow-up post-emergent herbicide, such as Othello OD, should be applied when a second flush of grassweeds emerges later in the winter.
But occasionally our autumns can be very dry and this can significantly change the grassweed control programme.
In 2019, shortly after many farmers planted their wheat crops, about 10 mm of rain fell. Enough to stimulate ryegrass germination but not enough to fully move Sakura to the weed rooting zone, meaning the first ryegrass flush was slowly controlled. By keeping the grassweed herbicide programme flexible, by applying the post-emergent spray earlier, it allowed this ryegrass to be controlled. Subsequent paddock monitoring then showed that any ryegrass emerging had poorly developed root systems and that it later turned brown and died. This demonstrated that Sakura was working well into the winter. Overall, the key lesson from 2019 was that, to control grass-weeds, especially ryegrass, bromes and wild oats, a flexible programme utilising different herbicides is needed.
Start the programme immediately after planting with Sakura and then careful monitor paddocks. This will ensure you get effective grassweed control for your customers.
For more detail contact your local Bayer representative.