“Black-grass is becoming more and more of a problem but is there something we have done to encourage it and are we creating a habitat it can thrive in?” We are using heavier machinery, cultivating deeper and deeper because we’ve got more power, but I think we need to change our focus,” says Mr Jewers.
Black-grass is a marsh-loving plant, so it can thrive in poorly structured soils which are prone to waterlogging. According to Mr Jewers, to get on top of the weed we need to improve the underlying soil structure and make sure field drainage is well maintained. For those on heavier soils, it is very important that we can get rid of water to make an environment which favours crops over black-grass.
He is also well aware of the highly adaptable nature of black-grass – reduced sensitivity to post-emergence sprays is frequent. It also responds to non-chemical control; he cites the example of weed-surfers used by organic farmers result in selecting for shorter black-grass which thrives below the canopy.
Crop rotation is an important part of black-grass control, particularly spring crops, but Mr Jewers thinks that we need diversity in other areas as well. “We need to rotate drilling dates. If there is a field with less pressure, drill it earlier and the more difficult fields need to be drilled later or in the spring. Rotate cultivation types and chemicals used as well.”
Black-grass is a ‘cultivation weed’ and responds to soil disturbance. When the crop is being drilled you want to disturb as little soil as possible so all the subsequent control – pre-em, post-em, patch spraying and hand-rogueing – isn’t fighting against huge populations.
Some may think that low-disturbance means buying a new no-till and adopting a full no-till system drill, but this isn’t necessarily the case as Mr Jewers explains: “We bought our drill to have flexibility; it can be used as a direct drill which is the best option for soil health. But I am a realist and if the ground isn’t in good enough condition or there is too much black-grass then we need to cultivate – and the drill works equally well after shallow cultivation or ploughing.”
For Mr Jewers a shallow cultivation means no more than two inches deep to stimulate black-grass emergence. He typically cultivates after the combine and again in late September to push as much black-grass into life as possible before spraying off and using the low disturbance drill.
For growers not planning to invest in a new drill, existing drills can usually be adapted to reduce disturbance by removing cultivation discs and simple steps like drilling more slowly – watch these videos with Philip Wright to find out more about this (add link)
When faced with high seed return, Mr Jewers isn’t afraid to use the plough and back it up with a spring crop to clean up the land. However, he makes sure that the land hasn’t been ploughed recently. “It is important to have a five-year gap between using the plough on any piece of land. Ploughing buries a problem but if you plough again too soon then you plough the problem back up.”
After ploughing in autumn, weeds are sprayed off in March and a spring crop is established with low disturbance drilling. To make sure the land is cleaned up he usually does back-to-back spring crops.
“My father spent his youth pulling out wild oats and we don’t have wild oats any more. So, with black-grass if we’ve got it to a level where we can pull it out then we pull it out.”
In his ideal system, the chemical and cultural controls reduce populations low enough that fields can be rogued clean. Once the field is clean, he can drill direct to improve soil condition and reduce autumn workloads. Underlying this is the understanding that pulling one plant in May is easier than controlling 50 the next season.
“Black-grass is a very prolific seeder, one plant with 6 heads could make 600 seeds in total. Researchers say that you can expect 50 of those seeds to grow so if we kill 49 plants we stand still.”
When rogueing, Mr Jewers advises other farmers to walk each field twice because you always miss some. Added to that, be prepared to use glyphosate in the knapsack sprayer to take out patches which are too thick to rogue effectively.
Planning your crop rotations to help manage black-grass? This article provides some helpful guidance on which crops to consider and why.
Read our top five tips to help eliminate black-grass using cultural controls