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Grassweed Surveys
- Thread starter skye @ bofin
- Start date
An integrated approach to weed management is needed, but the reaction to last autumn is mostly likely people drilling earlier this autumn for very understandable reasons. This however removes one of the most effective cultural control methods of delayed drilling. How do you compensate for this?
Both? If grassweed return gets greater due to lack of control then both are affected?
it affects my profitability as i have to buy chemicals to control it
but because we do control it it doesn’t affect my productivity
no because if we had no grassweed we would need no chemical and have no yield loss so i would be better off
grassweeds definitely affect my profitability but not my productivity
I'm not sure I agree with that argument, maybe I need to understand more what you mean by productivity. If you have no grassweeds then you do not need to spend anything on chemistry yes, but also do not need to do any IPM that might also impact yield, like delayed drilling that can impact yield potential. But if you do have grassweeds and do nothing then you lose yield immediately and over time as the weed burden builds you lose more and more yield until growing crops could become unviable.
no grassweed = no chemical required so no loss of productivity or profitability, ie nothing spent and no loss in output
grassweed = need for chemicals or other control which has a cost that will affect profitability vs no grassweeds (ie £’s spent but no loss of output) , it will only affect productivity however if control is not 100% successful (ie £’s spent and still a loss of output)
think that makes sense but i’m confusing myself now !
I think the estimates for blackgrass alone state that it costs the industry £400M per year. That will be a combination of lost yield through drilling dates, etc, compromised to achieve lower levels of the weed + herbicides purchased to control it. Did you know that just blackgrass reduce UK yield by 1 million tonnes every year? When it comes to herbicides, 111% of the cereal area is treated with flufenacet. That compares with 50% of the area treated with glyphosate. That is a HEAVY reliance. Also untold is the cost the herbicide application has on the crop, holding back emergence, etc. Reducing dependence on chemistry would definitely be a double win (if not a triple win!)
No that is not how that figure was calculated, and actually some of the data assumptions used to come up with that figure could be considered inaccurate. It is a well published and repeated figure that has taken hold, which just goes to show if you repeat something often enough it is taken as correct! Also not sure where you get you 111% of the area treated with flufenacet? This might be SDA, or (super developed area) so includes land that is sprayed twice in a season, so not actually 111% of the cereal area as it is impossible to spray more than 100% of the area. But there has been a heavy reliance on flufenacet, that is true. Reducing dependence on chemistry would be beneficial, but currently, particularly if you have ALS/ACCase resistance, you are reliant on soil residual chemistry to provide the top-up control after IPM measures. That 'top-up' is actually quite a chunky contribution in terms of control and the question is can alternative measures like mechanical weeding, surfing and harvest seed destruction fill that contribution, or in a blend of approaches how much of the chemical part can you reduce?
That's kind of my point. We rely far too heavily on chemistry. Mechanical weeding isnt the only alternative. There's cultivations & other IPM measures. We need a quick & easy way to turn these into 80% of the solution, whereas they're about 20% now, according to surveys we've conducted
Wrt data sources - the £400m figure comes from research carried out by BGRI I think it was conducted by inst of Zoology.
Pesticide usage - PUSTATS, so pretty robust. I believe if applied x2 that does then x2 the area applied. But still, that is a staggering reliance on just one ai
Chemistry is the cheapest and most reliable method currently, and only just about does the job with other IPM techniques employed. Remove any one at the moment and control becomes very difficult. With surveys never sure if people understand that creating a stale seedbed and using glyphosate is IPM, growing a spring crop is IPM, rotational ploughing is IPM. I think the amount of IPM that is already being utilised is under represented?
For sustainable grassweed control we do need a bigger armory and to become less reliant on chemistry.
I know the paper from the institute of zoology and I know that in my view the assumptions drawn were inaccurate. An algorithm scaled up the perceived black-grass pressure to calculate a country wide impact, but as with these things you only have to be slightly off at the start and you can end up a long way out at the end.
The very fact we cannot say to what extent we rely on chemistry is a problem in itself. The very fact that we cannot think beyond chemistry makes the problem even worse. And the very fact that if we remove any one, control becomes very difficult shows the industry is frankly at crisis point.
I suggest that as farmers we are failing to get a grip on grassweeds. We should be exiting chemistry, or at the very least using it precisely, which doesn't suit flufenacet. We should be bringing on new technologies - concentrated light & laser weeding, for example, so that these become mainstream in 5yrs time. We should look at RNAi and gene-drive as there are a raft of ethical considerations here, before you've even begun to consider their efficacy.
Ignore the bunch of new herbicide ai's coming out over the next 5yrs - this is not new technology & will simply prolong the death of chemistry
And no, glyphosate is not an IPM solution. It is part of the problem. If it's not dropped because it loses its approval, all our grassweeds will become resistant to it anyway - it'll be gone in 10 years time, so if we still rely on it in 5yrs time we'll be completely stuffed.