NIAB - National Institute of Agricultural Botany

Orson's Oracle

Changing behaviour of black-grass

Posted on 15/12/2017 by Jim Orson

I have regularly been asked whether black-grass has changed its field characteristics over the last 30-40 years. I have always given the same answer, an authorative “I dunno”. However, some recently published papers have suggested that the development of herbicide resistance may have had an impact on, for example, seedling emergence.

Resistance occurs by herbicides selecting plants with a mutant gene or genes that enable it to survive their application. Put simply, the predominant members of a population die as a result of herbicide application but a few individuals that have the mutant gene(s) will survive. Experience suggests that in black-grass such plants initially represented an incredibly small proportion of the population, perhaps one in 10-20 million.

Classically, resistant plants are less “fit” to survive, unless the herbicides to which they are resistant are used. This “fitness cost” may express itself in many ways, such as the ability to germinate and/or emerge or the size of the mature plant. This is perfectly logical because these resistant plants would not represent merely a tiny minority of the original population if they were as “fit” as the herbicide susceptible plants. Their only “fitness” benefit is likely to be the ability to survive the application of one or more herbicides.

A recent paper in Weed Science written by researchers in Denmark shows that the seeds from the non-target site resistant plants in a subpopulation of black-grass are less likely to emerge than those from the susceptible plants. The cooler the conditions and the deeper the depth of burial, the greater the reduction in emergence. This is a classical fitness penalty; the more hostile the conditions the greater the impact on some aspects of the life cycle of the plant.

Hence, this research indicates that the later the drilling in the autumn and the deeper the cultivations may have an increasingly negative impact on the emergence of seeds shed from the resistant plants when compared to seeds from the susceptible plants in the same population. This in turn may mean that such cultural control measures will now be more effective in reducing populations rather than when the original trials were done 30-40 years ago. It also suggests that early drilling and shallow tillage is likely to increase the proportion of non-target site resistant individuals in a population; this is provided that there are still viable seeds from susceptible plants remaining in the soil!

A few caveats before I get carried away. The subpopulation in this research was grown from seed harvested in one field. As we know, non-target site resistance is a variable feast and so these results may not represent all sites where this form of resistance occurs. On the other hand, there is typically a fitness cost to resistance. However, this is not always clear. A few years ago the implications of two mutations that confer target site resistance to the ‘fops’ and ‘dims’ in black-grass were studied. One mutation conferred increased dormancy, seedling vigour and seedling tolerance to environmental stresses whilst the impact of the other mutation was largely the opposite.

It is not all good news on the fitness costs of resistance. The same Danish group (Frontiers in Plant Science, November 2017) found that within the same subpopulation, the non-target site resistant plants had the same sized mature plants, the same number of tillers/plant and the same number of seed shed/plant as the susceptible plants. This suggests that if only herbicides to which there was no resistance were used, it would take decades or longer before susceptible plants would eventually become very dominant members of this subpopulation. So, do not hold your breath!

It seems that there must have been changes in the black-grass life cycle over the last 30-40 years due, if nothing else, to the development of resistance. The problem is that non-target resistance can involve a few mutated genes and target site resistance more than one mutated genes. Perhaps a simple pot experiment will indicate the likely extent of the changes. It is complicated but I can now say “I dunno” with even more authority.

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Sustaining conflicting ideas

Posted on 01/12/2017 by Jim Orson

Whenever I walk to Cambridge Railway Station I pass new buildings that are divided into ‘sustainable’ student flats. Each time I see that slogan I think “what makes them sustainable?”. They look like all other new build flats, which are no doubt well insulated. I also suppose they may have a few solar panels on their flat roofs. But sustainable no!

Sustainable is the in-word when discussing agricultural systems. It has been a ‘must’ for research applications for the last 25 years or so. However, it remains undefined and somewhat of a mystery to many. A bit like the student flats.

I recently attended a discussion on sustainable agricultural production at the Cambridge Department of Plant Sciences. For one speaker the answer was easy – ban cattle and sheep. She said that dairy cattle alone are responsible for 10% of the world’s greenhouse gas production. There is no doubt that agriculture is a major source of greenhouse gas production; I have not been able to verify that particular figure but it could be in the right ball-park.

Getting rid of cattle and sheep will also reduce the need for growing arable crops to feed them, further reducing the footprint of agriculture. I did ask the question what would happen to the upland farms if sheep production were banned. They not only provide an income and an infrastructure but also many tourists appreciate the landscape of fields being grazed by sheep. She was unrepentant and added that farming the uplands is responsible for flooding in many parts of the country.

Defra secretary Michael Gove is now talking about the loss of agricultural soils. He made the claim that Britain has lost 84% of fertile topsoil since 1850 and erosion continues in some areas at between 1cm and 3cm a year. I have been working in agriculture all my life and I do not recognise those figures. Hence, I read what I am pretty sure is the source document. It seems that the quoted losses are just for the peat fens and not all agricultural soils. Again, all agricultural production is implicated from a quote out of context. I am not sure if Michael Gove would recognise a fen peat if it hit him in the face but his advisers should know better. It should also be noted that in the 1960s and 1970s there was active state-funded research trying to find approaches to minimise carbon losses from the fen peats but, according to my knowledge, no research has since been done. There is one positive measure that could be adopted to prevent the loss of food production from organic peat soils and that is to prevent the construction of even more solar farms on this valuable resource.

Farmers do recognise there is a soil health issue and have moved much more positively than any policy maker. They are anxious to improve soil conditions and many use as much organic material as they can get. However, according to a House of Lords committee, there are apparently still some potential organic sources not being used. The recent widespread adoption of cover crops on the lighter and medium soils must be reducing soil erosion although their longer term benefits remain a subject of debate.

Large increases in soil organic matter remain an impossible task however desirable the objective. The necessary large scale use of organic manures is not possible because of limited supplies. The only other option is to sow long-term grass leys. Defra became keen on this idea a few years ago but then looked at the experimental data. For instance, in the often quoted ley fertility experiments carried out on the MAFF Experimental Husbandry Farms in the 1950s and 1960s, the lift in organic matter from a 9 year grass ley was almost completely lost in the following three years of arable cropping.

So the path to ‘sustainability’ is strewn with conflicts. Should we convert three quarters of our arable land to leys for a temporary small increase in soil organic matter? Should an increased population of cattle and sheep be allowed to graze on these leys because of the inevitable rise in greenhouse gas production? Will the banning of sheep and cattle result in a significant decrease in the availability of organic manures to improve arable land? Would it be asking too much to ask for some clear holistic thinking on the issue of sustainability based on what is possible through best practice rather than listening to, often unrealistic, solutions to individual issues?

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Turning the tide

Posted on 17/11/2017 by Jim Orson

My wife and I recently attended the screening of the film “Food Evolution”, which was funded by the Institute of Food Technologists. It graphically details the objections to GM food and also the people who are promulgating the scares. One amazing scare story that I have not heard before is that GM food affects your immune system which protects you from infections such as HIV?!

Mark Twain’s famous quote “It is easier to fool people than convince them that they have been fooled” is the first image of the film and sets the scene. It is illuminating how the scare stories are debunked in the film and also to hear that some leading objectors to GM foods in the US have shops on their websites selling ‘healthy’ foods.

One negative story about GM, which Prince Charles frequently quotes, is that buying GM seed has increased farmer debt in India and resulted in suicides. Each suicide is a huge tragedy but the suicide rate amongst Indian farmers did not increase after the introduction of GM crops in India. Sadly, it has long been at current levels.

Some objectors used to quote that there is a very close correlation between the increase in glyphosate use on GM maize and soya in the US and the increase in the number of autism cases in the US. Please, always remember that correlation is not causation and in fact there is a similarly strong correlation between the organic food sales in the US and autism (full details). Despite this close correlation I have never heard anyone suggest that organic food causes autism!

                     Number of children 6-12 with autism

                              The real cause of increasing autism prevalence?

Going back to Mark Twain, the scare stories have convinced many that GM food production and consumption is damaging both to the environment and their health. Getting them to accept that they have been severely misled is a major challenge. As one journalist asks in the film “when was the last time you changed your mind on a major issue?”. This simple question encapsulates the enormity of the task of convincing consumers that GM is safe.

In the panel discussion after the film it was agreed that the way forward is to quote the examples of successful niche uses that have been introduced by non-commercially funded researchers, rather than corporations, into a society that has a background of unease over GM technology. One of the prime examples used in the film is GM rainbow papaya that saved production in Hawaii from a virus and another concerned bananas threatened by a wilt disease in Uganda. These two cases have gained acceptance by the legislators and consumers and could open the gates to other uses of the technology.

The film was screened at a meeting of the University of Cambridge’s Global Food Security Initiative. I estimated that there were around 150 people present and if there was anyone present who objected to GM technology, they kept very quiet. This I think is illuminating in itself. Over the last ten years or so academia has not only become more accepting of GM technology and other modern biotech breeding methods but also of ‘intensive farming’. Most now agree that organic farming would use up too much land in order to feed people and hence would be environmentally disastrous. I hope that the media will eventually see this issue more objectively. At the moment they appear to accept lamely that all the world’s ills are due to ‘intensive farming’.

However, having said that, a paper in this week’s Nature Communications suggests that organic production could feed the world in the future but would require 16 - 33% more land or that the current cropped area would be sufficient if food waste is reduced by 50%. Also land that can grow arable crops should not grow crops for animal feed. This is a repeat of a story that is at least twenty years old and it still sounds far too good to be true. Mind you, even if these suppositions are correct, just think of the land potentially spared from conventional crop production if demand is similarly reduced by cutting waste and by not growing arable crops for animal feed. This spared land could be specifically managed to meet environmental objectives. It would be a veritable seventh heaven for many conservation organisations.

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WHO and ebola, Mugabe and glyphosate

Posted on 03/11/2017 by Jim Orson

My first doubts about the World Health Organization (WHO) arose because of its response, or lack of it, to the ebola crisis in Africa. It was founded to react rapidly to this type of issue but it initially failed when this true emergency came along. It was charities such as Save the Children that first stepped into the breach. The failings of the WHO have been attributed, in part, to the fragmented nature of its structure.

The WHO did not seem to learn from the ebola issue. Its organisational structure has allowed the now discredited scientist Christopher Portier the space to play out his own financially rewarding personal vendetta against glyphosate and also enabled Robert Mugabe to be – temporarily! - appointed a goodwill ambassador. I am not sure which is the sillier decision. Obviously there are no checks and balances to prevent individuals and cliques from following their own agendas rather than that of the organisation.

It is now clear that the International Agency for Research on Cancer (IARC), an agency of the WHO, describing glyphosate as a probable carcinogen is a scandal. I hope that when the WHO is re-organised, as it must be, it will review this decision and use independent minded scientists. In the meantime it is necessary to defend the herbicide.

There is more than sufficient good science to defend the safety of glyphosate in an independent forum. The impact of its withdrawal on arable agriculture and the wider environment would be immense. Whilst the list of its benefits is too long to detail in this blog, I should like to mention one issue in particular.

It is a widely held belief that no-till, enabled by glyphosate, increases carbon capture in the soil. This is not true. No-till and ploughing capture the same amount of carbon. With no-till there is a build up on the soil surface whilst with ploughing it is distributed throughout the plough layer. A recent AHDB report confirms this.

It may well be that concentrating the soil carbon close to the surface rather than it being more dispersed brings agronomic and environmental advantages. Of course, no-till or shallow till means moving less soil and so there can be massive savings in fuel usage and carbon emissions. As a rule of thumb, doubling the depth of moving all the soil in the primary cultivation increases the power requirement fourfold.

Soil health is now of tremendous interest to politicians as well as farmers and, in this context, reducing tillage is a way forward provided that the soil is suited to such an approach and rotations are adopted to help manage weeds. The potential cost savings are very significant. The use of cover crops can help facilitate no-till or min-till but they will need to be killed with glyphosate before the following crop.

With such major advantages from glyphosate use hopefully the regulatory authorities will not let slip their standards and attitudes to sound science.

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Slow pace of GMOs in Europe

Posted on 20/10/2017 by Jim Orson

There has been much talk and discussion this week on ‘The Great Storm’ in October 1987. I remember it vividly. I was giving a talk in Northamptonshire that evening and it poured with rain all the way there and all the way back. The farmers were down because they were just about to put on their single black-grass spray. Nearly everyone intended to use early post-emergence isoproturon but the rain had stopped play for at least a week or two. Hence, there was a long discussion on the possibility of applying it when the ground was frozen. I got home to Cambridge close to midnight and although it was windy it was nothing to worry about. We were then woken at around two in the morning when it seemed that the windows were about to blow in.

Black-grass control has changed radically since then but some things have moved more slowly. Paradoxically, one new technology has not moved at all in Europe. GM herbicide tolerant (GMHT) crops have been available for the best part of 20 years but have not been grown in the UK. We all know the reasons for this and there are strong views, both for and against.

This week sees the start of the Cambridge Festival of Ideas. The main theme is trust and truth. The first event I attended was on the safety of GMs. The two panellists were a leading plant scientist and a social scientist who is studying attitudes to GM. In many ways, the discussion was a throwback to 10-20 years ago. The issues were those that have been commonly raised since GM crops were first introduced. I think that this demonstrates clearly that GMO development has stalled in Europe and the debate is unable to move forward. On the other hand, the very large audience listened attentively to the replies to their questions and there did not appear to be a strong current against the technology. Perhaps that alone is a step forward?

There were one or two intriguing views that were expressed by the panellists. The plant scientist, with the benefit of hindsight, thinks that it was wrong to introduce GMHT crops first. He did not provide the usual opinion that this was because such crops appeared to benefit only the farmer. His reason was that the genes introduced were from bacteria. This almost fed the perception that the food produced was unnatural. He added that the latest generation of GM traits tend to be those where genes have been introduced from wild relatives. For instance, the GM blight resistant potato being field tested at the John Innes Centre in Norwich has an introduced gene from a wild Solanum species. Such an introduction would be possible through conventional plant breeding but would take decades to achieve a blend of current agronomic performance and market acceptability along with the blight resistance. He said that if these traits had come first there might have been more public acceptance; something akin to the ‘nudge’ theory in behavioural science. A nudge is small, a nudge is simple, and this is why a nudge is so appealing.

The social scientist highlighted that there appears to be no middle ground in views on GMOs. You are either for them or against them. She said that this reflects arguments on food security. Either you think that sustainable production of sufficient food to feed a rapidly expanding world population will be achieved by the responsible use of high-tech methods or by more ecologically-based farming.

She also said that Rachel Carson, in her polemic book ‘Silent Spring’ which initiated the green movement, argued for GM amongst her long list of suggested alternatives to pesticides . It is true that Rachel Carson did suggest biotic control methods, including Bt, although many in the green blob now raise their concerns over its use. This is probably because it is the basis of GM Bt insect resistant corn, cotton and soya. However, Rachel Carson was a scientist and would probably refute many of the arguments put forward by today’s green blob. It is clear from many of their statements that they have never read Silent Spring although they commonly refer to it. What is required is a balanced view of the way forward based on good science and not the strident anti-technology views, particularly from those ‘green’ groups that desperately need subscriptions to support their organisations.

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