- Conservation needs to break free from global priority mapping. Couldn’t agree more. And less.
- National climate and biodiversity strategies are hamstrung by a lack of maps. Wait, what?
- The evolutionary genomics of species’ responses to climate change. You need to combine niche modelling with genetic adaptation to get the best maps.
- Payoffs to a half century of CGIAR research. A benefit-to-cost ratio (BCR) of 10:1. Not counting the genebanks. And all the maps.
- A case for conserving plant pathogens. But will it be worth it?
- Poor data stewardship will hinder global genetic diversity surveillance. What’s the BCR for decent metadata?
- Mitigating tradeoffs in plant breeding. Cutting out the cross-talk changes tradeoff to payoff.
- Comparing Productivity of Organic and Conventional Farming Systems: A Quantitative Review. Conventional is more productive. But should yield be the only criterion?
- Priority micronutrient density in foods. Right. Micronutrients are also important.
- Reconciling yield gains in agronomic trials with returns under African smallholder conditions. And how was yield measured anyway?
- Data-driven, participatory characterization of traditional farmer varieties discloses teff (Eragrostis tef) adaptive and breeding potential under current and future climates. This might well be an example of applying the lessons of the above.
- Genetic Diversity and Utilization of Cultivated Eggplant Germplasm in Varietal Improvement. The wild relatives will save us.
- Quinoa Phenotyping Methodologies: An International Consensus. But will it work for the wild relatives? Just kidding, this is an important development for another crop (with the above) which doesn’t have something like the CGIAR and its 10:1 BCR behind it…
I was recently reminded of a post I wrote in 2006, and thought to myself that it could have been written yesterday. The trigger for this memory was a long piece in the New York Times that appeared more or less yesterday.
The subject is superweeds; that is, weeds resistant to one or more herbicides. In 2006, I was writing about waterhemp (Amaranthus tuberculatus), which had recently been shown to have developed resistance to an entire class of weedkillers. The thrust of it was that resistance involved mutations in two separate genes, taken together a one in a billion billion (1,000,000,000,000,000,000) chance. But it happened. Agriculture selects improbable events.
The NYT article was about another amaranth, Palmer amaranth (A. palmeri). The thrust of it was that Palmer amaranth is now resistant to at least six different classes of herbicide.1 In 2006 it was resistant only to glyphosate. That leaves farmers with almost no options to control Palmer amaranth, and control it they must.
In 2008, researchers scattered 20,000 seeds of glyphosate-resistant Palmer amaranth into a 1 metre diameter circle in the middle of four different cotton fields that had no history of Palmer amaranth. The experimental sowing was intended to represent survival and maturity in the field of a single resistant female Palmer amaranth plant.2 After that, they managed the glyphosate-resistant cotton as per recommendations, spraying to control the weeds.
One year later, in one of the fields, Palmer amaranth had moved 114 m from the original site in one of the fields. Two years later, the weed had spread to the boundaries of all the fields and covered 20% of the field area. “Three years after the introduction (2010), Palmer amaranth infested 95 to 100% of the area in all fields, resulting in complete crop loss since it was impossible to harvest the crop.”
That paper goes on to discuss some possible management options, suggesting a “zero-tolerance threshold” to eradicate every weed. I doubt anyone even tried. For its part Monsanto, which had developed glyphosate-resistant seeds, worked to stack resistance to another weedkiller — dicamba — into its genetically engineered seeds, a pointless exercise. As the NYT reports, “The agribusiness giant took a decade to develop that product line. The weeds caught up in five years.”
A squandered resource
The evolution of resistance to some life-threatening challenge is axiomatic in biology and it doesn’t matter whether the threat is an antibiotic, a herbicide, fungicide or insecticide, or even a predator. Anything that gives an organism even the slightest competitive edge in its ability to reproduce will in the end be selected. The problem is certainly not unique to genetically modified organisms. In the mid 1990s, wild oats resistant to three and four classes of weedkiller appeared on the Canadian prairies. Agriculture Canada blamed farmers who ignored advice to rotate crops and herbicides.3 But genetic engineering has exacerbated the problem many times over by giving natural selection so many more opportunities to do its inexorable thing.
Antimicrobial resistance is, belatedly, gaining a little recognition. Herbicide resistance might just be heading in the same direction, if the New York Times is taking an interest. These problems are, to some extent, a manifestation of a mismanaged commons; to begin with, using the stuff confers a benefit on the individual, but as everyone does so, everyone begins to suffer. In agriculture, they’re also a reflection on efficiency at any cost. Good weed control means good preparation of the soilbed, physical weeding three or four times during the life of the crop and other practices that take time and, therefor, money. How much easier to pay over the odds for seeds, buy weedkillers from the people who lent you the seeds, spray and pray. The same goes for antibiotics as growth promotors. Shave a fraction of a percent off feed costs and multiply that across millions of animals and you create a powerful incentive to abuse antibiotics. And just as it isn’t genetic engineering per se that creates problems of resistance, it isn’t agriculture per se that makes the improbable certain. It is the way agriculture is conducted.
What to do
Scientists have offered lots of advice on how to minimise the problems of resistance, some of which have even made it into policy. Just recently, the Food and Drug Administration tightened up a bit on its Guidance for Industry on the use of antibiotics on farms. From June 2023, a veterinary prescription will be needed for all antibiotics. I’m sure no veterinarians will be tempted to issue prescriptions that might not be absolutely necessary.
As it happens, organic farmers don’t use chemical herbicides on their crops, and superweeds are much less prevalent on organic farms. An excellent long article in Civil Eats uses one organic farmer’s fight against glyphosate-resistant giant ragweed as a jumping off point for a thorough discussion of the difficulties of controlling weeds in the oversimplified farm systems of the US corn belt. The key is hybrid rye, which overwinters and helps to smother ragweed as it emerges in the spring. Control can be achieved, but as the article makes clear, there are lots of obstacles, not least the difficulty of finding uses for hybrid rye. Longer rotations, increased diversity, more hands-on management, local cooperation: all are necessary, and all go against the grain for the majority of today’s corn belt farmers. Nevertheless, something is going to have to happen, and another technical fix is unlikely to be any kind of solution.
If you can’t beat them …
There is an additional approach, at least for Palmer amaranth. Its leaves, stems and, especially, seeds are edible, delicious, and highly nutritious (as they are for many amaranths). In theory, one could, perhaps, turn the noxious weed into a nutritious addition to the diet. And even though it is glyphosate resistant (not to mention the other five weedkiller classes), it come by that resistance natural, rather than through meddlesome genetic engineering, so there couldn’t possibly be any objection to eating it.
The two articles, in the New York Times and Civil Eats, are well worth reading in their entirety.
- A global database of diversified farming effects on biodiversity and yield. Always good to have the data.
- Dietary agrobiodiversity for improved nutrition and health outcomes within a transitioning indigenous Solomon Island food system. Maybe we should have a database of diversified farming effects on health and nutrition too?
- Exploring ‘beyond-food’ opportunities for biocultural conservation in urban forest gardens. Always good to have more trees.
- Community seed network in an era of climate change: dynamics of maize diversity in Yucatán, Mexico. Always good to have landraces. And neighbours.
- Microbe-dependent heterosis in maize. Maize hybrids need microbes.
- Assessment of genetic diversity and population structure of oil palm (Elaeis guineensis Jacq.) field genebank: A step towards molecular-assisted germplasm conservation. 30% seems a lot for a core collection. But it’s good to have the data.
- Sources of resistance to Pseudocercospora fijiensis, the cause of black Sigatoka in banana. 11 resistant accessions out of 95 seems pretty good, on the other hand.
- GWAS unveils features between early- and late-flowering pearl millets. Based on a national-level core collection in Senegal. Presumably this will scale?
- Germplasm Collection, Genetic Resources, and Gene Pools in Alfalfa. Lots of work has been done. More work is needed on the wild relatives though.
- Assessment and modeling using machine learning of resistance to scald (Rhynchosporium commune) in two specific barley genetic resources subsets. Fancy maths helps to identify the barley genebank accessions you really need.
- Strategic malting barley improvement for craft brewers through consumer sensory evaluation of malt and beer. More fancy maths, this time applied to a hedonic data in the service of beer. Germplasm evaluation we can all get behind. No FIGS, alas.
- Large-scale whole-genome resequencing unravels the domestication history of Cannabis sativa. 4 genetic groups: primordial (located in China, not Central Asia, and going back 12,000 years), 2 medicinal, 1 fibre. Now for the hedonic evaluation.
- The Origins of the Apple in Central Asia. Probably domesticated to cope with the munchies.
- Genetic Divergence and Population Structure in Weedy and Cultivated Broomcorn Millets (Panicum miliaceum L.) Revealed by Specific-Locus Amplified Fragment Sequencing (SLAF-Seq). There are interesting genetic differences between wild and feral forms, and between eastern and central-western cultivated forms. The Silk Road trifecta.
- Global range expansion history of pepper (Capsicum spp.) revealed by over 10,000 genebank accessions. Spoke too soon. The Silk Road had a role in pepper movement too. Among other trade routes. Interesting, and unsurprising, that genes for pungency show distinct geographic patterns.
- Genomic evidence supports an independent history of Levantine and Eurasian grapevines. First domestication in the Caucasus, and then in the Levant, but not clear if from local sources. No word on hedonic evaluation.
- Genotyping-By-Sequencing diversity analysis of international Vanilla collections uncovers hidden diversity and enables plant improvement. Belize seems to be a real hotspot. The Silk Road not involved.
- GAIN Discussion Paper 9: Food group diversity and nutrient adequacy. Eat a diverse diet…
- Can Underutilized Tropical Fruits Meet the Nutritional Requirements of Rural Indonesia? …which includes fruits, of course.
- The nutritional quality of cereals varies geospatially in Ethiopia and Malawi. And cereals, though it depends where they’re growing.
- Variation for Photoperiod and Temperature Sensitivity in the Global Mini Core Collection of Sorghum. Less than 10% are sensitive to neither. And yes, there’s another paper on the nutrient quality of the same subset. Though not on how that varies geographically.
- Habitat value of bivalve shellfish and seaweed aquaculture for fish and invertebrates: Pathways, synthesis and next steps. Eat more bivalves and seaweed too, it can be good for the environment too.
- Measurements of lethal and nonlethal inbreeding depression inform the de novo domestication of Silphium integrifolium. Always good to have a new oil crop, especially a perennial one, but careful what you cross to get it, and how.
- Genome design of hybrid potato. Re-inventing the potato as a seed-propagated crop could be good for nutrition, sure, why not.
- High Throughput can produce better decisions than high accuracy when phenotyping plant populations. As you make better and more nutritious crops, keep in mind it may be better to phenotype more plants in more environments than obsess about accuracy and precision. What does that mean for mini-cores?
- Insight into the introduction of domestic cattle and the process of Neolithization to the Spanish region Galicia by genetic evidence. But is any of this worth the hassle? After all, the early domesticated cattle of Galicia are similar to modern breeds…
- Why bulls and cereals go together.
- Finding out which old wheats go together with good bread.
- How in situ and ex situ conservation can come together for olives in Catalonia.
- 60 maize landraces come together in a cool display.
- Coming together for African yam bean, starting on 7 July.
- How national genebanks and community seed banks can come together.