The apples of our eye

Apples have been another recurring obsession on the blog, maybe because they make the conservation problem unusually tangible, and immediate. Pretty much everyone thinks they know what an apple is, but the diversity hidden behind that word is enormous, and not much visible in supermarkets. A lot of it may have disappeared, but you can pretty much guarantee a slew of heritage apple stories in the press come autumn (and so it begins), so I guess people care. Here’s a selection of posts about apples spanning 15 years. There’s a lot more out there in the archive for you to explore.

Let’s start at the beginning, or as close to it as the genetics can get us. In 2016’s The Adam and Eve of apples?, I discussed the wild apple forests of southeastern Kazakhstan, where all of the world’s apple varieties can be traced back to an ancestral population of Malus sieversii — spread, if you believe the more colourful tellings, by bears eating the sweetest fruit and pooping the seeds around the forest. As usual, though, the genetics turned out to be more interesting than the headline. The cultivated apple isn’t a simple straight line from one mother tree; it’s the product of a long history of movement, hybridization and exchange between wild and domesticated populations all along the old trade routes out of Central Asia.

But those forests are in danger. Back in 2009, in Wild fruit relatives threatened in Central Asia, I looked at how the wild relatives of apples and other crops were vanishing along with their habitat. Among them was Malus niedzwetzkyana, the remarkable red-fleshed apple of Kyrgyzstan. These aren’t just obscure wild trees: they represented genetic diversity that has already made its way into cultivated apples, and might still have something to offer breeders. That red-fleshed apple came back a year later in Not the world’s first red apple. A new red-fleshed variety was being breathlessly presented in the press as a novelty — not GM, just 15 years of patient crossing and 20,000 rejected seedlings — but nature had got there first. M. niedzwetzkyana has been doing red flesh for millennia.

The cultivated stock has its own story of loss. In 2009’s Saving an apple a day, I looked at the loss of American apple varieties, and at the people trying to rescue what remained. Thousands of named varieties had once been grown in the United States; only a fraction survived in orchards, collections and the memories of the people who knew what they tasted like. It was a nice illustration of a familiar conservation paradox: you can lose a lot of diversity without even noticing, because the supermarket keeps selling you apples.

However, that same year, a study added a wrinkle to the “thousands lost” narrative. In Lost apples found, Jeremy pushed back a little on the standard version of the story — the one where 6,800 of 7,100 named 19th-century American apple varieties are simply gone. A team from the University of Arizona and USDA had gone looking for ghosts among old apple trees on historic farmsteads in Arizona, Utah and New Mexico. Only 34 of the resulting genotypes matched a known variety. The other 110, spread across 160 trees, matched nothing on record. Some of those are probably unnamed seedlings that never had a name to lose in the first place. But some, surely, are the supposedly lost varieties everyone had given up on. Not extinct, just lurking.

Seven years on, the USDA apple folks came back with another version of the answer. In As American as apples, Gayle Volk summarized her and Adam Henk’s trawl through historic nursery catalogues, which turned up 891 named apple cultivars grown in the US before 1908. They went looking for the 150 that seemed to matter most. The payoff: 90% are still findable today, safely tucked away in genebanks, private collections or specialist nurseries. Only 51 high-priority cultivars remained unaccounted for in any collection. For now.

The lesson isn’t that genetic erosion doesn’t happen. It plainly does, and 30 fruit nurseries vanishing a year is not nothing. No, the lesson is that “extinct” is much harder to prove than “endangered,” and pomologists with their equivalent of a swab kit keep turning out to be more patient, and luckier, than we have any right to hope.

Conserving what’s left, of course, depends on people as much as on collections and gene sequencers. In 2014, I offered up Irish eyes smiling about apple conservation. The post was prompted by Michael Hennerty’s beautiful book on the Irish apple, but the real story was the people who had nurtured the 68 varieties documented in the book over the years. Conservation often depends on a motley collection of people keeping things alive long enough for some fancy institution to discover that they matter. A few years later, Jeremy went into much more detail on Irish apples on his podcast.

Institutions, though, can be just as precarious as the work of any orchard-keeper or amateur gardener. Across the Irish Sea, the story of the UK’s apple collection showed just how fragile even a major national genebank can be. The National Fruit Collection at Brogdale in Kent, with its hundreds of apple varieties, came under threat when its funding was thrown into doubt, prompting a succession of stories about sales, new management and relocations. Oh, and royalty. Anyway, the collection is fine, but the saga was a reminder that conservation is not just about keeping things alive. You have to keep them alive with enough institutional resilience that they can survive the next crisis.

Taken together, these posts highlight a sometimes overlooked aspect of safeguarding agrobiodiversity. Conservation is not just putting varieties safely into collections, nor, on the other hand, is it just protecting wild populations from destruction. Apples show that the two are connected — or should be. These are, in the jargon, complementary conservation strategies. The diversity in a genebank has a history outside it, and the diversity out in the wild and in farms may only have a future in a genebank. We really do need both, it’s not just mom and apple pie rhetoric.

There’s gold in that thar rice story

Carolina Gold is another one of those stories that we kept coming back to, and that I now want to recap as part of our anniversary celebrations.

Before the U.S. Civil War, Carolina Gold was the dominant rice of the South Carolina Lowcountry, grown on vast plantations by enslaved Africans and generating much of Charleston’s wealth. The war, emancipation and a series of hurricanes then shattered that cruel system; commercial plantings dwindled and the last U.S. harvest is usually dated to 1927. But that wasn’t the end of the story, as it turns out.

I first wrote about the variety in 2007, asking where it had actually come from. New genetic evidence from a USDA study complicated the conventional story that it had arrived from Madagascar, pointing instead toward a West African source that fit rather better with the history of the transatlantic slave trade. Check out the string of comments on the post too.

I came back to the story in 2010, linking to an IRRI piece about how cultivation was revived in Carolina thanks to — wait for it — genebank samples. In 2016, there was an update on the revival. And then friend-of-the-blog Mike Jackson picked up the thread in 2017 with an account of “Civil War destruction … genebank redemption”.

He did us all a great service by telling the whole story in detail all in one place: the decline of rice cultivation after the Civil War, Carolina Gold’s near-disappearance, and its rescue when Savannah doctor Richard Schulze discovered seed in the USDA collection. Fourteen pounds supplied to Schulze eventually became 10,000 pounds by 1988. Mike checked Genesys and found 19 accessions carrying the Carolina Gold name, raising the next questions: how different are they, and which one was actually used for the rescue?

Along the way, I actually tasted the stuff! And Jeremy found a film featuring it.

By 2018, Carolina Gold had become the precedent for the comeback of another “lost” rice, this time in Trinidad.

For a blog about agricultural biodiversity, Carolina Gold, with its origin debates, near‑extinction, and then real‑world use of what genebanks kept alive, really is a near‑perfect subject. Can you find others in our archive?

Cassava, revisited, and revisited again

Cassava has been a persistent thread through this blog since the beginning. It first appears as a staple with a dark side: capable of keeping people fed, but also of causing a nasty disease under some conditions. Over time, it resurfaced repeatedly, showing how one crop can illuminate many of the key issues in agrobiodiversity conservation and use. As part of our anniversary celebrations, let’s pull some posts out and see how that might work…

An early post we called Detoxifying cassava looked at the complex ways konzo epidemics in Africa are linked to the consumption of bitter cassava. A later Nibble pointed to a very digestible (sic) introduction to cassava and cyanide. And Manihot esculenta, I presume? widened the lens historically, drawing on Dr Livingstone’s Zambesi Expedition papers to show how he understood cassava’s diversity, its promise and its danger back in the day.

Several posts over the years have looked at how well we now know and conserve the diversity of the crop. Gaps in cassava collection in Africa highlighted sounded an alarm: eastern and southern Africa seemed to be under‑represented in international genebanks. Later, More on cassava germplasm from Brazil and an earlier post compared the geographic distribution of CIAT’s genebank holdings with the that of both accessions and cultivation in Brazil, illustrating how national and international collections overlap — and where they don’t.

A post on safety duplicating germplasm collections explained the mechanics of backing up diversity, using Embrapa’s genebank as a concrete example. It also included a reference to the global cassava conservation strategy, during the development of which I got schooled on the diversity of the crop. And a paper on sources of pest resistance in cassava we included in a Brainfood showed the value of genebank holdings, identifying landraces in CIAT’s global collection with resistance to thrips, mites, and whiteflies.

This particular arc culminates in a summary of two papers on 50 years of cassava conservation at CIAT, which looks at that genebank from both ends: what went in over five decades, and what actually came out in breeding. A recent Nibble notes that cassava’s diversity is spread across multiple genebanks, and why that’s a good thing, up to a point.

Then came the TME 419 saga: Is there more than one TME 419 cassava? unpacked confusion around an IITA genebank accession number; I say TME 419, you say TMe‑419 revisited the same named clone in Nigerian fields years later. Another intricate tale centred around how some modern varieties got their resistance to post-harvest rotting. Spoiler alert: a wild relative was involved.

Genebanks, however, are not the full story. Cassava’s diversity also has to survive in farmers’ fields, where diseases constantly test its resilience. An early post, Ho hum … another deadly disease, placed cassava brown streak virus (CBSV) alongside then emerging threats like Ug99 wheat rust. CBSV was duly much in the news a few years later in 2011, and we were of course all over it, though not always one hundred percent correct in our judgements. That’s what the comments are for.

A Nibble on cassava pests questioned the crop’s “indestructible,” Rambo-like image as new problems appeared in Southeast Asia and elsewhere. An experiment on cassava degeneration, Twitter‑style focused on what to do about the widespread viral infection of cassava planting material across Africa, which badly affects performance. And a Nibbles roundup on cassava bad and good news captured an apparent mismatch between FAO worry and CGIAR optimism back in 2011. Maybe we should do an update on that, now I think about it.

Another theme has been how the crop is promoted, produced, and woven into everyday food systems today. In Cassava on a roll? I traced production ups and downs in Kenya, intrigued by seeing new products in supermarkets on my return to the country. I followed that up with The flour of Kenyan agrobiodiversity marketing, which shows cassava (with finger millet) being used to diversify staple flour, connecting conservation to real products and diets. And a Nibble on Ugandan cassava from a couple of years back highlights local innovation in value chains, if you interpret it charitably. No doubt all part of the African cassava revolution touted by Forbes in a 2023 Nibble.

I hope this roundup of our past encounters with cassava, incomplete as it inevitably is, has given you a little taste of what twenty years of this blog have been about: following stories as they unfold, picking up old threads, occasionally digging really deep, other times not deep enough. Do search for your favourite crop in the archive, and tell us what you come up with.

Nibbles: African food systems, Uganda cassava, Uganda pastoralists, Butternut conservation, Seed transfer zones webinar, Frozen Zoo, India fish genebank

  1. Swapping maize for indigenous crops won’t fix African food systems designed around markets and policies that still favour a narrow range of crops.
  2. Cassava is both a food security fallback and a commercial crop in Uganda, but disease, climate change and declining diversity make its conservation an increasingly urgent form of insurance. But what about the markets and policies?
  3. When livestock and crops fail, Ugandan pastoralists draw on wild plants for food, underlining how much food-system resilience still sits outside the formal agricultural system, with its markets and policies.
  4. The Morton Arboretum is using living collections and genetic research to help the threatened butternut tree cope with changing conditions.
  5. Webinar discusses global approaches to seed provenancing and transfer zones, useful for anyone who wants to move native plants without moving the wrong genes. Butternut very interested.
  6. San Diego Zoo Wildlife Alliance’s Frozen Zoo preserves genetic material of plant and animal species that may disappear, from DNA to cells to organisms. Butternut volunteers.
  7. New Indian facility combines ex situ fish conservation with community aquaculture. Good model for much of the above?

Brainfood: Nutrition edition