A number of the world’s most nutritionally and economically important crops are currently under siege by fungi, bacteria, and pests. Various species of Puccinia are attacking wheat; Fusarium oxysporum has it out for bananas; coffee is succumbing to Hemileia vastatrix and potatoes to Phytophthora infestans, and there are many others. Plant diseases limit food supplies, and they also cause economic distress by depressing export production and eliminating agricultural jobs.
An exhibit at the Harvard Museum of Natural History revolves around the theme of our food supply’s vulnerability to plant disease, using an unconventional conduit: early 20th-century glass models of rotting fruit.
Known as Harvard’s “Glass Flowers,” the Ware Collection of Blaschka Glass Models of Plants comprises over 4,300 sculptures of plants and plant parts fashioned entirely in glass by the Dresden, Germany-based father-and-son artisans Leopold and Rudolf Blaschka between 1887 and 1936.
In addition to the selection of works on permanent display, the “Fruits in Decay” exhibit features the collection’s exemplary models of diseased, rotting, and blighted fruiting plants. Strawberries covered in snowy Botrytis fuzz, exquisitely detailed leaves shriveled by Taphrina fungus, and mummified pears all glow under dim amber light—as much art as science.
Harbingers of affliction
As fanciful as a glass sculpture of a withering peach may seem, the value of the plants has never been principally aesthetic or sentimental. Harvard originally commissioned the models as teaching tools, better than botanical illustrations or pressed specimens at demonstrating plants’ three-dimensional structure and color. The rotting fruit series was intended specifically to educate the public about the menace of plant disease.
“Ames was highly concerned about this economic botany aspect of how people and plants are interacting,” explains Donald Pfister, Harvard’s Asa Grey professor of systematic botany, referencing early 20th-century Harvard botanist Oakes Ames. He commissioned the diseased fruit models created by Rudolf, the younger Blaschka, toward the end of his life, from 1924 to 1932. “And so he thought about these as a way to look at what we now call food security—or insecurity.”
Though the models were made nearly a hundred years ago, the theme is as salient as ever. Most of the illnesses depicted on Rudolf Blaschka’s plant models still afflict those crops. The New York Times reported earlier this month on the fast-expanding incidence of fire blight—now often resistant to antibiotics—on American apple orchards, including the razing of the entire heirloom collection at a botanical garden in Massachusetts.
In certain ways, global agriculture is more vulnerable than it has ever been to pathogenic threats, largely due to the widespread practice of monoculture, the cultivation of one crop over large production areas, limiting diversity for the sake of efficiency. Less genetic diversity means that crops have less resistance to disease.
According to a recent UN report, the practice is becoming more common, and is accompanied by other unsustainable aspects of food production. “In many parts of the world, biodiverse agricultural landscapes… are being replaced by large areas of monoculture, farmed using large quantities of pesticides, mineral fertilizers and fossil fuels,” the report says.
In a particularly egregious example of monoculture, nearly all bananas grown for export are genetically identical clones, and now the fungal malady called Panama disease Tropical Race 4 is wreaking havoc on banana farms around the world, disrupting a vital source of both food and employment. Harvard’s collection features glass models of banana plant parts, likely of a banana variety called Gros Michel. Since the models’ creation, that variety became commercially extinct, wiped out by an earlier strain of Panama disease.
Investment and intervention
Without significant investment and intervention, food security threats from pathogens will almost certainly become more common. Besides the need to feed an expanding population, climate change promises to complicate matters.
“Climate change will make many plant diseases more rampant because warming temperatures disable a crucial plant defense system against plant diseases,” says Sheng Yang He, a professor at Michigan State University and researcher at the MSU-Department of Energy Plant Research Laboratory.
Fungi, for example, often thrive in warmer environments, and as the world warms, the host ranges of damaging fungi will inevitably expand. That’s not to mention the agricultural repercussions of droughts, extreme weather conditions, and other predicted consequences of climate change.
“All crops, and therefore the human population, are at risk if we do not drastically increase efforts to figure out how to make crop plants more resilient to climate change,” said He.
In a paper he co-authored on the topic, He estimated that major crop loss from plant disease is already at a staggering 20 to 40 percent.
Indeed, Rudolf Blaschka’s glass models of decaying fruits are beautiful harbingers of affliction. But despite its gravity, the threat of plant disease is seriously underrecognized. “I think there’s a lot to be done about convincing people,” Pfister says.
During the Blaschkas’ time, the public may have made the connection between the beautiful multichromatic rings on a glass pear and the threat of famine more readily.
“When these were made, botanical literacy was quite high,” Pfister says. “People could come in and look at and understand families and so forth of the plants. That’s not the case these days.”
What changed? “It’s not sexy,” he says.