Then there's the "hot" question of how much we can continue to engage in large-scale monoculture, maybe with genetically modified crops to deal with the manifold problems, an issue that's being played out in Britain today in a dispute over GM wheat. There's good cause to be worried about the risks of this controversial trial, but even more cause to be concerned about an attempt to use a simplistic solution to allow the continuation of our destructive broad-scale farming systems. Nature's a lot smarter and faster than we are, as Mabey illustrates with the example of the rice bred for South-East Asian conditions too "out-smart" weed grasses. "In the rice paddies... there are weed grasses so similar to cultivated rice that farmers are unable to distinguish them before the wild grasses bloom. Plant breeders thought they might be able to trick the weed into showing itself by developing a variety of rice with a purple tinge. Within a matter of years the weed grass had turned purple too. The slight pigment that had enable plant breeders to develop the coloured rice also occurs occasionally in the weed. With each successive harvets it was this strain that ... passed into next year's seed store."
Mabey shows how attitudes to "weeds" reveals so much about human society, most notably perhaps in the nightmare of the American lawn - a toxic monocultural sward, saturated with chemical weedkiller and fertilser (more used per acre than on any crop) that occupies from 50,000 square miles (about the size of Iowa) and on which more than $30billion a year is spent. Mabey explains the origins of suburbia with Frederick Law Olmsted, a landscape architect established one of the first planned communities in 1868, laying out rules saying that each house had to be set 30 feet back from the road, and any exterior divisions were banned. Mabey notes: "The sociologist Paul Robbins has coined a term for the suburban victims of the combined pressures of national tradition, neighbourly prissiness, commercial gardening pressures, and the insistent identity, the integrity, of the lawn itself. He calls them 'Turfgass Subjects'." Mabey notes how this is taken to extremes in Houston, Texas, where by-laws make any weeds "illegal", defined as "'any uncultivated vegetable growth taller than nine inches' - which makes about two-thirds of the entire United States' indigenous flora illegal in a Houston yard".
Mabey also reminds us just how much traditional wisdom and knowledge has been lost, and has had to be rediscovered. Medieval weeding techniques, as reconstructed by the historian Dorothy Hartley made full use of the power of mulching (and showed an economy of effort a modern time-and-motion type might envy).
"He uses two sticks: with the first, hooked stick, he plucks the weeds out from under the corn stalks, and with the second, forked stick pins the weed's head down under the fork. The weeder then steps one pace forward, placing his foot on the head of the weed, and with this forward movement, swings the fooked stick round behind him, lifting th root of the weed high out of the ground before dropping it in line. In this way each pulled-up weed is shaken clear of the soil, and laid with its root over the buried head of the previous weed. Thus, as the weeder goes along the line of the furrow her lays a mulch of decaying weeds alongside the roots of the corn..."
The focus is the UK, but there's plenty of international perspective, and Mabey has a particular interest in Australia, as might anyone interested in the damage done by the introduction of exotic species, astonishingly extreme by world standards. Among the reasons Mabey gives for this are "the isolation of the continent, and a flora that has few genetic or biochemical connections with plants in other parts of the world; the climate, hot and wet by turns; and the thin, nutriient-poor soils, which have had no ancient history of hoofed animals to scuff them up and encourage the evolution of plants resistance to disturbance". He goes to Australian biologist Tim Low (author of Feral Future) to describe the damage - 2,500 rampaging species, costing A$4bn a year, and destroying ecosystems and native plants. The ongoing chaos befits a Greek tragedy - Asian pampas grass was no problem for almost a century after introduction, because all were females, unable to set seed. Then in the 1970s someone introduced a pastel form that was a pollen-bearing hermaphrodite. It took off. Then there's the prickly pear cactus - a control success story, of sorts. By the 1920s this sub-tropical Amercian plant infested some 25 million acres in Queensland and New South Wales. A moth caterpillar, Cactobastus cactorum, was introduced to control it - a success story - sort of, except the species has now spread around the globe and begun to destroy wild native cactus populations.