From Mary Rose, Goolwa, South Australia
Discussing superweeds, you say that hand weeding crops is effective, though costly (22 June, p 12). But it can be effective only for crops grown in narrow rows with wide spaces between rows that people can walk along. Otherwise the weeders will trample the crop.
Some vegetables are grown like this. But here in Australia, commercial crops of cereals, oil seeds, field legumes and grass for hay are grown in a way that leaves no room for hand weeding.
A wheat crop could have 100 plants per square metre and 50 seedlings of the weed annual ryegrass per square metre. Not only would the wheat be trampled by hand weeding, but I suspect it would take more energy to weed than the crop would produce. Are there enough people in the world to weed the extensive areas that the world now farms to feed us all?
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