A BACTERIUM discovered in the roots of Scandinavian crowberry bushes can
prevent fungi ruining crops of oats, barley and wheat, according to research
unveiled last month in Brighton at the annual meeting of the British Crop
Protection Council.
Sprayed onto seeds, the bacterium combats many fungal diseases of barley and
oats including the two worst maladies, leaf stripe and net blotch, which can cut
yields by up to 20 per cent.
The bacterial treatment took eight years to develop at the Swedish University
of Agricultural Sciences in Uppsala. It has been approved in Norway, Sweden and
Finland, and was used commercially for the first time this year to treat 60 000
hectares of barley in Sweden. Approval for use throughout the European
Union is expected next year. 鈥淚t鈥檚 the first biological treatment for seeds,鈥�
says Berndt Gerhardson, head of the team which developed the treatment.
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Live spores of the bacterium Pseudomonas chlororaphis are grown in a
vat, mixed with edible rapeseed oil, and sprayed onto the seeds. 鈥淭he bacteria
are dormant until you plant the seeds,鈥� says Gerhardson. 鈥淥nce in the soil, the
bacteria proliferate as the seeds germinate.鈥� The bacteria perform as well as
chemical fungicides, Gerhardson reports. 鈥淭here鈥檚 no difference statistically.鈥�
Typically, between 98 and 100 per cent of the crops remain healthy.
But unlike many chemical fungicides, the bacterial spray and the seeds
treated with it are harmless. 鈥淵ou can handle seeds treated with the spray, and
even feed it to animals,鈥� says Gerhardson, who has since identified the bacteria
throughout Europe. 鈥淲hat we鈥檙e using is already there,鈥� Gerhardson says. The
spray has even been approved for use by Sweden鈥檚 organic farmers, he says.
Meanwhile, Jean-Claude Yvin and his colleagues at the marine biotechnology
company Laboratoires Goemar in St Malo, France, have discovered that a
polysaccharide called b-1,3-glucan, which can be extracted from brown kelp,
promises to be effective against a wide range of fungi. Tests by Biotransfer, a
company based in Paris, demonstrated that seedlings of wheat, rice, barley and
grapes treated with the polysaccharide were resistant to a wide range of fungal
diseases.
The glucan does not actually attack the fungal pests, according to tests by
Bernard Fritig and his colleagues at the French National Institute for Plant
Molecular Biology in Strasbourg. Instead it primes the natural defences of
tobacco, tomato and wheat cells to fight off the fungi. Fritig detected several
substances on treated plants that are known to combat fungi, including hydrogen
peroxide and protective proteins.
This year the glucan made its debut in outdoor trials on wheat fields in the
Loire valley. A week after being treated with the glucan spray, researchers
deliberately infected the seedlings with Septoria tritici, the fungus
that causes speckled leaf blotch. After 45 days, only 10 per cent of the leaf
area had been attacked by the fungus. A control crop protected with a commercial
fungicide fared no better. 鈥淭he results were good, and comparable with those of
fungicides,鈥� says Yvin.