a day
Seed tests in
a day
NEW seed testing technology could give growers the chance to use more untreated cereal seed in future, safe in the knowledge that it is not at risk from seed-borne diseases.
Slow disease testing means routine use of seed treatment fungicides is currently widespread, mainly because the seed trade cannot wait for leaf stripe test results.
"Typically more than 5000 winter barley seed lots need processing in the two months after harvest – so even seven days is too long to wait for a test result," explains NIABs Dr Jane Thomas.
But a new MAFF-backed genetic fingerprinting test can now confirm the presence or absence of the damaging barley disease in just a day. A similar test for seed-borne net blotch should be in place for harvest 2000, Dr Thomas adds.
Seed suppliers would then need just three days for a loose smut result, making it easier to delay seed treatment until a need is established, suggests Dr Thomas. "And we hope that we will be able to reduce the three days needed for loose smut testing."
The scope for significant savings is clear, she says. Results from the Official Seed Testing Station at NIAB show leaf stripe has never been found in more than 15% of samples over the past five years and in none for the past two.
"There is a lot of evidence that the disease really is quite rare. We now have routine testing and a clear opportunity to treat seed according to need," Dr Thomas maintains.
Such work is welcome in Denmark. Legislators there are seeking cuts in pesticide use beyond the 50% demanded in 1997, this time including seed treatments.
One option would be to limit seed treatment to early generation seed and only sow untreated C2 seed which was below threshold infections and discard the rest, says Bent Nielsen of the Danish Institute of Agricultural Science.
Although that would only be practical in spring cereals at present, it could cut seed treatment use by 30-70%, he notes.
A more drastic option which would cut use by 80% would be to do the same for both C1 and C2 seed.
However, both approaches would require faster and more accurate testing than now, with tighter thresholds and a larger seed area if the second option is adopted, he notes.
SEED TREATMENT
* Too much unnecessary use.
* Slow test results to blame.
* Faster tests ease pressure.
* Big savings possible.
* Denmark keen to use.
BIOLOGICAL SEED TREATMENT
Another way of cutting pesticide use could be to make better use of biological treatments. Scandinavian growers are already using an oil based live bacterial preparation to protect winter barley seed from a range of diseases. Discovered in 1889, bacterial strain MA342, marketed as Cedomon, was used on 60,000ha in Sweden, 10,000ha in Finland and in Norway last year. When applied correctly it consistently matched guazatine (Panoctine) for 98%+ control of leaf stripe, seed-borne bunt and net blotch in over 100 field trials, explains Prof Berndt Gerhardson of the Uppsala Research Centre in Sweden. "The difficulty is getting the agro-industrial complex to use it properly. The margin for error is much less than with a chemical." MA342 poses no environmental or health hazards, he adds.
Seed testing switch
New approaches to seed testing are endorsed by Harper Adams College researcher Simon Edwards, who evaluated one such test in Novartis-funded seed treatment efficacy trials. Compared with widely used plate tests the PCRapproach gives results in three days not two weeks, indicates the concentration of spores on seed and distinguishes between the four seedling blight pathogens, he says. However, DNA sequencing information is not yet available for all seed-borne diseases. "In the long-term it will allow the right choice and sensible use of treatment for each batch of seed. If no seed-borne disease is detected then treatment will be unnecessary."
SEEDTREATMENT
• Too much unnecessary use.
• Slow test results to blame.
• Faster tests ease pressure.
• Big savings possible.
• Denmark keen to use.
Swedish bio-control
Another way of cutting pesticide use could be to make better use of biological treatments. Scandinavian growers are already using an oil based live bacterial preparation to protect winter barley seed from a range of diseases. Discovered in 1889, bacterial strain MA342, marketed as Cedomon, was used on 60,000ha in Sweden, 10,000ha in Finland and in Norway last year. When applied correctly it consistently matched guazatine (Panoctine) for 98%+ control of leaf stripe, seed-borne bunt and net blotch in over 100 field trials, explains Prof Berndt Gerhardson of the Uppsala Research Centre in Sweden. "The difficulty is getting the agro-industrial complex to use it properly. The margin for error is much less than with a chemical." MA342 poses no environmental or health hazards, he adds.