Take-all variety response
DIFFERENCES in the susceptibility of wheat varieties to take-all could be a husbandry factor worth exploiting alongside fungicide seed treatments, which should be on sale for autumn 2000.
Promising differences are showing up in Monsanto trials on a Notts field where grower Geoff Donger normally avoids second wheat.
Least affected is Consort, which gets a take-all score of only 35 where left untreated. The lower the index the more resistant the variety, explains the firms Jonathan Griffin.
Cockpit, the firms first commercial hybrid, scores just over 40. Brigadier, Madrigal, Reaper, Rialto and Spark are close to 60, while Hereward is in the upper 70s and Equinox is on 80. Whether yields will reflect scores remains to be seen.
David Leaper, the firms field development manager, finds the Equinox result unexpected. "It is sold on the strength of its good finishing and resistance to drought." But even with the help of Monsantos anti-take-all seed treatment MON 66500 the short-strawed variety appears to have least potential in the experiments.
At first glance taller varieties seem less affected. Dr Griffin believes that is probably linked to tillering potential. "The higher the tillering the more likely you are to get a bigger root biomass." Other research by ARC suggests varieties with high stem sugars are more resistant to take-all.
lWith take-all widespread and even showing up in winter barleys, Monsanto is encouraging growers to check stubbles after harvest to pinpoint problem fields. *
A combination of seed treatment, correct variety and and proper husbandry should help keep wheat free of take-alls black root symptoms, says David Leaper.