Conflict over protection for seedlings

21 August 1998

Conflict over protection for seedlings

By Andrew Blake

ANTI-FUSARIUM seed treatments could prove especially valuable for protecting wheat seedlings this autumn. But fungicide makers disagree about the importance of their role in controlling spring stem browning.

Heavy rain during flowering suggests spore levels on seed could be at least as high as last year, says Bayers Richard Meredith.

Drilling untreated seed heavily infected with fusarium into poor seed-beds in cold dry conditions risks crop failure from seedling blight, he warns. But even where crop stands remain adequate, the disease may express itself as brown foot rot, weakening the stems and increasing the risk of lodging.

Small plot trials at the companys Elm Farm Development Station on naturally infected Riband this season highlighted distinct variation between the effects of treatments on fusarium stem base browning, says Dr Meredith. Although crop stands were very similar, there were clear differences in the health of the plants.

The knock-on effect on output is hard to predict. In Bayers mid-March assessments, where 98% of the stems of untreated plants were brown, Sibutol (bitertanol + fuberidazole) gave 95% control of the symptoms, reports Dr Meredith.

Next best results were from fludioxynil (as in Beret Gold) at 79% and guazatine (Panoctine) on 53%. Carboxin + thiram (Anchor) gave only 25% control.

Andrew Jones, of Uniroyal, manufacturer of Anchor, says trials to link stem base browning in spring to seed treatment have produced no sensible results.

"We put our emphasis on aut-umn establishment and in general Anchor does better in a hard winter when conditions favour fusarium."

Some seed treatments do reduce the amount of stem browning seen in the spring, confirms Morleys Doug Stevens. "But by the first or second node we do not see much effect. The main thing is to ensure reliable establishment." &#42


&#8226 Heavy seed infection expected.

&#8226 Causes seedling blight & foot rot.

&#8226 Seed treatment advised.

&#8226 Stem browning control debatable.

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