Black-grass seeds have a low dormancy this autumn which will give growers the opportunity to decrease numbers in the crop by allowing maximum germination and spraying off prior to drilling.

"This year looks like providing a good opportunity to reduce numbers before drilling, an essential part of any strategy and especially important to reduce implications of resistance," said Vicky Foster, HGCA Research Manager.

The final results from HGCA-funded research show that dormancy in black-grass seed samples is low this autumn. Seeds for the project were collected by ADAS, AICC and Rothamsted Research.

"Results were similar to 2001, 2003 and 2005, all after warm summers, highlighting temperature as the leading factor affecting seed dormancy," said Sarah Cook, ADAS and project leader. "Despite an average low dormancy, a few samples did show higher levels of dormancy indicating that local conditions are still important. However, we have not identified any consistent regional patterns. "

This year, like last year, is typified by non-dormant seeds which are likely to germinate readily with adequate seedbed moisture. The prediction is that germination should be rapid.

"This year some black-grass has already begun to germinate prior to harvest and with an unsettled weather forecast predicted for the next two weeks more are predicted to emerge," said Sarah Cook. "This gives growers the opportunity to reduce numbers before drilling. Keeping the black-grass seed in the top 5cm of the soil and retaining moisture to encourage germination makes shallow cultivations a suitable option for this season."

Most black-grass seeds are shed prior to harvest of winter cereal crops and most seeds have a degree of dormancy. However given favourable conditions many seeds can germinate in the autumn from August to November. Seedlings emerging prior to drilling can be destroyed easily by cultivations or use of a non-selective herbicide.

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