DOUBLING OF BROME INCIDENCE PROMPTS SPRING CONTROL ALERT

February 2005 - Serious brome incidence across the country has more than doubled in the past year, according to the latest information from ProCam Agronomy, confirming the company's worst fears at the start of last season.

Analysis of detailed field-by-field performance records from over one million acres of UK cropping in ProCam's unique 4-Cast crop management advisory package reveals a 100% year-on-year increase in the proportion of wheat crops treated with a spring brome herbicide in 2004. And agronomist reports indicate this almost certainly under-estimates the scale of last year's brome problems.

"In total, our recording system shows 14% of wheat crops treated with either Monitor (sulfosulfuron) or Ethos (propoxycarbazone-sodium) last spring," explains ProCam technical agronomist, Nick Myers. This compares with just 7% in 2003.

"At the same time, we know national supply limitations meant not all the 2004 treatments recommended by our agronomists could actually be applied. Feedback from the field tells us that many less serious infestations, in particular, went untreated. So the actual incidence of brome last season was undoubtedly higher than our 4-Cast treatment records show."

While Nick Myers regards this serious increase in brome problems as worrying, he is by no means surprised by it, having seen a steady build-up in levels of the weed in recent years and knowing just how easily populations can mushroom.

Indeed, last February he and his colleagues at ProCam very publicly alerted growers to the likelihood of a major upsurge in brome infestations in 2004. In particular, they pointed to increasing levels of minimum tillage, several years of poor stale seedbed conditions and a weed population shift away from barren brome towards a more mixed spectrum of brome species.

"A decent amount of soil moisture for the first time in three seasons meant good grass weed seed germination ahead of cereal drilling last autumn," points out Nick Myers. "But many people found it too wet to achieve more than a single stale seedbed dose of Roundup. Which, in most cases, will have been insufficient to really knock back the brome seed reservoir.

"More extensive use of Atlantis (mesosulfuron + iodosulfuron) will certainly have helped to reduce the extent to which many autumn weed control strategies have previously helped brome by selectively eliminating competitive weeds like black-grass," he adds. "However, we have found it gives highly variable brome control. And the persistent wet weather has played havoc with many post-em programmes. So we are certainly not out of the woods in this respect either."

Under these circumstances, Nick Myers is adamant that top quality brome control must be a priority for many wheat growers this spring.

He suggests Atlantis or the new spring formulation, Pacifica - if approved in time - will be an obvious early herbicide choice for many, especially where the weather interfered with autumn post-em applications. He warns, though, it is more suitable for mixed grass weed populations.

"For specific brome control, your choice is between Monitor or Ethos," he says. "Go for Monitor if you want to sow oilseed rape next autumn, hit cleavers at the same time, and give yourself the widest application window and flexibility. Alternatively, pick Ethos if you need to tackle mixed brome and black-grass populations, and want to get in early.

"All three herbicides have ALS sequence restrictions so they need to be planned into your spraying programme with care," Nick Myers warns. "And all three really must be integrated into a year-round management plan that focuses a good mix of cultural and chemical control on specific fields and species."