blackgrass

22 February 2002




Yorks growers bring down

blackgrass

WHEN David Hinchliffe and brother James took on 150ha (372 acres) of heavy clay loam near Thorne, South Yorks, they knew they faced a considerable grassweed challenge.

Severe blackgrass was the biggest concern – room-sized patches of the weed smothered the crop and knocked at least 2.5t/ha off yields, recalls David, winner of the 2001 farmers weekly/PBIC Wheat Grower Challenge.

Now liberal use of stale seed-beds and carefully timed autumn sprays have been so effective that over-spraying is unlikely to be needed this spring.

"It is a relief, because spring spraying is a costly fire brigade activity and risks the build up of resistance to fop and dim chemistry, which we can use more usefully elsewhere in the rotation," says Mr Hinchliffe.

The powerful weapon he is keen to protect for use later in the rotation is Aramo (tepraloxydim). Spring rape needed some control and received Laser (cycloxydim) last year, which was adequate. But it was nowhere near as effective as the Aramo in winter rape, says Mr Hinchliffe.

"That has done a marvellous job, giving us nearly 100% control. It is dim technology, but seems to be a dim spray with a difference. Competitor products being tested on the farm have not done nearly as well. Some plots might as well have been sprayed with water."

The clean-up started during the downpours of autumn 2000, which gave a good opportunity for deploying stale seed-beds, says Mr Hinchliffe, who also manages 320ha (800 acre) Top House Farm at Rawcliffe Bridge with his brother.

"We had 403mm of rain from September to December, instead of last years more normal 196mm, so we could not drill any wheat on the new land. One field of winter barley and one of winter rape went in, plus some late spring peas and spring rape, but the rest was set-aside.

"We had a tremendous seed return there at harvest, so used wet weather set-aside to get an extended chit and apply Roundup three times between April and July. Even the spring break land got two burn-offs, which left the land so clean that the peas didnt need any herbicide."

Stale seed-beds were used again last autumn and wheat drilling was delayed until Sept 16 to allow a full chit and effective burn off.

"It was a dilemma, especially after the problems the previous autumn. But we felt we had to gamble with the worst fields, particularly with barley where post-em options are not so good," says Mr Hinchliffe.

Ploughing is shunned. "The land is well structured – we had cracks down to 27in last year and it wasnt even a dry summer." Ploughing also risks a cloddier seed-bed, which can hit residual herbicide activity. "Its a bit of a trade-off, but we can get finer seed-beds with min-til."

Avadex (tri-allate) is used routinely. Crystal was considered, but the farm has its own 20m granule applicator, so the easy application premium was not felt worthwhile. However, anecdotal evidence from neighbours suggests it may have the edge over Avadex in efficacy, so some may be tried next autumn, particularly in barley. Aventiss new 04H also looks useful, Mr Hinchliffe adds.

Post-em treatment in wheat was full rate Hawk (clodinafop-propargyl + trifluralin) plus Lexus (flupyrsulfuron-methyl) with a methylated seed oil adjuvant. "We walked it in mid-January and would say control is 98-99%."

Correct timing was not easy. "It was a hot mix and the mild autumn brought a scorch risk, so we left it as late as we could. Some blackgrass was at first tiller. But we chose the right day and conditions and it has done very well."

Two years of testing seed for resistance has shown some enhanced metabolism resistance, but thankfully no target site resistance.

In barley, 3.3 litres/ha Stomp (pendimethalin) plus 4.2 litres/ha ipu left fields 100% clean. "We couldnt find a single blackgrass plant in mid-January," says Mr Hinchliffe, who like his brother is BASIS and FACTS qualified and does all his own field walking.

With seed return now under control, the challenge is to wind down the soil seed bank. "We are quietly confident. We havent cracked the problem, but it is manageable," says Mr Hinchliffe.

"It has had the kitchen sink thrown at it, but the land has good potential and should be able to grow 4t/acre wheat. The plan was to break the blackgrass in five years. So far it seems to be working." &#42

BEATING BLACKGRASS

&#8226 Severe problem – 2.5t/ha penalty.

&#8226 Integrated year-round control.

&#8226 Stale seed-beds vital.

&#8226 Aramo ideal in winter rape.

&#8226 Five-year plan on schedule.

BEATINGBLACKGRASS

&#8226 Severe problem – 2.5t/ha yield penalty.

&#8226 Integrated year-round control.

&#8226 Stale seed-beds vital.

&#8226 Aramo ideal in winter rape.

&#8226 Five-year plan on schedule.


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