21 June 2002

Velcourts top technical tips for grower survival

Making the most of todays

agronomic tools is the key

to survival with wheat

worth about £60/t, says

Velcourts Keith Norman.

But that does not

necessarily mean majoring

on all that is new, as

Andrew Swallow found out

in the Arable Event area of

Cereals 2002

USE pre-emergence sprays and consider some perhaps long forgotten herbicide options to get to grips with grassweed control this autumn, suggests Velcourts Keith Norman.

By doing so growers could find they can both cut costs and overcome rising resistance problems.

One example of over-looked old chemistry is Alpha-terbutryn (terbutryn), which used to be called Prebane, he notes.

"This product has really come back off the shelf. It fits in on ryegrass, annual meadow grass and is very good on resistant blackgrass. But it is not so good on wild oats."

In blackgrass and wild oat work the terburtyn was mixed with trifluralin, but for ryegrass the partner pre-em was chlorotoluron, the old Dicurane. Where that was followed either by an Ingot/Grasp-mix (diflufenican + flurtamone + ipu/trakloxydim), or Ingot alone, control was matched only by pendimethalin/ chlortoluron pre-em followed by Ingot/Grasp post-em.

But in all the work on the light, brash soils there was a play off between weed control and crop effect, says Mr Norman. Crystal (pendimethalin + flufenacet) and pendimethalin/chlortoluron mixes took the highest toll, leaving well below optimum populations of wheat (see panel).

"Avadex is probably the best compromise between crop safety and weed control – there are other options, but beware of the crop effects."

Whatever the choice, the importance of the pre-emergence herbicide must not be forgotten, he says. "No pre-emergence herbicide and you are struggling. It does 90% of the work." &#42

No grassweeds, but not much wheat either – beware the play off between control and crop effect with pre-emergence herbicides, says Velcourt technical director, Keith Norman.

Crystal clear

Velcourts problems with wheat emergence after applications of BASFs pendimethalin plus flufenacet product Crystal were limited to light brash or heavy soil that water-logged, says Mr Norman. "In between, on well-drained but heavier soil types, there was no problem." Disc-drills seem to have exacerbated the phyto-toxic effects, he notes, and work will be done to investigate the possibility of reduced rates. BASF acknowledges there were some problems with emergence last autumn but says growers should still use 4 litres/ha of the product pre-emergence for difficult blackgrass. "The challenge is to get a good, consolidated seed-bed," says herbicides manager Andrew Jones. "If you have lots of pebble sized clods or are direct-drilling and cannot keep a constant depth it is bad news."