2 April 1999

More to variety lodging control than NIAB list

By Andrew Swallow

VARIETAL rooting and stem character differences must be taken into account when planning plant growth regulator sprays, even if varieties have the same NIAB standing power rating, says distributor Brown Butlin.

"Growers have to ask themselves what causes lodging in a particular variety," says Suffolk based Jonathon French, of Brown Butlin subsidiary Key and Pell. "Is it root mass, stem base weakness, or pure height of the plant?"

That information for each variety, drawn from Novartis research, is matched with lodging risk due to field and agronomics to produce a pgr plan.

In high lodging risk fields, Consort, Claire and Madrigal, despite an eight for standing power from NIAB, get an early 0.2 litres/ha dose of Moddus (trinexapac-ethyl) at GS 25-29 to boost crown root development.

In the same situation Riband, also rated eight by NIAB, or weaker standing varieties such as Spark, Soissons or Rialto, are not targeted. "The anchorage on these varieties is quite good so they dont get the early Moddus treatment, even on high risk sites," he says.

Both groups of varieties, whether on a high or moderate risk field, merit a main GS31 pgr. Mr Frenchs recommendation is 0.2 litres/ha of Moddus plus 1 litre/ha of Stronghold (chlormequat + mepiquat chloride). On a low risk, low yield potential crop, that might be replaced with straight chlormequat.

One grower with both high and low risk crops this season is Charles Clarke, of Villa Farm, Otley Suffolk. His Oct 19 drilled Equinox is deemed as low risk by Mr French. "It will get 1.25 litres/ha of straight chlormequat, as soon as it is clear of the Hawk herbicide. I have no lodging concerns as the yield potential is limited, so the greater cost of Moddus is not justified here."

But Mr French reckons the rest of the crops at Villa farm are all high risk due to their yield potential, even though they are tough standing varieties Equinox and Mallacca.

"The most forward Mallacca is rather thick, so it had an early Moddus on Mar 20 to stimulate root length and strength. That should increase the mass of the root ball to hold the crop up," he says.

"As a new milling variety we do not wish to take any risks, so even though it is a second wheat we have made sure it stands," adds Mr Clarke.

The rest of the wheats, despite September drilling, are not over-thick, so the pgr programme will start with the main Moddus/ Stonghold mix at GS31. Mr Clarke hopes that will suffice. "On a similar programme last year the Equinox all stood and did 4.5t/acre."

Cost of the programme should be just £10/ha, plus £8/ha where the early Moddus was used. Last seasons pgr cost on Rialto and Abbot as second wheats was nearly £22/ha.

"They are weaker stemmed varieties and we were growing for milling markets. Both needed late Terpal to keep them standing," notes Mr Clarke. &#42

PGR PLANNING

&#8226 More to lodging than NIAB rating.

&#8226 All wheats worth main GS31 pgr:

+ early Moddus if weak rooting

+ late Terpal for long/weak stems.