Sow what for next season?

Both winter wheat and spring barley are very variable, with second wheats particularly poor in some situations (down as low as 5 t/ha or 2t/acre). Initial harvest results have not been too bad, but overall yield estimates have tended to fall as harvest has progressed and later crops have been taken. In more recently harvested crops, Hagbergs have taken a dive, and sprouting has become easier to find.

Most oilseed rape and winter barley stubbles have greened up well and could be sprayed-off with Roundup prior to cultivation.

Hopefully we will not have a repeat of last autumn's weather this year. However, there is a danger of over-reacting to last season's experiences and drilling too early and at too high a seed rate.

Below are recommendations for this autumn for optimum plant stands - the seedrates to achieve them will need to be adjusted to conditions and likely losses from pests. Local knowledge of soils, pests, the effects of weather on tilths and the weather that follows planting enable decisions to be taken over what is likely to be the optimum seed rate. It also assumes that subsequent canopy management will enable plants to tiller properly and maintain the required tiller number through to harvest.

In our experience, there is little to be gained from August drilling and many potential disadvantages. This sowing date is included for those with very big areas to get through, where the problems of very early sowing can be outweighed by bringing the sowing window forward and reducing the area of late sowing at the other end.

Wheat target plant population (plants/m2) - As a guide, August 100, September 150, October 250 and November 350.

Varieties and drilling start dates - Late August, Buchan, Claire, Consort, Genghis; September 8, Equinox, Madrigal, Malacca; September 16, Hereward, Napier, Shamrock, Tanker; September 26, Savannah, Soissons; October 10, Charger.

Most of these varieties can be drilled until January or February. Let's hope we will not need to do so this year.

First wheat after a break crop can be drilled from early September (or late August if you must) providing the break crop did not have a significant couch infestation or volunteer cereals which both host take-all. Wheat following set-aside with natural regeneration cereals as the green cover should not normally be drilled before mid-September. Second wheat ideally should be drilled from mid-October onwards, unless you choose to use Jockey or Latitude seed treatments to allow you to drill from late September.

Ensure you create stale seed beds and spray off with Roundup before drilling in all circumstances where grass weeds are present. Early drilling in high black-grass populations is to be avoided.

Winter barley target plant population (plants/m2) - Aim for 250 plants established and drill from mid-September to mid-October.

Seed rate calculation: Seed rate Kg/ha = Target plant population (m2) x 1000 grain weight (g) x 100

% Establishment x % Germination

Establishment percentage will depend on conditions at time of drilling. As a guide, Good is 90pc, Average is 75pc, Poor is 60pc. Establishment is often 10pc better where minimal cultivations have been used instead of ploughing, particularly on clay soils. Experience has shown on chalk soils with high surface stone content that establishment can be 20pc less than expected, take account of this when calculating seed rates.

All purchased seed should have a germination percentage of at least 85pc but normally it is over 90pc. Some crops have sprouted in the ear this year, which could affect the germination of home-saved seed. If you have treated seed left over from last autumn it would be wise to get it tested for germination before drilling.

It is important to get populations right, thick crops suffer from disease and are prone to lodging. Seed is expensive use it wisely.

This column is supplied by Derek Knight (01430) 861988 a consultant for ADAS in East and North Yorkshire.

Updated: 09:17 Thursday, September 06, 2001