4 September 1998

Early drill may suit right winter wheat varieties

By Andrew Blake

MANY winter wheat growers on thin drought prone land could usefully drill earlier, provided they choose suitable varieties and appropriate seed rates.

Three years of experiments on Sacrewell Farms shallow limestone brash near Peterborough, Cambs, show that early sowing, already widely adopted on Norfolk sands, is equally applicable elsewhere, provided sensible precautions are taken, says independent agronomist John Ward.

"Here we have only 10-12in of soil over rock, and crops often suffer in spring as soon as there is early drought," says Mr Ward, who runs the Scott Abbott Arable Crops Station trials near Peterborough, Cambs. "I believe that if we can drill earlier to get a better root structure and push the growth stages on a bit we really could be on to a winner.

"There are dangers. Take-all can be encouraged especially in second and third wheats, though at Sacrewell this year I believe most of the white heads were caused by fusarium, not take-all.

"By sowing earlier you lay yourself open to BYDV, so you are probably looking at two insecticide sprays when you drill in early September. You also need to keep an eye open for autumn yellow rust and mildew. Baytan seed dressing is probably a sensible precaution on varieties susceptible to yellow rust. And you may also have to consider applying a very low dose of fungicide in the autumn or early spring to tidy up mildew or brown rust.

"In our experience this year there was much more brown rust on first wheats drilled on Sept 1 than on those sown just a week later. One or two farmers round here who already drill in August went with an early spring spray and probably benefited from it."

Key aim of the trials, which are adding information to the recently completed LINK Integrated Farming Systems experiments, is to help wheat perform better on light land. But sowing earlier also eases workloads on farms like Sacrewell which have potatoes and sugar beet to lift, he points out.

"The main message is that you must take seed rate into account. Having too many plants is clearly detrimental. But reducing rates also saves seed costs."

Yield differences in this seasons replicated small plot trials of second crop Charger and Riband mirror those of the two previous years. Both varieties were sown at three rates on four different dates. "In most cases we achieved our target spring populations of 95, 125 and 155 plants a sq m which reflected seed rates of 52, 69 and 85kg/ha for Charger and 57, 75, and 93kg/ha for Riband."

"Apart from the unexplained hiccup with Riband sown at the highest rate on Oct 6, the results show a clear advantage from drilling it early. But it is a different story with Charger, which I admit we were taking a risk with drilling so soon."

The first sown Charger, chosen particularly for its low fungicide need under the IFS experiment, lodged despite the robust Moddus (trinexapac-ethyl) growth regulator programme also applied to the Riband.

"For both varieties our findings show the advantage of very low seed rates for the earliest drilling. By the second date, however, there is a need to increase the rate, though at Sacrewell it is still kept much lower than normal."

This autumn Mr Ward intends to shift Chargers trial dates back so drilling does not start until the third week in September but continues into late November or December. "We need to know more about how it performs for late sowing after sugar beet.

"What we need to avoid with early sowing are varieties which develop very rapidly in the autumn. In other joint trials with Morley Research Centre we have found Charger and Buster are clearly unsuitable. But there have been some very good results with Riband and Consort." &#42

EARLY WHEAT SOWING

&#8226 Boosts root structure.

&#8226 Counters drought.

&#8226 Raises disease risk.

&#8226 May increase lodging.

&#8226 Variety choice vital.

&#8226 Seed rate critical.

Table 1: 1998 Charger yields in Scott Abbott trials (t/ha)

Sowing rate (kg/ha)

52 69 85

Drilling date

Sept 9 7.9 7.1 6.9 (av 7.3)

Sept 22 7.9 7.9 8.9 (av 8.2)

Oct 6 8.4 8.5 9.2 (av 8.7)

Oct 28 7.5 8.2 8.3 (av 8.0)

(av 7.9) (av 7.9) (av 8.3)

Table 2: 1998 Riband yields in Scott Abbott trials (t/ha)

Sowing rate (kg/ha)

57 75 93

Drilling date

Sept 9 10.1 9.7 9.5 (av 9.8)

Sept 22 8.3 8.4 8.5 (av 8.4)

Oct 6 8.7 8.7 10.1 (av 9.2)

Oct 28 8.5 8.9 8.7 (av 8.7)

(av 8.9) (av 8.9) (av 9.2)

Sowing rate (kg/ha)

57 75 93

Drilling date

Sept 9 10.1 9.7 9.5 (av 9.8)

Sept 22 8.3 8.4 8.5 (av 8.4)

Oct 6 8.7 8.7 10.1 (av 9.2)

Oct 28 8.5 8.9 8.7 (av 8.7)

(av 8.9) (av 8.9) (av 9.2)