Delayed drilling


Delayed Drilling

Two dates were employed, 21 September and 23 October with black-grass heads being assessed in June. The results showed a significant decrease in the mean black-grass head counts when drilling was delayed for by one month.

Variety Seed rate (numbers m2) Plant Count m2 (21 September Drill) Yield (t/ha) Plant Count m2 (23 October Drill) Yield (t/ha) Yield Difference (late v early drilling)
Gallant 250 439 7.22 0 11.93 4.71
Solstice 250 527 6.72 12 10.57 3.85
Duxford 250 195 9.54 0 10.22 0.68
Warrior 250 212 9.68 17 10.94 1.26

Table reproduced from Ward et al., (2012) – A demonstration on the effects of winter wheat variety choice, seed rate and sowing date upon control of black-grass (Alopecurus myosuroides).

Delaying drilling from September to October can have a significant effect on the number of black-grass plants, and consequently the number of seeds ready for germination in the subsequent autumn . The benefit from delayed drilling is most pronounced when soils are moist, stimulating relatively early germination of black-grass enabling one or more sprays of a non-selective residual herbicide such as glyphosate.

Taking a simplistic point of view – delayed drilling can reduce yield. However, the extent to which yield is reduced depends on a variety of factors including (but not limited to): black-grass pressure/competition, crop variety and speed of initial establishment. It is due to these combinations of factors that, if there is less black-grass pressure on the crop during establishment (which hopefully should be achieved through delayed drilling) then yield potential may not be reduced and there could even be an increase!

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