Cultivation Principles – Common poppy
Control of Common poppy
The majority of freshly shed seeds are unlikely to germinate and are not greatly predated, so there is no particular benefit from leaving stubbles uncultivated. Shallowly burying poppy seed helps to break dormancy and germination is stimulated by shallow cultivation. Emerged poppy seedlings should be sprayed off with glyphosate.
Repeating shallow cultivations after each weed flush in the autumn followed by a further harrowing after emergence in spring is a useful technique to deplete numbers of both fresh and older (buried) seeds.
Deep cultivation (ploughing) may encourage seeds to become more dormant but will bury seeds that have accumulated in the upper layer. Only plough one year in four by which time 75% of the initial seeds are likely to have died.
Conventional, Strip Tillage and Direct Drilling are all appropriate when considering this weed. Note detailed comments on establishment.
Ensure even spread of residues across field and a good chop of straw to maximise herbicide efficacy and avoid unnecessary cultivations. Straw chopper knives need changing/reversing regularly – often 3 or more times a season.
Where appropriate (e.g. when direct drilling with appropriate drill into high residue levels) leave a longer stubble height. Stubble mulching of high stubbles can be used where straw needs time to become brittle after harvest.
Residue spreading and shallow stale seedbed cultivation by raking (multiple passes followed by glyphosate as needed) combined with surface rolling (for effective herbicide action, weed germination & slug management) or shallow discing/rolling is effective to manage residues, control slugs, and create the best conditions to stimulate weeds outside the crop. Depth to be only just greater than drilling depth of following crop, ideally <3/5cm. Consolidate after tillage to maintain moisture in the stale seedbed. Surface consolidation is essential after shallow tillage, and through to depth pressing plus surface consolidation is needed following deeper tillage.
Ploughing is the alternative to shallow surface disturbance by fully inverting and burying the surface seed bank to >20cm. This should be done one year in 5 or more. Effective burial by
(i) Suitably narrow furrow width (30/35cm on heavier soils)
(ii) Sensible forward speed
(iii) Appropriately set skimmers
(iv) Post plough pressing to close the surface
(v) Pre-cultivation very shallow if needed so soil/straw contact of the buried residues allows efficient breakdown and good rates of water movement through the profile.
Maintain seed bank horizons by controlled surface disturbance of all operations. Mixing weed seeds to variable depths reduces efficacy of residual herbicides and prolongs the germination period (Aug/Nov & Mar/May) for this weed.
Loosening as needed by low rake angle winged tines with adequate lift height for conditions and depth worked. This controlled vertical fissuring also minimises disrupting the weed seed bank horizons. Aim to establish a following crop ASAP after loosening (cover crop if spring drilling next main crop) to stabilise the resulting structure created.
NOTE: Effective loosening is vital where structure is likely to reduce or inhibit moisture infiltration levels. Consider headlands and the main field areas separately where loosening is needed as in many cases loosening depths are different, or not required across the whole field.
AT ALL COSTS avoid: (i) deep non- inversion mixing; (ii) re-inversion before 5 or more years; (iii) lower depths of disturbance when cultivating than during follow-on spring drilling, (iv) failure to consolidate after soil disturbance as this will lose moisture and adversely affect germination potential of the weed seeds.