Cultivation Principles – Fat Hen
Germination is unaffected by autumn cultivations, seeds are attractive to predators but many survive passage through the guts of birds which may even increase germination.
Deep cultivations spread seed throughout the profile. Shallow cultivations keep it on the surface. Given that it germinates late in the season cultivations will do little to reduce numbers.
Leave stubbles undisturbed as this will maximise predation and encourage germination if moisture is available. It is possible that seedlings will start to produce seeds, in warm autumn conditions, 4 weeks after emergence so monitor stubbles carefully and spray off the initial flush with glyphosate.
A shallow cultivation will bring fresh seed to the surface where it will germinate, this can then be sprayed off and the process repeated. Germination will decrease as soil temperatures fall below 5°C.
Where populations are very high plough to place seed below emergence depth (5cm).
Residue Management: 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 delayed 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 ≤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. Timing of tillage is preferably later and checks for seed heading should be regular as this can occur 4 weeks after emergence.
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 for weeds.
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. Poor drainage reduces crop competitiveness. 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.
Plough where severe infestations are present – note ensure policy suits other weed species if present. Skimmers need to be set adequately and depth, furrow width and speed need managing to ensure all weed seeds are buried below 5cm.
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.