Common yarrow, milfoil
Achillea millefolium s.l. (Schröter, 1888)
BOTANY
Perennial, with a rootstock and rhizomes.
Stems 30-100 cm high, quite robust, erect, long hairs scattered to dense, branched towards the top.
Foliage leaves scattered and pilose, becoming glabrous later; lanceolate in contour, basal ones tripinnately incised, 20-40 mm wide, intermediate and upper ones auriculate, bito tripinnately incised, 10-20 mm wide.
Leaflets remote, segments of last order linear.
Inflorescence an open, often compound umbel, 4-10 cm in diameter.
Calyx 4-5 mm long. Ray flowers white, pink or red, 2-2.5 mm long.
Achene 1.4-2.5 mm long.
Site-specific grasses and herbs - Seed production and use for restoration of mountain envi-5
SUITABILITY FOR RESTORATION
Euro-Siberian species with various ecotypes, very common; often found on soils that are nutrient-deficient to moderately nutrient-rich, on fields, along paths, even in semi-dry grasslands; on loam that is moist to moderately dry, medium-deep to deep, sandy, stony or pure.
Sensitive to long-lasting moisture or compactness of the topsoil as well as to deficient soil aeration.
Extremely common in the Alps.
All-purpose grass for restoration in lower altitudes up to the lower alpine region.
Good tolerance of nutrients and cutting, resistance to trampling, not likely to be grazed by livestock.
SEEDS
Achene 1.4-2.5 mm long, 0.8 mm wide, 0.3 mm thick; flat, thin like paper, oblongcuneate, cross-truncate at the apex. Hilum at the acute margin. Surface slightly vaulted, with fine longitudinal bands.
Surface silver-grey to light greenish-grey, margin brighter, glossy.
Thousand seed weight: 0.15-0.25 g.
Seeds
REQUIREMENTS
(soil and climate)
There are no special requirements for soil and climate. Common yarrow prefers an intermediate to good supply of nutrients. The pH should range between 5.5 and 7.5. Wet, waterlogged and badly aerated soils should be avoided, as well as soils that are rich in peat and very light, dry soils.
CULTIVATION
Open sowing is possible, if sowing is carried out by the beginning of June at the latest (at mild locations by the middle of June). Crop irrigation is recommended.
Sowing underneath low-density cover crops is also feasible.
Seed rate: 2-3 kg/ha.
Row spacing: 20-25 cm. Depending on the construction of the seeder and the method of weed control there should either be dense populations or sufficient row spacing (for mechanical and/or chemical weed control).
FERTILIZATION
For a satisfactory crop yield an intermediate amount of nutrients is required.
Phosphorus and potassium: on soils with an intermediate phosphorus and potassium content, basic fertilization with manure (15-25 tonnes/ha solid or liquid manure) is sufficient in autumn. For mineral fertilization 40-60 kg/ha P2O5 and 60-100 kg/ha K2O are recommended.
Nitrogen: a sufficient supply of nitrogen in autumn guarantees satisfactory tillering.
The following amount is necessary for seed formation: 50-60 kg/ha of N-total to be added in autumn and early spring.
MAINTENANCE AND WEED CONTROL
The species has intermediate juvenile development and produces little leaf mass. Thus, populations having low competition with weeds are only possible if mechanical weed control takes place (weeding, respectively brushing and hoeing between the rows), optimally combined with chemical weed control. As for the majority of herbs, focused chemical control of weed grasses poses no problems. To date there has been insufficient practical experience regarding the chemical control of dicotyledonous plants. But in summer and autumn of the seeding year and in spring of the harvesting year, it is possible to protect these plants by wiping wick and total herbicides (e.g. Glyphosate), thanks to the differences in growth heights between many weed grasses and common yarrow.
HARVEST AND YIELDS
Resistance to lodging: high.
Shattering tendency: low.
Ripeness: after flowering, the compound umbels change colour from dunnish, when ripe, to dark grey and dark brown. Until ripeness the seeds adhere fairly to the umbel quite well.
In order to check ripeness the inflorescence should be rubbed off on the palm of the hand: if sufficiently ripe, the silver-grey seeds will shed easily.
Ripening period: from the second to the third decade of July.
Red flowering ecotype
Harvesting technique: direct threshing is possible. The seeds are very small but have a good seed flow. During threshing the crop and sieves need to be checked frequently. The settings of the threshing concave should be narrow. Cleaning the seeds poses no particular problems.
Crop yields: yield forecasts are difficult, because of lack of experience concerning the cultivation of common yarrow. Yields range between 80 and 120 kg/ha. With proper experience, yields up to 100-150 kg/ha (and more) can be expected. Optimal maintenance leads to three harvesting years.
