(Phacelia tanacetifolia)
Family: Boraginaceae
General information
The phacelia is distributed mainly in western North America; individual species occur in Asia, Africa and Hawaii. In recent times, the plant has served as a green manure catch crop, but also as an ornamental plant, as forage, and honey bee forage.
Since phacelia is not related to any of the economically important field crops in this country, it is not a carrier of pests - diseases and enemies and is a wonderful component for any crop rotation.
Suitability for green manuring
The phacelia is characterised by rapid initial development, very high coverage and shading of the soil surface, thus excellent weed suppression; it has very good drought tolerance, a strong root with a moderate proportion of fine roots mainly in the topsoil (up to about 20 cm). As the plants frost fully when in advanced development, the phacelia is very suitable as a catch crop after which direct sowing can also be practised. Plant residues in spring are very easy to shred. However, immature plants in the rosette stage are more cold-hardy and can overwinter successfully, so sowing must be timed so that the plants reach at least 30-40 cm in height.
Botany
The phacelia is an annual plant. All vegetative parts are covered with hairs, the leaves are soft and deeply cut. The flower is a class-like raceme, whorled like a snail. The pale awned flowers have a characteristic fragrance that strongly attracts bees.
Soil requirements
Well aerated light to medium soils without a tendency to heaving are suitable. The phacelia is heat-loving and likes soils that let heat through. Overly rich soils lead to excessive growth and often to early seed set.
Fertilization
The direction of use of the phacelia should be taken into account when determining the nutrient requirement. If it is to be used as an catch crop, then it is neutral - undemanding. The nutrients that the phacelia will take up are left in place with the crop and residues. Even the nitrogen content of the site can be increased - this is because much less nitrogen is leached into the cover cropped soil than on bare fallow. If the soil is at least of medium stock and the pre-intercrop has not severely depleted the soil by nutrient removal, then there is no need to apply fertiliser to the phacelia.
The following nutrient requirements can be taken into account when sowing phacelia as a staple crop on soils with medium nutrient reserves:
Growing
As a stand-alone seed crop, phacelia can be sown from early April. Here are some numbers for sowing:
| Catch Crop | Main Crop | |
| Purpose | Green manure | For seeds |
| Seed germination in m2 | 300-500 | 300-500 |
| Absolute mass in g | 1.6-3 | 1.6-3 |
| Seed purity in kg/ha | 8-12 | 8-12 |
| Row spacing in cm | 10-15 | 10-15 |
| Depth in cm | 1-2 | 1-2 |
| Sowing time | 15.07-31.08 | 25.03-20.04 |
Diseases and enemies
No economically important fungal and insect pests are known so far.
Weeds
There are no registered herbicides in Facelia, so it is advisable to choose clean fields when producing seed. Particular care should be taken to ensure that there are no loblolly and dock weeds as the seeds cannot be separated. Mechanical control is difficult due to shallow sowing and plant vulnerability.
Harvesting and yields
Phacelia matures unevenly. When harvesting seed, it is important to immediately give it a rough cleaning to remove wet plant impurities - these can adversely affect germination. Harvesting can start when the first ripe seeds start to fall - and then there are still green unripe seeds. Desiccation makes harvesting much easier. Yields of phacelia seeds vary between 200 and 600 kg/ha (20-60 kg/dcaa).
This information is based on the current situation at the time of writing. It is not guaranteed to be fully comprehensive and up-to-date at future points in time. In any case, each technology must be adapted to the place of cultivation and the current situation. Also keep up to date with current registrations, for example for fertilisers and crop protection products, and with environmental regulations.
Publisher: Written by:
NÖ Landes-Landwirtschaftskammer Dir.Dipl.-Ing. Ferdinand Lembacher
Wiener Str. 64, 3100 St. Pölten Dipl.-Ing. Dr. Josef Wasner
October 2009