2.4.4.b.d Fermented plant extracts and plant juices

Fermented extracts

A fermented plant extract (purin) is made by soaking parts in water (ideally rainwater) and then allowing it to ferment for a few days. Stirring once or twice a day is recommended. Fermentation can give off a strong smell and produce bubbles on the water's surface. Filtration is the last step in preparing a fermented extract. Unlike juices and macerations, they can be stored for several months in a cool, dark place. A fermented extract can be applied to the leaves or the soil to stimulate microbial life or in combination with the treatment mixture.

For example, an extract made with 100 g/ha of dried ferns appears to be a good regulator of insect populations and is mainly used to control green leafhoppers and mealy bugs. Nettle, horsetail and comfrey can also be used in fermented extracts.

Plant juices

Plant juice can also be used in phytotherapy. The plant is left to ferment on its own without water and the juice obtained is pressed after a few days (usually two days), it can also be filtered afterwards. Only the juice is used on the vines. Ideally, it should be used quickly after extraction and not stored to avoid the juice fermenting and losing its properties. Plant juices can be used as a spray diluted at 10 to 20% on the soil or as a leaf application at 3 to 5%. For example, comfrey and valerian can be used in juice form. Comfrey can be used to stimulate the microbial flora in the soil, while valerian helps to strengthen the vines against frost.

Maceration

Maceration follows the following protocol:

• Finely grind the plants
• Macerate the plants in water for 24 hours
• Filter and use the macerate obtained

As with juices, it is preferable to use the macerate within a few hours of its preparation so that it does not ferment. Rhubarb leaves can be used to combat cryptogamic diseases, for example, and also against parasites. The recommended dose is 5 kg of fresh leaves macerated in 30 L of water.