Rust is easy to identify. It is a desease with a high destructive power which shows little pumps or little browned spots, with an intense orange surrounded by yellowish mass or even decolored, located at the backside of the leaves and also at the stems. The leaves attacked by this fungus end falling down and the plant keeps weak. In the branches and sprouts may appear red spots as well. The rust may produce a sticking substance that joins to the plant.
Its best conditions for propagation are very low night temperatures with a high humidity rate and lack of aireation, helping spores to be suspended in the air.
To avoid the spread of the spores we must clean carefully our worktools and the rest of the greenhouse, using bleach as antimicrobial agent.
The cure is extremely difficult, the main antifungals help to reduce the propagation rate, but don’t eradicate the plague completely, even though we can control it with sodium bicarbonate if the plague is not set up more than two or three days, something very difficult to evaluate, so it can work as a preventive agent.
It is a method which is based in pH control, making it more basic, hence getting hard the biological conditions for fungus proliferation. You only have to do an irrigation with a spray sodium bicarbonate solution direct to the leaves and steams two times a week, watching carefully any signal of fungus appearance.
Any vegetal matter infected by rust must be removed from the greenhouse , cleaning again all tools used for cropping, otherwise we could spread the plague out.
We may use other antifungal agents formulated with synthetic chemical products which are used to treat Oidium and mildiu plagues, but you will have to take security control actions to apply these treatments.
Mentioned treatmens are also basically preventives, and they have to be performed once or two times a week with an interval among 7-10 days, depending on the climate control you have in the crop, increasing the frequency of treatment the more humidity you have in the room (indoor crop) or in the garden (outdoor crop).
You can choose among a wide range of products, even you can make your own product if you prefer to treat your plants naturally. These products always are based on:
- Macerated or infused garlic in water: Always as preventive antifungal agent.
- Macerated or infused nettle in water: As preventive antifungal agent, or contact antifungal.
- Macerated or infused horsetail in water: Always as preventive agent.
- Cupric sulphate water solution (20% w/w) (Bouillon Bordelais): As preventive antifungal agent, or contact antifungal. It is made of aqueous cupric sulphate solution.
Would you mind to tell us about your experience?
By Noelia Jiménez, Team Piensa En Verde