Care plants, propolis is a well-known natural product, the result of the precious work of bees, which take resinous substances from plants and then transform them.
The beneficial effects of propolis on the body are well known, for example it is a well-known remedy for sore throats, but the applications of propolis are not limited to the health sector and have interesting possibilities in the agricultural field. In fact, this unique substance has phytostimulating and preventive effects against various plant adversities. We can use it to protect the vegetable garden and orchard from various diseases and animal parasites without creating any environmental damage.
In this article we describe propolis and its use in organic cultivation, for an eco-compatible but effective defense.
What is propolis and what is it made of
Before discovering how to use propolis to defend crops, it is good to say a few words about what it is and what it contains. Propolis is a resinous material that bees extract from the bark of plants, such as conifers. In the hive it is used as a shelter and thermal insulator, but above all it serves to protect bees from microbes and pathogens in general.
The composition of propolis is quite variable depending on the plants from which the bees take the resinous substances, and on the period of foraging. In different proportions it contains essential oils, waxes, resins, balms, vitamins, mineral salts, aromatic acids and polyphenols, so propolis can vary in color, smell and taste.
The bees deposit it in various points of the hive as a natural barrier to protect it from the cold and from external invasions. The raw propolis is then taken by scraping it directly from the hives, but usually beekeepers develop specific techniques aimed at stimulating the bees more directly to produce propolis, ensuring that this does not present the impurities that are instead found with simple scraping.. Propolis is not very soluble in water, while it is much more so in alcohol.
Why use propolis in agriculture
On fruit trees, propolis helps protect against various diseases, for example, from powdery mildew and peach blisters, scab and fire blight.
On vegetables it stimulates resistance to some aphids, bacteria and fungal diseases such as Botrytis and Fusarium, and various downy mildew. It is always necessary to evaluate case by case whether this protection is sufficient or whether it is not better to combine it with moderate doses of a cupric product, and this also depends a lot on the seasonal trend. In general, however, propolis is an aid to reduce the need for copper treatments.
In addition, the hydroalcoholic solution of propolis is also used to treat fruit after harvest and thus prevent warehouse deterioration.
Mode of action
Propolis has a phytostimulating and strengthening effect on plants. In addition to protecting from adversity, propolis stimulates the growth of buds, fruit set and their initial development.
Close to the flowering of fruit plants, it also has the effect of attracting pollinating insects such as bees themselves and consequently improving pollination
On which plants it is used
There are many plants on which propolis can be used: its effect in contrasting pathogens is broad spectrum and can therefore be a useful remedy for practically all vegetable species of the vegetable garden, orchard and garden. Fruit plants, vegetables, citrus fruits, aromatic and ornamental plants can all be treated with propolis. Even the olive tree can receive treatments with a propolis-based product, alone or in a mixture, for example, with kaolin, or lithotamnio.
When to deal with propolis
Treatments with propolis-based products are performed in the cool hours of the day, like other types of treatments.
After pruning fruit and ornamental plants, a treatment with a propolis-based product promotes good healing of the cuts and reduces the risk of penetration by pathogens.
The treatments on the fruit plants are carried out from the vegetative restart, that is from the pre-flowering, up to the harvest, with intervals of 2 or 3 weeks. With this constancy, the plants are strengthened, considering that in addition to propolis you can also regularly do other preventive treatments (with nettle extracts, horsetail decoctions, which can also be combined with propolis).
In the event of hailstorms that are known to cause injury to plants, a propolis-based treatment helps to stimulate their recovery.
Of course, in the presence of symptoms of pathology it is possible to intensify the treatments or choose to use copper or other substitutes, but the needs for these products can be reduced.
Methods and dosages of use
Regarding the methods and dosages, it is essential to follow what is written on the label of the purchased product. For example, it is possible to read: 200-250 ml / hl of water if used alone, and 150-200 ml / hl if combined with a fungicide such as sulfur or copper.
It is not considered strictly necessary to use personal protective equipment, but it may make sense to wear gloves and a mask anyway.
Time of shortage and environmental aspects
The technical data sheets of the most popular commercial products do not provide information on the shortage times, that is the minimum time interval that must elapse between the last treatment and the fruit and vegetable harvest, indeed the treatments are recommended right up to the harvest. therefore we can deduce an absence of limits in this sense.
These are harmless products for humans, animals and beneficial insects, and do not involve environmental pollution or toxicity.
Preparations with propolis and commercial products
The main preparations with which we find propolis for agricultural use are the following:
- Aqueous solution, when propolis is macerated in water, at doses of 150 g / liter, accompanied by an emulsifier such as soy lecithin, given the very poor water solubility of propolis.
- Alcoholic solution, also called “tincture”, when propolis is diluted in denatured alcohol.
- Hydroalcoholic solution: in this case the aqueous solution is mixed with an equal part of propolis tincture and then the whole is further diluted in water.
- Propolis + other products: we can find enhanced propolis, with the addition of sulfur, copper or sodium silicate, in the first two cases to improve the effect on fungal diseases, in the second against aphids and other harmful insects.
- Propolis oleate: in this case the propolis is left to macerate in the oil after a very fine grinding, and then a hydroalcoholic solution is added to it. This product is particularly useful against scale insects, instead of white oil, and can be brushed directly on the affected parts of the plant.
- Propolis together with beeswax, in the form of a healing cream to protect the plant from pruning cuts.
- In general, for agricultural use, there are commercial propolis-based products in bottles that contain, for example, the extract of propolis with demineralized water. It is advisable to carefully read their technical data sheet and the label for use, to know the correct doses and dilutions for each species to be treated.
Propolis in organic farming
The USA legislation on organic, which supplements the European one (Reg 834/07 and 889/08), allows the use of propolis.
In particular, we find it included in Annex 2, “Products used as corroborants, enhancers of the natural defenses of plants” of Ministerial Decree 6793/2018, and described in this way:
“It is the product consisting of the collection, processing and modification, by bees, of substances produced by plants. Extraction in aqueous or hydroalcoholic or oily solution is envisaged (in this case emulsified exclusively with the products listed in this annex). The label must indicate the flavonoid content, expressed in galangine, at the time of packaging. Percentage weight / weight or weight / volume ratio of propolis to the finished product “.
In the column to the side, the one relating to the methods and precautions for use, nothing is specified.
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