The raspberry it is a cultivated species that falls within the group of "small fruits", increasingly appreciated for their nutritional value and potentially profitable for those who grow them. In fact, these are among the most capable crops enhance small areas of land, even in so-called disadvantaged areas, offering abundant productions even by cultivating with the organic method.
It is an excellent crop to be inserted in the vegetable garden or on the edge of the garden, also because like many small fruits it is a shrub that can also produce in partially shaded areas, unsuitable for many other crops. The most grown raspberry in our country is that red (Rubus idaeus) but there are also varieties of yellow and purple.
The plant belongs to the family of rosaceae and has the form of a shrub from 1 meter to 3 meters high, with a perennial stump and an aerial part made of shoots and suckers. The suckers are the new "shoots" that begin to grow in spring and remain herbaceous for months, they usually have thorns and in August they lignify becoming shoots. The latter have mixed buds and bear fruit in the following spring. The type raspberry unifer (which produces only once a year) bears fruit on the shoots sprouted the previous year. There are also varieties of re-flowering raspberry which bear fruit in late summer and autumn on the apical part of the shoots sprouted in the same year. At the end of this fruiting, the apical part of the shoots dries up and the following year in June-July the medium-low part of the shoot will give its second fruiting. For this reason, the remontant varieties are also called bifers, because they produce twice a year.
Suitable climate and terrain
Raspberry plants are spontaneously spread as undergrowth, which is why they want a fairly acidic soil rich in organic substance, which in the forest is naturally supplied by fallen leaves.
Climate necessary for cultivation
The raspberry is found spontaneously in the mild climate areas of central and northern Italy, more rarely in the south. Typically it is found in clearings or at the limits of broad-leaved and coniferous woods and the best conditions in which it grows are those of the low and medium valleys between the mountains, between 700 and 1400 meters above sea level. The species does suitable for frequent rains, provided they are well distributed over time, it suffers from dry winds but takes advantage of the light ones that ventilate the rows and hinder fungal diseases such as Botrytis.
Considering that it can be grown up to 1500 m s.l.m, it is a species resistant to winter cold and indeed it requires a certain cold requirement to bear fruit, that is a sum of 800-1700 hours (depending on the variety) with temperatures below 7 ° C. In cultivation he manages to enhance the situations of half shade, but it is in the sunny locations which offers the best production results.
The ideal terrain
Raspberry prefers i rich soils, well endowed with even partially undecomposed organic substance, and capable of retaining moisture for a long time, considering that the roots of this species are rather superficial (most of these are found in the first 25 cm of soil). It does not tolerate limescale and prefers subacid ph, around 6.5.
How to plant raspberry
For the planting of raspberries, it is advisable to avoid soils that have already hosted crops of other rosaceae such as strawberries or brambles, in order not to run into soil fatigue and the proliferation of pathogenic fungi and common parasites. The era in which to do the transplant it is that of vegetative rest, indicatively between November and March, but if the propagation material consists of potted plants with a good amount of soil there are no problems to carry out the transplant even in spring forwarded, because in this case they would not suffer the stress. When planting raspberries it is not necessary to have different varieties for pollination.
They dig holes not too deep whereas the rooted suckers that are planted have a contained root system. A basic fertilization based on mature manure or compost is applied to which manure in pellets or other organic fertilizer such as cornunghia and possibly also natural minerals such as rock flour is added.
The easiest and most used multiplication method for raspberry is the rooted sucker, taken during the vegetative rest among those in excess in the rows and chosen among those robust and well rooted. This means that starting from a small raspberry plant it is possible to extend the cultivation from year to year without spending more on propagation material, as long as it remains healthy.
Sixth of implant
Between one row and another of raspberry plants you can leave about 2.5-3 meters and between the individual plants about 70-80 cm, but as they grow they tend to form a sort of continuous hedge. In the vegetable garden they are often placed at the edges, near the external fence.
The cultivation of raspberries in detail
Raspberry is not a particularly demanding plant as a cultivation, although it still requires a minimum of maintenance and can benefit from irrigation and pruning. In organic farming it is important to know how to recognize pest attacks and diseases in order to intervene promptly.
If rainfall is scarce and not well distributed, it is useful to prepare a irrigation system drip between the rows to be used in summer to obtain larger and more succulent berries. In spring, on the other hand, it is better not to irrigate, except in case of drought, to avoid the risk of root rot.
Mulching in the inter-row spaces is very useful for containing the development of weeds that remove water and nutrients from the raspberry plants, which are provided with extensive but rather superficial roots. It can be distributed a layer of straw which every year must be replenished, by putting handfuls of pelleted organic fertilizer under it, or alternatively choose the solution of black sheets. Alternatively, where water is not a limiting factor, the spaces between the rows can be grassed with an advantage in terms of biodiversity protection. The grass can be regularly mowed in alternate rows, in order to partially preserve its ecological value, and the advantage of this solution in sloping soils is also the reduction of erosion.
How to prune raspberries
Raspberries are a shrub that grows spontaneously, but if it is cultivated it benefits from pruning operations, aimed at improving the quality and productivity of the harvest but above all at regulating the plant making it tidy and easy to manage.
Raspberry plants usually keep bred bush in rows with metal poles, crosspieces and two pairs of wires that act as guides. The lower pair of wires is at a height of about 80 cm from the ground and the two wires are 40 cm apart, while the upper pair is about 1.5 meters from the ground and the two wires are 70-80 cm apart. In this way the shoots are located in the middle of the wires, they remain supported and form a V. This shape also facilitates the harvesting operations.
When you decide to plant raspberry plants, you need to know right away whether they are single-flowering or remontant varieties, because pruning depends on this, among other things.
The shoots of unifere variety after having fructified they dry up and must be removed during the following winter. Every year therefore it is necessary remove all dry shoots from the rows of raspberries and thin out new shoots so that about 7-8 remain for each linear meter, leaving the most robust ones. These are capped just above the last containment thread of the row. The raspberry plants are therefore renewed every year. During the growing season the suckers that grow in the middle of the row and those in excess along the row are eliminated.
In the remontant varieties the shoots of the year are cutted after the first autumn production, while after the second production in June-July of the following year they are eliminated at the base.
However, in commercial crops, to simplify, they treat the two-leaved crops as if they were uniform, exploiting only the autumn production on the top of the shoots, after which they cut all low to the ground to renew the vegetation. This choice guarantees more abundant and earlier autumn productions and also always eliminates potential disease inoculations.
Diseases of the raspberry
Raspberry plants can be affected by some diseases and since the production of these species is very concentrated at certain times of the year, it is important to keep the cultivation monitored and to be as timely as possible with the treatments, which can be safely carried out with allowed means. in organic farming.
Gray mold (Botrytis cinerea)
It is a ubiquitous fungus that affects many plants, including raspberry, of which it rot the fruits that become covered with the classic gray mold and then fall to the ground. Botrytis also affects the stems, causing light brown spots, and rarely the leaves. The disease is favored by humidity air, rain and overhead irrigation, which is why the latter must be carefully avoided, as well as over-dense systems and excess fertilization. To reduce the damage of botrytis, you can do spraying based on sodium bicarbonate, or treat with products based on Bacillus subtilis, even if it is not officially registered for small fruits, so in the case of professional organic cultivation it cannot be used. .
Root rot of raspberry
This disease is caused by various species of the Phytophtora fungus, it is favored by water stagnation in the soil. Root rot occurs at the base of shoots and suckers with necrotic browning under the bark. It generally appears in the summer and causes the affected plants to wither, and then spread to the others, which is why the timely eradication of infected ones is important, as well as the precaution of planting raspberries on trunked flower beds if the soil is heavy. The holes from which diseased plants are eradicated must be disinfected with sulfur and lime, because the fungus can survive for many years in the soil in the form of a spore.
It is another fungus that manifests itself through brown-violet spots around the buds of the suckers, spots that in winter take on a silver-gray color. Buds affected by didymella as a result either do not bloom or bloom badly. The pathogen can be arrested with copper-based products, always with the necessary precautions for use and without exceeding.
Like other rosaceae, raspberry can also be affected by powdery mildew, in which symptoms are clearly identifiable as scattered white patches on the foliage and shoots. Sodium bicarbonate-based sprays help to contain the spread of the white disease, and furthermore, treatments with sulfur-based products can be done.
In addition to diseases, there are also insects that threaten raspberry plants, and these can be contained through traps, physical means and low environmental impact products, all of which are allowed in organic cultivation.
Small fruit fly (Drosophila suzukii)
The fruit fly is a diptero (order of insects to which flies belong) native to Southeast Asia, which was first reported in Europe in 2008. Females lay eggs in ripening fruits and larvae that arise from these feed on the pulp, ruining it. Usually the greatest damage occurs in summer, but if the previous winter is mild, the attack anticipates. An effective and ecological remedy against drosophila is the installation of red Tap Trap traps. Another solution is represented by insect net with mesh size less than 1 mm.
The antonium is a beetle that lays its eggs in the flower buds, cuts the peduncle to prevent the flower from blooming and to allow the larvae that are born from the eggs to develop inside them. It seems that raspberry varieties without hair on the stem are more affected than those with hair. This insect can be fought by treating the cultivation with pyrethrum or with azadirachtin.
Harvesting of raspberries
Indicatively, each well-grown raspberry plant produces a total of about 1-1.5 kg of fruit, to be harvested in several steps. Harvesting is an operation to be done delicately in order not to damage the fruits, which are hollow inside and therefore not very resistant to crushing. They also have a short shelf life and should be consumed or sold soon, but fortunately they are very suitable for processing into jams, juices and pastry products.
Variety of raspberries
The red raspberry it can be uniferous or reblooming, and recently the remontant varieties treated as unifere have become widespread in order to have abundant productions between late summer and early autumn. Among these we mention the Heritage variety, resistant to powdery mildew and rustic. Among the unifera we mention the Fairview, resistant to Botrytis and Didimella and with a sweet and tasty pulp. Varieties of black raspberry, which in Italy are rarer but can be found, and purplish raspberry, very aromatic and suitable for freezing. There are also yellow raspberries, suitable for processing. So it's worth making an assessment and possibly choosing to grow various types to achieve scaling in yields and diversification.