If you have ever travelled through the Italian countryside, you may have come across “married vines”, which is a form of vine-tree intercropping. Depending on the region, this practice adopts different structures and is known by different names, such as alberata and piantata. However, the principle is always the same: training vines using trees as living supports. The field maple was traditionally used as a support, as were the elm, fruit trees (cherry, plum, quince, mulberry), olive, poplar and ash.
The technique of intercropping trees and vines by growing them in close proximity dates back to the Etruscans and has been a traditional agricultural technique ever since, especially in central Italy, as well as in Emilia Romagna and Veneto. Support trees were particularly useful plants, as they also provided a secondary crop (fruit and oil), food for animals or silkworms, firewood, material for making agricultural tools and so on.
It may be that ancient farmers noticed how vines which grew next to maple trees are healthier than others, but it was not until 50 years ago that scientists discovered why. Maple leaves host predatory Phytoseiidae mites that migrate to the vine and defend it from harmful mites. Exploiting natural enemies to keep parasitic insects under control is now referred to as biological control.
In a vineyard, however, the interaction between different organisms—essentially biodiversity—has wide-ranging impacts, and not just protecting against parasites. In this article we delve further into the topic, specifically with reference to plant biodiversity, and see which plants are best planted near to vines.
The importance of biodiversity for the vineyard
Biodiversity refers to the variety and variability of organisms that live in an environment: in a vineyard it is the entirety of plants, animals and microorganisms that inhabit its surface and soil. Interactions between organisms are not limited to the boundaries of the vineyard, but extend to the surroundings. Let's return to the topic of combating parasites: in nature it is biodiversity itself that ensures equilibrium between the different components of the ecosystem, such as by preventing harmful insects from proliferating unchecked. Up to a certain point in history, farmers relied on this natural system, and biodiversity flourished as a result of countryside management that encouraged all species to multiply. However, agricultural industrialisation has since altered the biological equilibrium and decimated populations of useful insects.
Biodiversity can be preserved or restored through intercropping, that is to say, by cultivating multiple species/varieties of plants on the same land and at the same time. Besides intercropping between trees and plants, as in the case of married vines, it is also possible to intercrop trees with herbaceous species, for example by planting grass. Here you can check out the benefits of grass cover-cropping for soil cultivation in the vineyard.
Besides grass, intercropping can involve other trees, shrubs and herbaceous plants—for example to create hedges and vegetatious borders around the vineyard—and can also make use of spontaneous vegetation.
However, intercropping is just one part of the whole picture. It must be accompanied by good agronomic practices that are implemented from the outset, even before planting the vine cuttings, right from the planning stage. Specifically, making the right planting choices (grape varieties, density and planting spacing, training method) is crucial to cultivating a vineyard that is exposed to the sun, well aerated and therefore less vulnerable to diseases.
Intercropping is part of what in technical terms is called "ecological infrastructures", which refers to spontaneous or non-productive vegetation—including plants specifically chosen to be sown or planted—that benefits crops, the environment and us humans.
In addition to grassing and tree intercropping as we mentioned above, other examples of ecological infrastructures are cover crops, trap crops (which attract and divert harmful insects, thereby protecting the main crop), flowering or grassy strips, borders of spontaneous vegetation around the edges of the field, hedges of shrubs and trees, and large fallow habitats such as meadows and woods. Small habitats are another solution, including groves and ponds (a biolake can also serve this function: here's how to create a do-it-yourself biopool).
What benefits does biodiversity bring to the vineyard? The benefits are numerous and varied in scope, from individual fields to the whole landscape. In practice, it’s like letting nature do your work:
It protects against parasites, by targeting them both directly (as in the case of trap crops and biocides) and indirectly (i.e. by providing predatory and parasitic insects with food, shelter and a place to relocate to).
It promotes pollination and provides a supply of nectar and pollen for friendly insects, including pollinators such as bees.
It improves the quality and fertility of the soil by supplying it with organic substances and nutritional elements such as nitrogen; increasing the soil’s capacity to retain water; stimulating the activity of microorganisms, earthworms, and so on.
It improves the physical characteristics of the soil by decompacting it, facilitating the passage of machinery and work on the vineyard (this is true of grassing and green manure).
It limits the erosion of sloping land.
It contributes to the quality of grapes and wine.
It keeps weeds under control.
It reduces the need for interventions such as plant protection treatments and fertilisation.
It enhances the environment from an aesthetic point of view.
What to plant near to vines
Biodiversity can be planned. When designing the vineyard, you can select plants that are beneficial for vines and the soil that they draw water and nutrients from. Whereas for a new vineyard, you can establish a system that works in synergy, for an existing vineyard you can intervene by deciding what to plant near the vines. When choosing what to plant, the approach must be targeted, i.e. tailored to the specific context (type of crop and its requirements, climate, type of soil, altitude, etc.) and calibrated to achieve the objectives that you have in mind (protecting the soil of the vineyard, using fewer pesticides, or other objectives).
Beware of plants that are harmful to vines, such as bindweed and nettle, both of which host a leafhopper that is a vector for blackwood disease and which can also live in spontaneous grassy areas. Weigh up the possible negative impacts: for example, flower strips can also provide food for harmful insects, hence the most appropriate flower species for friendly insects should be chosen.
So, what should you plant near to vines in order to conserve or restore biodiversity in the vineyard? We should reiterate that there is no catch-all solution, but here are some suggestions:
Manage the soil through grassing, which can be spontaneous or controlled (i.e. done with a mixture of selected species), temporary or permanent, total or partial. You can sow legumes such as tick beans, red clover and vetch, grasses such as oats, brassicas such as alyssum, or plants from other families such as phacelia and buckwheat. You can use a flail mower or garden tractor to mow the inter-rows, and a brushcutter under the rows. Here you will find more detailed information on cleaning under and between rows on the vineyard, using a flail mower to mow grass and guide on which tractor to choose for the vineyard.
As an alternative to grassing, opt for cover crops. These can be managed like green manure—that is to say, by shredding them with a flail mower and then burying them with a rotary tiller—or spread over the ground as mulch (on this subject, you can read our article on the advantages of mulching). The most commonly sown cover crops are brassicas, grasses and legumes, and it is advisable to sow a mixture of green manure species. Some brassicas (such as horseradish, radish, rocket and mustard) release biocidal substances that are effective against nematodes.
Cultivate flowering grassy strips: some widespread nectar- and pollen-producing species are alyssum, coriander, phacelia and buckwheat.
Plant hedges and trees such as hawthorn, honeysuckle, dogwood, spindle, blackthorn, dog rose, rosemary, bramble, hazel, Judas tree, elm, poplar, Prunus species or oak.
Avoid getting rid of any spontaneous vegetation bordering your crop.