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It’s an elegantly simple solution to a long-standing problem: protecting crops from harm, keeping them covered.
Netting is commonly used to keep pests out in vegetable production, particularly in high value areas such as seed.
However, the use of netting in fruit production is still being explored and tested, according to Mirella Aoun, an agronomist and researcher at Bishop’s University in Quebec, Canada, who has been studying agricultural netting for more than a decade.
The professor. Aoun explains that fruit producers initially put nets on trees mainly to protect them from hail damage. Now they are experimenting with nets that can protect against insects.
The mesh size of insect proof nets is determined by local conditions, including the nature of the insects.
Of course this could rule out the insects farmers really want – pollinators like bees.
One option is to apply the nets after the pollination period. Another is to open the nets during the day, while bringing in the hives.
Tree nets are particularly well established in French and Italian apple orchards, where nets draped over rows of apple trees restrict the movement and spawning of moths. This has helped farmers get rid of persistent pests and reduce the use of expensive and environmentally harmful chemical pesticides.
There are perks for fruit lovers too. “When you know you have less pesticide residues from crops that are under exclusion networks, that’s good news for consumers,” says Prof. aoun.
Networks are also seen as a way to deal with the effects of climate change. The warmer conditions have seen the resurgence of certain types of insects and diseases.
Some regions are seeing more intense periods of drought and heavy rain and networks can help with that.
For example, depending on the location, the type of netting and how it is used, a netting system can shield against solar radiation which leads to heat stress and inhibits photosynthesis in trees.
But introducing netting could mean a wetter environment around the tree, not helpful for crops prone to fungal diseases in wetter climates like the northeastern United States and Canada.
But some researchers are working on hydrophobic nets, where a treatment with a botanical pesticide essentially makes the nets water-repellent.
Photoselective (colored) networks can also affect the penetration of light. Dark, opaque nets reduce light intensity but not light quality.
Pearl-colored nets can better diffuse the light so that it reaches more parts of the vegetation. Meanwhile, the blue, red and yellow nets filter out certain solar wavelengths and thus can stimulate specific responses in plants related to fruit quality.
According to prof. Aoun, the fine-tuning of network usage often leads to an increase in high-caliber fruit. As his research in the Mediterranean has shown, trees covered in colored shade netting can produce larger, more vibrantly colored fruit.
Networks aren’t always the answer. They may not be appropriate for smaller, more varied orchards. Nor are they necessary for all climatic conditions.
Additionally, the netting used for fruit trees is typically made from polyethylene, which isn’t ideal for a world trying to move away from plastic addiction.
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One of the companies working on non-plastic meshes is Tesinov, a French company of technical textiles. Tesinov is researching various types of biodegradable nets, such as linen ones.
It has already introduced a biodegradable network based on polylactic acid (PLA), produced from fermented corn. Industrial composting is required to break down this type of net, which according to sales director Adrien Etienne is around 10% more expensive than a conventional net.
Etienne says biodegradable nets are currently more popular in Europe than in North America. This may be related to European policies aimed at reducing the use of insecticides. “Nets, I think, will become more and more popular because insecticides are less popular,” says Etienne, for example among French cherry growers.
The upfront cost has been a stumbling block for some farmers. “The nets are obviously a bit expensive compared to insecticides,” acknowledges Etienne.
Tesinov’s cheapest mesh retails at around €0.50 (44p) per square meter for private use in France, according to Etienne. This type of netting only lasts one or two seasons, although heavy weather netting can last much longer. The duration depends on factors such as sun exposure. “The nets are increasingly fragile due to the sun,” says Etienne.
Overall, Prof. Aoun says prices are coming down as products become more diverse and accessible. “In general, the positive impact of the network is overwhelming the negative side,” he sums up.
Jean-Marc Rochon manages the Pépinière Rochon apple tree nursery in Quebec and follows the progress of the network.
“In my eyes, this technology is more in development and improvement rather than large-scale application,” he says.
For Mr. Rochon to start using nets on his apple trees, the cost of the net would not be the only factor. “I see it more as a way to rethink our ways of doing things,” he explains.
To be viable for your nursery, the network should be reliable and not create overload. It should also be usable on large sections of orchard.
Clearly, improvements in technology and communication will be needed to convince more fruit growers that the network would be useful.
But the prof. Aoun believes, “As we move towards increasingly unpredictable climate challenges, protective cultivation with nets is the way forward.”
