The mycologist who researches how to grow boletus on poor soil: "There is a lot of interest in producing it"

The mycologist who researches how to grow boletus on poor soil: "There is a lot of interest in producing it"

In the northwest of Zamora, in the valleys of Carballeda and Benavente, small fungi grow that are sold under the name 'zamoranitos'. "There are some differences, such as size, but scientifically they are boletus edulis," they say from Gabemar, a family business in the area that sells wild mushrooms. "For whatever it is, they don't come out in other areas. But they're doing experiments with the jar: it's the easiest way for it to reproduce."

The 'zamoranitos' are not only reduced boletus, but boletus that are born associated with jars, plants that appear in degraded, abandoned lands, from the first that come out when there is a fire. Until recently, the jara did not attract any interest. But the research of a group of agricultural engineers, together with the doctoral thesis of the Palentine mycologist Olaya Mediavilla, has managed to highlight it.

"Boletus is always associated with adult trees. With jara, it is produced in plants of three to five years. We have researched how to associate the boletus with the jara, capable of growing in very bad soils, poor and with few nutrients", explains Mediavilla. "It's an experimental line: once it's done, plantations can be carried out."

Although it is far from the astronomical prices that come to be paid for truffle – which exceed a thousand euros per kilo — the boletus is one of the most valued fungi on the market. According to data from the last year of Mercamadrid, the largest distribution platform in Spain, the average price is 22.33 euros per kilo, well above 2.64 euros of the growing mushrooms (although it is an indicative data: in store they are more expensive and the collector usually sells them cheaper, with a lot of oscillation depending on the day and the season). The boletus is a wild mushroom, whose harvest is done on the mountain, by hand and as the campaign comes.

"There are more than twenty thousand species of mushrooms. On the tasting scale, there are the truffle, the morchella (colmenilla), l'ou de reig (in Spanish, oronja) and the boletus. Truffle is being lowered because there are already more regular crops and crops," says Joan Garriga, president of the Spanish Federation of Mushroom and Truffle Entrepreneurs. "And with the boletus they're testing, but the formula hasn't just been found."


To be found, he continues, would be good news for the sector and for Spain, which competes with France and eastern countries such as Romania in its commercialization. "The biggest consumer of boletus is Italy. Before, the first boletus of the season were in Spain and we could send them to Italy. But with climate change we have lost that," Gabemar founder Aurelio Gabella continues. "In the east they have more forest than here and are closer to Italy, so they have the advantage of the size. And if you get the campaigns you get lately because it's not that cold… It's a problem. In Spain there are not many kilos, but we are defending ourselves." Hence the findings of Mediavilla, which would facilitate the controlled cultivation of this precious good in many more areas of the country, open up an interesting world of possibilities.

"We are seeing if we can patent the association between jara and boletus. The results are promising," says the mycologist. "But we have to keep working."

How it all started

Mediavilla's research was born as a continuation of another done in Zamora, just where the 'zamoranitos' are born. The authors – Juan Andrés Oria de Rueda, Jaime Olaizola, Raúl Fraile and Pablo Martín-Pinto, of the University of Valladolid – pointed out that most boletus are collected in wooded areas, dominated by pines, chestnut trees or oaks.

"However, boletus edulis and boletus aereus also occur under shrubs dominated by shrubs of the cystaceae family," they wrote. "These tickets seem to be collected only in areas of Spain with a long tradition of mushroom harvesting, while in others, despite the abundance of cystaceous scrub, they are not used, making them an undervalued and under-exploited resource."

"The association of boletus and jara already exists in nature," explains the mycologist. "The group was doing that research, so we wanted to do it under controlled conditions. I joined in 2012 and started trying to reproduce it in the lab. We did different essays on what the fungus biology was on the ground. Then we tried to reproduce it."

The boletus edulis reaches 20 and 30 euros per kilo in Mercamadrid
The boletus edulis reaches 20 and 30 euros per kilo in Mercamadrid

Unlike more popular and inexpensive mushrooms like mushrooms, boletus is a mycorroid fungus: it needs a plant to grow. It's a symbiosis. "We did tests by putting the fungus and the plant together. The presence of bacteria could be of interest, so the next step was to isolate our own bacteria from the field, characterize them and inoculate it," he continues. "The association triples when applying native bacteria."

Mediavilla is optimistic, albeit cautious, with the result. "For it to grow up you have to see the roots. And mycorration, which is the fungus and plant at the root, has tripled. But we haven't made it to the seta. We must wait for the union to last in time and produce the seta itself." When the can comes out— three to five years from now—you'll have to see if it can be grown in a controlled way.

Growing boletus in middle of Spain

Zamora's study was considered the "first step" in determining whether jar bushes were actually unproductive or whether, on the contrary, "they could generate significant and reliable seasonal income in the form of mushrooms". The jara, notes Mediavilla, grows in areas of acidic terrain, which in the Iberian Peninsula are those of the west: all Portugal, Galicia, the provinces of León, Zamora, Salamanca, Avila and Palencia and Extremadura and Huelva.

With the defense of her thesis, which was in Cadena Ser in Castilla y León, she has contacted many people interested in putting their own plantations.

Researcher Olaya Mediavilla
Researcher Olaya Mediavilla. Photo: © Pilar Valbuena/iuFOR

"It's like truffle: there's a lot of interest in producing it," he says. Although cultivated for years, truffle is more expensive than boletus because the initial investment is high and requires more years to exit. "About seven or eight since you set up the plant. And the characteristics of the land have to be very concrete. In Spain, especially in Teruel and Soria, there is a lot of production. But it's not that easy to grow."

In the Zamorana region of Aliste are experts in boletus in general and in jara boletus in particular. There are several experimental plots there, also in adult trees, to investigate mycorrization. "The jara is the fastest produced," Gabella nods. "Although the jar comes out too much together and when you pick up you have to break the ground a little more. The woods used to be healed because people went for firewood and only took the big jar, so sunlight came in. Now the mountains are old, there is no light, it grows worse and less boletus come out."

Boletus is usually sold dried or frozen
Boletus is usually sold dried or frozen

Gabella, an entrepreneur dedicated to the seta for 20 years, explains that she buys boletus wherever she is and that they haven't been leaving in her area for two years.

"The climate is changing. But if they go out in the Sierra de Madrid, here we go. What we work most is our area, although sometimes it's your turn to do a hundred and peak kilometers." The boletus is collected by individuals or professionals who go out on the field for him—"there are people who say that he moves a lot of money, but maybe the wife and husband go, find nothing, and they go home"—or, at worst, gangs of foreigners organized by entrepreneurs who pay them little and wipe everything out. This was a problem in Castile and León a few years ago, where the Guardia Civil arrived to secomise several thousand kilos of mushrooms.

If the research were successful, the boletus would not only reach more sites that could benefit financially but would work better. Being so valuable, you run the risk of overexploitation. "In recent years there has been little production because it has not rained," Mediavilla concludes. "So when it rains and there's a lot of production, people go to the field with rakes ripping everything off. And this is like 'fish dyes': you have to let the small mushrooms grow because if they don't release the spores."

Entrepreneurs, for their part, believe that controlled plantations would give their business greater security. "To put up a plantation you would have to make a good study and a lot of money: a farm of one hectare will not produce anything, you need many. It's hard because of that and because you have to do a lot of research," Gabella concludes. "But if I came out there would be more wealth and security. I would settle the villages, because there are hardly any people left to pick up: the elders are already very old and the young are gone. When we started in '98, that didn't happen."