Historic Blizzard Threatens Olive Groves in Spain

Storm Filomena dropped up to 50 centimeters of snow across central and northern Spain over the weekend. Depending on how temperatures evolve over the next few days, olive groves could experience significant damage.
Photo: Olivos del Mundo
By Daniel Dawson
Jan. 11, 2021 13:19 UTC

Large swaths of cen­tral and north­ern Spain were blan­keted in up to 50 cen­time­ters of snow over the week­end as the coun­try expe­ri­enced its largest bliz­zard of the past half-cen­tury.

Four peo­ple have been killed by Storm Filomena, which bat­tered the Iberian Peninsula Friday and Saturday, bring­ing tem­per­a­tures as low as –8 ºC. Among the areas hard­est hit by the storm were the Community of Madrid, Castile-La Mancha and Catalonia.

The prob­lem is seri­ous when, after the snow­fall, the tem­per­a­tures drop and the snow freezes on the tree. In that case dis­as­ter is guar­an­teed.- David Marcos, Viveros Sophie

Castile-La Mancha is the sec­ond largest olive oil-pro­duc­ing region in Spain after Andalusia. Together with Catalonia, the two autonomous com­mu­ni­ties pro­duced an esti­mated 197,000 tons of olive oil in the 2020/21 crop year or roughly 12 per­cent of the country’s total out­put.

See Also:How Cold Temperatures Can Help Olive Production

While it is still too early to deter­mine the extent of the dam­age caused to the area’s olive groves by the storm – roads are still being cleared and some areas remain with­out power – there are some early indi­ca­tions that the region’s olive trees may sus­tain sig­nif­i­cant dam­age.

Olive trees are not plants adapted to extreme cold tem­per­a­tures or sim­ply sub-zero ones for long peri­ods of time,” said David Marcos, of Viveros Sophie, a nurs­ery spe­cial­iz­ing in the sale of olive trees.

The dam­age that can be caused is dif­fer­ent depend­ing on the age of the tree, time of year, cold level and period of time,” he told Olive Oil Times.

The two main threats to olive trees from a bliz­zard, Marcos said, are the weight of the snow on the tree limbs and the dam­age caused by the freez­ing tem­per­a­tures.

Having orig­i­nated in the Middle East and later spread across the rest of the Mediterranean basin, olive trees did not evolve with nat­ural cop­ing mech­a­nisms against snow and sus­tained freez­ing tem­per­a­tures.

Their wide-bladed leaves are not effec­tive at drop­ping snow and, in spite of the trees’ rel­a­tive flex­i­bil­ity, heavy snow­fall can cause branches to break. These break­ages, in turn, leave trees vul­ner­a­ble to infec­tions and pests.

However, the snow alone is not usu­ally respon­si­ble for the most dam­age. Instead, it is the cold that has the largest impact on the trees’ health and the qual­ity of the fruits.

The snow itself does not freeze and even has a mit­i­gat­ing effect against the cold, in addi­tion to let­ting light through. The plants could live under the snow at first,” Marcos said. The prob­lem is seri­ous when, after the snow­fall, the tem­per­a­tures drop and the snow freezes on the tree. In that case dis­as­ter is guar­an­teed.”

According to Aemet, Spain’s state-run mete­o­ro­log­i­cal agency, tem­per­a­tures are expected to hover around freez­ing through­out the week, with lows below 0 ºC through Saturday (the fur­thest date for which data are avail­able).

Aemet has also issued sev­eral severe weather warn­ings for cen­tral and north­ern Spain, with tem­per­a­tures as low as –14 ºC and –10 ºC expected in parts of Castile-La Mancha on Tuesday and Wednesday, respec­tively.

While the snow gen­er­ally causes vis­i­ble dam­age to the trees, Marcos said that the poten­tial for the root sys­tem to be dam­aged by the cold is even more con­cern­ing.

Another prob­lem is freez­ing the roots,” Marcos said. Young olive trees are the ones which will be affected by this.”


Although the dam­age does not appear seri­ous in the crowns, if it has dam­aged roots by freez­ing, it will be observed in spring,” he added. When the trees begin to sprout and grow, some can die sud­denly, with a char­ac­ter­is­tic appear­ance – wood with red­dish to dark col­ors, and loss of herbage.”

According to Italian agron­o­mist Angelo Bo, dam­age to roots is quite rare and requires extremely cold tem­per­a­tures for a sus­tained period of time. Based on the Aemet fore­cast, this sce­nario remains pos­si­ble, but seems unlikely.

See Also:Italy Approves Aid for Mills Hit by 2018 Snow Storm

However, Marcos warned that the bulk of the dam­age would be done to trees heavy with olives, although many pro­duc­ers have already con­cluded their har­vests. He said that the pres­ence of the olives on the trees makes them more sus­cep­ti­ble to dam­age from the cold and increases the risk of branch break­ages.

But the added prob­lem is that olives being har­vested later will be dam­aged by cold, the oils that are extracted will have a high level of per­ox­ides that as free rad­i­cals will cause a rapid degra­da­tion of the prod­uct that can even begin in the fruit before it is trans­formed into oil,” he said. These oils will never be edi­ble due to a seri­ous oxi­da­tion defect and a typ­i­cal wood fla­vor.”


While the extent of the dam­age remains to be seen and depends heav­ily upon the tem­per­a­tures of the next few days, Marcos said there is some prece­dence for what may be com­ing next for olive grow­ers.

We have antecedents of this type of weather from February 1956, a month of below-zero tem­per­a­tures, with frozen snow on the tops of the olive trees,” he said. That forced many olive trees to be cut to the base to sprout again and rebuild their branches and leaves over the years.”

This hap­pened to a large part of the olive groves in cen­tral Spain and large areas stopped pro­duc­ing olives,” he added.

Producers con­cerned about the impacts of the snow­storm on the 2021 olive har­vest can also look east to Italy for clues as to what may be in store.


Snow covers olive groves in Italy in the aftermath of the Burian snowstorm. Photo: Giuseppe Palestini

After the Burian snow­storm brought freez­ing tem­per­a­tures and blan­keted most of the penin­sula with snow in March 2018, pro­duc­ers across the coun­try reported sig­nif­i­cant declines in olive yields. Trees located on exposed hill­sides that bore the brunt of the freez­ing winds were impacted the most.

Along with dam­ag­ing the olives, the freez­ing and thaw­ing of water within the trees also led to necro­sis – the pre­ma­ture death of cells in liv­ing tis­sue – with some of the symp­toms of the con­di­tion show­ing up imme­di­ately while oth­ers man­i­fested them­selves later in the sea­son.

Damage caused to branches also led to some infec­tions in the affected olive trees in the after­math of the storm.

Burian had some indi­rect effects in terms of pests,” Bo, the Italian agron­o­mist, told Olive Oil Times. In fact, in the months fol­low­ing the cold wave, the wounds on branches affected by the cold were in sev­eral cases an access point for olive knot (Pseudomonas savas­tanoi) and even for the gall midge (Resseliella oleisuga). The lat­ter usu­ally does not cre­ate prob­lems, but in this case found access and spread more eas­ily to the small branches.”

Back in Spain, there is lit­tle for pro­duc­ers to do other than dig them­selves out and wait to see what the weather brings over the next few days.

The dam­age from this storm can­not be eval­u­ated until the dura­tion and tem­per­a­tures reached are known, which will occur in the next few days,” Marcos said. It can there­fore be seri­ous or light, depend­ing on how tem­per­a­tures evolve these days.”

Ylenia Granitto con­tributed to this report.


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