La dryness that affects holm oaks and cork oaks The disease has once again become a major concern in Extremadura. Faced with weather conditions particularly conducive to its spread, scientific authorities have issued a new phytosanitary risk alert to try to halt the damage to the dehesa (pastureland) in time.
The person responsible for this incident is Phytophthora cinnamomi, a soil pathogen which attacks the roots and causes the progressive decline of trees. To anticipate the most dangerous times, the Extremadura Center for Scientific and Technological Research (CICYTEX) has launched an early warning system that combines advanced climate models and management recommendations aimed at forest managers and owners.
A phytosanitary alert due to high-risk conditions
According to CICYTEX, a phytosanitary risk warning Due to the forecast of days with high humidity and temperatures very favorable for the development of Phytophthora, this agency, which reports to the Regional Ministry of Education, Science and Vocational Training of the Government of Extremadura, warns that the anticipated scenario could dramatically increase the pathogen's infection rate in many dehesa areas.
Phytophthora is considered the main agent associated with drought In holm oak and cork oak forests, this is a problem that has not only an ecological impact, but also an economic one, by compromising the cork productionacorns and other traditional uses of the dehesa. The gradual loss of these trees poses a long-term challenge for land management.
The models developed by CICYTEX indicate that, in the coming days, a peak in zoospore release could occurThese are the infectious structures of the pathogen. In situations of high soil moisture, these zoospores move easily in the water table and colonize the roots, opening the door to new outbreaks of drought in plots where visible symptoms may not yet have been observed.
For this reason, the alert is not limited to a mere technical warning. It aims to ensure that, during this critical period, preventive measures should be adopted in the field to minimize the spread of the disease between farms, which is key when environmental conditions favor the pathogen.
The role of Phytophthora in the dieback of holm oaks and cork oaks
This pathogen is favored by environments with high humidity and mild temperaturesThese are typical conditions following rain events combined with a slight increase in temperature. At these times, zoospores are generated en masse; these are small, mobile structures with a movement mechanism that allows them to "swim" in the soil water.
When the zoospores come into contact with the roots, They penetrate the tissues and cause injuries which hinder the absorption of water and nutrients. Over time, the tree loses its ability to respond, weakens, and may die, especially if several years of conditions favorable to the pathogen occur.
In regions like Extremadura, where the holm oak and cork oak pastures are ecological and economic pillarsThe presence of Phytophthora poses a significant threat. It not only impacts the biodiversity associated with these systemsbut also on activities such as extensive livestock farming or cork production, which depend directly on the good health of the trees.
Therefore, specialists insist that drought is not an isolated problem, but a slowly progressing and cumulative diseasewhich requires combining continuous monitoring with the application of management measures adapted to each farm and each time of year.
How the SILVA-F alert system works
To anticipate these high-risk episodes, CICYTEX has developed SILVA-F, an early warning system Focused on monitoring soil conditions, this tool relies on forecast data generated by the European Centre for Medium-Range Weather Forecasts (ECMWF), a world leader in numerical weather prediction.
Each week, the following are consulted: soil moisture and temperature predictions originating from the ECMWF. This information is processed on CICYTEX servers using a specific program that translates climatic variables into a risk index from 0 to 1, where higher values ​​indicate a greater probability of ideal conditions for zoospore production.
The result is reflected in maps, charts and monitoring panels by zone These tools allow us to visualize the situation in different areas of Extremadura. Currently, detailed monitoring is being carried out in several strategic areas with holm oak and cork oak forests, combining a regional overview with more detailed analyses of each monitoring area.
When the system detects that a period of temperature and humidity particularly favorable for Phytophthora is approaching, it activates the phytosanitary risk alertThis information is published on the website dedicated to the disease and is also sent to people registered in the notification service, so that they can prepare the actions on their farms.
The goal of SILVA-F is not only to report the situation in real time, but to promote a change in approach: to stop reacting when the damage is already evident to plan measures in advance, adjusted to the level of risk expected for each week and each area.
Access to information: website and WhatsApp alerts
To facilitate the use of the system, CICYTEX has enabled a specific web page on Fitóftorawhere you can check the current risk status, multi-day forecasts, and technical recommendations associated with each scenario. These panels display, among other things, daily risk maps and graphs showing the projected evolution.
In addition, the platform offers the possibility of Subscribe to a WhatsApp community announcements groupThis channel is used to distribute notifications when an increased risk of spread is detected, as well as relevant updates on research, trials, or changes in management recommendations.
This combination of web and instant messaging aims to ensure that managers of dehesas and forest owners They have the information at hand, without needing to constantly check official websites. This way, in critical moments, the alert arrives directly on their mobile phone.
The tool is not intended only for specialized technicians; it can also be useful for small landowners and livestock farmers They need to know when it's advisable to take extra precautions. The idea is to democratize access to complex predictive data and translate it into clear messages, accompanied by practical guidelines for action.
Although the current focus is on Extremadura, the type of approach adopted by SILVA-F could serve as a reference for other European regions with affected holm oak and cork oak forests for similar problems, where monitoring based on climate models can make a difference in forest management.
Recommended measures during drought episodes
Once the alert is activated, CICYTEX insists that the key lies in minimize the spread of the pathogen between plots with different levels of infestation. The first recommendation is to avoid moving soil from plots with symptoms to areas that are still considered healthy.
This implies taking extreme care with machinery, vehicles and implements that can drag soil adhering to wheels or components. Whenever possible, it is recommended to limit their movement outside of designated roads and, if it is necessary to move from an affected plot to an unaffected one, to apply basic cleaning measures to avoid transporting particles of infected soil.
Another notable measure is the temporary restriction on the entry of livestock In areas where trees affected by the drought have been detected, the movement of animals can facilitate the unintentional transport of soil between different areas of the farm. Therefore, it is advisable to reorganize grazing during the weeks of highest risk.
It is also advised reduce staff traffic and limit intensive field work while the critical episode continues, prioritizing essential actions and postponing those that could worsen the spread of the pathogen.
These biosafety guidelines do not eliminate the disease, but they do help to to stop the spread of new outbreaksCombined with continuous monitoring through the SILVA-F system, they allow management to be adjusted to the situation each week, adapting the level of precaution to the published risk index.
Research and long-term management of the dehesa
The development of SILVA-F is part of a several years of work by CICYTEX focused on the decline of holm oaks and cork oaks. The center has promoted scientific trials, field studies and technical publications aimed at improving forest management in the face of Phytophthora.
In earlier phases, the system was based on networks of pilot stations located in collaborating pastureswhich collected local data to feed the models. The evolution towards a platform supported by ECMWF forecasts represents a leap in the system's predictive capacity and territorial coverage.
In parallel, the following have been developed management and prevention manuals aimed at professionals in the sector, where guidelines are collected on tree densities, grazing management, soil conservation and other practices that can influence the evolution of the drought in the medium and long term.
The underlying idea is that, when faced with a progressive disease like Phytophthora, It is not enough to intervene only when symptoms appearIt is necessary to integrate risk information into everyday management decisions, from planning forestry work to organizing livestock loads on each plot.
In a context where climate change can alter rainfall and temperature patterns, prediction and monitoring tools like SILVA-F are increasingly considered a strategic piece for the resilience of the dehesa, both in Extremadura and in other areas of the Iberian Peninsula where drought is also a concern.
The combination of early warnings, biosecurity recommendations and specialized technical support strengthens the response capacity of managers and owners to a complex threat such as the dieback of holm oaks and cork oaks, helping to protect a key ecosystem and the economic benefits that depend on it.
