The General Directorate of Forest Ecosystems and Environmental Management from Department of Climate Action, Food and Rural Agenda of the Generalitat of Catalonia has issued a document with a series of phytosanitary recommendations in relation to the 2023 cork levy campaign that you can read below.

Introduction

Cork scald is a disease that causes necrosis in the regenerating cork tissues, causing the formation of cankers on the bark after peeling, sometimes with dark brown exudates.

Necrotic areas are unable to regenerate the cork and can also act as an entry point for other pathogens that can eventually lead to tree death.

Trees affected by cork scald suffer discoloration and shriveling of the leaves. This disease is attributed to the action of the fungus Diplodia corticola.

Apart from causing the drying of branches and, on occasion, the death of trees, scalding very seriously affects the production of quality cork and favors the entry of wood rot fungi which, in the long term, cause the loss of the tree.

Environmental humidity after peeling appears to be a key factor in cork infection and certain boring insects can carry spores of the fungus.

Background

The damage caused by this disease to Catalan corks has been known since 1920 (Sant Celoni) and its importance was increasing throughout the Serra Litoral and the Montseny-Guilleries area. Later, the most virulent effects occurred in 1985-86, when there was an extreme drought and irregular rains.

Faced with the growing concern of owners for this disease, in 1987 an agreement was signed between the Generalitat de Catalunya and the Autonomous University of Barcelona to study the etiology of this disease and possible control methods. The disease was attributed to the action of Diplodia corticola, different trials were made to find an effective preventive fungicide and its appropriate application was disclosed. Faced with the deletion of the selected substance from the Registration of Phytosanitary Products, between 2002 and 2005 the Department, the CPF and the IRTA carried out trials to find an alternative fungicide.

Recent studies 

This new fungicide also ceased to be authorized in 2020 and, for this reason, since 2018 the Department has been working in collaboration with the CTFC and the UdL and with the associations of forest owners to better understand the problem and find a solution

Although an alternative treatment has not yet been found, the studies carried out in the last five years are allowing us to better understand this disease. Among the main conclusions, the following should be highlighted:

– The fungus has great genetic and virulence variability and there are indications that it may be endophytic (always present inside trees becoming a pathogen only under certain circumstances).

– High relative humidities up to one month after peeling are related to the emergence and spread of the disease, although it is not clear that sporulation in summer is the main factor in the spread of the disease.

– Spores of the fungus have been detected in the boring insect Platypus cylindrus. The number of insects in flight is related to the temperature and humidity of the air.

- Although tests have been carried out with many products (chemical, biological plant protection products, possible antagonists, phytohormones, etc.) both in the laboratory, in the plant and in the forest, no effective product has yet been identified.

– We need to know the disease better to find specific tools or improve management to reduce the risks.

The Order of May 11, 1988 must be kept in mind¹, on the regulation of obtaining cork and cork and the improvement of corks.

Recommendations 

– The use of any product to prevent scalding cannot be recommended given that its effectiveness has not been proven and that some are not authorized.

– In addition to the obligation to cut the scrub in a radius of one meter around the trees that need to be stripped, it is advisable to extend this radius to two meters and to carry out a selective 50% of the scrub in the plots beforehand. those where the peeling must be done to allow good air circulation, avoid excessive humidity and reduce competition for water.

- If high environmental humidity is expected after peeling, it is recommended not to remove the cork. Given the general weather forecasts for this summer, this year there is no high risk of scalding foci appearing for this reason.

– Given the current situation of prolonged drought, it is especially necessary this 2023 campaign to pay attention to the vitality of the trees before starting the cork cam. Faced with symptoms of weakness in a foot, it is advisable to consider avoiding its peeling.

– Leaving aside scalding, it is recommended to follow traditional forestry practices, avoiding peeling in case of severe drought or high defoliation as a precaution against possible risks (fire, extraordinary drought...).

Attention to the Alpha Plan

You must follow the instructions of Alpha Plan, the operational procedure established by the Corps of Rural Agents for surveillance, prevention and control of risk activities, in the face of forest fire danger situations that may occur.

– When level 3 is reached, forest harvesting, including cork, and access to the forest are restricted, so the cam area cannot be reached.

– At lower levels of the plan, what is restricted in specific schedules are the forestry works that generate remains. In this case, the cork peel is not affected because it does not generate residues.

1 Amended by the Orders of 03.7.1991 and 04.19.1999