The pests and diseases that affect the Portuguese chestnut trees are the main obstacles to their productive capacity. This is a worldwide problem, since pests tend to “travel” between countries, namely through the import of species. Chestnut cancer, for example, arrived in Europe from the United States in 1938.
What is the value of the chestnut lost in national territory? According to RefCast - Portuguese Chestnut Association, in Portugal, diseases result in the loss of 40 to 50% of the chestnut along the production chain. This could mean a break of around 12K MT of nuts, something like 24 million euros less for the nut line. High intermediate costs, in turn, cause a price increase, which does not help its competitiveness.
Ink disease, chestnut cancer, and chestnut wasp are the three most concerning threats. Ink disease, is worrisome in particular, as there is still no biological way to control it. In addition to these diseases, brown rot is so a cause for concern. The warning about chestnut rot was given in 2019 by José Gomes Laranjo, a researcher at UTAD - University of Trás-os-Montes and Alto Douro. The fungus Gnomoniopsis castanea, which became more evident in Portugal that year, already affected European production for ten years. The symptoms are particularly visible in the flowers, leaves, and branches of the chestnut trees, and the incidence is higher in the chestnut trees previously affected by gall wasp. High, according to the researcher, are also the losses it causes, reaching 80 to 90%.