Stenphylosis

This disease was first confirmed in Portugal in 1996 in the Rocha and Passe Crassan pear varieties, and is now epidemic in the West region. Its effects are so devastating that, for example, between 2014 and 2016 it caused losses of approximately 30 million euros in the Rocha pear sector, according to data presented in 2017 by INIAV at the Fruit Growing Technical Days.

Caused by the fungus Stemphylium versicarium, Stemphylliosis (also known as the brown spot disease of the pear tree) attacks leaves and fruit and the symptoms vary depending on the variety of pear tree. The spots tend to invade the entire leaf, along the central vein, causing it to dry out and fall off; on the fruit, they appear on the sides most exposed to the sun and spread to the entire fruit if the weather conditions are favorable to the proliferation of the disease.

Also present in the orchard at flowering time, infections by the fungus Stemphylium vesicarium can occur on the flowers, particularly the anthers and sepals. And when there are favorable conditions of temperature and humidity, the fungus develops, infections increase, sometimes leading to fruit drop.

The incidence of the disease depends on the variety of pear tree and the ripeness of the fruit. It also seems to be linked to changes in treatment schemes for stone fruit (one of the most important pome fruit diseases in the world, such as pear and apple trees), in particular the use of active substances that only control stone fruit and have no effect on Stemphyliosis.