New Symptoms in Castanea sativa Stands in Italy: Chestnut Mosaic Virus and Nutrient Deficiency

Abstract

The European chestnut characterizes both the landscape and economy of mountainous Italian areas. In recent years, new canopy disorders have been reported: “chestnut yellows”, often ascribed to phytoplasma and/or nutrient deficiency, and “chestnut mosaic”, associated with a virus (ChMV). Therefore, research was carried out in four Italian regions to describe the two symptomatic frames and assess their etiology. Surveys were conducted on 101 chestnut trees (23 with mosaic, 38 with yellowing, and 40 without symptoms). The phytosanitary status was monitored, and the new canopy disorders were detected, distinguishing between yellowing and mosaic. Moreover, leaf samples were collected for molecular and nutrient analyses. No phytoplasma infection was recorded, while ChMV was detected in 91.3% of samples with mosaic symptoms, 31.6% of yellowing samples, and 30.0% of asymptomatic samples. Yellowing was associated with Mn deficiency. On the other hand, ChMV-infected and healthy leaves had similar mineral contents, showing that mosaic symptoms are induced by the virus. Both disorders negatively affected photosynthesis efficiency. These phytosanitary problems are present in Italian chestnut woods and cause local effects, and a relationship with other biotic and abiotic factors can be hypothesized. Considering the increase in new records, these symptoms represent an emerging issue whose impact and spread need to be further monitored.

Identification of a Unique Genomic Region in Sweet Chestnut (Castanea sativa Mill.) That Controls Resistance to Asian Chestnut Gall Wasp Dryocosmus kuriphilus Yasumatsu

“…It is a multipurpose tree species of high ecological and economic importance. In particular, sweet chestnut cultivation plays a key role in the economic development of the mountainous areas in Italy, Greece and North-Western Spain [3][4][5]. These three countries belong to the most important producers of chestnut fruits in Europe, together with France and Portugal [6].…”

“…in the 19th century, chestnut blight (Chryphonectria parasitica (Murrill) M.E. Barr) in the middle of the 20th century, and Asian chestnut gall wasp (ACGW), Dryocosmus kuriphilus Yasumatsu, at the beginning of the 21st century [4]. Native to eastern Asia, the ACGW is a parthenogenetic and univoltine gall maker Hymenoptera that infests all species and hybrids of the genus Castanea [7].…”