Application of the Principal Component Analysis to Disclose Factors Influencing on the Composition of Fungal Consortia Deteriorating Remained Fruit Stalks on Sour Cherry Trees

Abstract

The sour cherry production is concentrated in eastern region of Hungary. During last two decades the commercialized yield varied between 42000-90000 metric tonnes. One of the main constraints is the fruit decay (anthracnose) caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. (teleomorph: Glomerella cingulata [Stoneman] Spauld. & H. Schrenk). This disease has been known for centuries, and in certain orchards yield losses greater than 90% periodically occurred under epidemic conditions. In last decade, however, the grave infection has evolved in each season that resulted in disastrous yield losses and led to decrease of harvested area at about 25 %. Series of control measures were tried out, many of them with success with some degree (Borve & Stensvand, 2006; Borve et al., 2010), among them a newly developed biocontrol preparation was applied (Oros & Naar, 2008; Oros et al., 2011). Detailed analysis of weak efficiency of disease control revealed that beside C. gloeosporioides four other anamorphs of Glomerella were present (Table 1), among them C. acutatum (J.H. Simmonds, 1968), a new pathogen for the region, became recently dominant. Its strains, tolerant to recently applied fungicides to control the anthracnose, could be isolated of sour cherry orchards that might be the cause of ineffectiveness of control measures in 2006-2010 (Oros et al., 2010). At the increasing costs of cultivation only high yields may secure a profitable production of sour cherry. From this point of view, the anthracnose caused by Glomerella anamorph with special regards to C. acutatum is an important element of uncertainty that means elaboration of efficient control measures is the critical challenge to unconquerable sour cherry production. Efficient control measures reduce the yield loss in the orchard by suppressing the pathogen (i.e. by the reduction of the number of viable spores and infected fruits). On our major surprise, the pathogen can not be isolated of overwintering fruit mummies in industrial plantations of East Hungary contrarily to other sour cherry producing regions. A survey was carried out to disclose the cause of this phenomenon collecting samples of remained fruit stalks of varieties in sour cherry gene bank of East Hungary. The relationships between host (sour cherry variety) and fungi associated to stalks have been analyzed by multivariate methods: Non-linear Mapping