Data on nematode complexes of apple trees in the Republic of Moldova

Abstract

Apple tree agrocenoses with areas larger than 500 hectares from 5 administrative districts, 2 from northern part of the country (Briceni and Soroca) and 3 from central part (Criuleni, Ialoveni and Calarasi) were investigated. The study was conducted during years 2015-2016, data on nematode complexes were recorded using standard methods including soil sampling in apple trees rhizosphere on 30 - 55 cm depth and segments of tiny shallow roots. Overall more than 100 samples of soil and plants were examined using modified method of Baerman and fixation in 4 % formalin at 60ºC. As the result of conducted investigation was revealed that abundance of nematodes in the northern part of the Republic of Moldova ranged from 720 to 1170 specimens per 100 g of sampled soil. In the central part of the country the values varied more comparative to northern part, ranging from 460 to 1300 specimens per 100 g of soil, due to temperature variations and humidity. These values are specific for the environmental conditions of 2015 year, characterized by excess of high temperature and extensive soil drought (more than 45 days during June and August). The analysis of the soil samples from 2016 revealed an abundance of nematodes ranging from 870 to 1680 samples per 100 g of soil in northern part of the republic and 920 to 2200 exemplars per 100 g of soil in central orchards. The excessive abundance of nematodes with approximatively 5-28 % in central part is due to extended periods of high temperatures and humidity. Altogether 62 species of free living and plant parasitic nematodes from fruit trees crops were revealed. The most frequent proved to be species from genera Pratylenchus, Rotylenchus, ditylenchus and Criconemoides. Also three species Xiphinema index. X. brevicole, X. vuitennezi and Longidorus elongatus were identified as vectors of NEPO viruses. Symptoms of premature branches drying, chlorosis virus and embossment with serious and irreversible pathological consequences to apple trees were highlighted almost for all investigated apple agrocenoses, the degree of viral disease ranged within 5-18%.