1 Field Crop Institute – Chirpan, Chirpan, Bulgaria
2 Institute of Plant Physiology and Genetics – Sofia, Sofia, Bulgaria
3 National Institute of Meteorology and Hydrology – Sofia, Sofia, Bulgaria
Резюме
Several leaf spotting fungi were found to co-exist together in durum wheat
management systems in Bulgaria and to incite similar leaf symptoms. They
appeared every year but their proportion in the complex varied. This investigation
was undertaken to assess the occurrence of foliar pathogens over a range of different
environmental conditions across time and space and to discuss the impact of some
climate factors on the prevalence of individual fungal species. A 3-yr field survey
(2012 to 2014) was conducted at three locations including General Toshevo (alt.
236 m), Radnevo (alt. 135 m) and Burgas (alt. 25 m). At every site specimens were
taken from upper leaf level of two durum varieties (Predel and Saturn 1). At General
Toshevo two new durum varieties (Mirela and Severina) created and released from
Dobroudja Agricultural Institute were additionally included. Meteorological data
were obtained from the weather station closest to each field and compared to climatic
norm over long period of time (1981-2010). Among all analyzed leaves, three major
leaf pathogens were found: Pyrenophora tritici-repentis (46%), Monographella
nivalis (18%) and Parastagonospora avenae f. sp. triticea (15%). Zymoseptoria
tritici, Phaeophleospora sp., Cladosporium herbarum and Alternaria sp. were
represented by 4 to 6%. Parastagonospora nodorum and Cochliobolus sativus were
not detected at all during the period of the investigation. There was a variation in the
fungal community across the years. P. tritici-repentis had the greatest appearance level in 2012 and 2013. Percentage occurrence of M. nivalis was highest in 2014,
moderate in 2012 and insignificant in 2013. Pa. avenae f. sp. triticea occurred
every year but more noticeable in 2013 and 2014. Z. tritici was recorded in 2013
and 2014. Phaeophleospora sp. appeared only in 2014. The proportion in the leaf
spotting complex varied between the locations. At General Toshevo the most
common fungal species were P. tritici-repentis (36%), Pa. avenae f. sp. triticea
(21%) and M. nivalis (19%). At Radnevo P. tritici-repentis was the most prevalent
species (64%), followed by M. nivalis (23%) and Z. tritici (9%). At Burgas P. tritici-repentis
was prevailing (45%). Pa. avenae f. sp. triticea, Phaeophleospora sp. and
M. nivalis were found at 18, 15 and 13%, respectively. The occurrence and relative
prevalence of the fungal pathogens was also depending on cultivars. Among the
climate variables the most important role played temperature and in spring months
from March to May. The obtained results showed the influence of years, locality,
cultivar characteristics, and agrometeorological conditions on the occurrence of
leaf spotting fungi.
