INTERACTION BETWEEN THE CEREAL CYST NEMATODE HETERODERA LATIPONS AND COMMON ROOT ROT, COCHLIOBOLUS SATIVUS, ON BARLEY
U SCHOLZ1, V VILICH 1, RP SCHUSTER 1, OF MAMLUK 2 and RA SIKORA 1
1lnstitut fur Pfianzenkrankheiten, Universitaet Bonn, Nussallee 9, 53115 Bonn, Germany; 2International Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, PO Box 5466, Syria
Background and objectives
Materials and methods
The highest grain yield decrease was found with the early application of the nematode, followed by the simultaneous application of nematode and fungus, and was significantly different from the other treatments. The treatment with simultaneous application of nematode and fungus reduced the straw yield to the greatest extent, followed by the treatment with the early application of nematodes, but no significant differences were detected. C. sativus alone did not reduce the yield, but it had an additional effect when the pathogen was applied simultaneously with H. latipons or 9 weeks after the nematode application. An explanation for the additional grain and straw yield decline by C. sativus under simultaneous presence of H. latipons is the increase of discoloration of the SCI, the more extended root lesions and the significantly higher infection of crown, SCI, seminal and nodal roots by C. sativus compared to the treatment C. sativus alone. A similar effect, but without significant differences, was observed, when the fungus was applied 9 weeks after the nematode application. On the other hand the presence of the fungus at the same time as H. latipons reduced the multiplication of H. latipons to a pf/pi value of 3.8 by additional pathogen pressure compared with the treatment with H. latipons alone, which resulted in a pf/pi value of 7.6.