Test of Populus x euramericana cv. Pannònia resistance to the attack of Discoporium populeum (Sacc) Sutton by artificial infections

Abstract

Populus x euramericana cv. Pann?nia is an artificial hybrid, created in the Sarvar research station (Hungary), by crosses made by Kopecky Ferenc. It was registered in Hungary and its identification is H 490-31. Its parents are: Populus deltoides S-1-54 & Belgium (P. deltoides A 42 Iowa ? P. deltoides A148 Missouri) x P. nigra L?b?ny 211%. Inoculations were implanted by spore suspension and mycelium of the fungus, grown on the MEA medium, by standard method. The experiments were performed on the plants 1/2, especially singled out for the experiment and on the plants in the second year after transplanting (2/2 and 2/3), at the locality Siget. The inoculations were replicated three times: 15.05.2000, 14.10.2000 and 31.03. 2001 The study shows that the newly introduced cultivar Populus ? euramericana cv. Pann?nia is not immune to the attack of the fungus Discosporium populeum. The highest percentage of realised infections in the experiment with mycelium was realised in October (89.7%), and the lowest percentage in May (22.6%). Inoculations with spore suspension had the same trend, only the percentage of realised infections was considerably lower, with the maximal value for October, 23.5%. Infection with spore suspension implanted in leaf scar produced the positive results, with 10.4% percentage of infection. A very significant fact is that the percentage of random infections of the plants monitored during the experiment was only 4.4%. Only one plant was girdled and killed during the research. It must be emphasised that all the necrotised spots were callused and remedied in a short period after infection, which indicates the presence of the defence mechanisms in this cultivar The study results are a good base of further research. To be able to bring correct conclusions and recommendations to the practice regarding this cultivar in the study area, it is necessary to assess the degree of Discosporium populeum presence on one-year and two-year old trees .