Suchergebnisse

Rice blast, caused by Pyricularia oryzae, is one of the most important rice diseases worldwide. Each year it causes globally 30% yield losses, threatening thus global food security. Rice blast management relies heavily on fungicides, however, due to more and more restrictive legislation and increasing problems with fungicide resistance, a very limited spectrum of chemical control means is available. Therefore, there is an urgent need to search for and develop new efficient control strategies. Biological control is nowadays well accepted alternative to control plant pathogens in agriculture and among different biological control agents (BCA), Bacillus spp. have been among the most successful microorganisms in disease management. Here, two strains of Bacillus spp., BCA20 and BCA21, were isolated as plate contaminants inhibiting fungal growth. Their activity was tested by dual-culture assay against 15 strains of Pyricularia oryzae. BCA20 showed overall higher activity, it inhibited the radial growth of the tested strains on average by 85% and the mycelium growth area by almost 52%. The activity of BCA21 was approximately 20% lower than that of BCA20. The multi-locus gene identification based on eight genes (16S, ilvD, glpF, pta, purH, pycA, rpoD and tpiA) identified BCA20 as B. subtilis and BCA21 as B. halotolerans. The activity of the two strains on the germination and growth of rice plants as well as their biocontrol activity in vivo is being investigated.

The European Commission requested the EFSA Panel on Plant Health to perform a pest categorisation for Ceratocystis fimbriata f. sp. platani Walter, the fungal pathogen responsible for the "canker stain" disease of plane trees. C. fimbriata f. sp. platani is listed in Annex IIAII of Directive 2000/29/EC. Recently, the pathogen has been reclassified as Ceratocystis platani (Walter) Engelbrecht et Harrington, based on intersterility studies, progeny analysis and the morphology of isolates from different hosts. C. platani is a single taxonomic entity and sensitive and reliable methods are available for its detection and differentiation from other related fungal species. The only known hosts are Platanus occidentalis, Platanus orientalis and Platanus × acerifolia. The last two plane species are the most susceptible to C. platani and are widely grown in most of the European Union Member States. C. platani is a wound pathogen causing canker and wilt and eventually death of plane trees. It is currently present in part of the risk assessment area (Greece, France, Italy), where it causes serious consequences on P. orientalis and P. × acerifolia trees grown in natural stands, coppices, and public and private gardens in both rural and urban environments. There are no obvious ecological/climatic factors limiting the potential establishment and spread of the pathogen in the non-infested part of the risk assessment area where hosts are present. C. platani has multiple natural and human-assisted means of spread, including waterways, root anastomosis, contaminated pruning tools, insects, contaminated insect frass and sawdust. The movement of infected host plants for planting and wood is considered to be responsible for the introduction of the pathogen into new areas. Cultural practices and sanitary and chemical measures applied in the infested areas may reduce inoculum sources but they cannot eliminate the pathogen. Plane accessions resistant to C. platani are available in the European market.