Externally funded project

Vermeidung von Viruserkrankungen (Möhrenröte) im Ökologischen Möhrenanbau. (02OE088) - 5522409


Project Details
Project duration: 10/200212/2003


Abstract


The occurrence in organic carrot production of an apparently new type of symptoms, consisting of leaf reddening, stunted growth, hairy and „rat-tailed" roots is believed to be caused by viral infections. The project objectives were to identify the viral agents involved, to evaluate the current status of the symptom complex within Germany and to assess promising control strategies. At least eight different viruses were identified, namely 2-3 strains or even species belonging to the luteovirus complex Carrot red leaf virus (CtRLV), the umbraviruses Carrot mottle mimic virus/Carrot mottle virus, the closterovirus Carrot yellow leaf virus, the Anthriscus strain of the sequivirus Parsnip yellow fleck virus, the potyvirus Carrot thin leaf virus, one apparently new virus each of the genus Carlavirus and Vitivirus as well as an unknown 'beny‘-like virus. The 'beny‘-like virus and CtRLV were most frequently detected. Conventionally developed antisera are now available for CTLV and soon also for PYFV. Whereas the production of antisera to bacterially expressed viral coat protein of the CtRLV variants failed for unknown reasons, the same technique was successfully employed for producing a CYLV antiserum which is also expected to be commercially available in 2004. However, the high proportion of CtRLV-infected carrot plants that show no symptoms indicated that additional factors are likely to be involved in the development of the described symptoms. The survey concerning the current status of the symptom complex revealed its presence in all major carrot production areas in Germany. Most and increasingly affected was the Lower Saxony region south of Bremen , where carrots are grown most extensively. At harvest sampled carrots revealed an average weight loss of about 30%, whereas adversely affected quality parameters were not obvious. Symptom-related yield reductions amounted to 17% corresponding to an economic loss of up to € 600/ha. In field experiments the reduced susceptibility of fresh market carrot varieties in comparison to commonly used processing cultivars could be confirmed. Due to the extreme climatic conditions in 2004, all field trials studying the effect of different sowing dates on the supposed vector phenology of C. aegopodii gave inconclusive results and require further investigation.



Last updated on 2017-11-07 at 12:17