IMPORTANT STORAGE DISEASES OF CARROTS IN NORWAY
Twenty-three pathogens were isolated from diseased carrot plant tissues. The most important ones proved to be:
- Centrospora acerina (Hart.) Newhall
- Acrothecium carotae Årsvoll
- Sclerotinia sclerotiorum (Lib.) de Bary
- Botrytis cinerea Pers. ex Fr.
- Rhizoctonia carotae Rader
- Chalaropsis thielavioides Peyronel
- Pectobacterium carotovorum (Jones) Waldee
- Unidentified ascomycete
C. acerina and A. carotae caused most damage, the former especially in the South, the South-Eastern parts, and in Trøndelag, the latter especially in Western Norway. Both these pathogens attacked roots heavily during storage, even when kept at 0°C, and annually each of them caused losses estimated to several hundred tons of stored roots.
S. sclerotiorum caused damage in all the carrot growing districts, but generally losses were far less than those caused by each of the two pathogens mentioned above. This fungus did not cause significant damage on roots stored at 0°C. At higher temperatures, however, it developed rapidly and might cause severe losses.
Attacks of B. cinerea were found sporadically on roots in most of the storage lots, sometimes causing severe losses. However, the fungus never attacked roots kept in good physiological conditions. Shrivelling due to too dry storage conditions was the most common predisposing factor for attack by this weak pathogen.
R. carotae caused losses in several cold storages. Infested wooden crates were assumed to be the main source of inoculum, and wrapping the roots in polyethylene inhibited disease development.
C. thielavioides and P. carotovorum caused severe losses of washed roots prepackaged in perforated polyethylene bags, when kept at too high temperatures. At temparatures near 0°C these pathogens caused no damage.
An unidentified ascomycete evidently was the primary cause of a serious disease, called 'internal crown rot', in peatmoss soils in Smøla, an island outside the coast of Western Norway.
Literature. Åsvoll, K., 1969. Pathogens on carrots in Norway. Norg. Landbr.Høgsk. Meld. 48, no. 2, 52 pp.