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High damage potential of seed-borne spot blotch in organically grown spring barley in Denmark

Pinnschmidt, Hans O.; Nielsen, Bent J. and Hansen, Henrik J. (2005) High damage potential of seed-borne spot blotch in organically grown spring barley in Denmark. DARCOFenews (1).

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Online at: http://www.darcof.dk/enews/mar05/blotch.html

Summary

Spot blotch of barley (Bipolaris sorokiniana, perfect state: Cochliobolus sativus) occurs wherever barley is grown but is normally not considered a major problem in Danish barley production. It is therefore not included in routine disease surveys or official variety testing in Denmark. However, recommended seed contamination thresholds are 30% for spring barley and 15% for winter barley. Several spring barley varieties were grown under organic (no seed dressing, mechanical weeding) and conventional (seed dressing with fungicides, herbicide application) production conditions at three sites in Denmark in 2003. The harvested seeds were analysed for contamination levels of seed-borne B. sorokiniana using a blotter method. The percentage of seeds contaminated with B. sorokiniana ranged from about 5 to 95 % and was highly depending on the site, production system and variety. Contamination levels of organically cultivated plots were about twice as high as those of plots receiving conventional treatments. The germinating ability of seeds was highly affected by the level of B. sorokiniana contamination and declined drastically at contamination levels above 60%. This effect appeared to differ among varieties. The 1000-grain weight was not affected by the level of spot blotch contamination of seeds. The results indicate that the importance of spot blotch may be underrated, especially in organic barley production and that the role of varietal resistance should be investigated. More results are expected from ongoing seed analyses.

Summary translation

Spot blotch infection levels and the associated damaging effects in terms of reduced germinating ability of seeds were extremely high in seeds harvested from organically managed fields. Our results indicate that the importance of spot blotch may be underrated, especially in organic barley production, which entirely depends on organically produced seeds. Our results furthermore indicate that varietal resistance may play an important role in spot blotch control. This should be further investigated, especially because no information is currently available about the resistance against spot blotch of barley varieties on the Danish variety list.

EPrint Type:Journal paper
Keywords:Bipolaris sorokiniana, spot blotch, seedling blight, spring barley, crop damage, seed germination, seedling emergence, organic seed production
Subjects: Crop husbandry > Crop health, quality, protection
Research affiliation: Denmark > DARCOF II (2000-2005) > VI.2 (BAR_OF) Characteristics of spring barley varieties for organic farming
Denmark > DARCOF II (2000-2005) > VI.1 (ORGSEED) Healthy seed for organic production of cereals and legumes
Deposited By: Pinnschmidt, Dr. Hans
ID Code:4740
Deposited On:03 May 2005
Last Modified:12 Apr 2010 07:30
Document Language:English
Status:Published
Refereed:Not peer-reviewed

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