Sunday, August 16, 2009

Double click on the above photo and you will clearly see
the reddish brick coloured lesions on these soybean roots.THIS IS RHIZOCTONIA ROOT ROT.Rhizoctonia root rot is a fungal pathogen that will infect soybean roots after an extended period of cool moist weather.One will generally find the greatest expression of Rhizoctonia root rot in side hill seep areas as well as areas of fields with poorer internal drainage.Once infected rhizoctonia will begin deteriorating the roots surface tissue causing them to appear scarred and tattered and they will take on a reddish brick coloured appearance.Rhizoctonia root rot can kill plants.Generally they will die in one, two,or three foot sections of row beans or it can express itself in fairly large slower growing areas of solid seeded soybeans.Rhizoctonia root rot is not believed to be a big yield robber.As such Plant breeders are not breeding for specific resistance to this disease.The best means for controlling Rhizoctonia is to avoid soil compaction,improve internal drainage and extend your crop rotations so that soybeans are never grown on a field anymore than 1in 4 years.This will help avoid any kind of soybean disease build-up not only for rhizoctonia but all other soybean diseases as well.You will note in the above photo how these soybean plants express a hook in their roots.This is a sure sign that these plants experienced soil compaction within three to four inches of the soil surface.With no soil obstruction soybean roots should grow straight downward.

No comments:

Post a Comment