crown rot and southern blight Sclerotium Rolfsii

esther_opalMay 1, 2007

Crown Rot is the result of a diseased or stressed plant under attack by a host of organisms leading to the mushie condition we call crown rot.

Southern Blight or Sclerotium Rolfsii is a group of related soil borne organisms which are a bit more specific leading to something similar to crown rot. Southern Blight ususally appears in summer when temperatures reach high 80's or above. It also seems to appear after rains and high temperatures. Treatment is 10% household bleach or 1% by volume as a drench of the plant and soil. Since it is soil borne it will move down a slope and reappear next year in the general area so treating the whole area is proper.

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Is the treatment for crown rot the same as for Southern Blight? (10% bleach)


    Bookmark   May 1, 2007 at 3:29PM
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donrawson(Z 5)

Search this forum for "Southern Blight." This is what I've posted earlier:

Southern Blight is caused by the fungus known as Sclerotium rolfsii. Flutolanil is a relatively new fungicide (last 6 years)that has proven to be an effective prevention and curative of plants with the disease. Many fungicides are now available which contain flutolanil (in various concentrations) but not all are labelled for use on ornamentals. Some identical products, such as Scotts Contrast 70WSP and ProStar 70WP, are identical but sold under different labels.
Here are some links which may be helpful. This first article by Iowa State University introduces the reader to this fungus as found on hostas and mentions the fungicide flutolanil:
The next link is the label on Scotts Contrast 70WSP. You can see that it's for treating (preventative and curative) the fungus Sclerotium rolfsii, and that it's labelled for use on ornamentals: This last link is for Bayer ProStar 70WP, which is also labelled for Sclerotium rolfsii: For anyone who has battled Southern Blight before, I would recommend thoroughly cleaning their beds in the fall, making sure their hostas are planted high in the ground (mounded up rather than in a hole), and that their hosta garden receives adequate ventilation (trim tree branches up, etc.). I also think that applying the Contrast or ProStar to the affected areas in early spring as the hostas are just popping up is a good preventative for dealing with the problem later on in the summer. Hope this helps for everyone who is trying to find ways to deal with Southern Blight. Don

    Bookmark   May 1, 2007 at 10:02PM
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With crown rot you may not know what the cause is so removing the damaged material down to clean plant if you can find any, if not it is to late. It is usually recommended that you cut with a clean knife then run through alcohol then water and make another cut repeat with each cut. Picture dieing diseased plant on the outside and clean living plant on the inside. With each cut you drag diseased plant into the clean part inside so you keep making small cuts with an ever cleaner blade, hoping to finally make a relative clean cut.

As long as you have clean crown with root attached it will probably come back.

If it was a plant I really wanted keep then I would dig the plant wash off all of the soil and the part that looks like crown rot (mushy) then examine looking for crown with root attached. Wash with bleach then water and start the cutting process.

    Bookmark   May 1, 2007 at 10:22PM
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Has anyone found a place to purchase Scotts Contrast 70WSP or Bayer ProStar 70WP. I have been googling with no luck. I would be interested in this since each year it seems I find more and more cases of southern blight. If anyone has info I would love to know. Thanks!

    Bookmark   June 6, 2008 at 9:48AM
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