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Southern blight on hosta


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#1 Your Letters

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Posted 14 July 2020 - 06:50 PM

Last  year a well-established clump of Praying Hands Hosta began turning yellow, then brown and dying off.  The leaves were mushy at the base.  I did not have any testing done, but treated with a fungicide after cutting the hosta back at the soil.
I sterilized my tools and left it alone.  This spring the hosta came back so I thought my actions worked until we hit these high temps in northern Illinois.  The yellow/brown, mushy stems are back.
 
If this is Sclerotium or any other difficult fungus/disease, I will dig the hosta and throw it away.  That said, do I need to solarize the soil?  Or perhaps just find a different plant not affected by this problem?  I clearly did not fix the problem with my fungicide last year.
thank you,
 

C.G.



#2 Janet Macunovich

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Posted 14 July 2020 - 06:55 PM

We have been seeing southern blight, Sclerotium rolfsii for about 15 years in our part of Michigan. Back when, it did not occur much in northern gardens and farm fields but warming climate allowed it to move north. So it's theorized.

 

If the leaves suddenly wilt, brown and die on a hosta in mid-summer, tug on them and see if they are rotted right where they join the crown. If they are, take a look at that bud. If it is dry or deformed, chances are pretty good you are looking at southern blight.

 

It is a fungal disease (Sclerotium rolfsii) that can affect hundreds of plant species and it can reside in the soil. So remove any suspect hosta and destroy it.

https://www.apsnet.org/edcenter/disandpath/fungalbasidio/pdlessons/Pages/SouthernBlight.aspx

 
Remove the hosta, and the soil immediately around it. Discard them as NON-COMPOST because 140F composting temperature does not always kill this fungus. Alternatively, bury the affected plant and soil deeper than size inches. Then plant with something resistant to southern blight. Ornamental grasses and woody plants are the best bet.
 
The bulletin from U of Kentucky (link below) has very good images and clear replanting strategy. So many plants are susceptible - the one fault I find with the UofKY bulletin is the short list of susceptible plants. We usually see the growing points/buds/eyes of hostas with southern blight looking like the UofKY sweet potato example.
 
Janet


 





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