Re: CULT: Bacterial Leaf Spot

I wasn't on the list when this topic was discussed in March of this
year, however, I am currently having a problem with this on some of my
irises and my dahlias.

I was searching the internet on this topic and it appears there is a
very similar condition that occurs in other foliage plants.  There 
appears to be two schools of thought on this.  One - nothing can be 
done except remove infected leaves and keep plants dry (I guess you 
order dry weather for outside plants) and the other suggests the use 
of a copper spray.

I would like to know if anyone has tried the use of a copper fungicide
for this.  The information I was reading states copper hydroxide and
mancozeb to be particularly effective in the treatment, ( products
called "Junction DF","Champ" and "Phyton 27" are suggested).

Some of these articles also suggest the use of dolomitic lime vs
Cal limestone can be a contributing factor to the occurrence of this
disease.  It is the higher levels of magnesium that causes problems.

A question directed towards the nutrient specialists out there.

Does excess magnesium prevent copper from being available to the
plant and would a copper deficiency in the soil contribute to the
occurrence of "bacterial leaf spot" ?

Thanks.

Sandra Barss
SE Manitoba
Zone 3


> So are early signs of some horrible infection.  Only about a dozen 
leaves so far on various iris within a 6-ft. radius.  It's not leaf 
spot.  It hits on the top 1/2 of fans, a soft rotting blotch that 
turns the leaf to discolored mush as it spreads.  Anything with any 
sign of it gets tossed; if scissors are used (well below the infected 
area) they are scrubbed before touching anything else.  What is it
and 
how to prevent?  Don't know if it's bacteria or fungus.  I've seen it 
before; Fung-away, Fungiguard, Funginex, and Agristrep don't help.  
Dry weather does.  I hope it ain't coming after me this year.
> 
> John Reeds, in sometimes sunny southern California
> jreeds@m...


 

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