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Leaf spot

>Someone mentioned they had leaf spot problems.  If you interplant (put
>daylilies between the irises or something else) this helps a lot.  It seems
>to stop the spread.  Members of the daisy family are great plants providing
>food and shelter for beneficials.  If you want a mild spray I recommend Merit
>(R) which has a low LDL rating and is very safe to use.  This controls
>aphids, etc which spread the disease.  When we were in Oracle,  Arizona,
>north of Tucson, for two years, we saw irises that had no leaf spot, no
>borers and grew very well.  Maybe that was iris heaven.
>                                                             Ginny

Is there any evidence that aphids spread leaf spot?  I had always thought
it spread through the air or by the spores or bacteria being splashed from
plant to plant by raindrops.  Fungal leaf spot is a major problem for me
and first appears when the leaves are less than a foot tall.  However, a
single spraying of benomyl knocks it out until much later in the season ,
when a second hit might be required.  Left untreated it can completely
defoliate dwarf bearded irises.  Strangely I have never seen a case of
bacterial leaf spot in my garden.

Fungal leaf spot also hits I. tectorum but does not appear on any beardless
varieties and species I grow.

By the way, this past summer I saw the first attacks by Japanese beetles on
iris foliage--but only on I. virginica!  Has anyone else had this

Best wishes, Bill
William A. Shear
Department of Biology
Hampden-Sydney College
Hampden-Sydney VA 23943 USA
phone (804) 223-6172
FAX (804) 223-6374

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