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Mar 19, 2015 9:56 AM CST
Name: Lucy
Tri Cities, WA (Zone 6b)
irises
Charter ATP Member Cottage Gardener Irises Region: Northeast US Region: United Kingdom Region: United States of America
Enjoys or suffers cold winters
I am glad that you are skipping the drilling & that your ears seem clear.
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Sep 9, 2021 9:56 PM CST
Name: Timothy
NE Oregon (Zone 7b)
This is an old thread about iris diseases, so I thought id give an update on my issue (now past issue) with Botrytis.

Disclaimer:
Consult FIRST with a certified nursery professional or a local extension agent as to what products/methods of control that would be available in your area.

I've been able to come close (95%) to eliminating it by carefully timed, rotating fungicidal sprays of Chlorothalonil, Captan, and Clearys 3336. I start in late September and continue drench spraying with a rotation every 10-14 days depending on climactic conditions. Also i use a pre/post plant fungicidal dip on new arrivals and transplants.
I'm also experimenting with biological controls such as Cease (Bacillus subtilis strains)
I've consulted with Portland State Extension Service, University of Idaho extension service on which products to use and when to use them. Because my region has host crops that are susceptible to Botrytis sp. in agriculture -- wine grapes, strawberries, onions, etc. the pathogen is naturally endemic to my area.
Ive voluntarily suspended most of my retail sales in 2021 as i researched and worked to get this under control, which i have for the most part. Ive had great success this year and my iris field is looking the best its ever looked.
Botrytis sp. is one of the most commercially important agricultural pathogens, and is nearly universal in distribution except in regions with low rainfall, limited freezing and thawing with abundant sunshine where its incidence is much mitigated by climate. You can't escape it, you can only be vigilant in spotting it and treat without delay. I consider all bearded iris vulnerable to this pathogen, so I treat all plantings especially during the critical months beginning late Sept.
and continuing October thru March.
It requires persistence and a multi-season effort to control this problem -- but it can be controlled and suppressed with the right products and timing of spray applications.
Thumb of 2021-09-10/TBManOR/38972d


Thumb of 2021-09-10/TBManOR/270d43

Clump of "Cool Operator" -- M. Sutton '16
Thumb of 2021-09-10/TBManOR/1c84a8
Last edited by TBManOR Sep 9, 2021 10:16 PM Icon for preview
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Sep 11, 2021 4:24 PM CST
Name: Robin
Melbourne, Australia (Zone 10b)
Region: Australia Garden Photography Cat Lover Irises Seed Starter
Congratulations on almost eliminating it Thumbs up . I hope you continue to get closer to total elimination.
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Sep 26, 2021 2:08 PM CST
Name: Glendolyn
San Antonio, Texas (Zone 8b)
Irises Region: Texas
TBManOr, thank you for updating this forum thread.
I am just a small home grower so thinking your retail products are too
advanced for me. Your info does make me aware of problems you and
others are having and the solutions as they come along. I wish you
continued success and enjoyed your photos of inspiration. Thank you.

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