What’s Happening Here?
Let’s start the newsletter with one of our subscribers' favorite features—the diagnostic challenge. Honestly, I continuously receive positive feedback on these challenges, so let’s keep a good thing going. Take a look at these aster images:
These are two images showing different stages of the same issue. The image on the left shows an earlier stage and the one on the right shows a more advanced stage.
With spring behind us and the summertime blues kicking in, perhaps your diagnostic skills are a little rusty. I’m almost certain you can correctly solve this week’s challenge. Do you know “What’s happening here?”
Lock in your answers and I’ll tell you what's going on with these asters shortly ...
Four Must-Attend Perennial Events
In the last issue, I provided a listing of several trade events occurring during the month of June. Depending on the focus of your business, the relevance and value of each of those events will vary from business to business. Since I’m like you and heavily involved in the perennial side of the business, I think there are four events this June and July I would try to attend if you’re able to. Three are perennial focused, and one is just a well-rounded and invaluable experience for everyone.
Walters Gardens Perennial Expo
Walters Gardens is hosting their one-day
Perennial Expo on Tuesday, June 17, 2025 at its main growing facility in Zeeland, Michigan. Here's what’s on the agenda:
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Perennials Aren’t Just Plants—They’re People, Too! (Keynote), Rick Vuyst, co-host of the Gardening Simplified Show
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Planning, Productivity & Workflow Management: Is it Possible to be Accurate? Ryan Hop, Walters Gardens COO
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In Case You Missed it (Recent Walters Gardens plant intros) Cayla Olson, Regional Product Manager—Walters Gardens
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Innovations in Bloom: Plant Introduction Highlights for the 2025-2026 Season Hans Hansen, Director of New Plant Development—Walters Gardens
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Boost Sales with a Strong Fall Perennial Program Laura Robles, Regional Product Manager—Walters Gardens
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Potting Perfection: Pro Tips for Top-Quality Finished Containers Jessie Carle, Trials Manager—Walters Gardens
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Seeds of Success: Improving Home Gardener Engagement Through Strategic Programs Andrew Jager, Marketing Manager—Walters Gardens
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Greenhouse and facility tours
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Display garden tours
Wow, this looks like an incredible day!
Darwin Perennials Day
Darwin Perennials will be hosting Darwin Perennials Day the next day (Wednesday June 18, 2025) in West Chicago, Illinois.
Here’s what's on the Darwin Perennials Day agenda:
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Stroll through the extensive perennial gardens
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Visit the new varieties showcase
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See the cut flower bed and meet Dave Dowling, Cut Flower Specialist
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Visit the education stations
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Meet with more than 25 suppliers
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Visit with Darwin Perennials product experts
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Panel Discussion: "Stop Stressing About Perennial Production"
Tours
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Interactive video tour of Darwin Colombia
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Vegetative farm
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Ball's new Seed Distribution Facility
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The Perennial Gardens
Cultivate‘25
Cultivate is one of the industry’s top events; it attracts over 10,000 attendees each year and has something for everybody. Cultivate’25 has an expansive trade show covering over 8 acres of space (over 1,500 booths). Plus, there are more than 150 educational sessions, numerous workshops, several industry tours, a large new varieties display and much more.
Like any trade event, you can gain as much or as little as you allow yourself. Cultivate has been one of the most productive trade events I attend each year. If you’ve never attended or it’s been a while since you have, I encourage you to go.
Go
HERE to learn more about Cultivate’25 and to register.
PPA National Symposium
And here’s the big one: the largest multi-day perennial-focused event in our industry—it's the Perennial Plant Association’s (PPA) National Symposium. The National Symposium is packed full of tours, networking opportunities and educational sessions.
Tours
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Greater Des Moines Botanical Garden
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Three Oaks Garden (Norris & McKinney Private Garden)
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Enabling Garden—Linda Grieve Private Garden
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Krause Gateway Center
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Better Homes & Gardens Test Garden
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Susan Appleget-Hurst Private Garden
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Neal Smith National Wildlife Refuge
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Brandy & Mosa Shayan Private Garden
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Wilson's Orchard & Farm
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The Harkin Institute
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Oak Park Restaurant & Edible Prairie
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Cowles Commons
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World Food Prize Hall of Laureates
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Educational Sessions
General Sessions
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The Prairie: Past, Present & Future—Neil Diboll
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Ecological Responses to Climate Change: Lessons from the Past—Dr. Jack (John) Williams
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Specialist Bees—Heather Holm
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Landscapes That Connect Gardening Communities with Perennial Plants—Wambui Ippolito
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Designing Landscapes of Place—Darrel Morrison
Grower Track
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Accessing Plant Genetics—Jeff Carstens
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Propagating Native Prairie Plants—Bob Henrickson
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Panel: Strategies for a Thriving Fall Perennial Program—Laura Robles, Thad Kohlenberg, Bryan Benner & Chris Fifo
Design Track
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Sowing Resilience: Research on Directly Sown Vegetation for Urban Green Infrastructure—Michael Guidi
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Innovative Alternatives to Traditional Lawns—Liz Anna Kozik
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Panel: Effective Maintenance Strategies for Meadows and Prairies—Jack Pizzo, Ryan Drake, John Mark Courtney & David McKinney
Networking
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Trade Show Social
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Special Evening Dinners
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Trivia Night
As you can see, the 2025 PPA National Symposium has a ton to offer. There’s so much more, including lots of well-deserved awards. You can check out the program by visiting
2025 PPA National Symposium.
The Answer is ...
I first showed these images of an issue on aster at the top of the newsletter and asked if you knew what was causing the plants to look this way. Do you think you came up with the correct answer? Before we see if you’re right, the images I shared showed two different stages of the same issue; let’s take a look at an even more advanced stage.
I’m guessing most of you have locked in your final answer by now. Were you aware that I practically gave you the answer when I first started the challenge? The answer was in the sentence where I said, “... perhaps your diagnostic skills are a little rusty.” There it is—the answer is rust.
What, Where & How
There are several pathogens that cause rust on asters, including Coleosporium campanulae, Puccina asteris, P. campanulae and other Puccinia species. Rust is most commonly observed on the underside of the leaves, but can often be observed on the upper leaf surfaces and other above ground parts of the plant. The orange you see are actually pustules, or masses of spores, from the fungal disease.
Photo: Cesar Calderon Pathology Collection.
Spores of rust are spread by air currents from wind or fans from heating and cooling systems or they can be dispersed by splashing water. They germinate on leaves that are wet and when temperatures are between 50 and 75F (10 and 23C). Spores generally require three to six hours of leaf wetness for them to germinate. Rust infections are also likely to arise in areas where nightly dew formation occurs (warm days and cool nights).
As with most diseases, rust can be prevented when making preventative fungicide applications. There are a number of great fungicides for preventative applications, including Heritage, Mural and Pageant, as well as fungicides like Avelyo, Eagle and Postiva that are highly effective and specialize at managing rust diseases.
My email is paul@opelgrowers.com if you have any comments, article suggestions or if you'd just like to say hello.
Best regards,
Paul Pilon
Editor-at-Large—Perennial Pulse
Director of Growing—Opel Growers
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