Plant Database forum: For Plant Admins - Daylily Leaf Streak Data is Available

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Name: Tina
Where the desert meets the sea (Zone 9b)
Daylilies Cactus and Succulents Container Gardener Dog Lover Birds Enjoys or suffers hot summers
Garden Ideas: Level 2
Sep 9, 2014 12:03 PM CST
Hi Admins,

Just wanted to mention that I was recently pointed to data that is publicly available on over 400 daylily cultivar's performance with Leaf Streak disease (cultivars were supplied through AHS from all areas of the US, spanning introductions from the 1930s through the 1990s). Like Rust, leaf streak is an ongoing problem for sellers (can't easily ship fans that get infected with it in the spring and fall) as well as growers (infected fans create nearly identical display marring as Rust). Unlike Rust, it is very hard for non-academics to correctly identify and so it is not a self-report kind of measurement. The fungus that causes Leaf Streak is also considered to be one of the main causes of Spring Sickness, so the data are relevant for those interested in both.

Many hybridizers now include cultivars that share lineage with rust resistant varieties in their general breeding programs, and home display gardens are also able to access ATPs database to choose some cultivars that have performed well in studies, or that are bred from related lineages. Adding data about cultivars that have also performed well under observation for leaf streak/spring sickness might expand options for selection toward cultivars that have known beneficial genes to pass along. Fortunately, over 90% of the 400+ cultivars studied performed very well and offer a very large gene pool to find daylilies that might be used to supplement hybridizing programs, and to complement other daylilies in display gardens.

If there is interest I'd be glad to sort and get the data prepared for inclusion in the ATP database for daylily cultivars. A simple "Leaf Streak Resistance" and "Leaf Streak Resistance Decimal Score" could display the information on relevant plant pages, and also populate drop down selection boxes in the search engine for daylilies by characteristics searches.

More than 90% of the cultivars were in resistant range, with a similar scale used to the Rust scores. However, because of the way the percentile scores were distributed, the 50% visible leaf disease point for distinguishing resistant or susceptible falls at about 3.0 on their 5.0 scale. Not only might people be pleasantly surprised to see how few cultivars were actually found to be in the susceptible range, but it would be the first and only time that people could access a database to search for cultivars that they can have some idea may perform with desired resistance. As it is now, people must pick blindly, or spend years observing and culling on their own, or, for any who might know of the study's final results, still would need to try to match it up with information on cultivars in the database to see what might fit their goals.

I'm not personally invested in whether the data end up being provided or not (I already have the info I am interested in) - I'm simply motivated by the idea that this data could make a difference to others. The entire study has many facets, from overwintering information, to fungicide efficacy results, and the specific data on leaf streak ratings are included in Appendix C at the very bottom of the document (document page number 114), shown as the Overall score in the first column on the left. Scores were determined by percentage of leaf surface affected at the following ratios:

0-10% = 1
10-40% = 2
40-60% = 3
60-90% = 4
90-100% = 5!etd....
Do not seek to follow in the footsteps of old; seek what those of old sought. — Basho

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