Wednesday, February 1, 2017

Rust Resistant and Tolerant

Rust Resistant and Tolerant

For a complete listing of available daylilies and pricing, click here.

This list of cultivars at the bottom of this article is of those I have found to be resistant in 5 consecutive years of screening for resistance in my garden. This is the first basis for all of my descriptions. As of 2016, this screening program has ended in my gardens and I will now hope to receive feedback from growers in rusty settings. Many of these plants listed below are also part of various university/test garden studies that have been published. Where that it so I have tried to note it in the descriptions. Some may also have multiple anecdotal accounts derived from online reports and personal communication. It is not my goal to make any claims with this page, but only to offer directions for those interested in rust resistance and the possibilities of breeding resistant strains of daylilies. 

This is a jumping-off point. You will need to test things in your garden if you want to have an active rust resistance program. Those with naturally rusty gardens who don’t spray, where rust may be endemic and present in spring and fall, or even most of the year, and those gardens that bring in many daylilies from many gardens and combine many daylilies in close growing areas, may also have especially good situations for rust resistance screening. Feedback from such sources is deeply appreciated and can be completely anonymous. I am perfectly happy to receive your anecdotal observations, without requirement, but I would be very happy to communicate with those interested in a more methodical and predetermined approach as well. 

It is important to understand that all cultivars may not perform in the same manner, in terms of any trait, but especially so for rust resistance, from one garden to the next. There is good evidence that there are multiple strains of rust in North America (Buck, et al. 2013). There is no clear consensus on the numbers or types of genes for resistance that occur in various daylily species clones or hybrid cultivars. I do feel I can say from my experience that there appears to be several genes for resistance, based upon preliminary breeding/screening observations. It appears to me that there are both recessive and dominant genes found across the Hemerocallis. I also suspect that there can be additive effects when more than one gene is combined, especially in the case of the seemingly-recessive types. Some genes that appear to be dominant also seem to occur within a handful of cultivars that seem to have better-than-average resistance across multiple (or all) sources of observation and seem to have very high breeding value for the trait, possibly suggesting a dominant gene. 

Only a handful of cultivars have maintained total seeming-immunity to rust in my garden. They are the great minority and they should be actively studied by professionals to determine if there is particularly strong genetic resistance in these few, or if there are other reasons they retain such seeming-immunity, in my garden and in both university trials and anecdotal reports from other growers, in many instances. I have noted though, over the five-year period of rust screening, that these cultivars also have produced the most offspring with this same or nearly-as-high (shows some rust, but never much - heterozygosity for a dominant gene with slightly lower penetrance?) rust resistance. I think these are important plants and I hope to continue to gain anecdotal reports on them, whether those reports are negative or positive observations of rust resistance. It is especially important to look for instances of resistance failure in these individuals, as well. I would be happy to communicate with anyone interested in these cultivars. I want to stress, that while this listing is beginning as things I am offering, many of these are in very short supply and as they sell out, I won’t replace those plants. I will however, keep their pages up and offer them as information for those looking to learn about that cultivar. 

It is more important to me that you try these things than that you try them from me, but either way, please let me know your experiences. It is important to know what others are observing. In that way, we could start to build enough long-term information about a cultivar to have some idea of its range of usefulness in terms of breeding value and the possibility of longterm resistance to rust. I have collected anecdotal reports through testimonials online and through private correspondence. I hope to keep gathering reports. Even though I am not going to be actively testing for rust any further in my garden, I still want to keep up with reports. I hope to make approximately yearly additions to the pages of any cultivars I have received information about (scientific or anecdotal) in a given year. My goal is to bring together as much information as is known along with as many observations as I can gather and see if there are major trends that continue over time. Perhaps at some point in the future, if there is enough gathered information to suggest trends, someone in the plant research profession may want to perform the lab work to see if known genes for Puccinia resistance/suscpetibility have analogs in these Hemerocallis, or if such genes can be located in the Hemerocallis through basic comparison with know locations in model organisms such as Arabidopsis or Tricertum (wheat).

If I am temporarily sold out of any of these cultivars, or have permanently sold out of a cultivar or am simply not shipping when you need to plant, check my Articles and Links page for links to sellers. Many of these older, resistant cultivars are ubiquitous in commerce and easily sourced. Things like Frans Hals, Chicago Apache, Kindly Light, Spider Miracle, Mardi Gras Parade, etc., are widely available. A lot of these resistant cultivars I either don’t have much of or I am still breeding from them and so I only have a certain amount of stock that is available for division. There may be more availability on some things in fall as I am able to make further cuts in breeding plants. I encourage you to try the cultivars I list below, no matter who you get them through. Watch out at box stores, nurseries, plant swaps, or order a division from some of the sellers in my links. There may be multiple clones of some things out there - Kindly Light comes to mind, so every accession of the ‘same cultivar’ may not truly be the same clone. See my Articles and Links page for sources.

If you are interested, here is Some More Thoughts on Rust…

These cultivars are divided up into four main sections:

1.) Seeming-immunity (never seen spores no matter how hard I have worked to make them appear - these may prove to be less resistant in other gardens or when in contact with strains of rust different than those they may have been exposed to in my garden from 2012 through 2016)
2.) High Resistance (even when variable, these cultivars have stayed in the higher range of resistance while still showing rust. Some have been consistently rusty each year, while others may have shown some variation or have even shown no rust sporulate in a given year, appearing to be immune in that instance, only to have failure and sporulate in other years. However, sporulate never has gone below a ‘B’ rating on any of these in my garden)
3.) Resistance (consistently resistant, but only moderately or sporadically. Some of these may show consistent moderate resistance over the whole test period, or swing between more resistant or more susceptible in some years)
4.) Tolerant (susceptible but seemingly not diminished by hosting the rust fungus - some of these tolerant types may also have shown some breeding value for more resistant seedlings in my program - noted where so)

These observations are based on a combination of my personal experiences screening cultivars for rust resistance from 2012 through 2016, inclusion in published studies and/or anecdotal reports from other gardens. None of that is proof of anything. More research and many more reports are needed to attempt to gain a wide-angle view of the question of why these observations have been made and how long they might continue. Understanding that rust is not one pathogen but many and that any given genes may only encompass resistance to some of those strains, we want see if there is data to establish that some of these cultivars and their descendants show genetic factors at work, and real-world resistance in many gardens. Even one failing anywhere in the US is important to consider, but one report amongst hundreds to the opposite range of experience may be considered but should never completely disqualify an otherwise useful plant, as it may be an artifact of environment, an interaction of gene failure and environment or merely an analogous situation. Building upon multiple reports is where confidence might be found to the usefulness of some of these traits and their possibly underlying genetics. 

Reality tells us everything is going to fail somewhere, so when that happens, it is a piece of datum, not a deal-breaker. The plant that has resistance to 23 strains of rust but susceptibility to three other strain still shows remarkable resistance. The plant that has resistance to two strains of rust, but susceptibility to five still has some resistance, but at a lower level of expression. Please let me know about your experiences!


High Resistance

Prairie Blue Eyes (dip and tet)