Breeding for Rust Resistance in Daylilies: Part 12

Breeding for Rust Resistance in Daylilies: Part 12

In Conclusion

So now we come to the final post in this series. In the previous eleven posts we have looked at a wide range of subjects relating to rust and selecting for rust resistance in daylily breeding programs. It is my hope that these posts have been of benefit to you and that some few of you who have read them may now make use of some of this information and apply some of what I have offered herein to your own breeding programs. 

I would like to make a short review of what I consider to be the most important points made throughout this series.

1. Rust is now an inescapable reality on the North American continent. We have it, so there is no going back to the old pre-rust days. Even for those in climates cold enough to kill all foliage and suppress rust each winter, rust may still enter your areas through shipped daylilies or through the use of greenhouses. For those of us in warmer climates, even when an exceptional winter suppresses rust for one year, rust is still a reality and no single harsh winter is going to permanently eliminate rust. Rust is a reality we all face and the further south you go, the more persistent that reality is and the more extreme the impact.

2. There is resistance to rust in the daylily population. While resistance levels will vary from cultivar to cultivar, and may even vary from garden to garden or year to year, depending on the environmental factors at work and/or the strain of rust present, there is some consistent resistance amongst some cultivars and that resistance appears to have a genetic, and thus heritable, basis.

3. As rust resistance appears to have a heritable basis, active breeding and selection for rust resistance can be practiced. Simple Mendelian segregation ratios should not be expected, and we should be realistic and look for individual resistant seedlings, rather than being focused on a more idealistic goal of developing "resistant lines". While there is some circumstantial evidence that some family lines do exist that show higher than average percentages of resistant individuals, a more realistic and basic breeding goal is to simply select resistant individuals. Equally important is the reduction of the use of very susceptible individuals in breeding programs, except perhaps in 'salvage programs'. Finally, of equally great importance is the reduction of the number of susceptible individuals that are introduced as cultivars and put on the market.

4. It is important to remember that the term 'resistant' it not synonymous with 'immune'. They are different things. Further, 'susceptibility' and 'resistance' are broad terms that do not simply define one particular phenotypic expression, but represent a bell curve of phenotype variations with the two terms representing the extreme ends of the spectrum with many variations in between. Further, tolerance means the ability to tolerate the presence of rust without severe repercussions and lack of tolerance means those that suffer severe repercussions due to the presence of rust that can range from suppression of vigor to death in some specific environmental situations.

5. There is known to be more than one strain of rust. Rust will continue to mutate, but it is highly likely that one cultivar or another may show resistance to any given rust mutation. A daylily resistant to one strain of rust is valuable for breeding even if it shows lack of resistance to another strain of rust. The ultimate goal would be a layered or pyramidal resistance that combines multiple forms of genetic resistance into one individual. 

6. You need to make observations in your own garden when rust appears and develop your own observational system and approach to breeding and management based on your own experiences. The information I have imparted to you in this series is my experience, my basic approach or system and the gathered anecdotal and peer-reviewed information that I have been able to find. This information is presented to give you a jumping off point, tools to help you develop your own approach, for use in developing your own program based on your needs, interest, and available space and time. The information I have presented here is not set in stone. 

7. Any cultivar listed as resistant, immune, susceptible, etc, is merely a guide and may not apply to all situations or all strains of rust. You need to find what is best in your situation and work from there. Further, a cultivar that shows excellent resistance in one year, but susceptibility in another, may have encountered different environmental conditions or a different strain of rust. Don't be too hasty in eliminating a cultivar from your program due to variability between its response in one year or another. A better view is gained of resistance if the cultivar is observed for many years in one particular setting. Any list of resistant cultivars is merely suggestions and is presented as a guideline and no cultivar therein will be resistant permanently in all settings or all years. 

8. There is considerable difference between the approach of an average gardener, a collector, a seller and a hybridizer. Each will have different needs and may also have different approaches. The average gardener may choose to eliminate susceptible cultivars and may want to focus on only maintaining resistant cultivars in order to not have to spray and to keep a neat and attractive garden setting. Collectors and sellers may choose to maintain susceptible cultivars and may also spray, with sellers in most states being required to spray, at least for part of the year. Hybridizers who have any interest in increasing resistance to rust in their program will need to maintain susceptible cultivars, but are advised to not breed from such any more than is absolutely necessary (salvage projects). While hybridizers who are also sellers may be required to spray, those who can forgo spraying are in the best situation to observe actual resistance levels and make selections toward resistance.

9. Your location will determine how you will approach your resistance breeding project. Those in the most rust prone areas, where rust is present in spring and fall, have the very best environment for rust resistance selection. They can engage in an active resistance breeding program. Those in less rust prone areas or in the far north (and who do not use a greenhouse) are less able to actively select for resistance and are usually only able to participate in a passive program.

10. An active resistance selection program requires rust (at least in the fall and better if in fall and spring) yearly and requires no spraying so that all plants are equally exposed to rust and can reveal their resistance levels. A passive program involves the use of known resistant cultivars as breeders, rust present in the garden on occasional years, no spraying when rust does appear and active observation and notation of the performance of the resistance levels of the cultivars and seedlings in the garden with the use of the most resistant in the breeding program. Passive programs may also send seedlings into more rusty environments for testing and the gathering and recording of anecdotal evidence from those growing the plants from that program is also important. Finally, in a passive program, it is very important to keep up with information on resistant cultivars and advances in research as well as exchanging information with other breeders.

11. Greenhouses are an excellent way to keep rust active in a northern program and can allow a northern breeder to maintain rust for an active resistance breeding program.

12. Sprays will suppress the formation of rust spores, but do not kill rust. Some sellers are required by law to spray. This is unfortunate, but unavoidable where that is the case. As spraying does not kill rust, but only suppresses spore formation, any plant can still carry rust even if sprayed to control rust. As sprays are expensive and environmentally questionable, I do not advocate spraying for anyone who is not legally required to spray. I would recommend anyone who does use sprays or is considering using sprays to look into some of the side effects on the environment and beneficial insects of fungicides. Recent research suggests that many fungicides may play a role in bee colony collapse syndrome among other problems. This makes spraying even more questionable to me, especially since spraying does not kill rust, but only suppress spore formation. You will have to decide where you stand for yourself.

13. Keep researching. New information appears. Keep on top of it. This is especially important for those engaged in more passive programs.

What I have presented here in this series is a starting point. I have presented you with tools to use in developing a resistance breeding program, passive or active, of your own. However, this is not the final word, nor is it comprehensive. I have shown you my thoughts, feeling and observations - shared my methodologies and understanding. Now you need to develop your own.

I hope that even a few who have read this series of posts takes this information seriously and begins to apply even a small amount of it in their own programs, but I can't force you to do that. All I can do is lay out the basic points and then you have to pick up the ball and run with it. Most of you probably won't. It is too easy to spray, or ignore it, or feel that your cold winters insulate you from concern, but if even one for every thousand readers makes some effort, that is more effort than was being made before.

I believe that in time, this subject will become unavoidable for all of us, but I also hope I am wrong. Time will tell. I know that selection produces results. I also believe that those who do not ignore rust and who apply even some of the information I have presented in this series will be ahead of the curve and will be better prepared if we do see a rustier and rustier future. I leave it to you now to do what you will.

Breeding for Rust Resistance in Daylilies: Part 11

Breeding for Rust Resistance in Daylilies: Part 11

This installment will offer a list of links to websites, as well as a couple of books and a movie, that I think are of value in learning more about daylily rust, breeding for resistance to diseases in plants and plant rusts in general. This is not a complete list. There are many more sources of information on rust, breeding and genetics and the Puccinia genera. I would encourage anyone interested in any of these subjects to constantly research. New information can emerge at any moment. 

References and Recommended Reading

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Specific Information Regarding Daylily Rust

Resistance of Daylily Cultivars to Daylily Rust Pathogen, Puccinia hemerocallidis - HortScience 38(6):1137-1140, 2003, Mueller, Williams-Woodward, Buck. University of Georgia, Department of Plant Pathology

(Includes a list of resistant cultivars)

http://hortsci.ashspublications.org/content/38/6/1137.full.pdf

Microscopic and Macroscopic Studies of the Development of Puccinia hemerocallidis in Resistant and Susceptible Daylily Cultivars

Li, Windham and Trigiano, Dept. of Entomology and Plant Pathology, University of Tennessee, et al., 2007

(Includes a list of resistant cultivars)

http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-91-6-0664

Arkansas Daylily Rust Rating Field Study

(Includes a long list of resistant cultivars)

http://daylilies.uaex.edu

Cornell PDF on Daylily Rust

(Includes a list of resistant cultivars)

http://plantclinic.cornell.edu/factsheets/daylilyrust.pdf

Daylily Rust Information Page 

(Sue Bergeron’s Website - a great source of rust information online all gathered in one place)

http://web.ncf.ca/ah748/rust.html

AHS Daylily Rust Page

(A good general page on rust)

http://www.daylilies.org/ahs_dictionary/daylily_rust.html

Mark Carpenter’s Rust Information Page at the Lily Farm Website

(Viewpoint and advice from a large southern breeder with good information on sprays)

http://www.lilyfarm.com/rust.html

APSnet Daylily Rust Page

www.apsnet.org/edcenter/intropp/lessons/fungi/Basidiomycetes/Pages/DaylilyRust.aspx

Daylily Rust Yahoo Group 

(Run by Sue Bergeron and another good source of information in the archives and a place to ask questions)

http://tech.groups.yahoo.com/group/daylilyrust/?yguid=169754318

Maurice Dow’s Site on Daylily Biology and Genetics

(A very informative site focused on daylily biology and genetics. Maurice further elaborates on his AHS Journal articles here also. Very interesting!)

https://sites.google.com/site/daylilygenetics/

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Breeding for Resistance to Diseases in Plants and General Plant Genetics

CONCEPTS IN PLANT DISEASE RESISTANCE - FRANCISCO XAVIER RIBEIRO DO VALE, J. E. PARLEVLIET & LAÉRCIO ZAMBOLIM

(An excellent overview of resistance breeding in plants)

Fitopatologia Brasileira

Print version ISSN 0100-4158

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-41582001000300001&lng=en&nrm=iso&tlng=en

Principles of Plant Genetics and Breeding, George Acquaah, Blackwell Publishing. ISBN 987-1-4051-3646-4.

(This is an excellent book. You may need to filter out the industry propaganda and academic biases, but it is an excellent book non-the-less. I highly recommend it)

Amazon link - http://www.amazon.com/Principles-Genetics-Breeding-George-Acquaah/dp/1405136464/ref=sr_1_fkmr0_2?ie=UTF8&qid=1383608905&sr=8-2-fkmr0&keywords=George+Acquaah+-+Principles+of+Plant+Genetics+and+Breeding%2C+569+pages%2C+2007%2C+Blackwell+Publishing+%28%2499.95%29.+ISBN+987-1-4051-3646-4.

Breeding Plants for Disease Resistance: Concepts and Applications - R. R. Nelson

(An older book, but actually excellent for that very reason. Written before the advent of modern lab techniques, this book focuses on actual breeding methods for increasing resistance in domestic populations)

Amazon link - http://www.amazon.com/Breeding-Plants-Disease-Resistance-Applications/dp/0271011416

Michael Pollan - The Botany of Desire

(This is a fantastic book and movie that looks at the domestication and breeding of four genera of domestic plants. The sections on apples and potatoes are particularly relevant as there is considerable discussion of disease resistance breeding in both of those sections)

-PBS site about the movie

http://www.pbs.org/thebotanyofdesire

-Amazon Page for the Book

http://www.amazon.com/The-Botany-Desire-Plants-Eye-World/dp/0375760393

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Rust in Other Species

Puccinia Page @ Wikipedia

(A nice short overview of Puccinia)

http://en.wikipedia.org/wiki/Puccinia

USDA Cereal Rust Page

(Lots of information on rust in cereal crops)

http://www.ars.usda.gov/Main/docs.htm?docid=9854

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In the next and final installment of this series, I will review the points we have touched on in this series as well as looking at a few final points I would like to mention.

Breeding for Rust Resistance in Daylilies: Part 10

Breeding for Rust Resistance in Daylilies: Part 10

In this entry we will look at species clones, family lines and individual cultivars that have been said to show resistance to daylily rust.

A Short Look at a Few Cultivars

In this section I want to look at a few family lines that seem to have shown regular resistance in many settings and situations over many years. There won’t be many of these of course, because we have not been able to get enough data from enough growers to have a lengthy list of cultivars that meet this criterion. These cultivars will tend to be older cultivars, as will many of the members of their family lines. In addition, we will look at a list of cultivars that seem to show resistance, but have less evidence. Some of these cultivars come from surveys, some from lists compiled by growers from their own experiences, others derive from private conversations and others are from my own personal experiences in my own garden. None of this should be taken as proof of resistance, but rather as a starting point to help you find cultivars to test in your own garden setting. The cultivars on this list will be of any age range, from older cultivars to newer cultivars. These are not presented as a comprehensive list, but as a starting point only, and these are but a small sampling of what may be out there that shows resistance.

Beyond what I will discuss here, I strongly recommend that you do your own research into resistant cultivars. There are several sources online where some information is available. One good source is the All Things Plants daylily database. There are a number of the cultivars listed there that also show rust resistance or susceptibility data. It may not all be ‘proven’, and some of it will not be accurate or will not be accurate in all settings or in the face of all forms of rust, but it does give you a good place to start and is free and easy to use. I will list all the Internet rust resources I know of in the recommended reading list in the next installment.

Before we get started there are a few issues I want to comment on. The first is about the use of older cultivars. We often see older cultivars criticized for use as breeders, labeled as ‘useless to real breeders’ and generally treated as if they had no good traits to offer. This line of discussion though may say more about the limitations in understanding genetics of the accuser than it does about the actual usability of older cultivars. While it is true that older cultivars may be considered retired or obsolete, anyone with even a cursory knowledge of genetics should know that what is commonly labeled as “advanced traits” is the concentration of major genes with minor modifier genes. While these factors can be dominant, it is not uncommon for some or all of the factors involved to be recessive. With dominants, it can be rare for the heterozygous state to be fully penetrant, and with the recessives, we cannot expect to see them visually when heterozygous. 

So when we cross an individual with ‘advanced traits’ to one that does not express these traits or only shows part of the fully advanced trait(s)  (i.e., “older cultivars”), we can’t expect to see the full expression of the ‘advanced trait(s)’ in the first generation (F1), but we will have plants that carry those genes or show partial expression. Such F1 plants then are bridge plants to recombine the modern trait(s) with other desired traits brought in from an older or less advanced individual. You will hear people say that in such a cross you “loose your fancy traits”, but that simply isn’t true. It is true that you might not see the traits fully expressed in that generation, but the genes are there and can be brought out in the next generation along with other desired traits combined.

When someone tells you that you are wasting your time or ‘re-inventing the wheel' to use an old cultivar, ignore them. They may know how to accentuate one trait or another, but they do not have a comprehensive understanding of breeding, in the broader sense. Sometimes the wheel needs to be re-invented. In the area of disease resistance, and rust resistance especially, I say that the wheel most definitely needs to be re-invented! Among those daylily cultivars that we have the most data concerning rust resistance about, the majority are older cultivars because they have been around long enough to occasionally have some consistent and long-term data gathered about them. 

While a new cultivar may show resistance to rust, perhaps even in many settings, what it lacks is documented long-term, consistent resistance. In that regard, the older cultivars are perhaps more reliable to turn to when starting out to bring resistance genes into your breeding program. In addition to older cultivars having a better track record of resistance, they are perfectly usable for a number of breeding projects. For instance, old cultivars can offer proven hardiness, vigor, some will have great branching, others will have very sun-resistant flowers, some show very high fertility, others may have very nice foliage or very dormant foliage. What they won’t have is the most extreme flower combinations as seen in the “latest-and-greatest”. If the flower is your only concern, they may not offer much interest or use for you, but if you are concerned about anything beyond the flower (especially rust resistance), then old cultivars (and even species clones) can offer a plethora of breeding opportunities, are easily accessible and are available at affordable prices at that.

The second point I want to touch on is concerning new resistant cultivars. As new cultivars are introduced that show resistance, they are of great use. However, do not throw out the older tried-and-true cultivars that have consistently shown resistance over many years, as the new things may not be consistent over the long haul. The wisest approach is to cross the new resistant cultivars with the older ones and/or into the lines of resistant seedlings you have been breeding up in your own program. In that way, you are concentrating resistance genes, rather than just relying on the “latest-and-greatest” introductions for resistance. This will be even more important if people start introducing ‘patented’ and ‘lab-proven’ resistant cultivars at some point in the future. Rather than convert your work over to these ‘proven’ cultivars to come, have your own lines going that these cultivars can then be bred into and concentrate the genes for resistance that may be found in all the potential sources.

The third and final point I want to make is that ‘resistance’ may not prove to be a constant, nor will it apply in every situation. So, if it is genetic, how is that possible, you may ask? Well, the given environment can influence the expression of those genes, and all rust is not the same. By the latter I mean that there is now known to be multiple strains of rust, so every cultivar that showed resistance to one strain of rust may or may not show resistance to another strain of rust, so there is no way to make a list of cultivars that will be resistant in all circumstances and for all time. As well, in certain environments, a plant may show susceptibility to a strain of rust it has the genes to be resistant to, if the environment does not support that resistance. An excellent example of this is that a cultivar growing under great stress may show more susceptibility to rust, even if it is normally resistant - example - a hard dormant growing in a zone that does not allow it to go through a proper dormancy (i.e., a "hard dormant" in south Florida). Bear all these things in mind as you read over the following discussion of cultivars.

So with all of that said, let us now look at some cultivars that have shown reliable resistance over several years. If you want to know more about any given cultivar mentioned below in terms of registration information, registered offspring, color/pattern, ploidy, foliage type, etc., please do a search for any of these at the American Hemerocallis Society Database, Tinker’s Database or All Things Plants Daylily Database. You can find much useable information at all three sources and I use all three a great deal. Also, don't forget that at the All Things Plants daylily database, you can do a search for resistant and susceptible cultivars in their advanced search engine.

Species

In reading through many message board archives and various websites I have repeatedly seen the statement that there are no daylily species that are resistant to rust. This is incorrect and there are two major flaws in the statement. The first is that ‘resistance’ seems to be used in these statements to indicate ‘immunity’ and the second is that there are several clones of a few daylily species that show high resistance. The species that seem to show the most resistance are Hemerocallis fulva and Hemerocallis citrina and its allied species Hemerocallis vespertina.

Amongst the fulva complex, there are several clones that show very high resistance and possibly even immunity. The fulva clones ‘maculata’, ‘Hankow’ and the Korean form brought to the US by Apps in the 1980’s all have shown very high resistance in many settings, while the related species Hemerocallis sempervirens also shows resistance in many gardens in the US while showing some susceptibility in other environments. The well-known clone ‘Europa’ shows good to average  resistance, not as high as some of those clones previously mentioned, but still enough to be considered to show some resistance. Other fulva clones may also show resistance, and I have had reports that both of the double-flowered fulva clones show some resistance. However, all fulva clones do not show resistance and the clone ‘Cypriani’ has been observed to be very susceptible in many locations.

The citrina complex has many clones, many of which are not known in the west. As the citrina complex is a food crop in many Asian countries, it is likely to encompass many domesticated clones of the species. Here in the US though, we do have multiple clones of the species. I have worked with four clones, all derived from Joseph Haliner. As well as the actual citrina clones, there are the closely related species vespertina and altissima, and both are known in the US. Some of the clones of citrina have shown very high resistance to rust, as has vespertina in some gardens in the US. Altissima has shown less resistance, but still not high susceptibility. While citrina clones may show susceptibility in some clones, I have not heard of high susceptibility in any of those grown in the US, though it is certainly possible that there are clones that are very susceptible that I do not know about. My contacts in China have indicated that there is variability in resistance levels to rust of the many clones of citrina grown there with some being very resistant and others showing susceptibility of varying levels.

It seems obvious to me that some species of daylily would show some levels of resistance to rust, as these two life forms would have evolved together over a long period of time, with each constantly mutating to ‘outwit’ the other. I want to be clear that I am not saying any of the species clones are necessarily 'immune', but rather that some show resistance with variable levels that may be useful and some may even represent genes for resistance that may no longer be found in the domestic population. In many resistance-breeding projects in a great number of plant species, turning back to the species has been shown to reclaim important genes that may have been lost in the domestic population or to obtain those resistance genes that never were in the domestic population to begin with.

Many reading this will snarl at the thought of going out to species types and “ruining all their advancements”. While I think those willing can derive good benefit in going back to species at times (and not just for rust resistance) I am not suggesting anyone who doesn’t want to should. The reason I mention the species and those species clones that show resistance is because I feel that much of the resistance we see today in the domestic population derives directly from those species in their ancestry. There is certainly enough resistance in the domestic population, old and new, to not have to go back to species unless you want to, but I feel it is important to acknowledge the resistance in the species as we move forward and look at the domestic population.

Family Lines

Moving on from the species, and bearing in mind that those species mentioned above are in the background of many of our hybrid lines, I want to look at certain cultivars that have produced a good few offspring and descendants that also show resistance. To me, based on my experience and background in resistance breeding, this is the most important anecdotal evidence we have that there is a strong genetic component to the entire spectrum of rust response. I want to stress that just because a given cultivar may be resistant and the family that is related to it or descend from it has numerous members also showing some level of resistance, this is no reason to assume that every individual seedling, descendant or relative will be resistant. I have personally never seen or heard of the cultivar that can produce 100% resistance in its offspring.

Theoretically, it might be possible that a given cultivar with homozygosity for all its resistance genes might produce identical resistance in 100% of its offspring if selfed or bred to another cultivar with all the same genes and those genes also each homozygous, but this would be exceedingly rare. I am in no way claiming such for any of the family lines I describe below.  So be warned that just being part of one of these family lines, descending from one of these cultivars, does not ensure resistance. The point I am making is that there are already certain lines that show resistance in several generations of the line and in many individuals within that family. I do this both to illustrate the point that resistance seems to be heritable and to offer some suggestions for cultivars and family lines you might find useful for resistance breeding due to their track record, as well as encouraging the development of more family lines like these, developed also from resistant cultivars or seedlings with good breeding value. Be aware that every seedling from these will not thus be resistant, you will still have to expose them to rust and select for resistance, but we can see that each of these lineages offers resistance that is demonstrably heritable.

One important family line descends from Super Purple (1979 - Dove). This cultivar and many of its offspring and descendants including Grand Masterpiece, Big Apple, Crayola Violet, Mathew Dove, Regal Finale, Woodside Ruby, Super Honor, Super Magician, Uncle Bryan, Which Way Jim, Nowhere To Hide, Laura Harwood, Bela Lugosi, Nosferatu, Paint It Black and Mountain Majesty, just to name a few, show good to high resistance to rust. With so many descendants of Super Purple showing resistance, there seems to be a strong indication of genetic heritability in this line.

Another cultivar that has produced some very usable individuals is David Kirchhoff's lovely cultivar Forever Red. Being very resistant itself in many settings and over many years, its offspring Insider Trading is also exceptionally resistant and is a more modern style of flower with many good qualities.

Also in red tetraploid cultivars is Chicago Apache. While not immune, it does offer usable, good resistance and many of its offspring also show good resistance. As you will discover over time, there are a great many red cultivars, both tets and dips that show good to high resistance. Now let me be clear, I am not saying that ‘all reds are resistant’, far from it, but a great many are, enough to stand out, and I would conjecture this may be from the general descent of all red cultivars from the fulva clone ‘Europa’ that also shows some resistance.

Amongst tetraploids that show fancy edges, there is one very important cultivar and its family lineage that has many rust resistant members - Ruffled Dude. Amongst its many important rust resistant descendants are Ida’s Magic and Betty Warren Woods, with both having produced numerous rust resistant offspring of their own. The influence of this line on the modern edged cultivars can’t be overstated and there are many latest and greatest cultivars that will be revealed to descend from this line when you trace them back far enough. That, however, does not ensure that they are all rust resistant! A second edged tetraploid that is resistant and has been very popular and has produced a large number of resistant offspring is Ed Brown. 

A warning word about both lineages, though, is in order. Ed Brown is known to also carry a propensity toward crown rot, so its offspring should be carefully evaluated for this trait. As well, the Ruffled Dude lineage, especially through Ida’s Magic has also produced some offspring with the propensity to crown rot, and as with Ed Brown descendants, care should be taken to evaluate offspring of this line for crown rot as well as for rust resistance. With that said, though, I still encourage you to consider rust resistant individuals of these lines, especially those that don’t show a tendency toward rot.

Another diploid family that includes many tetraploid conversions, which seems to show a higher-than-average level of resistance is the When I Dream family. I have already mentioned Big Apple, Uncle Bryan and Which Way Jim in the discussion of Super Purple. In addition to those cultivars, another very important descendant of When I Dream that shows good resistance is the Richard Norris cultivar Substantial Evidence, as well as some of its lovely offspring.

In spider formed cultivars, the Kindly Light family line has produced many resistant members. However, I would note that I have seen some information indicating that Kindly Light and family may carry some tendency toward crown rot (though I have never witnessed it) and one source has told me that Kindly Light and kin can be susceptible to spring sickness (which again, I have never seen) in some gardens, while another source who regularly has spring sickness in her garden says that it is one of the most resistant cultivars she has ever seen for spring sickness, so I can only guess this is variable by region and environment also. While neither of these problems are a major issue for me, because they are important to other breeders and growers in other parts of the continent, I want to point those potential issues out to you. 

With that said, I have found that the Kindly Light family shows excellent resistance. Such cultivars as Aldersgate, Baitoushan, Boney Maroney, Cat’s Cradle, Claws, Divertissement, Gadsden Goliath, Nashville Lights, Cherokee Vision, Garden Party, Orange You Clever, Orange You Special, Spider Breeder, Tigereye Spider, Watchyl Dancing Spider, and Zip Boom Bah are just a few examples. It is thought that Kindly Light has descent from H. citrina.

An important older cultivar that has produced some notable offspring with many of its descendants being rust resistant is So Lovely by Lenington. A near white semi-evergreen diploid that is extremely hardy and exceptionally vigorous, among its resistant offspring are Starsearch and Frozen Mert, while So Lovely's most famous descendant is the very resistant 2013 Stout medal winner, Heavenly Angel Ice. (A photo from my garden of this lovely cultivar, Heavenly Angel Ice, can be found at the end of this post.) I have been told by several persons that So Lovely is exceptionally susceptible to spring sickness, so that should be considered when using it, but this susceptibility is not shared by all its descendants, so with care, So Lovely can still be a useful breeder for rust resistance.

There are undoubtedly other family lines that have a higher than average number of individuals exhibiting resistance, just as there will also be family lines showing higher than average susceptibility to rust. More importantly, there are family lines waiting to be created by you, the breeders of daylilies, through the use of resistant cultivars that may not have as yet been well used. The ones listed above are those I am most familiar with and have both found and received the most data about, both in the university studies and through anecdotal information. It is likely that any resistant cultivar could found a family line of many resistant offspring, if that cultivar shows good breeding value for both resistance and desirable flower and plant traits.

Finally, I strongly encourage you to look at pedigrees. All three website mentioned above (Tinkers, AHS Database and All Things Plants Daylily Database) are excellent sources of information on the descendants of the lines I have mentioned above. All Things Plants will even offer rust ratings for some of the cultivars in their listing, so it can be especially helpful when researching descendants of these family lines.

A Non-comprehensive Listing of Seemingly Resistant Cultivars

About Older Cultivars - There are many more old cultivars that are known to have resistance than there are newer ones. While there are likely a good many new cultivars that have resistance to some extent, these may not be as well known for their resistance and they may not have shown resistance over the course of many seasons or in a wide range of gardens. Time hopefully will reveal those cultivars to us, but they won’t be new either by that time. To use a newer cultivar that shows resistance is good and useful but the older, more verified cultivars have an important place in a resistance breeding program, at least in the building of base lines for breeding more advanced types with resistance, for outcrossing to newer cultivars that also show some resistance and for using in salvage projects with very advanced, but poorly resistant cultivars.

About Newer Cultivars - This will be a much shorter part of the list, as there is little data available on most new cultivars. A few breeders will make mention of the resistance levels of a few cultivars, but the only person I know of who is consistently doing this with their new introductions is Ted Petit. Those cultivars of Mr. Petit’s breeding that I grow have been consistent with the resistance levels he has listed for them. I commend him for doing this and congratulate him on the effort he is making in this important area while still turning out advanced and beautiful flowers.

I am very careful about adding new cultivars, as there is nearly no way to even guess if they will show resistance or not. For that reason, I am very cautious. When I consider the prices of most new cultivars, I just am not willing to take the risk to either end up with something useless to me or another salvage project. So for new cultivars, I rely on those few reports I find or receive and those few breeders/sellers who actually mention the resistance level they have experienced with their or another’s new cultivar(s), or are willing to honestly share that information with me.

Below is a list of 150 cultivars that have shown good to high rust resistance. Please bear in mind that this is not a comprehensive list, and is just a sampling of cultivars that have some data out there about their resistance, that I have had some experience with and/or that I have also received anecdotal reports from other growers about. These cultivars may not be consistent in all settings nor will they be consistent with all strains of rust. These are not peer-reviewed findings, nor has the resistance of any of these cultivars been ‘proven’. Many have consistently shown reliable scoring over many years and in many gardens and many of them have also been shown to be able to pass their apparent resistance on to some of their offspring. This is not a complete list of all the cultivars known to show some resistance, nor is it a complete list of those I am experimenting with, but it does represent a nice mixture of ploidy, ages, colors, patterns, forms, foliage types, etc. 

There are undoubtedly many more cultivars that show resistance that simply have never been evaluated or recorded and mentioned in public, but it is beyond the scope of this series of posts to attempt to assemble a complete and up-to-date listing. Please note that these are not listed in any order: alphabetical, by resistance levels, by ploidy, flower form, color, or any other system. Finally, I am not listing a specific "rating level" with any of these, as I think such ratings are often speculative, they can vary depending on the environment and the rating under one strain of rust may be very different when exposed to a different strain. I have seen conflicting reports of exact rating levels for some of these cultivars and have also seen variations amongst their levels, but in all cases, none of these have shown above average susceptibility or have been highly susceptible in my experience or in any listing I have seen. This list is only a starting point.

1. Jocelyn’s Oddity
2. Lily Munster
3. Early and Often
4. Kanai Sensei
5. Wild One
6. Pack Hunter
7. Grape Velvet
8. Little Grapette
9. Parallel Universe  
10. Pretty Graphic  
11. Mercedes
12. Milk Chocolate  
13. Orange You Clever
14. Spider Miracle
15. Debary Canary  
16. Rosy Returns
17. Night Wings
18. Insider Trading 
19. Chicago Apache
20. Bela Lugosi  
21. Sir Modred
22. Velvet Eyes
23. Pacific Rainbow
24. Brave World
25. Laughing Clown
26. Wilson Spider
27. Nanuq
28. Heavenly Final Destiny
29. String Bikini  
30. Chocolate Dude
31. Galaxy Explosion
32. Lusty Little Lulu  
33. Siloam Merle Kent  
34. Untangle My Emotions
35. Ancient Elf  
36. Notify Ground Crew 
37. Forever In Time
38. Heavenly Angel Ice
39. Dad’s Best White  
40. Spacecoast Sea Shells
41. Lavender Arrowhead  
42. Mama’s Cherry Pie
43. Spacecoast Royal Rumble
44. Autumn Minaret
45. Rainbow Candy
46. Oceans Eleven
47. Long Tall Sally
48. Grand Masterpiece
49. Startle
50. Mississippi Red Bed Beauty
51. Stare Master
52. Clean Slate
53. Alabama Jubilee
54. Bill Fall
55. Lavender Stardust
56. Super Magician
57. Priscilla’s Rainbow
58. Peacock Maiden
59. People’s Pleasure Palace
60. Nosferatu
61. Divertissement
62. Trade-Last
63. Plastic Pink Flamingos
64. Crazy Miss Daisy
65. Which Way Jim
66. Persian Ruby
67. Betty Warren Woods
68. Mister Lucky
69. Laura Harwood
70. Prince John
71. Men In Black
72. Fortune’s Dearest
73. Adena Inferno
74. Long Stocking
75. Aldersgate
76. Lynn Penn
77. Edna Selman
78. Red Hat Diva
79. Sour Puss
80. South Sea Enchantment
81. Ferengi Gold
82. Coral Majority
83. South Seas
84. Brocaded Gown
85. Gleber’s Top Crème
86. Buttered Popcorn
87. Karen Stephens
88. Spacecoast Dark Obsession
89. Spacecoast Irish Illumination
90. Megatron
91. Wild Wookie
92. Siloam Mama
93. Big Apple
94. Whale Tails
95. Love Comforts the Soul
96. Charlie Pierce Memorial
97. Key To My Heart
98. Rachel Billingslea
99. Tuscawilla Tranquility
100. Groovy Green
101. Green Flutter
102. Strutter’s Ball
103. One Step Beyond
104. Water Drops
105. Mint Octopus
106. Sunday Gloves
107. Almira Buffalo Bone Jackson
108. Witches Wink
109. Devil's Footprint
110. Lady Neva
111. Tangerine Horses

It is important to reiterate that I am not saying that any of the above cultivars are "immune". Some of them will be highly resistant in one garden, but not as highly resistant in another. Some will have high resistance to one form of rust, but less resistance to another form of rust. These should be givens, but I want to spell this out. There will be variations of resistance, not only amongst the cultivars on the list, but even with any given cultivar depending on the strain of rust to which it is exposed and the environment in which it is grown. This list is merely presented as an example, a random sampling, of cultivars showing resistance, to both give you a starting point in looking for resistant cultivars to grow and/or breed from and to illustrate that resistance is found in a wide range of cultivars, old and new, plain and fancy, tetraploid and diploid.

In our next installment, we will look at links and recommended reading.

Breeding for Rust Resistance in Daylilies: Part 9

Breeding for Rust Resistance in Daylilies: Part 9

In this post we will pick up where the last one left off and look at some tips and pointers I have for hobbyists, collectors and breeders who wish to pay any attention at all to the problem of rust in daylilies or who wish to pursue, actively or passively, a program of breeding for rust resistance in daylilies.

A Challenge and Invitation: Part 2

So what are my suggestions for those who would try?

Know your area and what might work for you. Obviously, if you are in the north, you can’t actively breed for rust resistance, because you are not going to consistently have rust in order to do so. If you get rust every year, but only in the fall, you still don’t have the conditions to do a full-on resistance program as would someone in the south with spring and fall rust, but if you are getting rust consistently most every fall, you can still make strides toward more resistant seedlings and the removal of the most susceptible seedlings from your population. This is a big thing and not to be underestimated, just because it is not the most extreme project that can be pursued by more southern located breeders.

However, with that said, if you are in the south and have rust nearly year round, if you spray, you can’t resistance breed, and if you only discontinue spraying in the fall, then you are creating an artificial condition that doesn’t allow you to take advantage of your location fully. That is fine, if that is your choice, but you still will not be getting the full advantage that your location offers. To take fullest advantage of near year round rust, you have to actually be exposing your plants to that nearly continuous rust cycle. Be warned, you will possibly loose plants, especially if you are in the most southern extremes of the country, but those that survive and show resistance under those extreme conditions will form the backbone of a true resistance-breeding project.

Educate yourself about cultivars. To resistance breed, actively or passively, you need to know what cultivars are already showing resistance and use them. To do this in your own collection, you must allow some rust exposure and you must evaluate your plants. Just one evaluation in a season is not really sufficient. You need to do an evaluation every week or two while rust is active to get a feel for how a given cultivar progresses through the season. While that season won’t represent ‘proof’ of a given resistance level, it will give you an indicator to work from. Another thing you can do is to talk to others who have been working with rust to find out about known resistant cultivars. You may even be able to get someone with knowledge of resistant cultivars to look over your accession list in order to point out what you have that is known to be resistant or susceptible.

To find other resistant cultivars, you need to look at the information that is out there. While there isn’t much, there is some: surveys, university evaluations, and anecdotal. Don’t discount the later. One of the most important things you can do is to talk to people, read threads on message boards, and see what people have to say about various cultivars. Ask questions! When you begin to hear the name of a given cultivar mentioned over and over by numerous people in many different locations as being resistant, take note. That one might actually be! Further, if that same cultivar also shows up on surveys and university evaluations as having resistance, it may turn out to be very usable for you.

Every report will not be found to be the same for you, but if even a few do, that will give you a basis to work from.  Finally, even if you aren’t breeding for resistance at all, you can at least know a few cultivars thought to have resistance to tell others, and if you happen to be a seller, it would be nice if you know that some of the cultivars you offer have been observed to have resistance or are susceptible so you can answer clients questions about either thing.

For breeders, listen to the reports of people growing your cultivars. If you can’t (or won’t) experience rust in your garden, this can be a valuable source of basic information to work from. I realize that these reports are only ‘anecdotes’ but they are a place to start, and if by chance you hear from several people that this or that cultivar has been resistant, there is a good chance that it is (or at least will have some level of resistance that may be usable for breeding). In time, enough anecdotes can be indicative of actual resistance. They at least give you a basis for further testing in your own garden.

Breeders please do publicize your observations and the received (anecdotal) reports of your customers. This is a point I think is important to make. Your anecdotal evidence, when added with that of others, is important. If you have observed a cultivar showing resistance or immunity or susceptibility, tolerance or lack of tolerance to rust, then those observations matter, and if by chance you have observed the given results repeatedly over the course of some years, it has even more weight. Now I do think it is important that you not treat your observations as absolutes. You don’t want to say, “I have proven that so-and-so is resistant or immune or whatever because it has been so in my garden for x# of years”. That is too definite, but to say that, “So-and-so has shown resistance or immunity or susceptibility, etc. in my garden (and in X# of my customers gardens, etc) during X# of years”, is perfectly acceptable, because you are making no absolute claims. You are not saying something ‘is’ this or that, but that is ‘has performed as’ during a given time in your garden (or other gardens you have been told about) for a given time period. 

You should also then report variations, so that if a given cultivar was strongly resistant for three years, then had a susceptible year (possibly another strain of rust?) then had a resistant year, you are not making absolute claims, but rather are offering your observations. If you want, you can also add a disclaimer that your observations are yours alone and may not reflect performance in other gardens.  Be clear, but pass on what you have observed. Just because the topic is ‘rust’ doesn’t mean it should be treated any differently than any other trait we select for. After all, many of you report your observations of say bud count and branching, even though we know they may not be the same in another garden in a different environment...

I don’t know of anyone in the daylily world who is afraid to make ‘claims’ or share their experience of things like branching, foliage type, fertility, breeding influences of a given cultivar on pattern, color, emo, or any other flower traits. Rust is not any different. The long wait for “proof” along with the scientific bludgeon of ‘unscientific’ has resulted in far too many hobbyists keeping quite about their experiences with rust and their observations of given cultivars. Imagine what the daylily world would be like if we treated every trait we select for with that same delicacy.

Now, I have to admit that I understand fully why so many clamor for ‘proof’ and why researchers have been skeptical. The claims of ‘rust resistance’ could easily be exploited for financial gain by the unscrupulous. It would be very easy for someone to have popped up and claimed rust resistant strains with no proof and have been claiming a premium for that claimed resistance. It is to the credit of the daylily world and a reflection of the honesty of the great people in the daylily world that this didn’t happen.

I would also add that I don’t see ‘rust resistance’ as being a trait to command a special premium. I think it is just another trait that daylily breeders need to be selecting for, where they can. I do think we need to be more open about our experiences, preface that they are merely our experiences and share those, letting go of fear of censure or attack as well as the prospect of our observations being ‘trade secrets’ that can eventually enrich us. We need to be sharing our knowledge and working to improve the plant we all love.

Be realistic about what you can do, but try to do something, no matter how small. Not every breeding program needs to be focused on the ultimate goal of 100% immune cultivars. That would be a worthy goal and a great thing to work toward, but to make that your expectation will likely lead to disappointment rather than a garden fully of nothing but rust immune seedlings. It seems inevitable that in time some researcher(s) may discover the gene(s) that offer both resistance and even full immunity to rust and from that, may be able to create cultivars (or even true breeding lines) of cultivars from those genes, but hobbyists, out in the trenches breeding by sight and experience, do not have the advantage of labs and funding, so we must proceed from a point that, while less controlled, can still give good and useable results, and even the best lab identification of a given gene offering rust immunity or resistance probably won’t apply to every strain of rust. So in that regard, whether in the lab or simply in your garden, all things are fairly equal in the sense that there is likely to always be a race against new strains of rust that make our old resistance genes obsolete, partially or totally. This has certainly proven to be the case in the examples of rust and rust resistance in other species.

For that reason, I don’t think the notion of waiting for the experts to ‘fix it’ is all that viable, and further, if someone does come along and introduce a ‘proven rust resistant’ strain, you can always breed those into your own lines. In effect, you are making preparations for the day when such ‘proven’ lines might become available. Just remember that no line of ‘proven resistant’ plants, mine, yours or those from a lab, are likely to remain that way forever, in the face of the constant evolution of new strains of rust. For this reason, I think a more realistic goal, and one fraught with far fewer pitfalls and less heartbreak, is to focus on good to high resistance with high tolerance to rust and the combining of many genes for resistance in the hopes of weathering the onslaught of many different strains of rust over time. Yet while this is my realistic approach, you should find yours.

At any rate, doing almost anything is better than doing nothing. What is realistic in the Far North is not realistic in the Deep South, and vice-versa. The important point I want to make here is that if we set the bar too high (a common failing in most places and endeavors), we almost invariably set ourselves up for failure. As I have pointed out in this series before, most gardeners and breeders aren’t too bothered by a bit of rust. It is the heavy rust coverage of the low resistance/highly susceptible cultivars as well as its negative impact on performance (and in some case survivability) that creates the most distress and the most severe problems we encounter with rust. In my view, the most realistic goal is to begin to move the genome of the genus toward resistance and away from susceptibility, and we can each make a contribution in whatever way we can, at whatever level is suitable to our location, situation, inclination and interest.

Remember that selection for rust resistance is just another form of selection, another trait amongst many you select for already. I can’t stress this enough. Yes, rust may have been a big, scary freak-out when it first emerged, and it may create the same response when you first have it in your garden, but by now we know that (except in a few very southerly locations) rust is not the end of the road. So now, rust is just another ‘problem’ many of us deal with, just like low bud counts, melting pigments, ugly foliage, etc. Consequently, resistance to rust is now a factor to select for, as any other. Don’t get too extreme (unless you just really want to or are in a situation where you can) and do what you always do for any other trait - make selections.

While that will not be considered a ‘resistance-breeding program’, you will be making your own small contribution and thus making a difference, even if only in a small way by simply removing the most rust susceptible. At the very least, you will be paying attention to your own plants and learning what shows the desired tendencies in your own garden. Beyond that, you can choose any level of project you want to pursue, setting your goals as low or high as you want. You just need to arm yourself with information and be prepared to make an extreme effort should you choose an extreme goal. In the end, whether simple or extreme, your goals will revolve around selection.

Have confidence! Nothing beats confidence for getting you through uncertainties. It is true for anything we do. Don’t have unrealistic confidence, but do know that you can increase the levels of resistance in your breeding projects. There will be naysayers who want to convince you that you can’t succeed. They could have any number or reasons. Those reasons aren’t important. What is important is that you stay focused on what you have chosen to do within your own breeding program. Remember, there are no ‘daylily police’ out there to force you to follow their dictates in your breeding program. If you let peer-pressure derail you from your goals, that is not really the fault of those others.

It will not be uncommon to encounter other hobbyists who want you to believe that resistance breeding is just beyond hobbyists abilities, way too hard to accomplish, something that can’t be done, there is no ‘proof’ for and just not important - just spray and don’t talk about silly pie-in-the-sky things like “resistance breeding”. On the other hand, you will encounter science types who are just as eager to derail your efforts. Now don’t get me wrong, I consider myself an amateur scientist and I work closely with PhDs and have for many years, but scientists, like all people, run the gambit from gleeful and light-hearted to dour and negative. That is human nature, and (even if they don’t all believe it) scientists are just humans too, with all the foibles and failings that implies. However, scientists will have a special set of tools for discouraging you.

First, they can use big words, talk over your head and generally make you feel stupid. They can use their favored bludgeon of declaring your efforts to be ’unscientific’. This can make you doubt yourself and your efforts, but you need to be very clear on what ‘unscientific’, as they use it, really means. While there may be a variety of meanings, it is generally meant that what you are doing doesn’t meet current scientific standards that would be used in a university or industry setting. What it doesn’t mean is that you can’t still be applying science in a more basic sense. You can use the scientific method without meeting current peer-review standards. After all, if your goal is merely to breed as a hobbyist, no matter how lofty the goal, why do you possibly need to meet peer-review standards?

The scientific method has four major points or procedures:

1. Formulation of a Question
2. Background research and formulation of a hypothesis
3. Testing the hypothesis through experimentation
4. Analysis of results

While these four procedures alone will not merit a project as ‘scientific’ by current industry and professional standards, if you are using them in your work, it is not ‘unscientific’, regardless of what anyone tells you. You don’t have to be preparing for peer-review in order to use the scientific method in your breeding program. Your goal is to increase the levels of rust resistance in your seedlings, not to ‘prove’ that it can be done to peer-review standards.

Finally, I would again point out that our ancestors managed to accomplish a great deal without any scientific understanding - they turned teosinte grass into corn (maize), wild triticum grasses into wheat, bitter and inedible wild potatoes into the modern staple, jungle fowl into chickens and wolves into dogs, just to name a few. What we seek to do in increasing the level of resistance to rust in our daylilies (a resistance that already exists within the overall daylily genome) is not nearly as radical or extraordinary as what our ancestors achieved before us, and we have much better tools at our disposal to achieve this.

Have confidence! There is already resistance to rust within some daylilies. The genes are there. We don’t have to find the genes - we already have some indication where to look. We don’t have to genetically engineer resistance - it exists in some plants within the population. All we actually have to do is identify it, concentrate it and compare it against various strains of rust. Not any one individual has to do all these things either. It is a job for the entire community of daylily breeders to do, so no one of us must carry the entire weight. Remember that the worst thing that can happen is failure and it is important to remember that if you do fail at increasing the level of rust resistance in your program the world won’t end, markets won’t collapse, civilizations won’t fall. Don’t get so serious that you give yourself an ulcer over a flower. While we daylily breeders don’t like to admit it, if worse comes to worst…there are other flowers…or we can learn to ignore some rust.

Finally, I would like to point out that belief creates your reality, in the sense that, if you believe you can’t select for resistance, then you will never try and it will thus be a self-fulfilling prophecy. What you never attempt, you will never achieve!

In the next installment we will look at some daylily family lines known to show resistance and a random listing of some cultivars that have shown resistance.