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.