Polymerous, lots of valuable info on your approach to dealing with rust. I too am looking for rust resistant varieties. I am in Australia zone 9b, frost free winters and mild summers, so rust does well. eradication of rust from my garden impossible as I also have a lot of Dianella ( indigenous plant) that is also a host apparently, but not affected itself.

nelli,

The database here is the best source I know for researching rust rankings for daylilies, lots of other good info available in the forums also.

Hi, nelli. Best wishes on your search for rust resistant varieties. The ATP database is a good start. (I've been busy making lists... )

I recently ran across this blog http://daylilybreeder.blogspot... , which may be of interest to some people here, particularly with respect to the entries on rust resistance. The author has a 12-part series on breeding for rust resistance, beginning in Nov 2013, as well as a 2-part series in Oct 2014, which focuses on the work of Ron Reimer in hybridizing for rust resistant diploids.

I had already been taking *some* care in my parents when making my crosses (wrt rust resistance), but now I am inspired to be much more focused (or ruthless) about it. I may have to use *some* rusty plants (because of certain genes), but one of my goals is to improve rust resistance (or maintain it, if there is already some high degree of resistance) in the next generation, regardless of whatever other traits I am trying to propagate.

It does pose an interesting conundrum for those of us who want good looking gardens, but who also want to hybridize with an eye to rust resistance. The issue is wrt evaluating seedlings for rust. I am not talking about climates where rust is not much of an issue (which makes evaluation difficult), although that is certainly one aspect of it, but rather the need to supply a source of rust in order to evaluate the seedlings for resistance (or not). That need more or less mandates the permanent residence of some number of rust buckets (to provide the rust), and rules out spraying (fine with me, maybe not so fine for other people in other gardens). I was going to keep a few rust susceptible daylilies around regardless (one I need for certain genes, others I like for their flowers), but that in turn means that even if the bulk of my daylilies are resistant, my garden will still never be "clean" of rust (if anyone's garden in the warm winter areas ever can be). That, in turn, rather makes this whole thread pointless - no use fretting over rusty pot soil if one is going to be keeping rust buckets around anyway! Doh!

Normally I would not care about having a "pristine" clean garden. My garden is a private one and for our pleasure, and so long as it is "clean enough" (the majority of the daylilies being resistant and showing little rust), that it is good enough for me.

But it does raise the interesting What-If question.... that of What If I ever hybridized a rust resistant daylily worthy of registration and introduction. (I'm not holding my breath, but hope springs eternal...) If one is required to spray in order to sell, that means no selling - because I ain't spraying (and not just because of the need to evaluate seedlings). And even though the plant may be resistant to rust (in *my* garden), hypothetically it might still *carry* rust (because it has been continually exposed since it was a seedling) which might then produce (a few) spores in a different garden, even if I did spray (which I'm not going to).

So how does one introduce a rust resistant plant once one has one? Even with spraying, one can't claim (at least in a warm winter garden) that the plant is clean (the sprays just suppress any rust). There seems no solution here, short of packing up the garden and moving to Zone 5 (which we are not about to do).

nelli said: eradication of rust from my garden impossible as I also have a lot of Dianella ( indigenous plant) that is also a host apparently, but not affected itself.

It has indeed been reported that Dianella tasmanica can get daylily rust (it's not reported for any other Dianella as far as I'm aware) but that shouldn't be the reason you can't eradicate rust from your garden. Firstly, if your plants are not producing visible rust (spores) then they can't pass rust on to other plants. Secondly, in the report for Dianella tasmanica, the researchers were not able to infect daylilies with the rust spores from dianella, or dianella with rust spores taken from daylily. The implication, then, is that although it is still basically the same fungus Puccinia hemerocallidis on dianella, it is a variant that has evolved specific to dianella (a daylily relative).

A similar thing applies to Polymerous's concern, even if a daylily you sell has had rust in the past, it won't pass it on to other plants in someone else's garden unless it sporulates there (produces spores). If it is resistant in your garden it may not be in someone else's who also has rust, however, when exposed to spores there. The environmental conditions may be more conducive in the other garden, or they may have a different race of daylily rust to which the cultivar is more susceptible. Daylily rust is not a systemic rust (always in the plant once it's had it).

'Small World Margarita', mentioned previously, has great rust resistant lines on both sides.
Always good to know another plant that is possible to use in my rust resistant breeding plan.

Checking for rust resistance is interesting; I've even found a rust resistant specimen or 2
that came from 2 rust prone parents. (Wish I'd recorded names)

Paid top dollar (for me) for some highly bid on new intro seeds this year
and wouldn't you know, they are ALL little rust buckets ('Biting Pumpkins' x 'Hooked')

In other cases, some sibs seem rusty while others resist.
I try to tag them at 1st show of rust after exposure.
Some appear to "learn" rust resistance.

Another aspect or rust is how devastated a plant becomes once it gets rust;
some #1 rust resistant will be torn up by rust once it takes hold while some only
moderately resistant will plod along -- getting rust sooner but not being as torn up.

Thus far, I'm having fairly good luck using Green Magic spray which seems less toxic to use.
Will let you know the outcome later when rust really gets going here in North Central Florida.

Pat, I have 'Small World Margarita' and was planning on using it in crosses this summer because of its rust resistant parents. It is lovely.



I just hope it really *is* rust resistant, as it is supposedly possible to get a susceptible seedling from two resistant parents. I may know soon, though, as there is quite a bit of rust in that part of the garden right now. (It is taking me forever to do the garden spring cleaning, but so far the plant looks good - but then again, the foliage hasn't been above ground for long.)

(I have plans to use it and (certain other yellow daylilies if they are in bloom and show resistance) in some "salvage" crosses with a certain rusty yellow daylily this season.)

Polly,

When I first read about Florida's rust infestation on the internet, (2001?) I had a box of new plants from Floyd Cove in transit. Because one of the things which attracted me to daylilies in the first place was their tough, easy-care nature, I saw rust as a deal-breaker which would devastate my large collection, and the box eventually went into the trash, unopened. I didn't buy any new plants for at least 10 years, and when I did start buying again, it was only from northern growers who had rust-free nurseries.

Up until the fall of 2013, I was rust-free, and was dipping new arrivals in a 10% bleach solution. At some point a bit of rust snuck in, and I quit dipping. Even then, I didn't see a lot of spread because of the low humidity. Wet, damp weather in the fall and spring is when it tends to become noticeable. January 2015 was extremely wet, and I saw a light, scattered outbreak, but now I can hardly see any evidence of it — even the rustiest of the rust-buckets are clean and green right now. Plants which get afternoon shade seem to be much more susceptible. If the summer is typical, as long as I water in the mornings, I'll see very little rust until the fall. Thankfully, it turns out that rust is something I can live with.

With regard to used soil being a problem, I have noticed that plants which had rust one year would be clean the next, without any intervention or obsessive leaf cleanup on my part, so I don't see it as much of a worry. A new topdressing, as suggested, would be good insurance.

If you were going to sell or distribute plants at some time in the future, I would think that a thorough cleaning, trim, and fungicidal dip would be fine. A contact fungicide would kill the active spores, but for maximum effectiveness I would consider a combination of systemic and contact. The solution would be reusable, and would not impact the ecology of your garden.

Ken
East S.F. Bay Area
USDA Zone 9 - mediterranean

Ken, thanks for your thoughts. I am aware that our low humidity climate usually helps us against rust. I did not realize that shade would be a factor; we have a lot of shade here. I had never considered using a systemic fungicide in a bare-root plant dip. (Bleach, yes.) You have a good point about spore persistence (or not) in the garden soil, and about laying down some new mulch or covering topsoil.

I don't mind occasionally having to do a foliage cut-back and spray with a Dawn (or bleach) solution - on certain selected plants. But when it gets to the point that too many plants need such treatment, because otherwise they are such rust buckets that they are ugly and are mass producing spores, then out they go. It is time for another Garden Purge.

My garden is by no means rust pristine, but by growing mostly resistant (or somewhat resistant) plants, the scourge is somewhat managed. And as you say - during certain parts of the year, you don't notice any problem, even on the rust buckets (unless maybe you look very closely and see the tell-tale dark brown spots).

I confess that it is problematic as to what to do when I want to give plants away. The reality - so far as I know - is that no amount of systemic fungicide is going to cure a plant once it is infected; all that they will do is suppress the rust. And as you yourself have noted, it is not always obvious if a plant is infected. (I have gotten at least one infected plant from a club sale; the plant looked pristine when I got it in the fall, but broke out in rust in the spring - it was the only rusty daylily in that part of the garden at that time. (I won't speak about plants which I have gotten from commercial gardens.)) This rust issue has kept me from giving plants away to the local club(s) (in the rare event that I can make a meeting). While I would not knowingly give away an infected plant, I might not be aware that the plant was infected, and I am not confident that any dip I would do would kill off any rust on AND in bareroot plants (and one club does potted plants, not bareroot). (Never mind that most of the daylily growers around here already probably have - or have had - rust in their gardens; no need to add to the problem. I am amazed that you managed to hold out until 2013. )

With regards to giving plants to certain select individuals (I am speaking of non-daylily gardeners who are friends or relatives), I have settled on the following: a) Don't knowingly give away an infected plant (but as you yourself have noted, it may not always be obvious), b) Warn the recipient of any potential rust problem (and what to do about it if it crops up), c) If the recipient is not picky about plants, try to give them only or mostly rust resistant plants. (Sometimes people want a particular color, or a particular plant, or need bloom at a particular season.) Some of these plants have gone out in pots, but when they have been sent bare-root, I did dip them in a bleach solution. It helps that some of the people who I have given plants to live in cold winter areas; any rust they get will likely winter kill.

It's a problem. I see no solution, short of hybridizing for rust resistance (and that is not a sure cure either, due to different rust strains). At this point in time, I half expect/suspect any new plant I get to harbor rust. I am trying to force myself to buy only resistant cultivars, but such information is not always known (newer plants), and I'm as much a sucker for a pretty face, or the new-and-exciting, as anyone.

One thing I've noticed about rust here is that one garden near, but not under, a huge oak tree is more rust prone.
I'm thinking because the tree is so large it must be making its own climate of humidity.

Other daylilies in a 2nd garden that also gets afternoon shade, but isn't near this tree remains relatively rust free.
Both gardens have an assortment of many different plants.