I didn't either, but I am beginning to wonder which would be worse... rust or aphids.

Well, in my garden Aphids have been easier to control than rust. Aphids may take a few spraying with soapy water and a very difficult case might require something a little stronger. In my garden rust is not so easy to control, and rust causes much more unsightly foliage. So, if I were given a choice, in my garden I would certainly pick aphids. But I don't have to choose, I already get both of them.

I'd rather have aphids as they are so much easier to control with soapy water or just a squirt of water!

I guess my concern was that I wasn't sure if aphids could actually kill the daylily. I know in most cases, rust doesn't kill the plant unless it gets terribly bad. I guess if aphid damage was bad enough, that could kill it too.

I have had different aphid species on different plants in my garden and have never lost a plant to an aphid infestation. Maybe I've been lucky or maybe the Ladybugs come in to rescue my plants .... but I never worry much about aphids. There are so many bugs here in Florida year round, I learn to live with most of them even the really pesky ones!

Ok, so I don't have rust!
I guess aphids are easier to control, I read they hate humidity so keeping plants humid helps.
I don't see any ladybug here, is there a way I can "import" some to my garden?

Can rust kill a DL?

I have read that rust will not kill a daylily, but I have had a couple that I blamed rust for killing them. I have no scientific evidence of it, but it seemed to weaken the plants to such a point they died. It could have been the actual cause was something else. But if rust weakens a plant so it loses it's ability to survive other stresses, then to me in essence the plant was killed by rust. Even though that might not be the "official" cause of death.

I have heard the same thing Larry stated. But I've yet to lose a DL that was a rust bucket. And I have quite a few rust buckets in my yard. I have looked at mine closely at times and they did multiply and bloom well, but the leaves were very ugly during the growing season. Mine are put through drought stress and poor soil.

But I have had "dormant" plants that didn't survive but 2-3 years before they completely disappeared. They had rust, so maybe the rust contributed to their demise?

Lalambchop1 said:Can rust kill a DL?

Typically rusts don't kill plants - they need living tissue to feed and reproduce so if the plant dies the rust dies too except for any spores it has managed to produce - but those spores themselves can only infect living tissue so that can be a "dead end" anyway depending on the life cycle of the particular rust. As Larry said, a plant that is weakened by rust (the fungal body inside the plant is "stealing" food from the plant and interfering with photosynthesis) may possibly be more susceptible to other problems. A few rust diseases are systemic (such as orange bramble rust) and therefore the plant is never rid of them, but fortunately that doesn't apply to daylilies.

In practical terms, though, in areas where rust is endemic and winters not cold enough to kill the foliage and/or the daylilies are evergreen year round, plants can presumably be infected and re-infected continually as long as environmental conditions favour the rust, which could be pretty hard on them if they are not rust tolerant (different from resistant).

Some cultivars have a reaction to the rust that results in the foliage dying back, or at least forming dead brown areas around the pustules (called a hypersensitivity reaction) - this was thought to be a form of resistance, i.e. kill the leaf or surrounding area and you kill/starve the rust. I think I read something recently that cast some doubt on that sequence of events but I'd have to try and find it again. There's also the "green island" effect where tissue remains green around each pustule, which would enable the fungus to keep feeding even while the rest of the leaf is dying. (There's a picture of that on the FAQ link I gave above - BTW I'm glad the other pictures on there were useful to some of you). So what with all that and the multiple life stages, rusts are quite complex diseases.

Regarding Becky's question about whether the non-survival of dormants could be related to being infected - dormants, or at least some dormants, have had a reputation for not doing well in hot climates since well before the advent of rust in North America, so it's hard to say what influence the rust might have had in an individual case. The species daylilies still survive in Asia, are often badly infected by daylily rust, and the majority of those are deciduous. The full life cycle in daylily rust that requires patrinia as an alternate host is based on daylilies being deciduous. I guess when the rust fungus arrived in North America and found all these evergreens in warm climates, meaning it didn't even need an alternate host to persist from year to year, it went

Thank you, Sue. It's so wonderful to have your knowledge on here.

I've lost a couple of rust buckets.....right to the trash can.

Coming *very* late to this thread... (I'll spare you the excuses...)

'Spacecoast Tiny Perfection' is rust prone?! I asked for it as a gift plant this spring, because I thought it was resistant!

Aphids and spider mites do THAT kind of damage? DANG.... (I may have thrown out some plants I thought had rust... but maybe it wasn't rust after all?)

I have more plants that right now look like they have rust... I was getting ready to either cut them back, or else dig and destroy them... I guess I'll have to look closer, and do the tissue test, before I toss any more plants...

THANKS for the warning (and the link with comparative pictures)!

As for plants that at one time had rust, but not since... I've seen that with 'Cameroons' and 'Green Dolphin Street'. I'm guessing that the weather was a factor there... the year they got rust, we had a lot of rain in the spring. It's been pretty dry here in CA the past few years.

I wonder how long rust stays dormant in a daylily plant?

Polymerous - Since you may not have had a true case of rust, maybe the rust is gone from your garden since CA has been in such a drought state?

Way back when, in 2006, there was no doubt whatsoever that it was rust ravaging through the garden. That was when 'Cameroons' and 'Green Dolphin Street' were hit; they were near 'Icy Lemon', which was an absolute screaming horror of a rust bucket. (And yes, I did the tissue test then...)

The plants right now that are showing "rust" are ones that get hit with irrigation spray, so in at least some of these plants, I am pretty sure it is rust. (I had rust break out on incoming plants, and I think I must have spread it around.)

I guess I get out there with the tissue tomorrow... just to be sure...

(While I have been tossing lots of plants, there does come a time when I struggle with myself when a plant with a particularly beautiful flower, or with some combination of desirable traits, gets hit. Then comes the question: how much rust grief am I willing to put up with, to keep this plant? (Especially given that I don't do the fungicide spray thing...))

Sigh...

beckygardener said:I wonder how long rust stays dormant in a daylily plant?

I don't recall any specific test other than the one summarized on the link below from my rust site, in which it was latent for a minimum of seven weeks because environmental conditions weren't conducive to sporulation. It could be longer than that, for example it may overwinter inside the foliage where the weather doesn't get cold enough to kill the daylily leaves. In ideal conditions (for the rust!) the infection is only invisible for ten days to a couple of weeks.

http://web.ncf.ca/ah748/latent...

Regarding irrigation spray - overhead irrigation would favour most fungal foliar diseases and it's most likely something like the leaf streak fungus getting into the insect damage that causes the brown spots with aphid/mite feeding. Another way to confirm rust besides the tissue test is to look at the spots with a magnifying lens. Rust is the only daylily disease that causes raised spots with yellow/orange spores. Sometimes you may only see the raised bumps if the spores have been blown or rained off. Bringing a suspicious leaf segment indoors and putting it in a plastic baggie (in a lid or something so that the plastic doesn't contact the leaf) for a day or two may make the spores more visible.

It is possible to just see flat brown spots with no raised bumps of spores in daylily rust if the cultivar is resistant but that wouldn't likely happen without some other plants sporulating because without spores there's no rust.

Unfortunately I've heard of several cases where plants were destroyed unnecessarily due to misdiagnosis.

I found one plant that definitely had rust this year - Tusk - and I tossed it as the entire plant was covered in it. I have heard it is a very rusty plant - of course that was after I bought it. Even though I live in zone 5 and rust doesn't overwinter, I hate the way rust looks and I would prefer it doesn't spread. There are plenty of other beautiful daylilies out there.