Here's another curiousity question. You all may think I am whacked asking this and I know this is a little " out there " but I am still going to ask . LOL !

How long do daylily plants need to be exposed to freezing conditions to kill rust spores? a week ? 2 weeks ? a month ? 2 months ? Wondering if someone who does experience rust could actually pot up a plant and put in a freezer for a length of time to kill the spores ? I know lots of people keep their daylilies in pots all the time .

I could actually try it as I have a couple of freezers but to my knowledge dont have any daylilies that have rust.

You need to kill not only the spores but the fungus itself which is inside the leaves. The fungus cannot survive if the leaves are dead. Putting a daylily into the freezer at a time of year when it is not cold acclimated will kill the daylily so that will effectively kill the rust inside it too If any spores seemed to have survived you would have to try to infect a guaranteed rust-free and susceptible daylily with them to find out if they were still viable.

Cold temperatures alone don't necessarily kill rust spores but a combination of outdoor effects cause them not to survive winter. See question 3 on this page:

http://web.ncf.ca/ah748/FAQ.ht...

What would be useful to study would be the survivability of the rust mycelium inside the leaves, i.e. whether it dies at a warmer cold temperature than is needed to kill the leaves.

What someone could do who has living foliage on a plant that had rust is take off a living leaf or the living part of a leaf. Bring it indoors. Get a container lid or something similar, about the size of a margarine tub works. Set a damp (not wet) kitchen paper towel in the base of the lid. Set the leaf (cut into segments to fit the lid if necessary but not too short) on the paper towel.

Enclose the whole thing in a plastic baggie. The sides of the lid are to prevent the baggie from touching the leaf. Set this at normal room temperature (about 72-75F if possible) somewhere out of bright light. If the segments survive long enough they should develop rust after about 9+ days or so if it has survived. This won't work if the cultivar has the kind of resistance that delays the appearance of rust so pick a "rust bucket" if you can.

One last question on this subject ,please .

Seeds ........from plants that have rust .......will they be likely to produce plants that are more prone to rust ? If not , why not ? For example if one buys seeds off the lily auction, and the seeds are of plants that are southern plants which I have read are prone to rust will these seeds be more likely to produce plants that could/would support rust? .

That is a good possibility. In Z:6 I don't believe I would be worrying about that. The main issue is plants that you buy from the warmer climate that can bring it in for later that season. Your normal winter temps would most likely kill it then.

I would be curious to know if there is a gene that would not allow rust to develop in a daylily, or if at best there is a gene that will just show resistant to rust. I would think that if the parent or parents are "rust buckets" the seed would have a greater chance of producing rusty parents. But, then again the seed might also produce some rust resistant plants, but I would think the chance of the plants having little resistance would be greater if both parents were very susceptible to rust.

signet said:One last question on this subject ,please .

Seeds ........from plants that have rust .......will they be likely to produce plants that are more prone to rust ? If not , why not ? For example if one buys seeds off the lily auction, and the seeds are of plants that are southern plants which I have read are prone to rust will these seeds be more likely to produce plants that could/would support rust? .

Resistance to rust diseases is controlled by specific genes so if the parents had rust badly then I would expect at least a proportion of the offspring to be susceptible also. That would apply whether or not the individual plant the seeds came from had rust at the time. (The potential for rust spores to hitchhike on seeds is another separate issue).

It's not that southern plants are more prone to rust, it's that the rust fungus lifecycle isn't broken in warm winter areas by either the plants being naturally deciduous or, in the case of evergreens, having the leaves killed by freezing. In other words it has more to do with the rust's ability to overwinter. In theory one might expect a daylily from an area where rust is endemic and survives winter to be less prone if one assumes the hybridizers are selecting for rust resistance, but how many are doing that I don't know. It's much harder to select for rust resistance in a climate where rust doesn't survive the winter, same as it's hard for hybridizers in mild winter areas to select for cold hardiness.

I haven't heard of anyone in Ontario having rust survive the winter outdoors.

Once again , I thank you all for your input . This has been a real learning opportunity for me in regards to this subject.