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Mar 6, 2017 4:11 PM CST
|For those plants that I moved which then developed rust, they were moved from pots and planted in-ground, where they were subject to sprinkler spray (as opposed to carefully aimed hose watering). Additionally, one of them had a rust bucket for a neighbor. So at a minimum, they went to a state where there would be wet foliage for some period of time.
I have a highly shaded enclosed area that I use both for potting and as a nursery/holding area for new plants. I tend to get a fair amount of rust in there. I think that is due to a combination of incoming plants with rust that is not obvious upon arrival (although I inspect plants, I don't go to extreme measures of cutting back foliage almost to the crown), less air circulation than in other parts of the garden, and the shade, which allows moisture to stay on the foliage longer, which promotes infection.
This winter, of all plants, J.T. Davis, which scored as highly resistant on multiple surveys (and garden anecdotes), seems to have gotten a mild case of rust. It is off in my potting/new plant ghetto. I guess if it was going to get rust anywhere, it would be there. (This also goes to show that there is probably no such thing as total immunity to rust.)
Evaluating an iris seedling, hopefully for rebloom
Mar 6, 2017 6:29 PM CST
Mayo62 said:Has there been any research into the possible different characeristics of the strains and how they came into being?
OK now these questions are really getting difficult
The only research article so far about the different strains is this one:
I do have the full paper but not in front of me so I will have to find it and re-read but I don't think it answers your questions anyway, or at least not all of them.
There was only supposed to be one strain in the USA to start with. It was speculated to have come via Central America on imported plants but I don't think this is known for sure. Presumably other strains could have since come in from outside the USA or they evolved after it arrived here. To the experts the spores do have some differences from the Asian isolates that have been looked at but it is still Puccinia hemerocallidis.
I don't think strain A in two different places would both evolve into strain B, I think it would be B and C. When we get into genetics and evolution I'm inclined to call on Maurice @admmad
I don't know if the different strains behave significantly differently, I would think other than the differences in ability to cause disease on different cultivars probably not.
Moving from one place to another in a garden more likely makes a difference due to how long the leaves stay wet (several hours are necessary for spore germination). Light intensity is also a factor. Possibly the direction of the prevailing wind. Structures that affect the temperature and so on. Fertility is also a factor with rusts, high nitrogen encourages them and adequate potassium discourages them.
Methinks you should sign up for courses in plant pathology
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