I haven't used anything on mine, I dead head them so they will bloom again and cut off dead leaves. If they get too bad I cut them down to the ground, so I will get new growth. If you cut them back now you'll have new growth in the spring, which should look pretty good until mid summer. Try to keep the dead leaves cleaned off so the rust spores don't get to the new growth. It's the same thing with plumerias, keep the dead leaves picked up. Hope this helps. :o)

Hi
That's about what I do with mine. i grow mine in pots because I have no luck at all in my sand lol. The best are in standing water in the Marsh garden though they are completely dormant right now. Had several rot out of those grown in standard soil. Still get 8/10 months of flowers out of them When they get too bad I just replace them. You can often find the corms very cheap at the box stores . gary

I use Em(effective microorganisms) on mine, my plumerias too. It really keeps the rust at bay. They are like probiotics for plants. I use them on all my plants and I see a definite upswing in their vigor, growth and health.

I haven't heard about EM, tell me more about it. Where do you get it? And how do you use it? How often? TIA.

I'm relatively new to cannas, just became interested when I found out the narrow-leaved ones attract hummingbirgs. These are all blooming now, I've grown them from seeds sent to me that were collected in different Central and South American countries. No signs of virus but now you all have me thinking I need to watch out for rust....

Tom

And my first non-red. Seed from Columbia, not sure if this is a sport or....

I have several of those small flowered cannas too. The red one is indica something. I also have orange and I had a yellow one with spots in the petals, but I don't remember seeing bloom last year. That pink is really pretty that you have.

Thanks Kat. Have you noticed any rust on these? I'll save the seed and see if the pink grows out true. If not and you want some I can probably divide it later in the summer.

Tom

Is rust on Cannas a Florida thing then? Here in sconny, I've grown thousands upon thousands of some of the horticultural varieties over the years. There never was any disease of any kind, nor did it seem you could overwater these plants. I always planted them into rich, compost-amended soil. I also always used Osmocote or equivalent fertilizer, along with regular but very light apps of water-soluble. Just surprised to hear of any problem of any kind with these things. I always found them to be foolproof.

+oM

Well, mine didn't have any for the first year, but now every year they have it with a vengeance along with the plumerias. If I just picked off the infected leaves, I would have ZERO leaves! So I would like to know if anyone has had any success with systemic fungicides. It rains a lot in Fl. and the humidity is very high, especially in summer when they do their best. I love both plants as they are star performers otherwise and bloom like crazy (when healthy).

Yes, it makes sense that the normally-high summer humidity down there could set the stage for rust fungi. I wonder-and of course, I can research this myself too-is much of anything known about the specific pathogen involved? Have any of you taken samples to a plant disease diagnostic lab? Does FL have such a lab?

+oM

I have some success using NEEM on the leaves. You don't wanna use it if they are in full sun and its over 80 degrees though. Wait for a cloudy day then spray. Other things that help:
Make sure not to water overhead only the roots.
Try not to water late in the day. I water all my plants early in the day so the water has time to evaporate if it gets on the leaves.
Try to keep some space between plantings for good air circulation. Also, keep them out from under trees or other plants that can drip on them.
Mulch around the roots so soil doesn't splash up on them when you water.
There are fungicides on the market but I haven't sprayed anything in 2 years. Not saying my plants are perfect without spray but I can live with a little imperfection. IF it got too out of control I would probably selectively spray certain things.
I have the indica from seed. They are one of the most fungal resistant in my yard.
The worst one is the dark leafed Australia. It does much better in a pot as far as being resistant to rust.

~SJN

This post was edited by sultry_jasmine_night on Fri, Feb 6, 15 at 10:46

Trying to wrap my head around this problem some of you are having-with a plant native to wet areas of the tropics/subtropics. Just seems like this genus should have high tolerance to things like water getting on foliage, high-water-table soils, high humidity. then there's my own experience, never having had so much as a spot of trouble. And while I know our summers up here are not on the same level as that of Florida, we do get our share of heat/humidity. Hmmm?

Not an argument-I just wouldn't have thought foliar blights to be an issue with this group. BTW, whether C. indica or C. glauca, all Canna genetics are originally from the Americas (and associated islands), the later hybridization and selection work taking place across the globe. The plants are originally American.

+oM

secret it to buy virus free cannas. I only buy from those that certify virus free, very few. Karckesky canna is my only "go to" place. Have never had problem other than normal rattiness at end of summer. I cut them to 6" from the ground and in Sep Oct have beautiful plants again. If you are z8 or warmer you can do that, not sure about cooler climes.

if cannas are a big deal for you, im afraid you wil have to yank all you have and start over with virus free rhizomes. Some soil prep may be needed before you replant, I think Alice or any certified seller can answer that. Virus is extremely contagious.

I think if you grow plumeria, you'll get rust on your cannas in time. Plumeria 101 says not to worry about it, it doesn't bother the plant much and you really can't stop it. The same for cannas, it doesn't hurt the tuber so a new one will grow and bloom. At the end of the summer I just cut them back and new ones grow and are clean for awhile.

While it is good practice not to buy known plants with viruses, that does not guarantee that a plant won't get rust. A non virus-ed plant can still get rust via wind or insect etc.
Viruses, bacteria, and rust/fungus are all completely different things with different treatments. Having a bacteria, virus, or fungal disease can lower immunity thus leaving the plant more susceptible to other diseases but having a actual virus doesn't actually cause rust, fungus does.

I was going to say......^

The Plumeria/Canna association must be a factor then, in Cannas getting rust. My understanding of the genus (Cannas) has always been that its origins are in the Amazon Basin, an area not known for dry air, let alone dry soils.

+oM

Here cannas are more or less yard weeds, they're pretty indestructible. Obviously your conditions must differ...sorry I can't help :(

All good info and I'm jealous of those who have no problems with their cannas! But seeing as how I'm not one of those fortunate ones, I'm still looking for experiences of those who have had to resort to fungicides to keep them going. What kind, how often, etc...

Thanks again for your input!

Cannas: In zone 5 in Central Ohio - I have always planted the Rhizomes around Memorial Day when the ground is warm. They come up very eagerly and the colour I have there is India Red. They multiply a lot. After the 2nd frost about, I cut off the stems about 2 " short & I dig them up and rinse off the dirt - dry for a couple days. I put them in cardboard boxes with a lid set up off the floor to store in the garage. In the growing season - My cannas like water on the roots and never get rust on the leaves. I cut the flowers off when through blooming and they might grow more blooms again. They grow approx. 5-6' tall and can be seen outside my sun room windows. I thought they grew best with the winter cold rest...

I did not know they would grow in the SW FL zone. I will learn new ways with Cannas now...

It is nice we don't have to lift the cannas here for the winter, but we do have to prune off the sick leaves. And yes cut off just the flowers and leave the stem so they will rebloom.

@Katkin gw. Em (effective microorganisms) are beneficial bacteria. Like I mentioned, like probiotics for plants. I used to get them from Teraganix www.teraganix.com but now I get them from The Smiling Gardener www.smilinggardene He has both a ready to use kind and a 'mother culture' that you can make more batches with, that's the one I have. I use it about once a month or once every other month. I don't know the specific action the microorganisms have on the plants but. I definitely see a difference in my cannas and plumerias., and my plants in general. Last summer I had only one plumeria leaf with some rust pustules, which I quickly discarded. The rest of the plant had green, healthy leaves. my 'Tropicanna' canna was a mess, once again, it popped up healthy as could be after I started using the Em, they almost bloomed but I went out of town and they didn't get watered and the above ground parts perished. It did come back though. I highly recommend the Em. You can also use it to deodorize and they also sell some that you can take as a supplement.

@Wisconsitom When i grew cannas and plumerias in Illinois I never had any problems with them, other than some mites when I stored the plumies indoors. When both were outside in the summer; healthy vigorous, no diseases or pests. I found it ironic and disappointing that when I brought them down to Florida, that they had all these problems. After all, they are tropical right? I thought they would flourish. Well, tropical plants in a tropical place, with tropical pests and diseases, ones that were nonexistent up north. I remember seeing plumeria trees and wondering why they looked so terrible. I didn't even know about rust. my cannas that I brought down really flourished for a long time, then they started declining. I also read about the dreaded leaf roller caterpillar, and my cannas did eventually get them, but they were very easy to control and they never showed up very often. I had more problems with the rust till I started experimenting with the Em.