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| At a community garden I ran across this planting of zinnias, which have bloomed their heads off for months. There is not a trace of mildew, even this late. These are smaller flowers, around 3 inches, and the plants are 2-3 feet tall. Does anyone have an idea what they might be. (Unfortunately, I have not run into the plot tender.)
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Follow-Up Postings:
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| Big mystery. Their height and flower size would seem to rule out them being Profusions or Zaharas. However, them not having mildew doesn't necessarily mean they are mildew resistant. It could be that the plot tender gave them a big dose of systemic fungicide, which would make them mildew proof for awhile, until it "wore off" or the tender gave them another dose. Best thing to do would be talk to the plot tender and find out what his secret is. I do use a systemic fungicide to extend the life of a few of my "breeder quality" zinnias. The stuff is fairly expensive, so it would be impractical to use it on a large scale. ZM |
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| For some reason, Magellan zinnias comes to mind. Not that I have grown them; have just been studying catalogs lately. |
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| Hi Alex, Magellan zinnias are a dwarf variety, only 12 to 14 inches high. These "mystery zinnias" are 2 to 3 feet tall. So they are not Magellans. OK, eating crow. See the messages below. Grin. I am going to learn to pay more attention to you. The Powdery Mildew that infects zinnias is caused by a fungus that is specific to zinnias of the species Z. violacea (elegans). So, it is highly unlikely (read impossible) that any zinnia of that species can be genetically immune to Zinnia Powdery Mildew. But "unlikely" doesn't rule out the possibility altogether. I wondered if tetraploid zinnias might be immune, due to their doubled chromosome number, so I grew some Burpee tetraploid zinnias and the heirloom tetraploid, State Fair. Both of those tetraploid strains exhibited vulnerability to Zinnia Powdery Mildew equal to the diploid zinnias I was growing beside them. The zinnias in the pictures look just like Z. elegans (violacea), so I think it highly unlikely that they have a genetic immunity to Zinnia Powdery Mildew. Mantis_oh mentioned that the PM-free zinnias were growing in a community garden. It is possible that the previous user or the present user of that plot deliberately or accidentally put something in the soil that those zinnias have absorbed that conferred their apparent PM immunity. Or, it simply may be that there are no zinnias growing in the immediate neighborhood of that community garden, so that those zinnias simply haven't been contacted by a spore or spores from the Zinnia Powdery Mildew fungus. I believe that fungus can only grow on zinnias, so zinnias can "catch" the disease only from spores from other zinnias. The spores can be airborne. I have wondered from time to time if zinnias could take up Selenium from soils that contain Selenium, and if they did, whether that Selenium would confer immunity to diseases. I am not about to add Selenium to any soil, because once you do, you simply can't get it out. And you would run the risk that anything grown on that soil would be poisonous. However, people have been known to treat the potting soil that African Violets are growing in with a Selenium-containing agent to combat some African Violet problem. People don't eat African Violets, so making their plants toxic is allowable. A trace amount of Selenium is actually good for you, and I have seen Selenium pills for sale in a health food store. But Selenium can be toxic to humans and to animals. The so-called "Loco Weed" in Texas accumulates Selenium from the soil and cows that eat the weed "go loco". But we still don't know why those zinnias don't have PM. I just highly doubt that it is their genetics. ZM |
This post was edited by zenman on Thu, Oct 16, 14 at 15:21
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- Posted by mantis__oh z6 OH (My Page) on Wed, Oct 15, 14 at 16:52
| I wonder if these are the Sun hybrids. Some of the flowers are quite large--more like 4 inches and up. You are right Zenman that there are not other zinnias around; it is basically a vegetable garden. Also there is a lot of space between plants. Still, it is amazing how floriferous and disease-free these plants are. Stokes, by the way, calls Red Sun a mildew-resistant cultivar. I have never grown the Sun series, so I am not familiar with it. Another possibility is that they are Zahara zinnias that have grown especially large. Some plants are almost 3 feet tall, whereas others are about 18 inches. Another po |
This post was edited by mantis__oh on Wed, Oct 15, 14 at 17:14
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| The Zaharas are a little higher then Profusions, and they have slightly larger flowers as well. The Zahara height is listed as 12 to 18 inches. There is a so-called "knee high" variety of Profusion that is a couple of inches taller than the standard Profusions. But neither Profusion nor Zahara approach the height and flower size of your pictured zinnias. They could be Sun hybrids. From time to time various zinnia strains are listed as "disease resistant" without really defining the term. I don't know of any Zinnia violacea (elegans) strains that don't get various zinnia diseases, including powdery mildew. ZM |
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| I ordered and started only Magellan's this year because they were advertised to only reach 14 inches. What I ended up with is beautiful plants 3 feet tall and look very similar, if not identical to, those pictured above. |
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| Hi geosankie , Very interesting. Did yours seem to be mildew resistant as well? Oh, and also. Just out of curiosity, if you don't mind saying, who did you order your Magellans from? ZM |
This post was edited by zenman on Thu, Oct 16, 14 at 13:01
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| Got the seeds from Swallowtail and never had any fungus problems right up until 2 days ago when the frost finally got them.. happy with the plants but was hoping they were a little shorter. I didn't measure them but they are at least 30". Bed is 18 feet long by 4 feet wide and became solid Magellan's.(supposedly)..no disease whatsoever. |
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| Hi geosankie , Thanks for the info. I will be ordering some zinnia seeds from Swallowtail. Actually, I was going to order some different zinnia seeds from them anyway, but now I will be adding some Magellans to the order. ZM |
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- Posted by grandmamaloy 7 (My Page) on Wed, Nov 12, 14 at 16:13
| I think they might be Zaharas, possibly Double Cherry. The blossoms are between 2 and 3 inches across and they are bred to be resistant to many diseases. I grow them and I don't use any kind of systemic fungicide and have not had problems at all. Your photos also look amazingly like mine and I went back to find out where I purchased mine from. Hope this helps |
Here is a link that might be useful: Zahara Double Cherry
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| Hi grandmamaloy, The Double Cherry Zaharas are described as having blooms 2.5 inches in diameter and plants 12 to 18 inches high. The Original Poster (mantis__oh) described the pictured zinnias as around 3-inches in diameter (a possible description for Zahara blooms) but 2 to 3 feet tall -- twice the height of the Zaharas. Of course, their height also doesn't match the Magellans, which geosankie reported as reaching 3 feet tall. But you are right that Zaharas have better disease resistance than Magellans, so that would tend to favor your suggestion. However, I personally don't know of any 3-foot disease resistant zinnias. ZM |
This post was edited by zenman on Fri, Nov 14, 14 at 17:35
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- Posted by mantis__oh z6 OH (My Page) on Wed, Nov 19, 14 at 21:00
| Note that the plants varied a lot in height. A few were near three feet, but some were only about 20 inches. The soil was probably especially rich. Note too that there was a wide range of colors, though some colors, particularly yellow, were shorter than others. All were at least semi-double; some more double than others. |
This post was edited by mantis__oh on Wed, Nov 19, 14 at 21:02
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