Thursday, March 19, 2015

Downy Mildew Testing

No, I guess I don't really like downy mildew all that much, but I am thankful when we can get some of it in order to see which seedlings show resistance.  Fortunately, we had a couple days of 90 degree weather after this outbreak to halt the devastation.

The new seedlings that were just moved out of the greenhouse are always the most susceptible (see photo below).

Even some of the very mature roses got hit pretty hard.  Below is a photo of foliage drop from 'Osiana', a cut-flower variety that appears to be very susceptible. 

However, some of the newer seedlings are showing little or no downy mildew.  The first below is a seedling of 'Darlow's Enigma', followed by a seedling 2 generations down from "Basye's Thornless", and a rugosa seedling.



The last photo shown below is of a crested seedling that is surprisingly showing a good amount of downy mildew tolerance.

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4 comments:

  1. Dave BangMarch 19, 2015 at 11:33 PM

    Wow introducing downey mildew, that can be scary. The last four seedlings look good after being exposed. Those are keepers. Did any of their parents have a predisposition to being resistant to downey.

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    Replies
    1. Jim SproulMarch 30, 2015 at 10:11 PM

      I didn't actually introduce the infection, the conditions were just perfect. Unfortunately, downy mildew can kill young seedlings and a couple didn't make it. Even so, I accept disease pressures as an opportunity to see which seedlings are most resistant.

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  2. fe_r556March 23, 2015 at 3:37 PM

    Crested!!! ( *o*) What were the parents?

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    Replies
    1. Jim SproulMarch 30, 2015 at 10:14 PM

      Yes, crested. The parents were a Hulthemia pollen parent and the seed parent was one of Mr. Moore's unreleased "crested moss" seedlings. I kept this one even though there wasn't a blotch.

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