Expert: Long Island Gardener - 8/7/2007

Question
I have some Stargazers that have been great all season.  When I thought they would be flowering I looked and there were just brown dried up buds that didn't look like they even tried to bloom.  The rest of the plant looks fine.  What happened?  I want to try to prevent this from happening next season.  I have pictures if that helps diagnose the problem.

Answer
Having dealt with this problem this year for the first time, I was hoping to send you a treatise on the subject of Lily Diseases.  But I am so backed up with questions it's ridiculous.  Let me dash this quick answer off to you so that you know what is going on with your Lilies.

You can read up on Lily Stem Rot at the Ohio State University Bulletin No. 614, 'Disease Control in the Landscape':

http://ohioline.osu.edu/b614/b614_27.html

Stem Rot is one of several diseases common to Lilies, sometimes initiated by winter damage to the bulb.  Drainage contributes to the vigor of the pathogen -- in other words, if your Lily soil does not drain out QUICKLY after it rains (Humidity will keep that from happening), if your soil is high in Clay, Lily Germs will breed and feed on your Lily bulbs, stems and buds.

Now, you should understand that Lily diseases are simply accidents waiting to happen.  It is rare to find a Lily lover who does not deal with something like you describe on a regular basis.

My favorite speech to date on this subject comes from a Plant Disease Specialist named Janna Beckerman, an Extension Plant Pathologist at University of Minnesota.  Beckerman happens to grow Lilies.  When they got sick one recent Summer, this Minnesota expert documented the attack, complete with photos that look very much like my Lilies looked this year in her report, 'Taking My Work Home With Me':

http://www.extension.umn.edu/projects/yardandgarden/YGLNews/YGLN-Dec0102.html#li...

Anthracnose -- 'Colletotrichum' -- took down the Beckerman Lily Collection leaf by leaf, stem by stem.

Beckerman writes, 'This disease began as small, oval lesions appearing on the lower leaves. Examination with a hand lens did not reveal setae, the black, horsehair-like structures associated with Colletotrichum infections. However, incubation and microscopic examination revealed infection by Colletotrichum, including the development of setae. That said, several of my colleagues, when reviewing the photos alone, suggested Botrytis elliptica, a more common pathogen of lily with similar symptoms. In hindsite, I made a critical error in not researching the disease more thoroughly. Had I done that, I would have realized that Colletotrichum on lilies was not well described.'

For the record, 'setae' are black stalks that you see in certain Fungi.

Beckerman continues: 'Quickly, a little infection became an epidemic about the time the plants were flowering. And by the time flowering had finished, there wasn't much left of the plants!'

Sounds like my Garden.  Yours too, Alison?

Beckerman was almost philosophical about what had caused this devastating outbreak.  In fact, Anthracnose thrives under cool, moist conditions.  This Fungus also attacks Crops, Grass, and Perennial Flowers.  Says Beckerman, 'We can't do much about the weather. But, if you look closely at the pictures at left, you'll notice that the plants are spaced closely-probably too closely together, preventing airflow, and increasing the amount of time the leaf is wet. This situation encourages infection of the plant and spread of subsequent spores produced by the offending Fungus. Increasing plant spacing would be one strategy that should be implemented for good plant disease management.'

Airflow.  Moisture.  Spacing.  And, Beckerman maintains, growing too much of the same Lily, a monoculture nightmare.  A recipe for Fungus.

The prescription for next year's crop, Beckerman says, will be 'sanitation'.  Leaves, stems, flowers were all disposed of, probably in the garbage (NOT Composted).  Nevertheless, it is clear that 'inoculum levels are so high, the stage is set for a new epidemic next year, assuming any of the Lilies survived!'

Another disease you may deal with eventually: Fusarium.  It thrives in rich, WARM, moist soil (rather than the COOL soil prefered by Anthracnose).  Fusarium Fungi in fact like the same living conditions as Oriental Lilies.  Once you have a population of any of these Fungi, spores wait underground, still viable, for FIVE YEARS after killing your Lilies.

I have not found a safe, effective cure for these Diseases.  It seems foolish to me to rely on helpful temperatures and weather to ward them off.  But I think you can count on the idea that somewhere, a scientist and his/her crew are studying these Lily Diseases and figuring out a user-friendly way to wipe them out.  Maybe some are even studying in their own garden.  It is possible that in the meantime, a Copper Spray treatment will effectively wipe out Fungi on your Lilies.  For me, it is too toxic, albeit Organic.

So today's advice: Throw out all dead diseased dying plant matter.

Cut off diseased tissue, discard.

Next year, raise the tree canopy to increase air circulation and the sun/heat factor in the Lily garden.  Make it unfriendly for Fungi.

Remove any stricken bulbs as soon as symptoms appear.

And watch for new developments in these awful Disease of our most precious, beautiful, deeply fragrant Lilies.

Thanks for writing.  I wish the news was better.  This is going to be a tough problem.