Re: ROT

From: celia storey <storey@aristotle.net>

"When you smell that 'special' odor, reach for bleach"

When Hurricane Frances broke Arkansas's drought last month some of us went
out to dance in the rain among our irises. "Guess you'll be happy now," we
told them.

Guess again.

Drought stress followed by the sudden surge in new growth has set up
perfect conditions for rot in bearded irises. Fans topple and once firm
rhizomes collapse into stinking containers of yellow mush.
The stench tells us this is bacterial soft rot, Erwinia carotovora (Erwin's
carrot-eater). Another rot that attacks the base of fans but does not stink
is crown rot. Crown rot is a fungus and can be controlled with fungicides.
But fungicides will not stop Erwinia.

If your rot stinks, it's bacterial. It's time to reach for the bleach.

Often you'll find soft rot in a rhizome around which offsets have shot up
quickly. Even if you can't save the main fan, surgery will save those
offsets. Do nothing, and chances are they also will die.

If the infection is confined to one rhizome, you can doctor it in the ground.
First remove all ruined foliage. Erwinia's contagious, so pay attention to
the bundle of leaves in your hand: Don't let them bump into healthy leaves.
Wash your hands before touching healthy plants.
Use a spoon to scrape diseased mush from inside the rhizome. If you find
maggots, grit your teeth and keep going. Be ruthless. Scrape until you
encounter solid matter. Be scrupulously careful to dispose of that mush. Do
not compost it or flick it off into the soil. And dip your spoon into
bleach before doctoring another plant.

Pour either dilute or full-strength household bleach into the wound and
over the surrounding soil. Bacteria cannot live in bleach. Dry cleanser
containing bleach, such as Comet, also works.

Expose the rhizome to sunlight. Sunlight discourages rot.

If several rhizomes in a clump are infected, lift the damaged parts and
divide, clean and soak them for 30 minutes or so in a dilute bleach
solution. Some sources suggest one part bleach to five parts water, others
say to use nine parts water; but precision isn't crucial. Bleach does not
harm bearded irises.

Remember to reset the lifted irises the way you would new starts: Trim the
fans to balance lost roots. If rot persists, repeat the bleach and spoon
treatment.

Sooner or later everyone sees rot. But it is worst where soil drains
poorly, where rhizomes are buried, where clumps crowd together, where heavy
fertilizer (or the weather) encourages fast growth and where the gardener
doesn't keep on eye on things.

Visit your irises every day this fall. Nip rot in the bud.

celia
s*@aristotle.net
Little Rock, Arkansas, USDA Zone 7b
-----------------------------------
257 feet above sea level,
average rainfall about 50 inches (more than 60" in '97)
average relative humidity (at 6 a.m.) 84%.
moderate winters, hot summers ... but lots of seesaw action in all seasons



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