New topic/ seedling damping off

J. Agoston
Fri, 30 Dec 2011 15:50:13 PST
cymoxanil: sytemic fungicide for oomycetes, this includes rhizoctonia,
pithyum, and fals meeldew (peronospora, plasmopara, bremia, plasmoverna,
...), resistance may occure
mancozeb: contact fungicide, which blocks simultaneously multiple sites of
fungus physiology, wide range of pathogens are killed, like fusarium, but
is effectiveless on oomycetes. there is a very low risk of resistance
copper salts: contact fungicide and bactericide, universal cell poison.
very effective against oomycetes, because these pathogens accumulate copper
ion in their mycelia. normaly it is only used for oomycetes, because the
effective dose on other fungi is so high as it is also toxic to the plant
we want to save. very low resistance.

Now it is very important to know how clean your seeds are and if they are
susceptible to fusarium, rust and other things. because if you cannot get
rid of the damping off with cymoxanil and copper it means you might have
fusarium, or you have a resitant strain of e.g. rhizoctonia.

I have used the folowing mix: 1 part Curzate R (4,2% cymoxanil + 70%
copper) and 1 part Dithane M-45 (80% mancozeb), i used a salt sprinkler to
make the distribution of the powder even and just dusted the trays and
seedling with it and then the usual watering. it has reduced the damping
off visibly after 2 weeks. i applied weekly. To be honest i just used it
when i saw i'm going to have serious losses in the tray :/

i used the powder not the water soluable granulates because the powder can
be distributed more even and does not need a lot of time to dissolve. The
goal is to have a thin but even cover and watering with small drops of

you may try to dissolve in water, and water with it, but i have no first
hand experience on this.

don't use strobilurin or triazole, they are less effective against soil
born diseases and it is a high risk developing resistant strains.

scout for fungus gnats and shoreflies, because the adults can spread
spores, conidia and hyphae of diseases on their body.

be aware of Rhizoctonia's mycelium can grow very fast under favourable
conditions, like 2-4" a day, especially in wet situations. the hyphae have
an ability to grow on water surface and it can spread from tray to tray. if
you see seedlings to collapse you cannot help them. infection occured days
before that.

I've heared about biological means and i also learned they are less
effective, and they have to be incorporated in the potting mix. If you
apply mancozeb to biologicals you kill both the good and the bad fungi.


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