question re: daconil and light

[kewpie]

ok. i found some black, soft spots on my eplc. charlie brown and invested in daconil. the stuff is working...but i have a question:

daconil leaves a white film on the leaves of my plants. this surely affects how much light the leaves can photosynthesize. right? i want my plants to get enough light (esp. in these dreary winter months) but i also want to kill the bacteria/fungus thats giving me spots. so how long do i leave the residue on the leaves?

thanks, all!

[LJA]

kewpie, spray with the daconil every ten days for a month (three applications). A week after the last treatment, you can go ahead and wipe it off. Daconil works both topically as well as systemically, so there should be enough of the stuff in the plant's tissues by that point to keep working until mid-February or so. The month's worth of reduced light won't hurt a thing.

[dosal]

Thanks, Louis! That is great information. I use it as well and was wondering.
Another question regarding Daconil - how long can I keep it before it loses its potency? Wish I could find the powder.

[LJA]

I've never seen the powder sold anywhere convenient for U.S. folks to get it (Tanya has apparently managed to buy some in Hong Kong!). The typical rule of thumb is that after a year of being opened, the stuff will begin to lose its effectiveness. (That never stopped me from finishing off a bottle if I happened to have some left, though...)

[kewpie]

thanks for the great info, louis!

is it *all* powders that lose efficacy after time? even if you keep the stuff screwed tight and in the dark?

very interesting!

[LJA]

The powder should stay good pretty much indefinitely as long as it's kept sealed and dry. It's the liquid form I've heard loses potency over time.

[Tanya]

The powder should stay good pretty much indefinitely as long as it's kept sealed and dry. It's the liquid form I've heard loses potency over time.

Thanks for that info Lja . This is my second time to use fungicide in powder form after Benomyl disappeared from the shelves several years ago. Apparently, the distributor buy it in bulk and then re-pack it in small packets, they put all the necessary warnings but forgot to include the dosage .

[dosal]

thanks again, Louis. I am with you, I use up what I have started am wondering though if I should increase the dosage maybe by 1/2.

Tanya, in liquid form you use 1 Tbsp/gallon after you shake the bottle up thorougly. It is thick stuff so I guess you could make a thin slurry and use half the amount usually recommended. If you don't see a white film on the leaves after, just increase the powder to water ratio.

[LJA]

No prob at all. As far as increasing the dosage goes (maybe I shouldn't say this...), I *have* been known to "throw an extra dollop" into the three gallon sprayer when I mix the stuff up. (For people who like precision, that would be an extra 1/3 tablespoon per gallon...) So far, no problems; just be sure you don't hit any blooms when you spray or they'll turn brown in less than 24 hours.

[dosal]

I don't blanket spray in the greenhouse. I don't want to let them get immune to what works now. Even for scale I pull the few plants that have it and spray individually.