Daconil! Another question?!!

[dcarch]

Sorry if this has been answered before, but I didn't find it.

If Daconil is rainproof (I think that's what it says), then why so many of you recommend spraying after a rain fall?

Shouldn't you spray just before rain to protect your plants from rain carried fungus (fungi?)

dcarch

[bcday]

I tried that last year, making sure the Daconil would have time to dry on the foliage before rain or nightfall arrived. When the rain came, I could see moisture beading up on the leaves the way it does on a freshly waxed car. The Daconil didn't get washed off, so it makes sense to me to do it that way, too.

I can't say for sure if there were more or fewer foliage disease problems that way, though. Not sure how that could be measured.

[feldon30]

Daconil is hardly rainproof. The bottle says to apply every 7-10 days, but it may be necessary to spray twice or even three times during a week because of torrential rains.

[Tomstrees]

Dcarch -

You're using that stuff ???!!!

~ Tom

[Suze]

IME, Daconil is somewhat rain-resistant, but it isn't entirely rainproof. Duration and amount of rain matters. It will eventually wash off, which is why I might not bother to apply before rains. I more or less stick to a 7-10 day schedule, and when it's time to spray, I look at the forecast before doing so.

For example, if seven days have passed and it's definitely going to rain in the next day or two, I wait. But if I'm on day ten, and it *might* rain in the next few days, I will probably spray. Judgement call.

Also, I'm going to be more likely to spray more frequently for younger plants than I would large plants that have already gotten to the point of decent fruitset. At that point, a little fungal disease isn't going to be the end of the world, and a healthy plant can generally handle it/outgrow it. For larger/older plants, I'd rather do things like clean up foliage around the base of the plant, remove diseased foliage, and make sure there's plenty of mulch instead of spraying and spraying.

[bcday]

Probably the manufacturer could best settle this question, but here's my reasoning.

I use Daconil mostly against septoria and early blight. The APS site (http://www.apsnet.org/education/Less...o/discycle.htm) says that early blight spores are spread by wind and splashing rain, and will germinate in approximately 40 minutes in the presence of free moisture (free moisture being water on the leaf from rain or a garden sprinkler).

Daconil was not designed to kill the live fungus after it has infected the leaf. It's only a barrier to prevent the germinating spores from penetrating the leaf surface and starting an infection.

So it makes no sense to me to wait until after the rain to apply the Daconil, because the spores are germinating and infecting the leaf while it's still raining. The Daconil won't do any good after the leaf is already infected.

Septoria and early blight spores don't do so well on dry foliage, so the Daconil is most useful when spores will be blown or splashed onto wet foliage. As I see it, a good coating of Daconil needs to be in place just before the rain. Otherwise the foliage will be infected before it dries off and I have a chance to get the Daconil on.

The label does say to apply more often when conditions are favorable for development of disease (frequent rain). But the Daconil didn't wash off right away. It stayed on long enough to remain effective as a sealant until the rain stopped and the foliage was dry again.

[dcarch]

Originally Posted by feldon30

Daconil is hardly rainproof. The bottle says to apply every 7-10 days, but it may be necessary to spray twice or even three times during a week because of torrential rains.

I think Suze is right, may be it should say rain-resistant, which means something very different.

7-10 days makes a lot of sense, because you are getting a lot of new growth. My plants are going at about an inch a day, and suckers coming up everywhere.

P.T. Barnum must be a tomato grower, he said, "There is a new sucker born every minute"

dcarch

[feldon30]

The bottle says to use 1 tbsp (3 tsp) per gallon, but at that concentration, it doesn't stick very well for me. So I usually do 1 1/3 tbsp (4 tsp) which sticks a LOT better for me.