So is BT to be applied in a mist rather than a drench just as Daconil is? The instructions say to spray bottom and top of the leaves very thoroughly, and to do so it is normally dripping a fair amount. How do you apply?

This seems to be a concept I have trouble grasping. I've always been told that plants need to be drenched in order for a specific fungicide/pesticide/insecticide to be effective, and it's quite a learning curve to spray less. I'm always tempted to spray way more than is needed because I don't feel I'm putting enough on!!!!

How many tomato plants are we talking about? Can't you just pick off the hornworms? Weekly spraying is the standard. Just alternate sprays weekly if you have to use both.

Dave

PS: the point isn't to drown the things you are spraying for. ;-) All they have to eat is a bit of the BT and they are done for so yeah, if you miss a leaf here or there or you don't soak it till dripping the odds are still stacked heavily against the worms.

Dave, I have about 2 dozen tomato plants. I suppose I could handpick, but I had wanted to do at least one spray, as the infestation was quite bad. Judging from how many it killed I don't believe I will need another spraying. Thanks

Hi Jacob:

You said you have been spraying Daconil weekly? You do know the label limits how many times you should spray in a season, I believe for daconil the limit is 7 times per season.

Daconil does work as a preventative, but it doesn't help to spray unless conditions are right for disease to form. Otherwise you are wasting time and money.

"but it doesn't help to spray unless conditions are right for disease to form. Otherwise you are wasting time and money."

Sorry but I would have to disagree with that approach. Daconil is one of the few commonly used garden chems that works best if applied BEFORE the diseases appear and/or the conditions are "right". Spraying from day 1 of plant out is common. The label instructions vary with the brand name but every 7-10 days when conditions favor disease development is the average instruction.

Dave

How much product you apply depends on the package instructions. Pesticides are regulated and following directions ensures safety. There is a difference in pesticides that are contact pesticides and those that must be eaten by the pest. Bt has a short half-life and will break down in sunlight. Daconil is supposed to be rainproof, so I don't see how a spray of Bt could wash it off.

That's a good catch, if true, about Daconil being "rainproof". Where exactly does that come from? It's not on the instructions. Of course, that means that fruit that had Daconil applied, and was rinsed off, still has Daconil on it. I always rinse my veggies to remote pollutants. Now the oral toxicity of Daconil/Chlorothalonil
is pretty low, but I'd rather not ingest it if I don't have to.

GardenTech Daconil says theirs is RainProof. They still say you can wait 0 days to harvest, but don't mention a limit on how many times a season you can spray. Maybe they changed the requirements but I am sure it used to have a 7ish time limit. I always err on the safe side, and re-read the label each year, but haven't started spraying yet so I could be mixing that up I guess. But I have always used Ortho Brand.

GT Daconil

Hmmm. Thanks. My GardenTech Daconil label instructions didn't say that. But maybe I missed it. I have heard that Daconil leaves a waxy sort of coating on the foliage, which would repel water somewhat. I guess I need to start washing my tomatoes with soap.

Dan, little vinegar in the water sure works well. We do that with most storebought veggies, as it can also help as preventative of the E. Coli outbreaks that seem to be so common with bought vegetables.

Personally, I'd rather not ingest the bad stuff if possible, but with how many chemicals we are exposed to daily, I don't know if some Daconil residue would make much difference. Thus I sure do like to pick a tomato and eat it right there :-). Course, most of the time I wash as you mention.

Vinegar won't scrape off a waxy surface, will it? But yes, I'm not inclined to be paranoid about ingesting small amounts of Daconil. It's not like I'm chugging the stuff, and chemical names don't scare me. MSDSs can scare me, but in the case of Daconil, the MSDS is pretty benign.

You soak it for 20-30m Dan. By then the surface erodes.

Geez, I gotta soak my tomatoes for half an hour before eating them? A few seconds with a drop of dish soap will do the job. But that's interesting to know that, given time, vinegar can penetrate a waxy surface. I believe it is true that you can use vinegar to remove old wax from a hardwood floor.

I suppose you could always soak them in xylene to de-wax, if you need a nonpolar solvent. Not highly recommended, though. I'd stick with soap.

I'll guess that xylene is more toxic than Daconil. But I believe xylene, like ethylene, has been rarely used as a ripening agent.