The reason you don't want leaves to get wet when watering is that splash from the soil may contain disease like early blight. Other than that the liquids will just evaporate off. Now with whitefly you can spray them with a mixture of neem oil, dish detergent and water. The detergent helps the oil to mix with the water. Spray directly on the whiteflies for a few days and they'll die off pretty quick. They like to hang out on the underside of the leaves so be diligent as you won't get them all with the first application. Sneak up on 'em. The mixture is 1 qt. water, 1 tsp oil and 1/2 tsp detergent (mild). Shake well and spritz the underside of the contaminated leaves. If you can't find Neem then just use a little mineral oil, it suffocates the buggers. Same thing works for aphids. Hope this helps.

Also, try to spray on a cloudy day....they don't fly around as much on cloudy days, they tend to hang around on the plants more then.

"Yet, I should spray this water on the leaves to kill the whiteflies?"
jbann23 provided a good answer above. The only thing I would add to that is to spray in the morning or evening so as to avoid direct sunlight which could burn the leaves of the plant.

"Also, I was wondering, how effective would it be to plant some marigolds or basil next to the tomato plants? I have heard that these repel whiteflies. Anyone have success with this?"
You can certainly plant marigolds or basil next to the tomato plants and they may be a slight deterrent. But, if you're going to get whiteflies you're going to get whiteflies.

"If we bought ladybugs, what would keep them from going away? Is there a way to keep the ladybugs around on our patio to eat the whiteflies? Is there any downside to buying ladybugs for this problem? Would they get inside the apartment and infest the apartment?"
The only thing that I know of that will keep the ladybugs from going away is an adequate food supply. You may have a few ladybugs get into the house. As the weather cools they may try to get in the house to hibernate. Ladybugs aren't destructive in the house (they don't eat fabric or paper products or household items). Ladybugs do emit an odor, but it takes a pretty large quantity for it to be a problem depending on one's sense of smell of course. If they get to be a problem in the house and are in large numbers use a shop vac to vacuum them up then release them outside.

Good luck. Hope this helps.

Randy

Thanks for all the replies.

I heard somewhere that you can use any vegetable oil such as soybean or canola oil instead of Neem. Do you know if this is true? (It's just that the Neem is more expensive and I don't know where to get it other than the internet.)

In further research this morning I also hear that putting up yellow cards coated with petroleum jelly or motor oil will also attract and kill the whiteflies. Anyone tried this? (sounds like spraying the oil/water right on them is probably a better solution, though)

Thanks much for all the help! Hopefully this will work so we can have our delicious home grown tomatoes! (I swear our's were way better than any I've ever bought, last year! We grew a variety called Bush(?) -cant read it- Goliath. Tough skins but super sweet!)

I've tried the yellow sticky cards for whitefly and they didn't work in the least. The whiteflies just clung to the leaf bottoms and multiplied like fury. The oil/water/detergent mix did 'em right in. And yes, canola oil and the likes do work, it's just that the Neem is a bit stronger and seems to repel insect life.(the bad kind, that is)

* Posted by jbann23 6 RI (My Page) on
Sat, Mar 15, 08 at 8:58

jbann23 wrote:
"I've tried the yellow sticky cards for whitefly and they didn't work in the least. The whiteflies just clung to the leaf bottoms and multiplied like fury. The oil/water/detergent mix did 'em right in. And yes, canola oil and the likes do work, it's just that the Neem is a bit stronger and seems to repel insect life.(the bad kind, that is)"
****************

Thanks for the clarification. We put up some yellow posterboard with vaseline on it, just for the heck of it, since we had the ingredients. I made some of the spray yesterday and sprayed it on our new plants. I'll report back on my success. We used olive oil. If that doesn't work, we'll buy Neem oil and try that.