I have a problem. Needs some help. I raise my own tomato plants from seeds this year. I don't know if this is were it started or from my Rose bush's. I first found the problem on my Roses. I went to a nursery with some leafs from them. They told me what it was, so I bought some thing from them for it. A few days later it showed up on my tomato plants so I sprayed them to. It only stops for about a week or so then it comes back. I live in southcentral ky. They told me that humidity starts it. My question is. If I mix a low dose of bleach in water and spray the roses and tomato plants will it hurt the plants? If any one can help me I would be very thankful. Have a Great Day and keep gardening.

I get it on monarda and phlox. I spray with milk

Here is a thread from Tomatoville that discusses spraying with bleach: http://tomatoville.com/showthr...

Rick, the thing about powdery mildew and other fungal stuff is that it's floating around in the air. Once you have it in your garden, unless you spray everything every few days for a few weeks it will keep re-infecting the leaves especially when the weather's humid and warm.

Couple of things can help - first of all never water your plants in the evening, unless you have a drip or soaker system that doesn't wet the leaves. If the leaves are sitting with water on them over night, this invites fungus to land and take hold on the leaves. Water in the early morning so that the sun dries the leaves off quickly as the day heats up.

Second thing is that most fungicides - esp. the ones you can use on edibles - work as preventative measures. They don't actually kill the fungus once it's growing on the leaves. So, you need to quickly remove infected leaves, and I mean remove! As in put them in a bag and into the garbage can, not on the compost pile or on the ground where spores from them can still fly around.

Then you need to keep spraying the leaves, whether it's milk, baking soda solution (1/2tsp. per quart of water) chamomile tea, or your bleach solution. It needs to be on the leaves so that when a spore lands there it can't take hold. Most of the preventatives wash off with rain or sprinkling, so this means every day or two you need to spray fresh stuff. On edibles, you need to use non-toxic substances, of course. The chlorine in the bleach is going to evaporate, so something else will be preferable I think. I use the baking soda solution every second day when I'm growing veggies. Seems to work fine.

dyzzypyxxy said:I use the baking soda solution every second day when I'm growing veggies. Seems to work fine.

Do you start spraying before you see the mildew. Last year I struggled without luck and realized that given the humid air and many cloudy days I need to be aggressive this year about powdery mildew. Just not sure when I should start spraying.
Last year, it felt like by the time I realized there was a problem, I had already lost the battle.

Absolutely, it's purely a preventative measure, in making the pH on the leaf surfaces unreceptive to the fungal spores. So the sooner, and more often you spray, the better it will work. Since baking soda is soluble, it will rinse off if it rains, or the leaves are sprinkled.

As I said above, one of the best ways to keep these fungal things at bay is to keep the leaves of your plants dry as much as possible, so soaker watering systems that don't wet the leaves are a big help.

Air circulation around the plants is also very important in keeping the leaves dry. So be sure to space your plants far enough apart to allow the wind to blow . . .

Do follow advice given here.

A word about powdery mildew (not other diseases):
--- This disease lives on the tops of leaves, so if this is the only reason for spraying there is no need to be sure to get the undersides.
--- Unlike other diseases, powdery mildew spores are prevented from germinating by free water. They germinate in high humidity. Of course this can happen after wetting leaves while watering, so it's still a good idea not to get leaves wet.
--- Most species of plants will have their own particular species of powdery mildew that attack them. For instance, the powder mildew that attack lilacs will never infect roses. Likewise, and especially since roses are unrelated to tomatoes, powdery mildew on roses cannot infect any tomatoes.

Thanks for all the replies to my problem. I sprayed my Roses and Tomatoes 2 days ago. We had bad storms last night so I will spray the baking soda solution again as soon as every thing dries off. The dang stuff is showing up on every thing. I have noticed it is on some of the broad leaf weeds in my yard. I usely plant my cucumbers under a section of fence I put up for them to grow up on. I love my home made Pickle's, so I know I would be fighting a loosening battle this year with them. I have been raising a garden or been around one all my life and this is the first time I have seen this problem. Last summer Blue Mold hit my cucumbers late in the fall. I new what it was from raising tobacco before, we always use a bleach solutions to spray for it. It would be visible when you went to strip it in the winter, but this problem has got me stumped. So thanks again for all your help.

>> --- Unlike other diseases, powdery mildew spores are prevented from germinating by free water.

Maybe that's why the coastal PNW doesn't have as much trouble with mildew as I expected. During the "rainy season", there's at least a little rain several times per week, washing the leaves.

During the other 2-3 months, it's quite dry.

Re Monarda and Phlox, at least, above.

I plant and maintain many perennials close together and have an especially large number of garden phlox.
At least for our weather (our summers are quite humid), I'm convinced that the main way to prevent powdery mildew and a host of other garden problems is to attend to "garden hygiene".

Apart from the sine qua non of having enough sun, the latter for me includes cutting back (at least the flowering parts of) plants right after they bloom (to promote air flow within mixed perennial beds and expose other plants to sunlight) and cutting back and removing all plant debris before our cold winter sets in (to remove or expose potential disease organisms).

This year I cut my phlox down by half by mid June, don't know if its coincidental or our weather which was cool and very wet, but I had virtually no powdery mildew on the Phlox vs other years when they were covered.

I've found that IF you catch it early, just washing the plants off with the hose early in the morning will do the job. I've tried the milk, but that didn't work well for me. Dr. Bonners peppermint soap (1Tbsp per quart or 4 Tbsp per Gal of water) not only killed the thrips I was spraying for, but killed all the mildew AND rust on my roses, but it does leave a residue if you don't rinse it off after a couple of hours.