Don't spray any pesticide if the temps are, or will be, 80F or above.

Reason: The spray will damage the plants, perhaps severely.

Do it in the evening, after sundown.

Yeah, all you need is time for it to dry out a good bit...sundown or as the sun is going down is a great time to spray any horticultural oils during the worst of summer.

Unless it's excessively (like, off the charts) humid it should be enough time to be safe by the time the sun is beating down on plants the next day.

Or consider another fungicide, safer than an oil.

Well, I did a vinegar solution this morning. Plants will be dry before the heat kicks in.

Wish me luck!

Kevin

Be advised that vinegar is often used as a herbicide. That is, to kill plants.

Vinegar was a bad idea. Although I used a more diluted version of the recipe, I still had foliar damage. I've moved on -- I'm now using potassium bicarbonate... too early for a review, but so far, so good.

I'm having to clip a lot of foliage due to the vinegar fiasco. I should have just used neem, but I was told that if it was going to be hot the next day, that I shouldn't use it. I bet the neem wouldn't have done as much damage as the vinegar. :(

Kevin

I'm constantly boggled on this board by the fact that people have fungus problems and persist in using anything but an actual fungicide to treat them.

ltilton: People have been using concoctions other than bottles that are labeled "fungicide" forever.

Baking soda -- used in households for mold and mildew
Vinegar -- same thing
Milk -- who da thunk? But everybody that I talk to that say they use it for PM say they're satisfied.

And if you had followed my quandary, I was told NOT to use neem(LABELED FUNGICIDE) by a very well respected member here on GW, because I was in the midst of a heat wave.

Glad I could boggle your mind.

:)

Kevin

I might have missed something here, but apart from possibly 'frying' foliage on hot days, why else shouldn't you use neem oil extract?

soraystud:

Burning was my main reason. But also... Neem is an oil. Oils smother eggs. And I really am trying to make a concerted effort to instill the whole Integrated Pest Management agenda into my garden. I've noticed a nice explosion of beneficial insects in my garden this year and I fear that if I continue to use neem on a consistent basis, it will kill future generations of those beneficials.

I could be wrong. maybe neem doesn't smother eggs. I just assume it does because other OILS do.

The other reason is price. Between 4 full grown indeterminate tomatoes, 27 pepper plants, 6 cantaloupe vines, 4 squash, 3 cukes, 6 swiss chard, 2 kale, and 8 broccoli, that's a lot of neem oil every 2 weeks. If I can find something at a fraction of the cost and have it be as effective, I'm going to use it.

Kevin

Every two weeks is not enough to contain powdery mildew. More like spraying every week.

I has been hot as get go here with actual temps in the high nineties and heat indexes of 100 or more. No problems here spraying with the Neem. I simply wait till very late in the day as the sun is going down. One should spray late anyway as you don't want to get the bees with the neem.

I was really lucky last year and didn't have the pests we have this year. I had some sesame oil/fish oil blend left from year before that I had used for aphids on seedlings. 1.5 tsp per quart sprayed on raspberry and blackberry canes for leafhopper (the JB kept munching along though) and the zukes, trying to get underside of leaves for SB eggs and nymphs but also trying for leafhopper on zukes since I saw them on stems. Sprayed 8pm when it was still hot but no direct sun.

Should they be rinsed off in the AM before the sun hits them and it gets over 80-85 (supposed to be mid 90s)?

Ajsmama: I rinse off the next morning after I use soap. Not sure about oils actually rinsing off well.

Wouldn't hurt to do it. And it just may hurt if you don't.

Kevin

soraystud - I wouldn't use neem as a fungicide primarily because there are more effective fungicides available without the drawbacks of neem, the potential for burning foliage and, more importantly, its insecticidal properties. Using neem on flowering curcubits, in particular, is risking harm to pollinating bees.

I have used it as an insecticide on some occasions.

Thanks Kevin - I'll brave the mosquitoes and do it now. Heck, I braved a bear to spray the berries (not really, as soon as I saw it on the edge of the woods 10-15ft away I ran back into the garage! But DH came out and stood sentry while I finished).

When we say "oil" Mazola, animal fat, Olive oil, ... pops in our mind. But there are different kind of oils. For example, perfumes are oil, the heat in chili is oil etc. The latter ones are not that stable. I think Neem oil is somehow like that too not like lard. me thinks.

I use neem on my squash to control the powdery mildew. I can't think of anything that might work better. Plus it also kills any eggs of SVB.

I spray late in the afternoon towards evening when the bees are done for the night and the squash flowers are closed. I have lots and lots of bees.

One of the reasons I will not use neem on cucumbers is because of the bees. I don't want it to get into the open flowers and hurt the bees.

rita - may I suggest Immunox for gardens against the PM. Be sure to get the formula w/o insecticide.

I am very short on bees and hesitate to use anything insectical where anything is flowering.

I wish cukes and melons were like squash and their flowers would close up at night.

Immunox is a systemic fungicide. Don't care for the idea of systemics in my veggies. The neem works just fine on the squash and I don't use anything on the cucumbers.

Do you use the Immunox on cucumbers?

Yep. On all the cucurbits and on the tomatoes and potatoes, too. It's the systemic aspect that makes it effective.

Also on the fruit trees, which is how I first used it, against scab.

Really? On tomatoes? I use a Daconil product on my tomatoes, nothing on the cucumbers.

Have tried growing Armenian cucumbers twice now but they come down with powdery mildew bad and I ripped them out. Wonder if Immunix would have cured them? Maybe have to start before they get sick.

The tomato/potato is experimental on my part. I alternate it with other fungicides like daconil.

PM is what it's specifically listed for. It's not an all-purpose fungicide. I wish it did double duty for DM, too, but alas not.

Sprayed all my squash again with the Neem. Really want to get back on top of this powdery mildew stuff. Already today the squash look so much better than they did on Monday when I last sprayed them. So today being Friday that means 4 days in between sprayings. Now I should be able to go back to weekly spraying. Actually I would like to keep to a spray in just under a week. That should work well.

I had to wait until late in the day, I just came in from spraying. Not that it is hot. I could have sprayed in the middle of the day as temps are really mild. But the bees were out all over the squash all day. Lots and lots of honeybees. I don't honestly know what they were doing but they were at it ALL day. Not in the flowers, they were landing under the leaves and then looking like they were eating or vacuuming along under the leaves. And only on the leaves that had powdery mildew. How really strange. I guess eventually they had enough and went home or it just got late.

I was using my battery powered wand sprayer again. Found a spray setting that works really well and the spraying didn't take as long to do this time as it did the first time I used the sprayer.

Milk spray works against fungal infections on plants because of the lactobacillus and other types of cultures in it. Dunno about pasteurised milk, but adding some yogurt to the milky make the spray out of would probably ensure or increase its efficacy. I once used just "micro filtered" milk mixed with water and it worked.

For the cypress tree disease in Italy, Neem oil (be sure to get the one made for mixing with water) mixed with Marseille soap, sprayed with a big agricultural sprayer, on the tree, and the trunk and on the ground around the tree, when the temperatures won't rise above 30 degrees centigrade, used with magnesium sulphate (Epsom salts)--a few heaping soup spoonsful scattered on the ground around each tree twice a year, or a stronger magnesium solution poured on the ground if the tree is really pale and wan, along with watering weakest trees in periods of drought helps. It is important to also prune allthe dead branches out and to take off any damage at the tip of the tree. The trees can grow back if there is even one good branch left, it will form a new tree. You need to spray in the weather which puts them most at risk, hot humid weather when it rains in the summer--it is tricky to time it properly. Be sure not to plant anything against the trunk that would hold water on the trunk, as it can cause the trunk to rot and kill the tree. I have the idea of trying using the natural mineral fertiliser fulvic acid around the trees at the beginning of summer. The magnesium sulphate makes the trees visibly greener. Neem oil seems to be more than a fungicide and insecticide, it seems to nourish the trees too. Another possibility for the fungal diseases is Effective Microorganisms (EM). The magnesium sulphate furnishes the central mineral that they need to use to make chlorophyl which should help them fight the disease by raising their metabolism. These things should help combat fungal disease on roses too.

Neem oil sprayed on the ground around the plants and watered in is taken up by the roots and becomes a systemic fungicide, which I suspect would be safe for bees (???) EM is safe, read one of the books on Effective Microorganisms by professor Teruo Higa, it was an amazing discovery, as it works as fertiliser too.