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Hello all, I have some peppers and tomatoes on my plants and was wondering if I can still spray with liquid copper as a fungal preventative? My tomatoes are green yet and my peppers have a ways to go also before they will be ready to harvest. I am not seeing any signs of fungal disease but just want to prevent any problems. Thanks all.

If you're not seeing any problems you risk causing more harm than good. Spraying anything can damage crops, so I never spray unless there's an actual reason to.

If you do spray you'll have to read the label for your spray to find out of its considered "safe" to do close to harvest or not.

If you are not allergic to milk, I like milk and a little yogurt whey diluted with chlorine-free water at about 1:8 for using as fungal issues preventive. I spray on top of morning dew when cloudy or near sundown, avoiding strong direct sunlight.

applestar, I have seen you give this suggestion several times. I might have to give it a try. I assume it works in the same way an aact does, by using other microbes to out compete the microbes that are causing the problems

Another very good and safe fungicide is baking soda, or, a similar chemical and even better, potassium bicarbonate. This can be found cheap on Amazon or ebay, as a brewing ingredient. Use 1-2 tb/gal, and a spreader/sticker. Even better, but you can only use when temps will stay below 90°, is a mix of potassium bicarbonate or baking soda and oil - 1 tb + 1/4c/gallon - and many years ago a study was done using a number of fungicides, and this combo rated better than most and as good as copper, when used as a cure.

I spray Actinovate as a prophylactic early in the season, and switch over to KHCO3 later on, as this also kills a lot of fungi. Seems to work well for me.

Thanks for the replies everyone. I am a little confused though, It says that liquid copper is a preventative? I am not seeing any signs of fungal issues right now but we have had a lot of rain and some humidity. I also had some leaf spot on my tomatoes earlier but it seems to be better.

Most fungicides are best used as preventive, since they are not so good as cure. You only need to spray when conditions are right for fungal growth like long periods of rain where the leaves don't have a chance to dry out and especially after the rain has stopped and the humidity is high. Preventive spraying is done before the disease appears or is just beginning.

Fungicides do not work on everything, so you need to know what plant you are protecting and what disease you are trying to manage. Sometimes you may need to use a different fungicide on another plant or for another disease.
For any chemical you should read and follow the label instructions.
https://www.bonide.com/assets/Products/Labels/l811.pdf

Copper sulfate needs to be used with caution as it is an eye irritant so propper clothing and handling is required. It can be toxic to some plants, so you should test it on a small area first. It can usually be used up to day of harvest.

Thanks for the replies all