My first recommendation is that you do your research very carefully and be sure to match up the fungicide you decide to use with both the plant on which you'll be spraying it and with the disease or diseases you're dealing with. Some fungicides are only labeled for use on certain vegetables and some fungicides are only effective on certain diseases, so it can be a waste of time and money if you buy a fungicide and take it home only to realized that (a) you cannot spray it on some of the things you're growing and (b) it is not effective on the particular disease or diseases you're dealing with.

Also, be sure that you understand which fungicides are organic in nature and which ones are synthetic, if it is your preference to use only organic products.

Most of the fungicides that are readily available to the home gardener do not 'cure' a fungal disease once the plant already has it. Most of them can slow down the rate at which the disease spreads and that can mean your plants may live long enough to produce a crop. Most of the home gardener-type fungicides work by coating the plant, in effect sealing it, so that the fungal spores cannot attach to the plant parts. In order for them to be as effective as possible, it is best to carefully remove every diseased leaf from every plant and then to spray. However, in a rainy year like this, the fungal diseases can spread very rapidly and you may find yourself in the position of having to leave some diseased leaves on the plants to prevent the crop you're growing from sunscalding and being ruined.

One of the best multi-purpose synthetic fungicides available, sold under such names as Daconil or Ortho Disease-Control Spray, is chlorothalonil. It is most effective, though, if sprayed on the plants from Day 1 that they are put into the ground (or sprout, if grown from seed) and then re-sprayed at regular intervals per the label direction. Beginning to use it well after plants already are infected will help a little, but not as much as using it regularly from Day 1 would have worked. Other synthetic fungicides available for use on some vegetables include Maneb and Mancozeb.

Some of the organic fungicides available include Green Cure (Potassium bicarbonate), Serenade, neem and copper.

To answer your question, no it does not harm a plant to be sprayed with fungicide IF that fungicide is labeled for use with that plant. It is important to read and follow all label directions. Some fungicides will help many veggies but harm or even kill others. Some fungicides are fine to be used at any reasonable temperature, but others burn plants and can kill them if sprayed in hot weather. Some fungicides cannot be applied within a certain number of days of some other products (like oil sprays) being sprayed. Some fungicides cannot be combined with other products (like an insecticide or water-soluble fertilizer).

Do I think fungicides are worth the time and expense? To me, it depends on the time of the year. I sprayed my tomatoes with Daconil once or twice in May in an effort to slow down the spread of fungal diseases. It worked okay but not great (totally the result I expected given that we over 25" of rain in May alone and everything in the garden stayed wet 24/7). I am not sorry I did it as we are getting a gigantic harvest of tomatoes. Would I do it again? No, now that we are in mid-June I wouldn't spray the tomatoes again. First of all, I don't like eating any food crop that's been sprayed with anything. Since I am a realist though, I do know that in a year like this, spraying once or twice with a fungicide gives my plants the best chance of survival. Secondly, when you read the MSDS on any given product and see that it is considered a possible carcinogen, you ask yourself "Do I want to use this on plants I'll eat?". Also, notice my remarks are confined to tomatoes. It is very hard to keep tomatoes happy here all summer long. In a dry year, the stink bugs damage the fruit heavily and the spider mites sometimes damage the plants heavily. So, I'm content to harvest tomatoes early and often from late April through late July or early August and then to let the plants go. I'd rather be starting over with fresh new tomato plants for fall tomatoes. My decision on whether or not to use a fungicide depends on the plant being affected, how well it will produce if it survives, etc, and whether or not there is a safe organic fungicide that I can use in high heat. Also a part of the equation is whether the rainfall is continuing. Rain will wash fungicide off the leaves of your plants pretty quickly, so it can be hard for them to remain effective in rainy years.

LSU has a great document that gives very detailed info about the garden fungicides generally available to the home gardener. It includes a chart showing which fungicide is effective on which diseases. I'll link it below.

Hope this helps, and there's no need to apologize for discussing a garden-related topic on a gardening forum! : ) Having said that, I do feel bad when I focus too much on my poor garden and forget the plight of others who have been badly affected by the floods. I keep telling myself that if the garden's issues are my worst problem, then I'm pretty lucky indeed.

In a few minutes, our son will be arriving home with a friend of his who is going to move into our guest room and live with us for a while. This young man is fiercely independent and has been trying to stay afloat financially by selling all his personal belongings after losing his job when his employer (a golf course) was shut down after suffering massive flood damage. My heart goes out to him, and I am happy we are able to offer him a place to stay. I wish he'd told someone he was having trouble before he sold almost everything he owned. When I think of what he has been through and how upsetting it must be to find oneself in that position, and how he was just planning to live in his car, I feel immensely small for worrying and fretting over spots on my tomato leaves. I am going to try really hard to bite my tongue and not complain about any of my garden problems (which ALL are so minor compared to what he is going through) to him. His situation helps me put my yard and garden issues into perspective, you know?

Now, the great LSU link is below!

Dawn

LSU: DIsease Management in Vegetable Gardens

Dawn, I have never met you and only know you through this forum but I believe you are a wise and compassionate person. I know this young man will pull through this tough time and turn his life around, all he needs is a little help. It is not an easy thing to open your home to another person. I agree, our garden issues are indeed small potatoes compared to his problems. Pride can be a very powerful and destructive emotion, with your common sense and compassion he will take the right path. Good luck to both of you.

Dawn, it's kind of you to help your son's friend--thanks for being a light in this world. You're a wonderful example. I know many of us appreciate your help with our garden things--you give thoughtful ideas and solutions that probably take up a large spot of your time. Hopefully with you and your family's help your son's friend will be able to get back on his feet.

I wish I knew how to upload a pic of this cotton ball fungus. I've never seen anything like it and can't find anything online that looks similar. I'm always confused on fungicides, plant food, fertilizers, pesticides, etc. I usually just use nothing because I'm so bad at identifying exact issues.

stockergal, Well, you know, I had verbally lamented the fact that rising flood waters were putting folks out of work at lakeside marinas, restaurants and other attractions, so when I learned this young guy was selling his possessions in order to stay in his apartment until the end of June, I knew we needed a game plan to ensure he didn't end up having to sleep in his car. It was time to put my money where my mouth is, so to speak. I have faith in him---that he will come through this just fine. It is really a small thing to do----we have a spare room and he needed a place to stay. Y'all give me too much credit---anyone with the space would have done the same thing---imagine if every family in American that had a spare room could offer it to a person struggling to keep a roof over their head. What a wonderful world that would be. And, to be clear, it should be carefully-screened person, not a mentally ill homeless person you don't know. He is a delightful young man and I intend to enjoy the time we have with him here in our home for the next few months. I jokingly told Chris "Surprise! Here's the little brother you always wanted."

Hazel, You are too kind and I thank you for your kind words. I think we are the lucky ones here. He's going to be fun to have around, and he is a highly-motivated, high-achiever so I expect he will aggressively search for work and get back on his own two feet in no time at all.

With the cottony type fungi, I've seen similar things before, several times on squash plants and there is a similar disease called Southern Blight that causes a white, cottony fungi at the soil line where the plant emerges from the ground. I had it on a tomato plant in one of our first years here---probably in 2002 which was wet well into June. I kinda think a lot of these fungi are in the soil at a low level all the time and when we are really wet and humid and warm, they just experience explosive growth.

Have you looked at Vegetablemdonline or the TAMU Cucurbit Problem Solver? They have photos of lots of diseases. I'll link the Cornell md site first. Their disease diagnosis pages are really helpful.

One of the easiest ways to identify fungal issues is to look for signs of sporulation. It can occur in various ways, sometimes as little black dots and other times as cottony or stringy growths. If a plant has a disease that is reproducing via spores, it is a fungal issue. You also could be seeing something bacterial.

The way I learn diseases is by encountering them. Before we moved here, I barely knew any diseases at all, but now I know a lot of them. Oddly, with all but the most common things, I rarely see the same thing twice. I've had a plant with Tomato Spotted Wilt Virus just once, and at the time (pre-Internet, ha ha) I had no idea what it was. About 10 years later I saw photos of a plant and tomato fruit with TSWV online and say "Aha! That is what is was." The same thing happened with Southern Blight---I've seen it only once. Usually if I just dig and dig and dig, I eventually figure out what disease a plant has, though sometimes it isn't until after the fact.

If you haven't already, remove the fruit with the fluffy white disease mass on it. You don't want it sending a billion spores airborne to infect your entire garden. It might be sclerotina white mold which will be in the page I link. You can see this form of white mold get much bigger and thicker/denser than it is in the photo from Cornell. It is somewhat common here on pumpkins and squash in rainy years.

Dawn

Vegetable MD Online: Cucurbit Fruit Rots