Yes, now that you point me in that direction, I think you are right. I didn't think about anthracnose in watermelons, but one of the devastating things about this fungal disease is that it seems it can attack practically anything.
It is a fungal disease and the hydrogen peroxide is an anti-fungal. Baking soda solution is another.
Whether you want to use the chlorothalonil depends on how you feel about spreading environmental poisons around.
https://www.cdpr.ca.gov/docs/emon/pubs/f ... alonil.pdf
If chlorothalonil leaches into waterways, it is highly toxic to aquatic organisms, even at very low levels. Although animal studies have provided sufficient evidence to classify chlorothalonil as a probable carcinogen, it is not known if it is a human carcinogen or not. It is not directly toxic to birds, but it reduces their reproduction -- egg production, hatching survival, etc. Its degradate SDS-3701 (compound it breaks down into) is much more toxic. Berries treated with it were found to still have residue 76 days later. It can inhibit growth in plants treated with it
Department of Environmental Toxicology, College of Agricultural & Environmental Sciences, University of California, Davis, CA 95616-8588, USA
https://www.tampabay.com/news/environmen ... gs/1162355
It's part of the same chemical family, organochlorines, as the banned pesticide DDT. It is known to cause severe eye and skin irritation in humans if handled improperly. Chlorothalonil's label says not to spray it directly on waterways, so the researchers did not do that. Instead, they used a federally approved formula that calculates how much of a concentration would run off of a farmer's field and wash downstream into a nearby waterway. It killed nearly 90 percent of the frogs, no matter what species
It is not acutely toxic to honey bees, but
https://www.bloomberg.com/news/articles/ ... tudy-finds
Fungicides used on apples and other crops lower the honey beesâ€™ ability to defend against a potentially lethal parasite linked to bee colony deaths, a study found. Commercial honey bees exposed to the fungicide chlorothalonil had a three times greater risk of being infected by the parasite linked to Colony Collapse Disorder than those not exposed to the chemical used to fight off fungus, according to research today in the journal PLoS ONE.
and so on....