Will baking soda control peach diseases?
Answer: There are at least two baking soda products that are registered with the Organic Materials Review Institute (OMRI) as “certified organic”?Milstop? and Green Light?. Milstop is aptly named because it is used primarily for mildew control in cherries and other susceptible crops. But it apparently has little or no efficacy against brown rot and here are two reasons:1) Baking soda is very water soluble, so if you get any rain big enough to cause water to run off the leaf, the baking soda is washed off.2) The etiology of the disease is such that the first symptoms are often not obvious until many days, even weeks, after the infection. The initial infection might take place even during bloom, but the most common time is during early fruit development. During this time, spores are spread by wind and rain (if you have any) but also by insects that are feeding on the fruit. It might be a plum curculio or a stink bug, but any number of insects can spread the disease. Then, the disease remains more or less quiescent until the sugars begin to develop in the ripening fruit?that is when the brown rot really becomes visible. It’s a very common observation of backyard growers to pick an apparently edible peach in the afternoon, leave it on the kitchen counter overnight, and discover a half-rotted peach in the morning.For more information, see the ATTRA publication Peaches: Organic and Low-Spray Production at https://attra.ncat.org/attra-pub/summaries/summary.php?pub=6. Among other information, this publication describes the major diseases and insect pests of peaches and discusses organic or least-toxic control options for each.If you could keep baking soda on the leaves and fruit, you might be able to combat this disease a little with baking soda, but ATTRA is not aware of any scientific literature suggesting this is true. Even the organic fungicide that does work against brown rot, sulfur, must be reapplied after every rain. It’s a pretty good bet to say that brown rot can’t be controlled with baking soda, but it never hurts to conduct a little experiment. If you don’t want to experiment, stick with sulfur. It is worth mentioning that there is at least one other fungal disease that has been effectively controlled with baking soda, and that is sooty blotch of apples. The point is that baking soda has been researched for effectiveness in controlling fungal diseases of fruit, and the only two diseases that it is very good at controlling is powdery mildew (of cherry, apple, peach, etc.) and sooty blotch of apples. Again, as always, it’s not hard to conduct a little side experiment of your own to see if baking soda might work against brown rot in your particular situation. Finally, the Chinese and others are using plastic-covered high tunnels to produce organic peaches. Keeping any and all rainfall off the fruit is an almost perfect control?the insects can still spread it, but the fungus, Monolinia fructicola, needs free water in order to germinate. Similarly, the bagged fruit option discussed in ATTRA’s peach publication protects the fruit from infection, though the labor might be prohibitively expensive. Research is being conducted at Rutgers in New Jersey.