Identifying Fungal Issues on Tomato Leaves & Using Hydrogen Peroxide as a Treatment

First rule, always test spray any new sprays you use in your garden. Spray a few leaves and wait 24-48 hours for damage. If there are no issues, write down the recipe and spray away. Second rule, it is best to spray in the morning or early evening. Third rule, don't mix other ingredients with hydrogen peroxide. Fourth rule, learn what the patterns on leaves means so you know when or when not to panic, or calmly treat your tomato plants.

Basic 3% Hydrogen Peroxide

Hydrogen Peroxide (3%) can be purchased at many locations. You do not need an organic stamp on it. H202 is used to actually clean the leaf and kill off any active fungal issues (spores) on the leaves. It does not prevent future fungal spores from showing up and taking hold but actually kills what is on there. You can use 4 ounces per gallon for general maintenance and leaf cleaning every 10-14 days to prevent leaf problems. You can use up to 8 ounce per gallon to treat outbreaks on your plant. If you have an out break, I recommend spraying every 3-5 days for 3 cycles to get things under control.  Spray the top and underside of the leaves well, including stems and fruits. It won't harm flowers or beneficial insects.

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1. 4 ounces of H202 in 1 gallon of water for maintenance spraying
2. 6-8 ounces of H202 in 1 gallon of water for managing outbreaks.
3. Start with the lower mix ratios and see how it works.

Basic Tomato Leaf Spraying

It is best to wait 24 hours, after spraying H202, before putting on any new sprays such as an antifungal like baking soda. Hydrogen Peroxide breaks down quickly, cleans the leaf, and is gone. You have to follow up with and antifungal to prevent future fungal issues from returning.  Or if you have lower disease pressure in your garden, you can just do maintenance H202 spraying.  The bottom line is to set up a routine of prevention spraying that works for you and stick to it. Your consistency with your spray and care routine is often more important than the actually sprays you choose.

Concentric Circles Means Tomato Leaf Fungi

It is very hard to identify every issue with tomato leaves as yellowing, die off, and appearance of fungi on weakened leaves is really normal and common. Especially when the high heat of the summer shows up. Watch my video for more details and examples on identifying leaf problems. They biggest sign you have fungal issues is not yellow or uniform brown patches on leaves. It is a pattern of brown circles within circles that is a sign you have a fungal outbreak. Smaller spots covering leaves is often a leaf spot fungal issue, larger spots are often a sign of early blight. The spots often have a yellow halo around them which signals, an active fungal outbreak. The above spray routine works on tomato leaf fungus in general. 

Hydrogen Peroxide, in theory, can be used on any plant in your garden. However, these ratios are what I tested for using them on tomato and pepper plants. Each time you try this spray on new plants, do a test spray. There is nothing sadder, I've been there, than defoliating plants because a spray that doesn't harm plant A damages plant B.

Here is a 2nd video that really goes in-depth on using hydrogen peroxide in your garden. The recipes and frequency may vary as I often tweak things year to year. There are 1000 ways to garden, so use what I teach as principles and adapt them to your garden needs.

"Good Luck in Your Gardens"

Cheers!

Gary (The Rusted Garden)

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