The best fungicide late tomato blight needs is chlorothalonil. Mancozeb works well too. Organic growers should use copper sprays for this disease.
I tested all three types during a bad late blight outbreak in my garden. The chlorothalonil late blight results amazed me right away. My treated plants kept their green leaves while untreated tomatoes lost all their foliage in just two weeks.
Late blight comes from a water mold rather than a true fungus. This water mold goes by the name Phytophthora infestans. Your regular fungicides might not touch it because it needs different chemicals to die.
NC State Extension and WVU research point to proven choices for your home garden fight against late blight.
You can find chlorothalonil at most garden stores under brand names like Daconil. This product sticks well to leaves even after light rain. Spray your plants every 5 to 7 days when late blight shows up in your area.
Mancozeb blight control kills the pathogen in a different way than other products. You should swap between mancozeb and chlorothalonil to stop the disease from building resistance. This two-product approach gives you better long-term results than one spray alone.
Copper fungicide tomato sprays work great if you garden organic. Look for the OMRI label on products if organic status matters to you. These copper sprays coat your leaves and kill spores before they can start new infections.
Your spray timing matters as much as which product you pick. Apply fungicide before rain when you see storms coming. Wet leaves help spores swim right into plant cells where they cause new damage.
In my experience, you save far more plants when you spray before symptoms show up. Late blight can wipe out your whole tomato patch in 10 to 14 days once it grabs hold. Those dark water-soaked spots mean the disease already has a big lead on you.
When I first grew tomatoes, I grabbed whatever fungicide sat on the shelf. Learning about water molds changed everything for me. Now you should pick products based on what pathogen you face rather than buying at random.
No fungicide cures tissue that late blight already infected. These products only protect your healthy leaves from new attacks. Cut off and bag any spotted foliage before you spray so the chemicals can shield what remains of your plants.
Keep your sprayer clean between uses to avoid spreading problems around your garden. Rinse it out with clean water after each treatment session. Dirty spray gear can carry disease from sick plants to healthy ones if you skip this step.
Watch your local weather reports during late blight season. Humid nights above 50 degrees create perfect growth conditions for this disease. You should spray within 24 hours before these conditions hit to get ahead of the infection.
Some gardeners mix their own sprays to save money on fungicide costs. Stick with the label rates when you apply these products to your plants. Using too little leaves your tomatoes unguarded while using too much wastes your money and can harm the plants.
Your choice of sprayer affects how well the fungicide coats your plants. A pump sprayer with a fine mist setting works best for full coverage. Make sure you hit both sides of every leaf since spores can attack from any angle.
Store your fungicides in a cool dry spot away from kids and pets. Check the expiration dates before each season starts. Old products lose their punch and may not protect your plants when you need them most.
Read the full article: Tomato Blight Treatment Guide: Control & Prevention
