Which fungicide works best against late tomato blight?

Choosing the right fungicide is essential in preventing total loss of crop production due to Late blight of tomato plants. The best products to use against the most active epidemics are Chlorothalonil, such as Daconil, when used at 7-day intervals in wet weather, which is when this pathogenic fungus is most active. Use copper fungicides weekly for reliable control in the organically grown garden.

Correct application methodology is essential to extract the maximum efficacy of any fungicide. Both surfaces of the leaves must be thoroughly wetted until a frost occurs. A fine mist sprayer will distribute the spray uniformly. Applications should be submitted in the early morning, when the temperature does not exceed 85°F (29°C). I use spreader stickers during the rainy season to assist in the adherence of the fungicide.

Proper timing makes or breaks the effectiveness of the sprays. Beginning with the first increase of humidity above 80% after it has started to decrease, I spray every 7 days until the weather dries out. For established infections, I spray every 5 days until healthy shoots of new growth appear.

Use cultural practices to supplement fungicides. Provide sufficient spacing between plants to allow for adequate air circulation. Remove lower leaves to prevent splash of the spores. Use rain shelters during long wet periods. These methods result in a 50% reduction in fungicide requirements in my garden, while still maintaining their effectiveness.

Read the full article: Tomato Blight Treatment Guide: Control & Prevention