Our tomatoes suffered badly from late blight last year. Our small backyard has high fences, and combined with being in a built up area, lacks good air circulation so I was already taking anti-fungal precautions such as watering only at the base of the plant. A few days of rainy weather made keeping the leaves dry impossible though, and shortly after I started seeing the dreaded septoria spread.
I should mention that I'd also been spraying the plants with aspirin water weekly. Hard to say whether it helped or not, but I've decided to discontinue it for now to avoid wetting the leaves unless absolutely necessary.
Instead, I've decided to try:
Bicarb Soda Fungicide - based on the Cornell University study.
1 litre of water
1 teaspoon of bicarb soda
1 teaspoon of cooking oil
A drop or two of dishwashing soap
Shake well before and during application. Spray both sides of leaves every five to seven days.
Brew as directed and mix 1:10 with normal watering.
I've also mulched the plants with sugar-cane mulch to keep the spores in the soil from splashing up on to plants, and will up the Seasol feeds.
We had some powdery mildew on our grapevine and sage last year, so I will also try the Bicarb spray on those and the new zuccini plants as a preventative.
Wish me luck!
Applied the Bicarb Soda spray Dec 16th to tomatoes, zucchini, rose and sage. It didn't emulsify very well and I think horticultural oil might work better than cooking oil + soap. Applied lime sulfur to the grapevine.
Now using Eco-Rose which is Potassium Bicarb rather than Sodium, mixed with Eco-Oil to make it stick. See post 'Eco-Rose and Eco-Oil'.