Any organic sprays for tomato diseases?

Any organic sprays to prevent early blight, late blight, and septoria leaf spot on tomatoes? If not what are some of the safer non organic sprays?

Quadris is expensive, but effective. Azoxystrobin is one of the ingredients in Quadris, but can be purchased separately. Neem oil is partially effective. Copper alternated with neem is better than either alone. If you look up Chlorothalonil, it is a moderately effective fungicide, but be careful to use it according to directions for tomato. Pyganic is a very effective pesticide.

1 Like

I’ve used copper and chlor, but I don’t like spraying them much past the first formation of fruit. Copper soap can be sprayed right through, I think, but i still don’t like the idea of it on my fruit. My approach is to start a late crop so that when my first tomatoes are fading from early blight the new plants are plugging in. If you include some of the really good plum and cherries they will keep you in tomatoes till the first frost, and right before that you can bring in the green ones and have better than store bought for another month.

Someone gave me some seeds for a small slicing tomato that he recommended for disease resistance and it is pretty good and seems resistant. I will include some of them with my later crop this year so I have more than cherry types late in the season.

The small tomatoes I grow are the famous Sungold, Valentine, and Snack. Snack can be almost black and is very productive and delicious… same for the other two. Totally Tomatoes has them all.

1 Like

I decided to write a bit more given that a few tomatoes are available that have genetic resistance to the three fungal diseases mentioned. Mountaineer Pride and Mountaineer Delite are available from Southern exposure. Both have some tolerance to all three diseases. Several hybrids are available using ph2 and ph3 genes to provide resistance to late blight. Big Beef Plus was released this year with tolerance to several viral and fungal diseases. Big Beef Plus Hybrid Tomato Seeds | Tomato Growers – Tomato Growers Supply Company

Heirloom tomatoes and/or open pollinated tomatoes have some resistance to a few diseases. Burgundy Traveler and Eva Purple Ball both have some early blight tolerance. Tropic has very useful tolerance to gray mold. Lorelei is tolerant to Septoria and somewhat to bacterial leaf spot. I could name half a dozen more, but the key point is that there is some tolerance to a few fungal diseases, but no heirlooms have broad tolerance.

Late blight - ph2 and ph3 genes in combination are moderately effective
Early blight - unknown genes, but measurable tolerance in a few varieties
Septoria - only recently have varieties with tolerance become available, see Mountaineer tomatoes
Tomato Mosaic Virus - many varieties available with tolerance
Tomato Spotted Wilt virus - sw5 gene provides reasonably effective resistance
Stemphylium - several available varieties have resistance, Big Beef Plus is a recent release
Ascosphara - Many available hybrids are ressistant, Big Beef Plus has it
Nematodes - heat sensitive resistance is available via one known gene, above 82 degrees, it fails
Ralstonia - A very limited few have tolerance
Bacterial speck and spot - two diseases, a few varieties have tolerance to one or the other, Kewalo is an example
Gray Mold - a few varieties such as Tropic have effective resistance
Fusarium 0, 1, and 2 - limited resistance in a few mostly hybrid varieties
Southern Blight - Some resistance, have to look hard to find varieties that have it
Brown Rugose virus - commercial hybrids just entering the market with 2 genes for tolerance

I’m typing this with a headache so may have a few errors.


I would try to plant resistant types, organic sprays aren’t going to be too practical. Plus the normal cultural controls like keeping foliage dry and good air flow.

If your going for organic you can try to make a LAB (Lactobacillus bacteria) serum and try spraying w a combination of water on your plants. The pH of the LAB is super low and will kill off spores of those fungi you mentioned while the LAB will colonize the plant instead. This is a bacteria that will help make nutrients more available to your plants as well. Can be made for pennies with milk and carbohydrate (think rice) wash. If you want organic it doesnt get much more organic or cheaper than that. Google if you are interested there is lots on the subject.

You could also try sulfur dustings on leaves in very early stages of disease to control/try to eradicate but not as a spray. Pretty old school stuff

If you can, try to make the soil as ideal as possible for your crops. If you get the nutrition right your plants will be more resistant to diseases. Making sure the micronutrients are there for your plants as well as plenty of calcium can help a lot, especially in wetter seasons when fungal issues are more likely to pop up anyways

Picking resistant varieties is also very helpful.

1 Like

Here a lot of small commercial growers do it under plastic because the market is for real tasty heirloom types is very good at farm markets where customers will pay $5 per pound for them. You can grow tomatoes under plastic and call it organic. Not sure about sustainable.

Tomatoes are easy to grow so planting two crops a season to get full extension seems practical, although there are sometimes seasons of nearly non-stop rain where the rewards can be diminished. Before early blight showed up here we had a year with about 25 inches of rain in August. Most gardeners lost their tomato plants but mine were on mounds and survived that Aug. to thrive in the dry Sept and Oct that followed. Huge late crop, perhaps made sweeter by the dearth of local tomatoes elsewhere.