Now that it seems the monsoons are here, we need to protect our tomato plants from fungal diseases. Here in the southwest we don’t get the dreaded Late Blight that the Northeast has experienced (not yet at least) because we are drier than most parts of the US. We don’t seem to get as many fungal diseases but we do get some.
The one I see the most in everyone’s garden is Early Blight on tomatoes. It starts anytime but especially under these conditions: when you water your tomatoes from the top, the humidity is higher, and the rain comes.
Early Blight lives in the soil and is transmitted by water splashing soil up on the lower leaves. It starts on the lower branches and leaves where they start to turn blotchy yellow and start dying from the bottom up and will continue up your plant and eventually kill it.
To help prevent and control this disease, I do these things:
1. I water with a drip system, thereby keeping the soil from splashing up on the lower leaves.
2. I put straw all around the bottom of the plant to help keep the soil splashing up on the plant when it rains.
3. I trim any branch throughout the season that is going to touch the ground. In fact, I trim all the way up to the first flower or fruit set.
4. I trim ANY branch that shows signs of Early Blight no matter how high it is on the plant.
5. I dip my scissors or shears in rubbing alcohol or a 10% bleach solution between trimming plants to avoid spreading diseases. Bleach breaks down quickly (in a day or two), so don’t reuse it-make a new batch.
4. I spray ‘Serenade’, an organic fungicide which provides protection from a broad spectrum of common fungal and bacterial diseases. Early blight is one of the diseases it can control. Spray it on when the leaves are dry. It is rainproof and is non-toxic for bees and other beneficial insects. Respray every 7 days. Spray all parts of the plant-both on top and underneath.
Serenade is also good to spray on other vegetables. Spray for powdery mildew on squash, cucumbers and melons and leaf rust on beans. I use it for all my vegetables. Now that the rainy season is here, don’t wait till you get the disease—it works best as a preventative.
You can get Serenade from Agua Fria Nursery (call for availability) here in Santa Fe or at Amazon.com. I buy the concentrate, not the little bottle of pre-made spray—lasts a lot longer.
Here is a pdf of some of the common diseases and organic controls for tomatoes growing in the Southwest: TOMATO DISEASES