Tomato leaves turning yellow and then brown
I've read through your articles about tomato plant issues, and I still can't quite figure out what is happening to mine. I have three plants planted in the ground in my backyard in Brooklyn, NY. They are all heirloom varieties, so it sounds like they might be more susceptible to diseases. They are all full of fruit, but started to show signs of stress right before the fruit turned red. I started noticing the issues about 2 weeks ago and our Black Brandywine is basically dead with the fruit rotting on the vine, and now our Beefmaster is starting to show similar signs. The leaf veins stay green, while the space in-between is turning pale yellow. Then the edges start to brown. Finally, the leaves turn totally brown and dry up. We checked the pH of the soil about a month ago and it was fine. We thought that yellow leaves could be low nitrogen, so we added some worm compost, but that didn't help. I've tried neem oil, but also that didn't help. We have a third plant that is still doing okay, so we are debating if we can find a cure, or if we should pull out the two plants asap. It has been raining a ton and very hot (mid 90's) with super high humidity. So I'm wondering if this could be too much water and humidity? Any suggestions would be super helpful!
Certified GKH Gardening Expert
Tomato plants need lots of warm sunshine and a well draining soil. You should water your plants at the soil line and water them deeply.
Uneven watering can stress your plant.
Make sure the soil is draining, if your plants roots sit in soggy soil it can cause root rot.
Poor air circulation can cause fungus diseases.
Tomato plants are heavy feeders and a regular fertilizer schedule through the growing season will help your plants stay healthy.
I've listed several links including link that has the most common diseases with images for you to compare to your plants.
Some issues can be treated if caught early.