Master Gardener: Troubleshooting tomato plant woes | Home & Garden

My tomatoes have brown spots on them. Can I save them? — B.V.

The hot, wet conditions we have been experiencing are perfect for the development of fungal diseases in tomatoes. Brown spots on the blossom end of tomatoes would suggest blossom end rot, but the tomatoes in the photo we received have a different kind of brown spot. This one is indicative of a fungal disease known as buckeye rot.

Buckeye rot is one of several tomato diseases cause by pathogens that are found in the soil. Many of the fungal disease in tomatoes tend to affect the stems and leaves, but this one affects the fruit, which places it in a special category called soil rots. Soil rots include buckeye rot, southern blight, pythian rot and rhizoctonia. Once we begin to get educated about all the maladies that can affect tomatoes, we can start to feel like it’s amazing any of us gets tomatoes at all.

One good thing is that there are some simple things you can do to minimize any issues you might potentially have with these and other fungal diseases in your tomatoes.

Since most of these maladies begin when the pathogen moves from the soil to the leaves or fruit of the plant, your first line of defense is to reduce the opportunity for this to happen. This can be accomplished in a variety of ways.

First, you can apply a layer of mulch around your plants. I know we talk about mulch a lot in these articles, but mulch provides a barrier between the soil and your plant, and this has many benefits. In this instance, it keeps soil-borne fungi from splashing up on the plant when watered or via the rain. Mulch also helps retain moisture in the soil and reduces that amount your soil temperatures vary during the day. Both of these help keep your plants healthy.