Many people have asked me what they can do to prevent their tomatoes from succumbing to disease. The first answer to protecting any of your crops from disease is to start with the soil. Have your soil tested and correct any imbalances with organic amendments. Compost, of course, should be part of your soil fertility plan. Cover crops in your rotations are also pretty important for soil building. Compost and cover crops build organic matter in your soil, always a plus for any crop. Throwing some fertilizer at your tomatoes when you plant, thinking the more the better, might only result in lots of foliage and less fruit. If you do want to add something extra, wait until the plants have flowered and have started to set fruit.
Start with good strong plants. I used to start all my tomato plants in the house on March 1 for transplanting on, or soon after, April 25. I used grow lights and thought my system was quite good. Then one year we had an unexpected (at least to me) killing frost about May 1. I lost many of my tomatoes. The day that I surveyed the damage, a neighbor called to see if I wanted any tomato plants, since she had more than she needed. (Thanks Carol!) Of course, I went right over and she had the strongest, stockiest plants I had ever seen. She never even started the seeds until April 1 when she planted them in a spot outside surrounded by a wood frame with a sheet of plastic thrown over. Seeds were planted in my mind that day about re-thinking how I started things. Now, everything is started outside in the cold frames. They are naturally hardened off and ready for what comes. If it is frost coming, I would still cover them, but they are hardier than anything grown inside under lights.
The varieties you choose make a difference. Some varieties are designated as resistant to certain diseases. Over the years, the ones I tried solely on disease resistance looked great, but weren’t as flavorful as others I grew. Find a seed company that specializes in varieties for your region. I look to Southern Exposure Seed Exchange for information on varieties suited to the humid mid-Atlantic. Once you have some tomatoes that do well under your conditions, save the seeds for next year, providing you have grown open-pollinated varieties.
The biggest problem here in the mid-Atlantic is blight. It doesn’t really matter to me the exact name or if it is early blight or late blight. The bottom branches of the plants begin to turn brown and die and it gradually works its way up the plant. The fungal spores that cause that are in the soil and the disease begins in the leaves that hang down and touch the soil. Furthermore, if the soil is bare under the tomatoes, when it rains, those spores are splashed onto the plants. Now is the time you can take preventative measures. Trim the lower branches of your plants so nothing hangs down and touches the soil, and mulch around the plants. You will need to come back in a couple weeks and trim your plants again because they will have put out more growth. It is hot and humid here in the summer and giving tomatoes a little breathing room will do wonders. Open up that space at the bottom and get the air flowing. Listen carefully, your plants will be thanking you.
No matter what tomatoes you have in your garden this year, you can learn a lot by watching, taking notes, and talking with others. When you are planning your garden next year, be sure to look back at your notes and plan accordingly. Find more information about disease prevention for tomatoes at Homeplace Earth.