Tomato blight has been a problem for many gardeners in our area (myself included). There are a few key things you should know about tomato blight. The blight comes from spores that can travel through the air and land on the soil. Once your ground is infected the spores can live for 3-4 years. If your plant has tomato blight it’s important to remove all the debris at the end of the season. Do not work it into the soil or you are just causing more problems for the coming years. You can spread the spores to other areas of your garden either on your hands or your gardening tools. So if you’ve been working with infected plants, be sure to wash everything thoroughly with bleach.
I’ve put together some helpful pointers for you about how to help minimize it’s effects on your tomato crop.
1 - Stake your tomato plants or use a tomato cage. Good airflow is very important. Excessive humidity or moisture on the leaves makes them more susceptible to blight.
2 - Try to minimize the amount of water that splashes onto the plants. Avoid watering with a sprinkler. Instead water the plants at the roots. You may also want to put some straw or wood chips around the base of the plant to minimize the splashing from heavy rains.
3 - Pick off the very bottom leaves. Any leaves that are really close to the ground are more likely to get blight.
4 - Spray weekly with copper sulfate. Mix as directed on the label. Believe it or not - copper sulfate is an organic material which makes it suitable for organic gardeners.
5 - If your plants still get tomato blight, pick off the affected leaves at first sign of blight. Dispose of them either in a garbage bag or by burning them. You do not want to put them into your composter as this again will just reintroduce the blight spores to your garden.