Answer: Sounds as though some diseases have spoiled your plants. Your best defense is to purchase disease resistant varieties. There are several things you can do to minimize fungal diseases and their spread. The disease affects both potatoes and tomatoes, so keeping these plantings far apart can help control the spread. Plant your tomatoes in a new location every year, and avoid planting them where potatoes have grown. Choose tomato varieties that have flat leaves as opposed to curly leaves, which take longer to dry off after rain and are thus more susceptible to fungal infection. When spots first appear in early summer, cut off the leaves and destroy them. Then spray the plants with compost tea. You can make the tea from aged compost that contains some manure. Add one part compost to five parts water in a bucket and let it sit in the shade for 2 weeks. Then filter and spray on a cloudy day or in early evening. Wet both sides of the leaves. Repeat every 2-3 weeks. Another strategy for managing blight is to set out some plants in the spring while leaving space for more plants to be set out in early and midsummer. The older leaves are the most susceptible to the fungus, so if you have plants at different stages of growth, you are more likely to have some relatively free of the disease. Since plants under stress are more likely to be attacked by disease, be sure to keep your plants well watered (preferably avoiding overhead watering) and use mulch to conserve soil moisture. I hope your garden this year convinces you not to give up on tomatoes!
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