Soil restoration?

Asked August 30, 2018, 9:52 AM EDT

Hello!! I live in SE MI (Detroit). I have several questions (sorry) 1. I container planted 20 tomato plants, which suffered from blight. This is the first year this has happened. Is the soil not good any longer? If not, what is the best way to dispose of it? Also, how can I avoid this from happening next year?. 2. I also have pumpkins growing, which now have powdery mildew :)'s been a tough season. I sprayed with a copper fungicide, but that seemed to kill even more of the vines. Is this soil no good now? The pumpkins & tomatoes are in seperate areas but are these diseases related? Am I just a terrible gardener? Is this soil unwell to use next year too? Any advice is greatly appreciated. Thank you!!

Wayne County Michigan

1 Response

Hello, With respect to your questions about your tomatoes, I refer you to the attached article, Michigan Fresh: Growing Tomatoes. You will see that it is not recommended to plant tomatoes in the same soil that tomatoes or other members of the nightshade family such as potatoes, peppers or eggplants were grown in the previous year. I suggest that you remove the soil from the containers, scrub the containers using a bleach solution of one part bleach to 10 parts water. Also clean any gardening tools with the same solution. You can dispose of the soil in the trash or a hot compost pile. With respect to the pumpkins, I refer you to the two attached articles Powdery mildew spores can overwinter in the soil. What happens is that a plant infected with powdery mildew can be a source of asexual spores while alive and then the dead plant’s leaves and stems may be infectious until the plant breaks down. Exactly how long the fungus survives is unclear but a safe bet would be to wait 3 years before planting the same species in that soil. To treat the soil, I suggest that you remove all plant material, place in bags and discard it. You can treat the area by solarization. Wait until weather becomes warm in the spring, cover the area of dampened soil with plastic sheets of 1-4 mil and leave 4- 6 weeks. The top 6 inches of soil should reach a temperature of 110-125 degrees F. Prevent powdery mildew by providing ample space between plants, do not over fertilize and remove plant debris and weeds from the garden.