Soil Fungus and Disease - Ask Extension
I have had issues the past couple of years with powdery mildew and my flowers just dying. I planted petunias last spring that were beautiful and stron...
Knowledgebase
Soil Fungus and Disease #923880
Asked January 22, 2026, 6:18 PM EST
I have had issues the past couple of years with powdery mildew and my flowers just dying. I planted petunias last spring that were beautiful and strong and then one by one they all wilted and died. No obvious reason. Most things I planted in those areas died. Not over watered or anything like that. Plants seemed fine and then just wilted and died. Can soil be tested for disease or fungus? I'm not sure what to do. Please help
Baltimore County Maryland
Expert Response
A soil test will test for soil acidity and macro and micronutrients. There is also a soluble salts test if you think your garden could be affected by salt spray or brackish water inundation, i.e. living near the beach or a marsh.
In order to test soil for a pathogen (fungal or disease), we would need the roots of the plants as well as the soil surrounding them.
Can you tell me a little more about your garden area and a few photos uploaded to this site would be helpful.
1. Is this area irrigated and if so, does it spray the plant leaves from overhead spray? Powdery mildew is often associated with overhead watering and lack of air circulation.
2. If irrigated, what time of day? For how long and how frequently?
2. What is the sun position of this garden? (Full sun = 6-8 hours/day, part sun 4-6 hours, shade - less than 4 hours per day.)
3. Is this a protected area, i.e. up against the house, in a corner or is it in a windy area?
4. Were any of the plants that seem to keep dying adjacent to a lawn area? If so, do you use a lawn service for liming and fertilizer applications?
Facts about the environment are important in making a diagnosis.
In order to test soil for a pathogen (fungal or disease), we would need the roots of the plants as well as the soil surrounding them.
Can you tell me a little more about your garden area and a few photos uploaded to this site would be helpful.
1. Is this area irrigated and if so, does it spray the plant leaves from overhead spray? Powdery mildew is often associated with overhead watering and lack of air circulation.
2. If irrigated, what time of day? For how long and how frequently?
2. What is the sun position of this garden? (Full sun = 6-8 hours/day, part sun 4-6 hours, shade - less than 4 hours per day.)
3. Is this a protected area, i.e. up against the house, in a corner or is it in a windy area?
4. Were any of the plants that seem to keep dying adjacent to a lawn area? If so, do you use a lawn service for liming and fertilizer applications?
Facts about the environment are important in making a diagnosis.
When the weather warms up a bit you should do a soil test before planting any new plants in this location. You can obtain a soil test kit at any of our extension offices. The Sussex County office is located at 16483 County Seat Highway, Georgetown.
Information on soil testing can be found here:
UD Plant Diagnostic Clinic | Cooperative Extension | University of Delaware
Information on soil testing can be found here:
UD Plant Diagnostic Clinic | Cooperative Extension | University of Delaware
