Growing tomatoes - Ask Extension
I have been growing tomatoes for several years and the past 2 years I have what I believe is a fungus of some sort. It starts on the leaves and looks ...
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Growing tomatoes #891542
Asked January 13, 2025, 6:08 PM EST
I have been growing tomatoes for several years and the past 2 years I have what I believe is a fungus of some sort. It starts on the leaves and looks like a brown or black dot. I have tried to treat this with copper fungicide but with limited success.
I have also had what appear to be very nice looking tomatoes but the bottom is black.
Are there any tips you can give me? I trim the plants from the bottom so the first leaves are about a foot off the ground, and i water from the bottom.
Ashland County Ohio
Expert Response
Thank you for your question to Ask a Master Gardener Volunteer with eXtension.
These first two sites are loaded with good information about tomato diseases and should help you identify further your specific problem:
https://hgic.clemson.edu/factsheet/tomato-diseases-disorders/
https://ag.purdue.edu/department/arge/swpap/tomato-diseases.html
It sounds like you are doing everything correctly to manage your tomato planting. Make sure going forward you practice crop rotation and continue those good cultural practices - spacing plants adequately to ensure good air movement, starting with healthy tomato seedlings, finding disease resistant varieties, trimming up lower leaves and bottom watering and proper fertilizer application.
Climatic conditions can sometimes favor some of these diseases. In that case, it is very important to make sure you have done what you could to minimize potential problems.
To reduce disease severity, test the garden soil annually and maintain a sufficient level of potassium. Lime the soil according to soil test results. Side dress tomato plants monthly with calcium nitrate for adequate growth.
The following information sheet from OSU specifically targets bacterial leaf spot:
https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/8/3691/files/2014/05/Bacterial-Leaf-Spot-Fact-Sheet_English-1a4aw7c.pdf
And this one deals directly with blossom end rot:
https://portal.ct.gov/caes/fact-sheets/plant-pathology/blossom-end-rot-of-tomato
Best of luck to you with your tomatoes in this new year!
These first two sites are loaded with good information about tomato diseases and should help you identify further your specific problem:
https://hgic.clemson.edu/factsheet/tomato-diseases-disorders/
https://ag.purdue.edu/department/arge/swpap/tomato-diseases.html
It sounds like you are doing everything correctly to manage your tomato planting. Make sure going forward you practice crop rotation and continue those good cultural practices - spacing plants adequately to ensure good air movement, starting with healthy tomato seedlings, finding disease resistant varieties, trimming up lower leaves and bottom watering and proper fertilizer application.
Climatic conditions can sometimes favor some of these diseases. In that case, it is very important to make sure you have done what you could to minimize potential problems.
To reduce disease severity, test the garden soil annually and maintain a sufficient level of potassium. Lime the soil according to soil test results. Side dress tomato plants monthly with calcium nitrate for adequate growth.
The following information sheet from OSU specifically targets bacterial leaf spot:
https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/8/3691/files/2014/05/Bacterial-Leaf-Spot-Fact-Sheet_English-1a4aw7c.pdf
And this one deals directly with blossom end rot:
https://portal.ct.gov/caes/fact-sheets/plant-pathology/blossom-end-rot-of-tomato
Best of luck to you with your tomatoes in this new year!
