Tomato Early Blight
Hi - I would love some advice. I have a 40X40 vegetable garden, rotating my crops within that space each year. It doesn't matter where I plant my tomatoes - early blight always finds them. Can you advise me as to how to treat this? Thanks!
Washtenaw County Michigan
Early blight is very common on tomatoes grown in Michigan because our climate often provides ideal conditions for this fungal disease. The spores become active in late spring/early summer when moisture is able to sit on the leaves for an extended period of time. These spores may overwinter in the soil. Steps you can take to help prevent this disease inlcude:
Water the soil, not the plants using drip irrigation, soaker hoses, etc.
Mulch around the plants to provide a barrier that may reduce the risk of spores being splashed or blown onto wet leaves.
Prune the bottom set of leaves on the tomato plants and remove them when you plant the tomatoes.
Diseased plant leaves & stems should be removed from the garden to help prevent re-occurrence.
Plant the tomatoes far enough apart so there is good air flow and light allowed to reach the bottom of the plants.
Tilling the soil in the fall can expose the upper level of soil to the freezing winter temperatures which may kill these spores.
Fungicides containing copper sulfate are organic options but are only effect as a preventative measure.
Please refer to this fact sheet for additional information: http://learningstore.uwex.edu/assets/pdfs/A2606.PDF
The good news is that early blight is generally not detrimental to the crop, unless the infestation is severe.
Thank you for contacting Ask an Expert.