Symptoms include: tan-brown circular lesions that coalesce resulting in severe blighting of foliage. Lesions can also be water-soaked, as in the below, righthand picture. Eventually diseased tissues are covered in small black fruiting bodies (the 'mushroom' part of the fungus).
Colletotrichum is seed borne, so using disease-free seeds is the best way to avoid it. I've heard washing seeds in hot water will kill this kind of disease, but I think you need a special seed-dishwasher. (Does anyone know about seed washing?)
This is the second really gross disease spinach has had. (Remember the downy mildew problem last fall?) This leads me to a very bold idea:
Maybe spinach is not a good crop for bench-top winter growing.
- Spinach is susceptible to many diseases when grown in greenhouses.
- Spinach is slow growing. It has a slow turnover time.
- Spinach takes a long time to harvest.
- Spinach can have low yields per square meter.