Answer: Fusarium wilt is most common on tomatoes but it can show up in other crops. It is most common when the cucumbers are grown in the same place year after year. It causes the leaves to turn yellow, then brown, then die. Lower leaves are affected first. Fusarium is a soil inhabitant, and it infects
plants through the roots. Fusarium overwinters in the soil or plant debris. Once established, this pathogen can remain indefinitely, although its populations may vary. Cleaning up crop residue at season's end can help. The best solution is to rotate your crops and plant resistant varieties.
There has been some success in defeating this wilt pathogen through summertime soil solarization. The process is simple. You need to solarize during the hottest part of the summer, for up to 3 months. To solarize, smooth out the area (removing sod, plant debris and rocks), moisten the soil, lay a 4 mm to 6 mm thick sheet of clear plastic over bare soil, and seal the edges of the plastic with rocks or soil. This can naturally heat up to over 140 degrees F, which kills most pathogenic organisms in the top 4-8" of the soil, depending on soil type and temperatures.
Also, soil that is rich in organic matter (OM) will be "cleaner" faster than soil that is low in OM. Solarization may deplete some OM, so you can "beef" it back up again with clean compost. The process may have to be repeated after turning the soil to bring the next few inches of soil to the surface for solarization. You may want to consider growing your most wilt-susceptible plants in containers filled with commercial potting soil rather than soil from your garden. I hope this info helps!
Q&A Library Searching Tips