Here are some of mine in no particular order.
1. Tomato disease, more specifically interruptions in having a continuos supply of tomatoes from spring to frost. Efforts to solve this involve or have involved succession planting, wide selection of varieties with inclusion of resistant varieties, planting in sterile soil, bottom watering, mulching, pruning, shading, spraying with natural products.......
2. Breaks in production of cucumbers and squash from spring to frost. Mostly fight this issue via succession planting.
3. Over run with leaf footed bugs on tomatoes and squash.
4. Aphid infestation on greens. Once established, the are difficult to eradicate.
5. Deer damage.
6. Root not nematode damage.
7. Competing against oak tree roots.
8. Losing the battle against squash vine borer. I fight this pest by using screened covers on younger plants and by succession planting to keep young vigorous plants at different stages of growth.