Zucchini leaves are fully spotted in brown and are covered with small holes. Leaves seem to be eaten away. Never saw this before and have been growing them for years. I used my own seeds this year. . . have they been contaminated?
Zucchini Leaves That Are Fully Spotted in Brown
Certified GKH Gardening Expert
If it's insect damage, the culprits could be either slugs (which feast at night) or vine borers (which hang out near the base of plants). These articles will help: https://www.gardeningknowhow.com/plant-problems/pests/facts-about-slugs-and-how-to-kill-garden-slugs.htm
If it's due to a fungus, neem oil may help. It's also good for many insect pests as well. Here is more information: https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm