The challenges each year change. Two years ago a major problem was slugs and snails. I have hardly seen any this year, perhaps due to the very dry weather.
The dry weather brings its own challenges and they are varied, with one thing leading to another. A major factor this year has been the early warm weather followed by a normal frost, the result of which was that both the pear tree and the apple tree had no fruit. This would not be a concern since we eat very few of the pears and none of the apples. However, the pears and then the apples are a major source of food to the squirrels that visit our yard. In the absence of the fruit the squirrels have moved on to other sources of food. In the food garden they went after the early raspberries (and probably will go after the later raspberries since it is probably fruitless to try to protect them). They have eaten the unripe pagoda dogwood berries, which would have become a major source of food for the robins and catbirds. I fear that as the Concord grapes ripen the squirrels will eat those. We are planning to put paper bags around some of the larger bunches in an attempt to protect them. So far I haven't seen any damage to tomatoes, which are beginning to ripen.
The dry weather has affected the productivity of the garden. Rain always seems to be in the near forecast but with few exceptions has avoided our gardens this year. On the Doppler radar screens we can see rain passing to the north or the south or sliding past diagonally in such a way that we are missed. But with the forecast of rain I have put off properly watering the vegetable garden in the hopes that it won't be necessary. The major effect that I have noticed has been on the blueberries and eggplants. The blueberries were small and some were wrinkled. We harvested very few berries. Even though I erected our deer fencing over the blueberry area we were frequently releasing catbirds (and the occasional robin) from the area. I never discovered how they got in. Chickadees also ate blueberries, perhaps more than the other birds combined. Chickadees would just fly over and land on the netting, go through the spaces, and fly to the plants and eat what they wanted. Next year I will have to replace the deer netting with bird netting and figure out how to tie it together without places for the birds to enter.