The first thing we need to know is where you live. So much about gardening is specific to location. Seeing all the holes and chewed leaves it is evident that you have some garden pests. Without knowing what the plants are it is impossible to say what they could be. If you wish to use insecticides it is very important to correctly ID the pest and get the specific insecticide for that pest. Most fungal diseases are weather triggered. You can spray for them but it's best to do that before you have symptoms to prevent it. Doing it once you have it will only protect future foliage. What is already infected will continue to die off. But, once weather conditions change most fungal infections will disappear on their own.
