Plant leaf damage
I first noticed leaf damage on the very top of the mountain mint: discolored, shriveled leaves. Have since noticed similar damage on other plants such as black eye Susans, etc: a large section of leaf will be dry and brown/gray. No insects are readily visible. Recently while inspecting garden I noticed the pictured web on a hydrangea. It was swimming with tiny whiteish wormlike things. I don’t think that’s what is causing earlier described leaf damage, but another emerging pest. Not sure how to treat because not sure what I’m dealing with. Any help would be appreciated!
Left photo - We cannot say for sure what is going on. Prune off the damaged areas during dry weather. Monitor new growth and send us photos if you notice more symptoms.
Middle photo - We notice some feeding damage possibly slugs or leaf feeding beetles. Usually the plants can tolerate damage. This plant is susceptible to septoria, a fungal disease. The disease shows up as irregular black spots on the leaves. This can disfigure the plant significantly if the weather is favorable, wet, hot and humid. Once established, it is difficult to control.
Try managing the bed culturally. Alleviate poor air circulation, crowded conditions, or standing water to help lessen humidity levels. Keep mulch thin and away from the base of the plants. Inspect new foliage and older foliage regularly for signs of infection to catch infections early. Removing infected leaves if there are only a few helps.
At the end of the season really clean up the area well, discard the infected plant material, don’t put in your compost pile. Monitor throughout the season and if disease pressure is heavy, you may want to consider growing something else.
Right photo - This looks like fall webworm. Prune off foliage and discard in the trash. https://extension.umd.edu/hgic/fall-webworm-trees