I have spiders, they are not mites, that are killing trees, shrubs and vegetable plants
I have seen this question before but it seems the reply is that spiders don't do this. They do now. For 6 years I have been battling spiders that are prolific, killing my shrubs, trees, hydrangeas& other flowers, and in my vegetable gardens.The leaves turn brown and the spider moves on the another area of the plant/shrub/tree and the same thing occurs. Eventually, the branches die. I can not find anything on the internet about this phenomenon. I had a nursery owner look at them and he said he didn't know what they were. I have one in a glass jar that I caught today. They vary in size and are gray and black with 8 legs with a somewhat pointed body. I am at my wits end with this. It's been years of me battling them. I am not winning. They are not mites! They range from 1/4" long up to 1.5 inches or so, from what I've seen. They make webs quickly. I need someone to figure this out, please.
Chester County Pennsylvania spiders
Spiders are predators feeding on insects and other small animals. So it is unlike that they are causing your plants to die. Perhaps they have increased in numbers due to and abundance of something that is eating your plants (that can be prey for the spiders).
Your best bet is to collect some of the spiders and take to a one of the Penn State puny offices near you. The locations are available at this website: https://extension.psu.edu/county-offices/
Also take some of the dying plants. They should be able to tell what the spiders are, and what may be wrong with your plants.