Our hedge and 2 pyramid trees are looking terrible and a neighbour parks and runs his van every morning directly beside them (in winter it idles for at least 20 minutes) while everything else not in the vicinity of his vehicle is doing great. Could this be the cause of them doing badly? Prior to his moving in, they were great.
Can Shrubs Be Killed by Vehicle Exhaust
The property next door to me is a rental property. Over the years there have been renters who leave their vehicle idling (the driverway for the property runs along our fence line, and over the years I have had damage to azaleas, dogwood tree and pine tree from exhaust. My conclusion is plants do not like carbon monoxide.
I could find little information but one source states that exhaust makes it impossible for plants to photosynthesize, (convert light to energy.). I would hate to confront him only to find out the plants have a totally different problem. HOpe you find a better answer.............