We don’t sell Grub-ex but, the best time to kill grubs is when they are small, and freshly hatched which is mid-August through mid September.  This requires a systemic insecticide (Bonide Season lon Grub Control)  More on that here:  https://blog.timesunion.com/gardening/lawn-grub-control-apply-in-july-when-the-beetles-fly/7370/

Crabgrass preventer is best applied around the time the first lilacs bloom.  Applied too early, it breaks doen and isn’t effective.  More on that here:  https://blog.timesunion.com/gardening/when-it-gets-cold-put-crabgrass-preventer-on-hold/7446/

Start spraying for the blight as soon as the shrubs show signs of new growth and then every 14-21 days.  Always dread and follow the direction on the package:  https://www.bonide.com/assets/Products/Labels/l147.pdfhttps://www.bonide.com/assets/Products/Labels/l147.pdf