Juniper and grasses.
I've found that three cups of coffee every day and a thrice-weekly cigar from late January through April and October until about now keep it under control with but only the occasional dose of antihistamine, decongestant, and a shot for the juniper.
It also helps to forego dairy products during the peak juniper pollen season in February / March.
I took weekly shots for grass for 14 years. Guess what? It worked!