English Dwarf Boxwood Dying One by One
I have four parterres about 6' x 4' each with roses surrounded by a boxwood low sheared hedge. The parterres are raised, they are in full-to-medium sun, and they are irrigated. The boxwood shrubs were originally planted about a foot apart. I sheared them by hand once a season-- wider on the bottom than the top. I did not thin them (unfortunately). They did great for 6 years. Now one-by-one they are dying in one parterre. They go from dark green to light green to yellow to death. Probably phytophthora? I'm desperate to save what I can. I've moved the remaining box to another area. Have tried drenching the parterre with Infuse systemic. no luck. Heard subdue maxx might work, but costs a fortune. 2 questions: can I prevent this from happening in the other parterres. What do I replace the box that died with?? I've read you can't replace with box in the same bed. What about another variety? Am desperate to save my investment.