Plants are living creatures that need care. Many things are obvious such as watering in case of drought, but other things, such as fertilization, can sometimes be forgotten.
We would like to refer you to the website www.buxuscare.com where all aspects of the care of Buxus are discussed.
The BetterBuxus® hybrids are resistant to fungal diseases (Calonectria: old name Cylindrocladium) so you do not need to treat them.
The 4 new hybrids, based on Asian species, have a higher tolerance against the boxwood caterpillar than the Buxus sempervirens native to Europe. The plants are not eaten completely bare and remain green. Treatment against the boxwood moth is therefore still recommended and can be done by products premitted in organic fruit and vegetable cultivation.