Collocations for morale - noun

good, high
Morale is very high in the school.

low, poor, shaky | national, popular | staff

affect, be bad for, be damaging to, damage, hit, lower, sap, undermine
These unfortunate incidents sapped both our morale and our resources.

be good for, bolster, boost, do wonders for, improve, lift, raise, restore
measures designed to boost the morale of the police

keep up, maintain
The bonus helped maintain morale among the staff.

destroy

improve, rise | be at rock bottom, decline, sag, weaken

booster
Mail from home is a great morale booster for our soldiers.

~ among
Morale among nurses is at rock bottom.

a collapse/loss of morale