Collocations for morale - noun

good, high
Morale is very high in the school.

low, poor
national
employee, faculty (esp. AmE), staff
civilian, troop
team

affect, be bad for, be damaging to, damage, hit (esp. BrE), hurt (esp. AmE), lower, sap, undermine
These unfortunate incidents sapped both our morale and our resources.

be good for, bolster, boost, build, do wonders for, help, 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
decline, plummet, suffer
be at rock bottom, hit rock bottom (both esp. BrE)

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

issue, problem
The army has a major morale problem.

morale among
Morale among nurses is suffering.

a crisis of morale, a loss of morale