I'm no expert, but I am pretty sure the leaves curling up is a sign of heat stress from a high temperature to heat ratio.

Whats the RH% and has it gotten really hot lately? You say 27-30 C, so that is like 86F? You can wait for an expert to come by but I am pretty sure that is a tell-tale sign of heat stress.

Just my :twocents:
oSecretGardeno Reviewed by oSecretGardeno on . Whats wrong with my plants? Hi i decided to take a look at my plants right now and i was shocked at what i saw... The leaves on all the plants are starting to shrivel up. I have no idea what happened they were fine yesterday. Its 3 bluebrries and 2 lowryders... Please someone help me before its too late if it isnt already. I posted some pics of the plants to make it easier to figure out the problem. Rating: 5