Watercore disorder in Japanese pear ‘Niitaka’ is increased by high fruit temperatures during fruit maturation

•We investigated the effects of temperature on watercore incidence in Japanese pear.•Temperatures around ‘Niitaka’ fruits were increased using electric heating coils.•High temperature during fruit maturation statistically increased watercore occurrence.•High temperature also affected other parameters of fruit quality.•Shade hat treatment only slightly reduced temperature and watercore incidence.