How do I control pear fruit problems like fruit fly, scab and stony pit?

Three separate issues. Maggots in plains pear are usually fruit fly; manage with methyl eugenol traps from before ripening, daily collection and destruction of fallen and infested fruit to break the cycle, fruit bagging on premium trees, and recommended bait or cover sprays only at label dose with the correct pre-harvest interval since fruit is eaten fresh. Black scabby spots, more common on hill (European) pears in wet weather, are pear scab, a fungal disease managed by sanitation (rake and destroy fallen leaves), pruning for airflow, and recommended preventive fungicide sprays from bud break through early fruit, observing the pre-harvest interval. The hard gritty stony lumps inside fruit are stony pit, a virus disorder spread mainly through infected propagation material; there is no cure, so the control is to use certified virus-free planting material and remove badly affected trees, since it does not respond to sprays. For all chemical use follow label and KVK guidance and mind residue and pre-harvest intervals.