Pale spots on Griselinia then leaves yellow

Some plants on my 5 year old, otherwise vigorous, Griselinia hedge (in city, fairly sheltered, sun in afternoon) have developed pale, irregular spots on leaves, any part of leaf but especially nearer tip. leaf turns yellow, some have brown at tip, then fall. Neighbouring yew, skimmia and box ok just now.I’d be glad of advice as more and more leaves affected over the last 2 weeks.