Wisteria in Pasadena, California (established for 30 years) on large trellis, about 100 sq. feet, with much sun has bloomed profusely over the years. It bloomed very well this spring but suddenly is not showing any new growth, no new shoots and thin leaf coverage. Long shoots drying off at end but no evidence of pests of any kind. The leaves look slightly lighter colored than usual with a slight 'papery' feel to them (watering pattern is same as for last 30 years).
Wisteria Stopped Growing
Certified GKH Gardening Expert
I would first check for signs of crown gall. Then, I would consider pruning since it is such an old vine. Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-diseases.htm