Q.bignonia capreolata
My vine is 3 years old, and it’s the 1st year it’s going to bloom BUT the buds form but the flower is not forming. the tube is there but it doesn’t open, it just falls off. It doesn’t look like I have a bug on it. Any suggestions to help it along.
Training to avoid crowding of stems will aid in the formation of flower shoots. Branches can be cut back in the spring to encourage flowering.
Best flowering is achieved in full sun.
Water regularly to occasionally when actively growing in the warmer months for best results .
Thrips can be the cause of flowers just dropping form a plant. They can be difficult to see in some cases.
You can use Neem Oil if you suspect that pests are the cause.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm