British Columbia: Troubled Wisteria sinensis

I have a tree year old Wisteria. Each spring as the flowers are developing on their pendulous racemes something must be sneaking up onto the central stalk of the raceme, scarring the juicy outer layer and sucking the sap, or so it looks like. It leaves a scar 2,3 mm up to 1 cm long. As the wound dries up, it turns brown and the entire cluster dies and eventually falls of. Beside ants, I never see any insect on any part of the plant. I see the bite being fresh in the morning, therefore suspecting some possible nocturnal invader. I have repeatedly sprayed it with Bug B Gone. I used a dormant oil kit on it and managed to burn the leaf buds in the process. I painted the trunks with a Vaseline, hoping something would stick to it, but to no avail. Does anyone have any idea what should I do? Or am I defeated?

 

Can you post pictures of the whole plant and the leaves?

 

It is dark now, I will on Saturday.

 

Hi, I hesitate to call you Skunk cabbage ;) yet it is a strikingly architectural plant.
I don't understand how a picture of the entire plant would help you though? It was a challenge, but here they are. If you look closely you will see the effected recemens hang down in a sharp angle.
Here are the pics. It was challengiWhen you look closely

 

Well sorry to put you to that trouble for the pictures. I must admit, this looks more like mechanical damage than anything else to me. I see you have a feeder on the post. Do you have squirrels or rats after bird food in the feeder damaging the plant on their way to the feeder? I don't really know what it could be. Perhaps someone wiser than I (not hard) can suggest something else.

 

Definitely no mechanical damage; no feeders, squirrels nor rats; bears, yes. It is a riddle a few tried to solve. I thank you for trying.

 

I'd tend towards birds as the culprit, but others are involved: the bird feeder brings them in, the ants may have a few aphids grazing and secreting honeydew, and the birds nip the buds and shoots to get to the honeydew apertif. Alternately, and perhaps most relevant to this occurring in the early morning: dew drops tend to form on the developing buds, and instead of honeydew, the birds are attracted to the water droplets while they're feeding. You could also look for nocturnal snails, but based on what I can see in the photos, I'd go with birds. Maybe move the feeder away from the wisteria and see what happens.

 

I ought to explain that the bird house in the picture is entirely symbolic. No bird has ever been there as it is too close to human activity. And since we have bears roaming around we have no bird feeder either. Still, I thank you anyway.