wisteria

(Question)

We have had a wisteria for 13 years, and it has flowered since year seven. Early June the plant looked healthy although no signs of flowering. We went on vacation June 26th. On our return one week later all leaves had fallen off. What happened? Will it survive?

(Answer)

I have been unsuccessful in determining what actually happened to your wisteria. Leaf drop, on many plants,  usually occurs if a severe drop in temperatures happen, like a few springs ago when mid- April, we had freezing temperatures which killed a lot of fruit tree blossoms. This does not seem to be the case.

Wisteria are susceptible to:

– late frost – not likely in late June

– wet roots – we’ve had a lot of rain, and depending on where your wisteria is growing, could have water logged roots, as the soil doesn’t drain. To check this, dig down and see if the soil is very wet. If so, addition of sand to improve drainage may help.

– check around the soil level – if there is white fungal growth, this is Phytopthora – a fungus favouring wet soils. It causes browning and wilting of leaves and brittle branches

– sometimes poor grafting, even on a mature plant, can break the attachment of the graft to the root. Check to see if there is breakage, as movement of water and nutrients have been cut off

If you found brown and wilted leaves when you came home, perhaps any of the above could explain the leaf loss. Check the branches by scraping the bark to the under bark; if it’s still pliable and fresh, then the plant is still alive, and may even show secondary budding – this often happens with frost leaf drop, secondary leaves form. If they are brittle and break, then the plant may be dead.