I brought all four vines back to the garden, quickly disposing of the two Mandevilla that were past rescue, and cut back the remaining Mandevilla and Passiflora. After I'd finished my pruning and picking, both vines looked like they might once again be performers in the summer garden.
For the first part of the summer they grew quickly, with new vines and foliage sprouting what seemed like every day. I placed them in one of the sunniest corners of the back border, hoping to give them enough light to thrive. Both plants formed flower buds an eventually bloomed with a beauty I grew to expect last year.
In the last couple of weeks, however, it appears the insect problems have returned.
Along the woody base of one of the Passiflora vines, an army of scale insects covered the surface of the vine from the soil base to about 14 inches up the vine. I was able to remove this vine and the rest of the plant seems clear of scale, but I'm not confident the scale won't return en masse over the rest of the plant.
And just today, while photographing the unfurling bloom pictured above, my arms and legs were soon covered with small ants. Upon close inspection, hundreds of ants were in a conga line up and down the Mandevilla. Since I wasn't aware of any other reason ants would be interested in this vine, it could only mean aphids! Ants will milk the honeydew from the aphids and project the aphids in an act called mutualism. Lifting up a few of the leaves, I instantly saw the infestation of both aphids (and I believe mealy bugs) congregated near the branching points of the vines.
At this point, these vines have provided beauty in the garden for two summers and still have a number of flower buds remaining this year. So I will likely attempt to keep them alive for the rest of the summer and then dispose of them, so I don't chance bringing the pests inside during the cold months and infecting the rest of my overwintering plants.
I suppose it just means that I get to go shopping for tropical vines come Spring 2011.