Garden Detective

Over the weekend, I got a phone call from a friend who was busy prepping her house for a major renovation. She was digging up perennials and moving bushes to clear the way for a poured concrete foundation where her euonymus and lilies and irises had lived undisturbed for many years.

"Come and take what you want," she beckoned. Naturally, I dropped everything and bolted over - empty pots and shovel in tow.

The timing couldn't have been more perfect -- I'm in the midst of a complete garden overhaul (more on that later,) and that day I was planning to plant my spring bulbs.

So I clear out the hatch in my minivan and drive the half mile to Vicki's, where I find her digging with her husband, Rob. I help myself to some common orange daylilies and some Siberian irises. Orange and purple is my favorite color combination.

Now I know what you're thinking: daylilies and irises have different bloom times. True, but I could pair the daylilies with purple liatris, and the irises with apricot-toned tulips, and I'm good to go.

What I wasn't expecting was the generous offer of some nice-sized variegated euonymus ground cover. Though I wasn't sure where I would put it, I knew it would be put to good use. But when Rob unearthed the behemoth, I noticed some hard, corky lumps hanging onto the roots. Hmmm, these looked a lot like the black knot I saw recently on a friend's plum tree. But euonymus doesn't get black knot, and these knots weren't black, anyway. They were tan and beige. I knew it wasn't good, but I loved the euonymus, and it looked otherwise healthy, so I took it.

On the way home, I stopped at the home of a friend and neighbor, Roxanne Zimmer, who very conveniently also happens to be a master gardener. "Crown gall," she diagnosed, even before taking a look at the plague.

She was right, of course. Once home, a few minutes of detective work confirmed that the bacteria Agrobacterium tumefaciens, which causes crown gall, must be at work in Vicki and Rob's soil. What to do?

I wasn't going to throw away a perfectly good plant. Like I said, it was otherwise healthy. No yellowing leaves, no signs of weakness. So I clipped off all the corks, being careful to spray my shears with Lysol after each cut to avoid spreading the disease. Crown gall affects mostly fruit trees, roses, euonymus shrubs, and certain perennials (among them, asters and chrysanthemums.) I won't be planting anything else in the bed where I've decided to lay the groundcover, so even if I've inadvertently left a bacterium behind, it won't infect anything else.

Crown gall can live in soil for several years after the infected plant is removed. I've heard it suggested that grass be planted for at least three years to ensure the soil is free of the bacteria before using the bed for anything that's susceptible. A lot of folks recommend dipping the roots in a bactericide such as Galltrol before transplanting. Galltrol and other such products have an antibiotic effect on the plant, theorectically preventing the formation of galls.

Others suggest using a tar-based wound paint to seal the cut. I'm of the mind that doing so might actually seal in the disease. Instead, I'm letting the wounded roots air out for a couple of days in a nice, shady spot, and giving it a few shots of the hose to keep it moist.

I'm not too worried about it.