Close Encounters
Sick plants welcome here

By Cathy Cockrell, Public Affairs

25 October 00 | Above a din of animated conversation, Professor Emeritus Robert Raabe offers a warm welcome, and a chair, to a gardener clutching a sickly frond.

"What goodies do you have?" he asks eagerly - as if to say that here at the UC Botanical Garden Sick Plant Clinic, there's no shame in failure.

On the contrary, the blighted, mited, pesticide poisoned and poorly potted all get royal treatment at this free monthly happening in their honor.

"I was curious about this lemon," Raabe's client says, tentatively handing over her specimen as she lowers herself into the seat.

With intense interest, Raabe studies the citrus branch, each leaf measled with black bumps on one side of its central vein.

"Looks to me like something we call edema. But why it's only on one side of the leaf like that ..."

Probing its surface with a needle, Raabe is a quiet spot amidst a hubbub of sick plant talk. Professor and insect expert Nick Mills reassures a worried gardener that her root ball is mealy-bug free. Alumna and plant pathologist Ann Gabrick debunks the notion of an all-purpose insecticide. A garden volunteer admires an Asian lady beetle pupae through the lens of a microscope.

"Is this the side that's exposed to the sun?" Raabe asks, intrigued by the disease pattern on the citrus leaf.

It takes educated sleuthing to solve some of the cases brought here the first Saturday morning of each month - at times by doggedly questioning many gardeners presenting similar plant disasters.

When gnarled and discolored rosebuds kept turning up at the clinic, Raabe eventually pieced together a theory: airborne weed killer mist had drifted from neighbors' yards onto his clients' dormant rose stems, deforming the flowers and leaves in the next blooming season. A call to a commercial rose grower confirmed his hunch.

For the citrus grower with a suspected case of edema, Raabe offers to assist, with free lab work: "I'll culture it, and we'll see." "Interesting! Fascinating!" Raabe adds, as a novice gardener nearby asks another resident expert, "What's a bud?"

A respectful explanation follows. Indeed, no over-fertilized, under-watered or sunburned leaf is dismissed as too pedestrian for the clinic's multidisciplinary team of sick-plant pros.

But novice and master gardeners alike can learn a good deal of science, too, if they're interested - from the wily ways of plant viruses (which trigger their hosts to do tasks they're unable to do for themselves) to the hows and whys of rose propagation.

Other clients get the low-down on plant conditions so strange, or so new to the area, they can't be found in local gardening books.

This morning, Mills counsels a despondent gardener whose story-and-a-half-high avacado has fallen ill. The culprit, he tells her, is a new mite that has recently made its way up from Mexico. "It won't kill the tree, but it will make it sick ..."

Meanwhile, Raabe examines yet another weirdly misshapen rose bud plucked from an East Bay garden.

"That's beautiful," he tells its surprised grower, after offering a diagnosis. "I'm going to take a picture of it. You don't mind if I take a bit? It's for the education of others."

"Close Encounters" is an occasional Berkeleyan column documenting unofficial moments in campus life. If you have an idea for a column, contact Berkeleyan writer Cathy Cockrell at or 643-9259.


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