controlling white fly infestations

I have a white fly infestation on Helleborus. Is there any natural control (Rodale recommends tobacco tea) — anything less labor intensive?

According to The Organic Gardener’s Handbook of Natural Insect and Disease Control, edited by Barbara Ellis (Rodale Press, 1996), whitefly can be controlled in the following ways:

– Catch adults on yellow sticky traps.
– Vacuum adults from leaves.
– Attract parasitic wasps and predatory beetles.
– Spray with insecticidal soap, kinoprene (Enstar) or garlic oil.
– Last resort: spray with pyrethrin.

Disease-resistant roses for the PNW

My neighbor wants a rose, but it will be planted in an organic
garden. It is a sunny warm spot (for Seattle), but I think disease
resistance is a must. What is a source for disease resistant roses
for our climate? Also, does growing clematis on a climbing rose limit its disease
resistance?

The reason that clematis and rose make good companions has to do with the
rose providing the structure the clematis needs, and the pairing allowing
for interesting combinations of color and shape, rather than one
providing disease resistance to the other.

Generally, the most disease-resistant roses are species roses, but there
are additional choices.

This list from Pacific Northwest Pest managment Handbook lists resistant roses.

This article from Washington State University Extension is entitled “Disease-Resistant Roses for the Puget Sound Area.”

There are several excellent books on growing roses in our area:

North Coast Roses : For the Maritime Northwest Gardener by Rhonda Massingham Hart (Seattle : Sasquatch Books, c1993)

Jackson & Perkins Beautiful Roses Made Easy : Northwestern Edition by Teri
Dunn & Ciscoe Morris. (Nashville, Tenn. : Cool Springs Press, 2004)

Roses for the Pacific Northwest by Christine Allen (Vancouver : Steller Press, 1999)

Roses for Washington and Oregon by Brad Jalbert, Laura Peters (Edmonton : Lone Pine Pub., 2003)

Roses for the Inland Northwest. Washington State University Extension ; [Washington, D.C.] : U.S. Dept. of Agriculture, [2004])

This book is a comprehensive guide to combining clematis and roses:
The Rose and the Clematis As Good Companions by John Howells ; photographs
by the author ; flower arrangements by Ola Howells (Woodbridge : Garden Art Press, 1996)

All of these titles are available in the Miller Library.

pests affecting currant trees

We moved into a new house which has a large currant or gooseberry bush. Now that it has leafed out there are numerous caterpillars eating the leaves. I know they are not tent caterpillars, but I cannot identify them. They are whitish-green with yellow bands across the top and bottom, with many black dots or bumps. The head and first six legs are black. It would be nice to learn more about them.

I cannot make a conclusive pest identification remotely, but there is a possibility these caterpillars are currant sawfly, or imported currantworm. Here is some information about this pest from the Pacific Northwest Pest Management Handbooks.

If this pest is the culprit, the book, The Organic Gardener’s Handbook of Natural Insect and Disease Control edited by Barbara Ellis (Rodale Press, 1996) recommends using Pyrethrin spray, spraying into the center of the bush. Bees are severely affected by this pesticide, so follow the guidelines shown on this University of California, Davis Integrated Pest Management page. Also see this guide to reducing bee poisoning from pesticides.

For a definitive pest identification, you may want to bring a sample of the pest and its damage to a Master Gardener Clinic.
Using the following link, you can locate a Master Gardener Clinic in your part of Washington State.