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Garden detective: Damaged leaves

Published: Saturday, May. 19, 2012 - 12:00 am | Page 8CALIFORNIA LIFE

We live in Herald in south Sacramento county. About 18 years ago, we planted several eucalyptus trees for a fast-growing light shield from a neighboring light.

A few years ago, we noticed that some (not all) of the eucalyptus seemed to have leaves that were chewed on their edges. We don't see any pests, but obviously something was there.

What feeds on eucalyptus and what can we do about it?

We also have two flowering plum trees, on either side of our front steps. One of them has leaves that have holes in them; those damaged leaves seem to be mostly near the top. Any idea of what is there, and again, what can we do about them? Thanks for any ideas you can give!

Naomi and Jeff Burns, Herald

To provide an accurate diagnosis of what's chewing your leaves, samples would need to be viewed, says UC master gardener Fran Clarke.

But here are some possibilities:

A relative newcomer to the Central Valley, the Eucalyptus tortoise beetle chews distinctive, irregular notches along the margins of eucalyptus leaves and sometimes clips tender leaf shoots. Both adults and larvae chew leaves.

Two species of this now-common pest of many eucalyptus species are found throughout California. The Australian variety was first reported in Riverside County in 1998 and gradually spread north.

Disfigured leaves seldom threaten the survival of the affected trees, so pesticides are not recommended. Pesticides may also kill beneficial insects that are actively monitoring the pest insects.

Keep the trees healthy by providing monthly supplemental deep watering during summer and fall, but avoid frequent shallow watering.

Your plum tree probably has shot hole, also called coryneum blight, which was common on flowering plum trees after last year's long, wet spring. The leaves developed small tan to purplish spots that fell out as the leaves expanded, causing a "shot hole" appearance.

To combat shot hole, rake up fallen leaves, which will help eliminate a source of infection next year if there's another wet spring. On flowering plum trees, this is a cosmetic problem.

To get a more specific diagnosis if either problem persists, bring sample leaves, enclosed in sealed plastic bags, to your nearest UC cooperative extension office during regular hours.

I saw this interesting and pretty plant last June. I was wondering if you can tell me what it is and give me some information on it. I would like to have one.

Lethana Collins, Sacramento

According to UC master gardener Annie Kempees, the plant pictured in the photograph you provided appears to be a member of the Lupinus genus – a lupine.  Of the lupines that grow in the greater Sacramento area, four varieties are annuals and four are perennials.

Although lupines grow wild in California, hybrids are the most widely sold.  They were bred in the United Kingdom, taking stock from plants native to western North America.  They are often called "Russell hybrids" or the "classic lupines." 

They tend to be short-lived, three to five years, and are prone to powdery mildew.

The "New Generation" hybrid lupines are similar to the classics yet are sturdier and do not require staking.  They live longer, seven to eight years, and are mildew resistant.

Lupines bloom late spring to late summer. If spent flower heads are removed regularly, these hybrids may rebloom in autumn. Of all the resources checked, there was not an exact match to your photo. It may be one of the hybrids or one of the named varieties.

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