A Pest of Landscape Eucalyptus in Southern California Becomes an Ornamental Pest By James A. Bethke, UCCE San Diego Floriculture and Nursery Crops Advisor, Valerie J. Mellano, UCCE San Diego County Environmental Issues Advisor, and Timothy D. Paine, Professor of Entomology, UC Riverside

Healthy Garden—Healthy Home

Retail Nursery Newsletter An Information Source for Retail Nursery Professionals

Volume 1, Issue 6 February 2006

Healthy Garden—Healthy Home

Helping to improve water quality in

San Diego County through the

implementation of Integrated Pest

Management practices.

It’s The Water

That Connects Us!

Eugenia Pest 1

Eucalyptus Pest 1

Myrtle Pest 3

Free Workshops and Educational Materials

2 & 4

Inside this issue:

CONSERVE WASPS THAT PROTECT EUGENIA By Vincent Lazaneo, UCCE San Diego County Home Horticulture Advisor

Neatness may be a virtue, but you should not clean up all of the clippings when a Eugenia hedge is trimmed. Leaving cut foliage on the ground will improve the hedge’s ap-pearance. The cut stems harbor a beneficial wasp which controls the Eugenia psyllid. The woody, broad-leafed evergreen known as Eugenia (or Australian Brush Cherry in California) is often grown as a hedge or to-piary in coastal areas – especially in Southern California. The plant – known botanically as

Syzygium paniculatum – is native to Australia, where it is called “Willy-Pilly”. The plant was in-troduced into California long ago and it remained free of pests until the Eugenia psyllid arrived in the state. The Eugenia psyllid, Trioza eugeniae, is a small winged insect about the size of an aphid. The pest was na-tive to Australia and was first detected in California in May, 1988. It was found in the Inglewood area of Los Angeles County. The psyllids spread quickly along the coast and infested

Eugenia from San Diego County to the Napa Val-ley within a year.

The psyllid had no effective natural ene-mies in California and it developed high popula-tions, which severely damaged Eugenia. Adult, female psyllids lay golden eggs on the edges of young, develop-

(Continued on page 2)

A large number of introduced Eucalyptus pests have invaded Cali-fornia over the last ten years or so, including boring beetles, psyllids, gall forming wasps, and leaf chewing beetles in the family Chrysomeli-dae. The blue gum psyl-lid was the first to be-come a pest of ornamen-tal eucalyptus, silver-leaved mountain gum or baby blue gum, Eucalyp-

tus pulverulenta Sims. The blue gum psyllid was not a pest for long, how-ever, due to the introduc-tion of Australian parasi-toids.

A new pest of orna-mental eucalyptus was introduced from Australia into southern California around 2003, and it is not easily controlled by na-tive parasites or preda-tors. In Australia it is commonly known as the

southern eucalyptus leaf beetle (SELB), Chrysophtharta m-fusca Boheman. It is known as

an outbreak pest of com-(Continued on page 3)

Eugenia Psyllid Adult

Chrysophtharta m-fuscum Adult

Chrysophtharta m-fuscum Adult

PAGE 2 RETAIL NURSERY NEWSLETTER VOLUME 1 , ISSUE 6

EUGENIA continued from page 1

FREE Integrated Pest Management Community Workshop Series for Your Customers

Pests, Irrigation & Lawn Mainte-nance, Plant Selection, Benefi-cial Insects, Whitefly, Compost-ing, and Tomato Pests & Dis-eases. Our next workshop is on Controlling ANTS which will be held at the Discovery Center in Carlsbad starting at 10:00 AM on Saturday, February 25, 2006. The first 50 attendees will receive a FREE gift. For additional information contact Scott Parker at 858-694-2184 or saparker@ucdavis.edu

The Healthy Garden –Healthy Home program is conducting a series of FREE community workshops integrating the con-cept of Integrated Pest Man-agement (IPM) with a variety of topics. The underlying mes-sage of each workshop is to demonstrate how residents can be an important part of the solu-tion to improve water quality in San Diego County. Monthly workshops will include topics such as Weed Control, Ants, Snails & Slugs, Backyard Citrus

ing leaves. Newly hatched nymphs crawl on to the undersides of leaves, where they feed in pits, which are galls that the plant forms in response to their feeding. Foli-age is disfigured by red colored bumps, which form above the pits on the upper surface of leaves. The nymphs remove sap from leaves and excrete excess sugar as small, white beads of solid honey dew. Leaves become soiled with the sticky residue and black, sooty mold, which does not directly harm the plant.

To control the psyllid, re-searchers looked for its natural enemies in Australia and found a tiny, stingless wasp in the genius Tamarixia. The stingless, benefi-cial wasp was evaluated in a quar-antined facility, and then initially

released at Disneyland in Anaheim, California in July 1992. The wasp was also released at the San Diego Zoo in 1993 and other locations throughout California. It is now es-tablished throughout the state and can not be purchased commer-cially. The female Tamarixia wasp lays eggs singly under psyllid nymphs. The larva, which hatches from the egg, feeds on the psyllid nymph – eventually killing it. The larva then transforms into an adult under the psyllid’s carcass and emerges through it. Development from egg to adult takes about three to six weeks during warm, summer months, but can take several months during winter. The Eugenia psyllid repro-duces very rapidly in spring, when Eugenia produces abundant new growth. Parasite populations often do not increase fast enough to pro-vide satisfactory control of the pest. Good control usually occurs in summer when parasite reproduc-tion increases and psyllid reproduc-tion is inhibited by hot weather and a lack of new growth on Eugenia. By late summer, psyllid populations are usually very low. This causes a corresponding decline of the para-site population.

Sheering new growth on Eugenia hedges can be very effec-tive in managing psyllids if para-sites are conserved. Inspect Eugenia in spring and clip off new growth when it is infested with psyl-lids. Leave the clippings as mulch below the shrub to allow parasites developing within psyllid nymphs to emerge. The psyllid eggs and nymphs on cut foliage will die. Con-sider sheering Eugenia at about three week intervals during the pe-riod of new plant growth. Sheering is the only way to eliminate dam-aged foliage before leaves age and naturally drop. No pesticide or other treatment will restore pitted foliage to a healthy appearance. Eugenia should not be sprayed with insecticides to control psyllids. Products which leave a toxic residue on treated foliage kill parasitic wasps long after the plant has sprayed. A soil-applied sys-temic insecticide is the most practi-cal chemical treatment for high value plants, large shrubs and trees. Home Gardeners can pur-chase a product containing Imida-cloprid (Bayer Advanced Garden Tree and Shrub Insect Control Concentrate) at retail nurseries. Soil application does not kill natural enemies and avoids plant injury that occurs when systemic insecti-cide is injected into the trunk.

Eugenia Psyllid Nymphs and Damage

VOLUME 1 , ISSUE 6 RETAIL NURSERY NEWSLETTER PAGE 3

Eucalyptus Pest continued from page 1

Chrysophtharta m-fuscum Larva

Australian Tortoise Beetle AdultAustralian Tortoise Beetle Adult

Australian Tortoise Beetle LarvaeAustralian Tortoise Beetle Larvae

Rust on Myrtle Found in San Diego County By Val Mellano, UCCE San Diego County Environmental Issues Advisor

Eucalyptus Rust (Guava Rust) Puccinia psidii was recently found on myrtle plantings in northern San Diego County. This pest is also commonly found on guava and is a serious disease of Eucalyptus spp. in other parts of the world. Symptoms include bright yel-low-orange pustules on both the up-per and lower leaf surfaces and also on the stems of the plant. Powdery-looking spores are released from the pustules and can spread the disease to nearby plants, or they can be air-borne, or carried on clothing, boots, tools, plant materials, animals etc. to other locations.

Treatment of the disease is extremely important, as it can poten-tially cause devastating losses to plantings of myrtle locally. To date, recommended treatment includes applications of Heritage + Daconil for

control of the rust if an infection oc-curs, and the careful removal of any infected plant material. Destruction of the infested plants through burning or burying is important in minimizing the spread of the rust. Once the disease is eliminated from the field, the use of Daconil as a protectant is recom-mended following label directions. It is very important to continu-ously be on the lookout for the pres-ence of the fungus, and to eradicate it immediately if found. For more information, please call the Farm Advisor’s Office, at (858)694-2845.

Rust on Myrtle San Diego County, November 2005

mercial E. globulus, blue gum planta-tions in southeastern Australia.

SELB prefer to oviposit in batches of 30-60 eggs on younger foliage; whereas, adults will feed on older foliage. Hatchlings feed gre-gariously on the younger foliage causing extensive damage to leaf edges that resembles caterpillar feed-ing damage.

The immature stages of SELB are daytime feeders. In contrast, the Australian tortoise beetle (ATB), Tra-cymela sloanei, feeds at night.

The ATB was introduced into California in 1998 and has become a pest of many species of landscape eucalyptus. In Australia, it also has been known to feed on E. globulus.

Both beetle species are about the size of a ladybug. The SELB adult is

gray to reddish brown and the larvae are greenish-gray. The ATB adult and larvae are both dark brown.

SELB has mostly fed upon land-scape planted blue gum in San Diego, Orange and Riverside Coun-ties. Recently it has become a pest of baby blue eucalyptus in northern San Diego County.

At present, research on pesticide

efficacy against these beetles is un-derway. Further, there are no regis-tered pesticides specifically for use on these pests. Certain pesticides, however, are recommended for use on leaf beetles such as the elm leaf beetle, and should be considered for control of these pests. The neonicoti-noids, imidacloprid, acetamiprid, thia-methoxam, and dinotefuran, are used against a variety of beetles including leaf beetles, and may be a good con-trol measure against SELB. Other soil-applied systemics like Orthene may also work well.

Pyrethroids like cyfluthrin and older products like Carbaryl may re-pel adults and will most likely cause mortality to immatures. However, it is very important to remember that the blue gum psyllid is under excellent control by beneficials. These prod-ucts may well interrupt biological con-trol and cause resurgence of the psyl-lid to serious pest status. For more information about leaf bee-tles on eucalyptus and all integrated control options, see the following UCIPM web site, http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74104.html

Chrysophtharta m-fuscum Larva

Australian Tortoise Beetle Adult

Australian Tortoise Beetle Larvea

HEALTHY GARDEN—HEALTHY HOME

University of California Cooperative Extension Farm and Home Advisors Office 5555 Overland Avenue, Building #4, Suite #4101 San Diego, CA 92123

Phone: 858-694-2184 Fax: 858-694-2849 E-mail: saparker@ucdavis.edu Web Site: www.cesandiego.ucdavis.edu

FREE Point-of-Purchase Educational Materials and Training Workshops Available for Local Nurseries and Garden Centers!

As part of the Healthy Garden – Healthy Home Integrated Pest Management (IPM) outreach effort, research based educational materi-als, and the fixtures necessary to display them, are available to nurs-ery and garden centers throughout San Diego County. Materials in-clude water resistant pest cards and informational tear-off sheets. Pest Card topics include; Ants, Aphids, Cockroaches, Earwigs, Fleas, Giant Whitefly (coming soon), Head Lice, Snails & Slugs, Spiders, Termites, Safe Use & Dis-posal of Pesticides, Lawn Insects, and Gardening with Good Bugs. Tear-Off Sheet topics include; Gen-eral IPM Information, Ants, and Snails & Slugs. And coming soon; Aphids, Giant Whitefly, and Gar-

dening with Good Bugs. In addition to these Point-Of-Purchase items, several educa-tional videos ranging in length from 15 second to 3 minute are available for use in your store. Both DVD and video format are available. Workshops for nursery staff focusing on topics related to IPM and Water Quality are also avail-able for booking. For more information about any of these opportunities or to make arrangements for your nursery or garden center to participate in this program please contact Scott Parker by phone, 858-694-2184, or email, saparker@ucdavis.edu.

Funding for this project has been provided in full or in part through an Agreement with the State Water Resources Control Board (SWRCB) pursuant to the Costa-Machado Water Act of 2000 (Proposition 13) and any amendments thereto for the implementation of Cali-fornia’s Nonpoint Source Pollution Control Program. The contents of this document do not necessarily reflect the views and policies of the SWRCB, nor does mention of trade names or commercial products constitute endorsement or recommendations for use.

The University of California prohibits discrimination against or har-assment of any person on the basis of race, color, national origin, religion, sex, physical or mental disability, medical condition (cancer related or genetic characteristics), ancestry, marital status, age, sexual orientation, citizenship, or status as a covered veteran (special disabled veteran, Vietnam-era veteran or any other veteran who served on active duty during a war or in a campaign or expedi-tion for which a campaign badge has been authorized). University policy is intended to be consistent with the provisions of applicable State and Federal laws. Inquiries regarding the University’s nondis-crimination policies may be directed to the Affirmative Action/Staff Personnel Services Director, University of California, Agriculture and Natural Resources, 300 Lakeside Drive, 6th Floor, Oakland CA 94612-3560. (510) 987-0096. University of California, County of San Diego, and the United States Department of Agriculture cooper-ating.

Sample Pest Cards Display Racks