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

Healthy Garden—Healthy Home

Retail Nursery Newsletter An Information Source for Retail Nursery Professionals

Volume 1, Issue 9 May 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!

Diaprepes Root Weevil 1

Eugenia 1

Retail Nursery Seminar August 10, 2006

3

Free Workshops and Educational Materials

2 & 4

Inside this issue:

The Diaprepes Root Weevil (Citrus Root Weevil) by John Kabashima, Count Director and Farm Advisor, UCCE Orange County

The Diaprepes root wee-vil, Diaprepes abbrevia-tus (L.) (Coleoptera: Cur-culionidae), is a large, colorful weevil, 3/8 to 3/4 inch (10 to 19 mm) long, with numerous forms, or morphs, ranging from gray to yellow to orange and black. This weevil is native to the Caribbean region and was acciden-tally introduced into Flor-ida in the 1960’s where it has caused extensive damage. It has been in-tercepted in shipments of plants to California and in 2005 two isolated popu-lations were found in Newport Beach (Orange County) and Long Beach (Los Angeles County).

The California Depart-ment of Food and Agri-culture has established quarantine zones in Newport Beach and Long Beach to control this pest and prevent it from spreading.

This weevil will feed on about 270 different plants including citrus (all varie-

ties), hibiscus, palm, birch, roses, guava, lo-quat, holly, and other ornamentals. Because of its broad host range, the Diaprepes root weevil poses a great threat to citrus and ornamental plant industries in Califor-nia.

(Continued on page 2)

Neatness may be a vir-tue, but you should not clean up all of the clip-pings when a eugenia hedge is trimmed. The cut stems harbor tiny parasitic wasps which control a harmful pest, the eugenia psyllid. Leaving cut foliage on the ground will conserve the wasp and improve a hedge’s appearance. The shrubby Australian tree Syzygium panicula-tum, commonly called eugenia or Australian

brush cherry, is often grown as a hedge or to-piary in San Diego and other coastal areas of the state where winters are mild. The attractive and versatile plant was brought to California long ago and it remained free

of serious pests until May 1988. That’s when the eugenia psyllid, Trioza eugenia, a small wing insect about the size of an aphid was found in the Inglewood area of Los Angeles county. Within a year the pest had spread along the coast from San Diego to the Napa Valley. The psyllid had no effec-tive natural enemies in California and it devel-oped high populations on

(Continued on page 3)

Diaprepes Root Weevils Frass Left by

Feeding Adults

Eugenia Psyllid Adult

PAGE 2 RETAIL NURSERY NEWSLETTER VOLUME 1 , ISSUE 9

The Diaprepes Root Weevil continued from page 1

Integrated Pest Management Community Workshop Series For You & Your Customers

The Healthy Garden –Healthy Home program is conducting a series of FREE community workshops integrat-ing the concept of Integrated Pest Management (IPM) with a variety of topics. The underlying message of each workshop is to demonstrate how residents can be an important part of the solution to improve water quality in San Diego County. Monthly work-shops will include topics such as Ants, Snails & Slugs, Backyard Citrus Pests, Irrigation & Lawn Care, Plant Selec-tion, Beneficial Insects, Whitefly, and Tomato Pests & Diseases. Our next workshops will be on Irrigation & Lawn Care (Lakeside 6/10/06 and Chula Vista 6/21/06) and How to Con-trol Whitefly (Carlsbad 6/24/06). (Please see ads.) CCN Pro CE Units have been approved for all work-shops. For more information contact Scott Parker at 858-694-2184 or saparker@ucdavis.edu

The Diaprepes root weevil dam-ages both the leaves and the roots of plants. The adult weevils dam-age leaves by chewing semi-circular areas out of the leaf mar-gin. There may also be frass or weevil droppings near the areas that have been fed upon. The grub-like larva feeds upon the roots of a plant weakening or killing a plant.

An adult female weevil lays clusters of eggs in leaves that are folded and glued together. The eggs hatch

in 7-10 days, and the newly emerged larvae drop to the soil. The larvae enter the soil and feed upon the roots of plants for several months. The larvae then pupate in the soil. After the appropriate amount of time, adults will emerge and the life cycle begins again.

If you see the adult weevils or have damage to plants you suspect is caused by the weevil, please con-tact the CDFA Exotic Pest Hotline at 1-800-491-1899. Personnel from

CDFA will inspect plants for the presence of the Diaprepes root weevil and send any specimens collected to the CDFA diagnostic laboratory for identification.

For more information, read Publica-tion 8131: Diaprepes Root Weevil (free) found on the University of California Division of Agriculture and Natural Resources publications website: http//anrcatalog.ucdavis.edu.

Diaprepes Eggs About 0.04 Inch Long

Diaprepes Larva

Pupal Stage of Diaprepes

VOLUME 1 , ISSUE 9 RETAIL NURSERY NEWSLETTER PAGE 3

Eugenia continued from page 1

SAVE THE DATE! RETAIL NURSERY SEMINAR SCHEDULED FOR AUGUST 10 in Carlsbad

Mark your calendar! The Healthy Garden/Healthy Home program will be hosting a day-long Retail Nursery Seminar on Thursday, August 10 at the Windmill Banquet and Conference Center in Carlsbad (across from the Flower Fields). The program will include 8 well known speakers which will cover a variety of topics including Inte-

grated Pest Management, Insect Pest Identification, Water Quality, Responsible Pest Management, Irrigation, Understanding Fertiliz-ers, and Landscaping and Hard-scaping to Reduce Water Runoff as well as an update on Landscape Insect and Disease Pests. We have applied for 5 ½ CE units from CCN Pro. The seminar is being

offered for the low cost of $20 and includes all workshop materials, lunch, refreshments, and a tote bag. Registration forms will be available in June. Attendees who pre-register will receive a special gift. For additional information or to request a registration form please contact Scott Parker at 858-694-2184 or saparker@ucdavis.edu

its primary host eugenia. Heavily infested plants were stunted and badly disfigured. Nurseries stopped selling eugenia and landscape plants looked terrible unless they were routinely sprayed with a broad spectrum insecticide. The psyllid damages new leaves and shoots on eugenia. Adult fe-male psyllids lay golden eggs on the edges of young developing leaves. Newly hatched nymphs crawl on to the undersides of leaves and feed in pits, which are galls that the plant forms in response to their feeding. The upper surfaces of leaves are disfigured with red col-ored bumps, which form above the pits. The nymphs remove sap from leaves and excrete small white beads of sugary honeydew. Leaves are soiled by the sticky residue and black sooty mold that grows on it. This does not seriously damage the plant, but it looks unsightly. To combat the pest, researchers looked for its natural enemies in Australia. They found a tiny para-sitic wasp in the genus Tamarixia that is stingless and smaller than a pin head. The wasp was evaluated in a quarantined facility and then released in Anaheim, at Disneyland in July 1992, and at the San Diego Zoo in 1993. It is now established throughout the state and can not be purchased commercially.

The female Tamarixia wasp lays eggs singly under psyllid nymphs. The wasp larva feeds on the psyllid nymph and eventually kills it. The larva then transforms into an adult wasp and begins the process again. Development from egg to adult takes three to six weeks during warm summer months, but in winter the process take several months.

The wasp’s effectiveness changes with the seasons. The eugenia psyl-lid reproduces rapidly in spring when there is lush new growth on eugenia. Cool spring weather can keep the Tamarixia wasp from re-producing fast enough to effectively control the psyllid and gardeners often think the wasp is not present. Biological control improves in sum-mer when the weather is warmer and parasite reproduction in-creases. Hot weather and a lack of new growth on eugenia also causes the psyllid population to decline. By fall, psyllid populations are usually very low. This causes a corre-sponding decline of the parasite

population and it remains low through winter. Sheering new growth on eugenia hedges can be very effective in managing psyllids if parasites are conserved. Inspect eugenia in spring and clip off new growth when it is infested with psyllids. Leave the clippings as mulch below the shrub to allow wasps developing within psyllid nymphs to emerge. The psyllid eggs and nymphs on cut foliage will die. Consider sheering eugenia at about three week intervals during the pe-riod of rapid plant growth. Sheering is the only way to eliminate dam-aged foliage before leaves age and naturally drop. No insecticide 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 resi-due on treated foliage kill parasitic wasps long after the plant is sprayed. A soil-applied systemic insecticide is the most practical chemical treatment for large shrubs and trees. Home gardeners can purchase a product containing imi-dacloprid (Bayer Advanced Garden Tree and Shrub Insect Control Con-centrate) at retail nurseries. Soil application does not kill natural ene-mies and it avoids plant injury that occurs when systemic insecticide is injected into the trunk

Tamarizia - Parasitic Wasp

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, Head Lice, Snails & Slugs, Spiders, Termites, Safe Use & Disposal of Pesticides, Lawn Insects, and Gardening with Good Bugs. Tear-Off Sheet topics include; General IPM Information, Ants, Snails & Slugs, and Aphids. And coming soon; Preventing Irri-gation Runoff and Giant Whitefly.

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