UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION TREE TOPICS

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1 UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION TREE TOPICS INFORMATION FOR TREE FRUIT AND NUT GROWERS IN CALIFORNIA S CENTRAL COAST REGION MARCH 6, 2006 VOLUME 31, ISSUE 3_ IN THIS ISSUE: WALNUT INSTITUTE APPLE INSTITUTE OLIVE GROWERS MEETING BLOOM DISEASES OF APRICOTS EYESPOTTED BUDMOTH - APPLES NEW PEST MANAGEMENT GUIDELINES APRICOTS, CHERRIES FUNGICIDE EFFICACY CHARTS APRICOTS, CHERRIES WALNUT INSTITUTE This is just another reminder that the Walnut Institute for local walnut growers will be Thursday, March 9 in the Veterans Building in Hollister. Please see the enclosed announcement for further details. APPLE INSTITUTE There will be no joint CAFF/UC Santa Cruz/UCCE apple meeting this year (Moth Madness meeting). I will hold my own research update meeting on Tuesday, March 21 in Watsonville at the UC Cooperative Extension Auditorium, 1432 Freedom Blvd. from 10 a.m. until 12 noon. Please see the enclosed announcement for more details. OLIVE GROWERS MEETING Our first local olive growers meeting will be Tuesday, April 4 from 10 a.m. until 12 noon in Hollister at the Veterans Memorial Bldg., 649 San Benito Street. This will be for both growers and prospective growers thinking about planting olives for olive oil production. The meeting is free and will feature Sonoma County Farm Advisor Paul Vossen, our University of California olive oil expert. U.S. DEPARTMENT OF AGRICULTURE, UNIVERSITY OF CALIFORNIA AND SAN BENITO COUNTY COOPERATING

2 BLOOM DISEASES OF APRICOTS The primary diseases infecting apricot flowers and/or the early fruit stage are brown rot, jacket rot, shot hole disease, powdery mildew and fogspot. Brown rot (Monilinia laxa, Monilinia fructicola) causes the flowers to turn brown and die. The associated fruit spur may also die often with a drop of gum present. Usually, fungicides for brown rot control are applied at redbud and days later (often about full bloom). I am beginning to observe the erratic bloom that was predicted from the low chilling winter and this will make timing more difficult. Apricot flowers are susceptible to brown rot from redbud until petal fall, so two or even three sprays may be necessary to cover the long bloom period. Jacket rot (Botrytis cinerea, Sclerotinia sclerotiorum, Monilinia) develops after bloom under remnants of the flower called the jacket or shuck. It causes a brown rotted area in the fruit which usually results in fruit drop. Jacket rot is controlled by a fungicidal spray at full bloom (the second brown rot spray). Not all materials that are effective for brown rot are adequate for jacket rot control check the efficacy charts. Shot hole disease (Wilsonomyces carpophilus) causes purple spots with tan centers on the fruit and leaves but is not very common in the Central Coast. The spots on the leaves drop out and leave holes. Shot hole disease can be controlled by the appropriate fungicides applied between full bloom and pit hardening. The same applies to powdery mildew (Sphaerotheca pannosa) which causes white fuzzy areas followed by purple patches on the fruit. Fogspot is still being studied. It causes red or purple spots on the fruit which may scab over by harvest. There is no shot-holing of the leaves. Although we can isolate Alternaria fungi from the spots, fogspot is believed to be a non-pathogenic disease caused by moisture during a critical period between petal fall and pit hardening. There is no UC recommendation for control but we are hopeful that current research will result in some answers. Occasionally, bacterial canker (Pseudomonas syringae) may also damage blossoms, twigs and even branches. It may appear similar to brown rot damage. Make a glancing cut under the bark of twigs and branches in affected areas. Bacterial canker will produce orange or red spots and patches under the bark in the cambial region. Bacterial canker often re-visits the same portion of the orchard where it has appeared in the past. Some factors increasing bacterial canker are rootstock (Marianna 2624 is the worst), shallow or gravelly soils such as old creek beds and high ring nematode populations. It is usually worse when we have cold, wet periods in late winter. EYESPOTTED BUDMOTH - APPLES Eyespotted budmoth has become a significant pest in Central Coast organic apple orchards. The overwintering larvae may already be active feeding on the developing buds. The summer generation feeds on the fruit surface. You may be able to reduce the overall population level by applying prebloom sprays of Bt or Entrust based upon limited testing last year. Visual monitoring of buds and leaves should begin in March. Pheromone traps usually begin catching moths in early May.

3 NEW UC IPM PEST MANAGEMENT GUIDELINES A new University of California Pest Management Guideline for apricots was released in February. A new guideline for cherries is expected very shortly and one for apples possibly in April or May. For a complete list of pest management guidelines in PDF download format go to the website If you wish to take a look at individual insect, disease and weed pests with associated color photos, go to the UC IPM website at If you don t have internet access, contact me for a printed copy. The guidelines are written by various UC Farm Advisors, Specialists and Professors and coordinated by Barbara Ohlendorf of UC IPM at the UC Davis campus. FUNGICIDE EFFICACY CHARTS I have attached the latest apricot and cherry fungicide efficacy charts. These are written by UC Plant Pathologists Jim Adaskaveg, Brent Holtz, Themis Michailides and Doug Gubler. The complete publication including a lot of additional information about fungicide properties is available at the web site Look for the 2006 edition which is due out soon the attached sheets are from that 2006 edition. Contact me for a printed copy. William (Bill) W. Coates Univ. of Calif. Cooperative Extension Farm Advisor, Fruit and Nut Crops 649 San Benito Street, Suite 115 San Benito, Santa Cruz, Santa Clara Hollister, CA and Monterey Counties (DO NOT USE ABOVE ADDRESS FOR MAIL) (831) phone Mail: P.O. Box 1956 (831) FAX Hollister, CA bwwcoates@ucdavis.edu web: For those without Internet access, call or write me and I will provide hard copies of any information mentioned above. Reference to commercial products or trade names is with the understanding that no discrimination is intended, and no endorsement by Cooperative Extension is implied. The University of California prohibits discrimination against or harassment of any person on the basis of race, color, national origin, religion, sex, gender identity, pregnancy (including childbirth, and medical conditions related to pregnancy or childbirth) physical or mental disability, medical condition (cancer-related or genetic characteristics), ancestry, marital status, age, sexual orientation, citizenship, or status as a covered veteran (covered veterans are special disabled veterans, recently separated veterans, Vietnam era veterans, or any other veterans who served on active duty during a war or in a campaign or expedition for which a campaign badge has been authorized) in any of its programs or activities. University policy is intended to be consistent with the provisions of applicable State and Federal laws. Inquiries regarding the University s nondiscrimination 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 , (510)

4 CENTRAL COAST COUNTIES WALNUT INSTITUTE UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION THURSDAY, MARCH 9, :30 A.M. 12 NOON 649 SAN BENITO STREET VETERANS MEMORIAL BUILDING HOLLISTER, CA 8:30 WELCOME, INTRODUCTIONS CODLING MOTH MANAGEMENT Bill Coates, Farm Advisor, University of California Cooperative Extension, San Benito, Santa Cruz, Santa Clara and Monterey Counties 9:00 PESTICIDE REGULATION UPDATE Ron Ross, Senior Agricultural Biologist San Benito County Agricultural Commissioner s Office 9:30 WALNUT HUSK FLY CONTROL Bill Coates, Farm Advisor 9:55 BREAK 10:00 WALNUT RESEARCH UPDATE Dr. Bruce Lampinen, Extension Specialist, University of California, Davis 10:30 WALNUT BREEDING PROGRAM: NEW VARIETIES AND ROOTSTOCKS Dr. Gale McGranahan, Pomologist/Lecturer, University of California, Davis 11:00 USING RETAIN FOR SERR PISTILLATE FLOWER ABORTION Bob Beede, Farm Advisor, University of California Cooperative Extension, Kings County 11:30 WALNUT MARKETING BOARD / WALNUT COMMISSION ACTIVITIES Dennis Balint, CEO, Walnut Marketing Board / California Walnut Commission Continuing education credit has been approved for 0.5 hour of Laws and Regulations and 1.0 hours of other pest management. All day parking is available on the south and east sides of the Veteran s Building. All other parking is 2 hour. Enter building from the main (west) entrance facing San Benito Street. For further information contact Bill Coates at , FAX at or at bwwcoates@ucdavis.edu.

5 CENTRAL COAST COUNTIES APPLE INSTITUTE UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION TUESDAY, MARCH 21, :00 A.M. 12 NOON COOPERATIVE EXTENSION AUDITORIUM 1432 FREEDOM BLVD., WATSONVILLE, CA 10:00 PESTICIDE REGULATION UPDATE Dave Moeller, Santa Cruz County Agricultural Commissioner 10:30 EYESPOTTED BUDMOTH AND OTHER LEAFROLLERS Bill Coates, University of California Cooperative Extension Farm Advisor, Fruit and Nut Crops, San Benito, Santa Cruz, Santa Clara and Monterey Counties Cathy Carlson, University of California Cooperative Extension, Monterey County 11:00 FINDING PEST MANAGEMENT AND TREE CROP INFORMATION ON THE INTERNET Bill Coates, Farm Advisor 11:30 CODLING MOTH MANAGEMENT WITH REDUCED RISK PESTICIDES Janet Caprile, Farm Advisor, University of California Cooperative Extension, Contra Costa County CONTINUING EDUCATION CREDIT HAS BEEN APPROVED FOR 0.5 HOURS OF LAWS AND REGULATIONS AND 1.5 HOURS OF PEST MANAGEMENT. FOR FURTHER INFORMATION CALL BILL COATES AT OR FAX AT OR E- MAIL AT

6 APRICOT FUNGICIDE EFFICACY DO NOT USE SULFUR AT ANY TIME ON APRICOT TREES OR USE CAPTAN PREHARVEST ON APRICOT FRUIT Fungicide Resistance Brown rot 2 Jacket rot Powdery Shot risk (FRAC#) 1 Blossom Fruit mildew 2 hole Benlate 3 high (1) Indar high (3) ND ---- Orbit (Bumper) high (3) /- Pristine medium (7/11) Rovral 4 + oil 5 low (2) ++++ NR Scala high (9) ND ++ Topsin-M 3 high (1) Vangard high (9) ND ++ Rally high (3) Rovral 4 low (2) +++ NR Elevate high (17) Abound high (11) ND +++ Botran high (14) ND ND Bravo/Echo 6,7 low (M5) Captan 7,8 low (M4) Copper low (M1) +/ Ziram low (M3) +/ Rating: ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, ---- = ineffective, ND = no data, and NR = not registered. 1. Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Fungicides with a different group number are suitable to alternate in a resistance management program. For more information, see 2. Do not use with the same FRAC number and high resistance risk more than twice in one year. 3. Benlate label withdrawn. Strains of Monilinia fructicola and M. laxa resistant to Benlate and Topsin-M have been reported in some California apricot orchards. Resistant strains of the jacket rot fungus, Botrytis cinerea, have been reported in California on crops other than almond and stone fruits and may have the potential to develop in apricots with overuse of fungicides with similar chemistry. 4. Blossom blight only; not registered for use after petal fall. 5. The oil is a light summer oil, 1-2% volume/volume. 6. Do not use after jacket (shuck) split. 7. Do not use in combination with or shortly before or after oil treatment. 8. Causes fruit browning as a preharvest spray. 9. High summer temperatures and relative humidity reduce efficacy. 10. Has not been tested on apricot but is effective against the jacket rot pathogens. 11. May cause staining on fruit.

7 CHERRY--FUNGICIDE EFFICACY Fungicide Resistance Brown rot 2 Botrytis Powdery Shot hole risk (FRAC#) 1 Blossom Fruit mildew 2 Leaf spot 3 Benlate 4 high (1) ND Elite high (3) ND Indar high (3) ND Orbit (Bumper) high (3) ND Pristine medium (7/11) ND Rovral 5 + oil 6 low (2) ++++ NR ND Topsin-M 4 high (1) ++++ NR ND Abound high (11) ND Cabrio high (11) ND Elevate high (17) ND Quintec medium (13) ND ND ND ++++ ND Rally 7 high (3) ND Rovral 5 low (2) +++ NR ND Rubigan high (3) ND Botran high (14) ND Bravo/Echo 8,9 low (M5) ++ NR ND Captan 9 low (M4) ND Copper low (M1) +/ ND Sulfur 9 low (M2) +/ ND Ziram low (M3) +/- NR ND Rating: ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, ---- = ineffective, ND = no data, NR = not registered, and? = insufficient data or unknown. 1. Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Fungicides with a different group number are suitable to alternate in a resistance management program. For more information, see 2. Do not use the same fungicide or fungicides with similar chemistry more than twice in one year. 3. Shot hole and leaf spot occur infrequently on cherry in California; control usually is not necessary (ND = no data available). 4. Benlate label withdrawn. Strains of Monilinia fructicola resistant to Benlate and Topsin-M are present in some California cherry orchards. 5. Blossom blight only; not registered for use after petal fall. 6. Oil is a light summer oil, 1-2% volume/volume. 7. More effective when applied as a concentrate ( gal/acre) than as a dilute spray. 8. Do not use after jacket (shuck) split. 9. Do not use in combination with or shortly before or after oil treatment.

8 TREE TOPICS NEWSLETTER MARCH 6, 2006 COOPERATIVE EXTENSION UNIVERSITY OF CALIFORNIA P. O. BOX 1956 HOLLISTER, CA