Volume 7, No. 4 Farm Advisors October-December 2009 Editor’s Note: Please let us know if your mailing address has changed, or you Gary Bender – Subtropical Horticulture, San Diego would like to add someone else to the mailing list. Call or e-mail Phone: (760) 752-4711 the farm advisor in the county where you live. Phone numbers Email to: [email protected] Website: http://cesandiego.ucdavis.edu and e-mail addresses can be found in the right column. Mary Bianchi – Horticulture/Water Management, San Please also let us know if there are specific topics that you would Luis Obispo like addressed in subtropical crop production. Copies of Topics Phone: (805) 781-5949 in Subtropics may also be downloaded from the county Email to: [email protected] Cooperative Extension websites of the Farm Advisors listed. Website: http://cesanluisobispo.ucdavis.edu Akif Eskalen Ben Faber – Subtropical Horticulture, Ventura/Santa Editor of this issue Barbara Phone: (805) 645-1462 Email to: [email protected] Website: http://ceventura.ucdavis.edu Neil O’Connell – Citrus/Avocado, Tulare Phone: (559) 685-3309 ext 212 Email to: [email protected] Topic Page Website: http://cetulare.ucdavis.edu Craig Kallsen – Subtropical Horticulture & Pistachios, The State of Dothiorella Canker on Avocado Kern in California 2 Phone: (661) 868-6221 Email to: [email protected] Website: http://cekern.ucdavis.edu The Parent Washington Navel Orange Tree - Eta Takele – Area Ag Economics Advisor Its First Years 4 Phone: (951) 683-6491, ext 243 Email to: [email protected] Website: http://ceriverside.ucdavis.edu Mechanical Harvesting of California Table and Oil Olives 7 Jeanette Sutherlin for Mark Freeman – Citrus & Nut Crops, Fresno/Madera Phone: (559) 456-7285 Email : [email protected] Website: http://cefresno.ucdavis.edu The University of California prohibits discrimination 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 service in the uniformed services (as defined by the Uniformed Services Employment and Reemployment Rights Act of 1994: service in the uniformed services includes membership, application for membership, performance of service, application for service, or obligation for service in the uniformed services) in any of its programs or activities. University policy also prohibits reprisal or retaliation against any person in any of its programs or activities for making a complaint of discrimination or sexual harassment or for using or participating in the investigation or resolution process of any such complaint. 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/Equal Opportunity Director, University of California, Agriculture and Natural Resources, 1111 Franklin Street, 6th Floor, Oakland, CA 94607, (510) 987-0096. 1 The State of Dothiorella Canker on Avocado in California Akif Eskalen, Virginia McDonald Cooperative Extension Specialist and Plant Pathologist Department of Plant Pathology, UC Riverside [email protected], http://www.eskalenlab.ucr.edu Branch and trunk canker on avocado was formerly attributed to Dothiorella gregaria, hence the name Dothiorella canker. So far Botryopshaeria dothidea (anamorph: Fusicoccum aesculi) is the only known species causing Dothiorella canker on avocado in California. Symptoms observed on avocado with Dothiorella canker include shoot blight and dieback, Fig. 2. Dothiorella branch and shoot dieback symptoms on leaf scorch, fruit rot, and cankers on branches and Hass cv. avocado tree. bark (Fig.1, 2, 3). According to preliminary results from a continuing survey throughout avocado growing areas of California, multiple species of Botryosphaeria (Neofusicoccum australe, B. dothidea, N. luteum, and N. parvum) were found. Fig. 1. Dothiorella branch dieback and canker symptoms on Hass cv. avocado tree. However, recent studies based on DNA analyses suggest greater species diversity of this pathogen group than based on morphological characteristics alone. Thus far, multiple species of Botryosphaeriaceae have been found to cause the Fig 3. Dothiorella perennial canker on branch typical Dothiorella canker (Fig3.) and stem-end rot (Fig 5) on avocado in California. Percent recovery of Pycnidia (overwintering structure) of Botryosphaeria spp. based on morphological Botryosphaeriaceae species were also observed on old characters ranged from 40-100% in Riverside county, diseased avocado tree branches. Sequenced rDNA 42-53% in Ventura county, 33% in Santa Barbara fragments (ITS1, 5.8S rDNA, ITS2, amplified with county, 60% in San Diego county and 32-60% in San ITS4 and ITS5 primers) were compared with Luis Obispo county. sequences deposited in GenBank. 2 Fig 4. Dothiorella perennial canker on trunk Fig 5. Stem end rot symptom of Dothiorella pathogens Pathogenicity tests were conducted in the greenhouse These results are significant because on 1-year-old avocado seedlings, Hass cv., with one Botryosphaeriaceae canker pathogens are known to randomly chosen isolate from each of enter the host plant through fresh wounds (pruning, the Botryosphaeriaceae species noted above. Four frost, and mechanical). With high-density planting replicate seedlings were stem-wound inoculated with becoming more common, which requires intensive a mycelial plug and covered with Parafilm. Sterile pruning, the transmission rate of these pathogens PDA plugs were applied to four seedlings as a control. could increase in California avocado groves. The Over a period of 6 months, seedlings were assessed Eskalen laboratory is currently investigating control for disease symptoms that included browning of leaf measures for dothiorella canker and stem-end rot edges and shoot dieback. Mean vascular lesion lengths pathogens. on stems were 64, 66, 64, and 18 mm for B. dothidea, N. parvum, N. luteum, and N. australe, respectively. Refernces: Each fungal isolate was consistently reisolated from inoculated seedlings, thus completing the V. McDonald, S. Lynch, and A. Eskalen. 2009. First pathogenicity test. To our knowledge, this is the first report of Neofusicoccum australe, N. luteum, and N. report of N. australe, N. luteum, and N. parvum parvum associated with avocado branch canker in recovered from branch cankers on avocado in California. Plant Disease. V.93, No.9. p.967. California. Pedro W. Crous, Bernard Slippers, Michael J. Wingfield, John Rheeder, Walter F.O. Marasas, Alan J.L. Philips, Artur Alves, Treena Burgess, Paul Barber and Johannes Z. Groenewald. 2006. Phylogenetic lineages in the Botryosphaeriaceae. Stud. Mycol. 55:235. F. F. Halma and G. A. Zentmyer. 1953. Relative Susceptibility of Guatemalan and Mexican avocado varieties to Dothiorella Canker. Calif. Avocado Soc. Yearb. 38:156. W. F. T. Hartill and K. R. Everett. 2002. Inoculum sources and infection pathways of pathogens Fig 4. Leaf scorch symptoms of Dothiorella canker causing stem-end rots of ‘Hass’ avocado (Persea americana) New Zealand Journal of Crop Hortic. Sci. 30:249. 3 The Parent Washington Navel Orange I shall be glad to forward whatever number of cuttings Tree - Its First Years may be desired and would suggest the month of May Chester N Roistacher as being the most suitable for the purpose." Capron Retired Citrus Virologist, replied to Edes on February 21, 1871 and on April 20, University of California, Riverside. 1871, Edes acknowledged the letter and said that he Part-I would forward the desired navel orange cuttings. In January, 1995 during my second consultancy visit The first successful introduction of the navel to Thailand, I was asked to lecture to the staff of orange. (Dorsett, Shamel and Popenoe, 1917) Kasetsart University located in Bangkok. The lecture reported on the recollection of William Saunders was on the problems of the greening disease in their made some 29 years after receipt of budwood of the country where trees die between 4 and 8 years and Bahia navel from Brazil. Saunders was then rarely reach 12 years of age. The lecture was well Superintendent of the Gardens and Grounds of the attended by many young staff and scientists. During USDA in Washington D.C. and recalled that "Some the lecture I showed them a picture of a large citrus time in 1869 the then Commissioner of Agriculture, tree dying with the greening disease (Fig.1). While Horace Capron, brought to my office and read me a showing this picture, almost half the audience raised letter which he had just received from a correspondent their hands and one by one, said that picture of this in Bahia, Brazil. Among other matters, special tree could not have been taken in Thailand for they mention was made of a fine seedless orange of large had never seen a tree of this size. In truth, the picture size and fine flavor. Thinking that it might be of value was taken in Thailand by Dr. E.C. Calavan who in this country, I noted the address of the writer and visited Thailand in 1975 and gave me this slide. In sent a letter asking to be the recipient of a few plants truth, all of these younger scientists assumed that of this orange. This request brought, in course of time, citrus trees lived a short period of time and were a small box of orange twigs, utterly dry and useless. I replaced. I then showed them the picture of the Parent immediately sent a letter requesting that someone be navel orange tree which was 120 years old the time of employed to graft a few trees on young stocks and that my lecture and they could not grasp that a citrus tree all expenses would be paid by the Department. could live that long. Today, this historical parent navel Ultimately a box arrived containing 12 newly budded orange tree located at the corner of Arlington and trees and being packed as I had suggested, were in Magnolia Avenues in Riverside is 134 years old (Fig.