Citrograph May-June 2010 - Citrus Research Board

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suckers and watersprouts will be required, especially beginning in the third year after planting, and earlier, if grown under stressful conditions. • Fukumoto on Carrizo rootstock, generally, will produce fewer suckers, watersprouts and stunted trees than on C-35, although both rootstocks have been associated with severe decline in some orchards. • Early replacement of stunted trees that have both excessive sucker scars and small diameter scions compared to the rootstock appears advisable. Future plans involving collaboration and utilization of research results In cooperation with Dr. Georgios Vidalakis of the California Citrus Clonal Protection Program (CCPP), we have plans to put the information that we have gathered to further use. Our results suggest that the current source of Fukumoto budwood may not be as compatible with our commonly used trifoliate and citrange rootstocks as is Washington navel. Spanish researchers have reported that they have not had problems with Fukumoto on Carrizo such as those observed by California growers. Dr. Vidalakis has obtained budwood of Fukumoto navel from a Spanish source and has ensured that it is free of disease by passing it through the CCPP cleanup program. Fukumoto trees on Carrizo rootstock grown from the existing California source of Fukumoto budwood and from the new Spanish source will be compared with LREC Fukumoto budwood. This trial was planted in May of 2010 on the property of a commercial citrus grower where previous plantings of Fukumoto navel have demonstrated high rates of stunting and suckering. As a result of the current project, we have identified the following measurable characteristics that will be used to determine if the new budwood source is different from the existing source when grown on citrange rootstocks: 1. The number of water sprouts produced within four inches of the graft union and all suckers on the rootstock. 2. The percentage of two-year-old trees showing stunting, typified by smaller scion diameters, and scion diameter/rootstock diameter ratios less than 0.70 and especially less than 0.60. The comparisons will continue until the trees begin to produce fruit to ensure that the fruit has a similar maturity date to the existing Fukumoto navel line. Since differences in irrigation or soil pH within the ranges of these experiments did not appear to affect the growth of Fukumoto navel, these environmental variables do not need to be included in the future bud source evaluation trial. If trees from the Spanish budwood source demonstrate growth characteristics similar to the Washington navel trees evaluated in this project and less like the Fukumoto trees from the existing budlines in the Foundation Block at LREC, then the budwood will likely be replaced with the Spanish line. Additionally, new methods of detecting diseases in citrus have been developed by researchers with Citrus Research Board funding. Again, while not part of this project, samples from declining and good performing Fukumoto trees will be collected and evaluated for foreign DNA, which, if found, may suggest that the decline is caused from a previously undetected disease agent. l Project Leader Craig E. Kallsen is Farm Advisor, University of California Cooperative Extension Kern County, and Co-Project Leader Neil V. O’Connell is Farm Advisor, University of California Cooperative Extension Tulare County. Custom Cultured Citrus Start With The Best 30+ years of custom propagation Deliver fully matured nursery trees Grown to order Uniform & Disease free Practicing I.P.M. 20 years Aphytis melinus rearing Orange Cove, CA Phone: (559) 626-2525 Fax: (559) 626-0302 mcsales@delite.com mulhollandcitrus.com 24 Citrograph May/June 2010
May/June 2010 Citrograph 25
Page 1: Citrograph May/June 2010 Citrograph
Page 4 and 5: ON THE COVER Citrus Pest and Diseas
Page 6 and 7: EDITORIAL By JIM CRANNEY, President
Page 8 and 9: A Mexican technician employed by AP
Page 10 and 11: Eyes under the soil Carl T. Gwillia
Page 12 and 13: Citrus Roots Preserving Citrus Heri
Page 14 and 15: By: Rahno Mabel MacCurdy, V.A. Lock
Page 16 and 17: Dowlin L. Young, co-founder of Youn
Page 18 and 19: Governor Schwarzenegger at center w
Page 20 and 21: CRB Funded Research Reports 2009 Re
Page 22 and 23: and trees were obtained from a priv
Page 26 and 27: Citrus Quarantine, Sanitary, and Ce
Page 28 and 29: California Citrus Clonal Protection
Page 30 and 31: that environmental conditions in th
Page 32 and 33: annual budwood distributions. Any t
Page 34 and 35: Table 1. Comparative summary of the
Page 36: C L E A N C I T R U S Clonal Contai

Citrograph May-June 2010 - Citrus Research Board

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