California Strawberry Commission ANNUAL PRODUCTION RESEARCH REPORT 2011 — 2012 ® CALIFORNIA STRAWBERRY COMMISSION ANNUAL PRODUCTION RESEARCH REPORT 2011 - 2012 TABLE OF CONTENTS Introduction – Message From The Research Committee Chairman ................................................ 5 PATHOLOGY A Comprehensive Approach To Management of Wilt Diseases Caused by Fusarium oxysporum and Verticillium dahlia ..................................................................................................... 9 Dr. Thomas R. Gordon Operating A State-wide Strawberry Disease Diagnostic Services Center ...................................... 21 Steven Koike Continuing Development of Management Strategies for Charcoal Rot (Macrophomina phaseolina) of Strawberry in California .................................................................. 27 Steven Koike Fungicide Trials For Fruit and Foliar Pathogens of Strawberry ....................................................... 35 Mark Bolda Steven Koike PLANT NUTRITION Establishing Nutrient Management Practices For High-yield Strawberry Production ..................... 41 Dr. Timothy Hartz IRRIGATION MANAGEMENT Effects of Sprinkler, Partial Sprinkler/Drip and Drip Only Irrigation on Strawberry Transplants ....... 59 Dr. Stuart Styles ENTOMOLOGY California Strawberry Commission Lygus Management Program in Strawberries: Evaluating the Degree-day Model and Insecticide Resistance ....................................................... 77 Dr. Hillary Thomas Strawberry Insect and Mite Control ................................................................................................. 85 Dr. Frank G. Zalom WEED SCIENCE Weed Management In Strawberry ................................................................................................. 101 Dr. Steven Fennimore 2 CALIFORNIA STRAWBERRY COMMISSION ANNUAL PRODUCTION RESEARCH REPORT FARMING WITHOUT FUMIGANTS Efficacy of Drip Treatments for Management of Macrophomina and Fusarium Pathogens of Strawberry ......................................................................................................................................111 Dr. Husein Ajwa Steven Koikev Effect of Substrate Air-filled Porosity on Growth of Strawberry ..................................................... 121 Dr. Richard Evans Active Management of Soil Microbial Communities to Limit Soilborne Disease Development in Strawberry Production Systems .................................................................................................... 133 Dr. Mark Mazzola Non-fumigant Strategies for Soilborne Disease Control in California Strawberry Production Systems ......................................................................................................................................... 145 Dr. Carol Shennan Evaluation of a Substrate Based Raised Bed Trough (RaBeT) Strawberry Production System in California ....................................................................................................................................... 161 Dr. Hillary Thomas REGULATORY Predicting Harvester Pesticide Exposure From Leaf Residues ..................................................... 171 Dr. Robert Krieger APPENDICES Commission Members and Alternates for 2011-2012 ................................................................... 184 Research Committee Members 2011-2012 .................................................................................. 186 2012 Grower Resource and Contact Information ......................................................................... 187 3 2011 - 2012 RESEARCH PROJECTS 4 CALIFORNIA STRAWBERRY COMMISSION ANNUAL PRODUCTION RESEARCH REPORT Introduction A Message From the Research Committee Chairman The 2011-2012 Annual Production Research Report summarizes the results of 15 research and extension projects funded by the California Strawberry Commission. These reports are progress updates for the research projects funded by the commission during the 2010-2011 fiscal year. These projects include strawberry nutrition, Lygus bug monitoring, farming without fumigants and fumigant emission reduction, and many others. The commission is a leading funding source for strawberry production research and we hope that these reports help strawberry growers address production problems. These reports are also intended to document research that may not be readily available in other in other publications. It is hoped that these reports will be used by researchers in California and elsewhere to guide their own research. On the behalf of the California strawberry industry and the California Strawberry Commission, I would like to thank the researchers and their associates for their dedication to the needs of the California strawberry industry. California strawberry growers face increasing production and regulatory challenges and the research efforts of these researchers are critical for the continued viability of the California strawberry industry. I also want to thank the Research Committee, the Research Committee Leadership Group (Will Doyle, Bryan Gresser, Brian Driscoll and Dan Legard) and the members of the Science Advisory Committee for their help to ensure that we fund projects appropriate for the California strawberry industry. I would like to especially thank the many growers, PCA’s and other members of the strawberry industry who have provided assistance, plants, field plots, labor and materials for this work. I also want to thank the California Strawberry Nurserymen’s Association, The University of California and the USDA for their continuing support of the commission’s research programs. Sincerely, Carl Lindgren Research Committee Chairman 5 2011 - 2012 RESEARCH PROJECTS 6 CALIFORNIA STRAWBERRY COMMISSION ANNUAL PRODUCTION RESEARCH REPORT PATHOLOGY 7 2011 - 2012 RESEARCH PROJECTS 8 CALIFORNIA STRAWBERRY COMMISSION ANNUAL PRODUCTION RESEARCH REPORT PATHOLOGY A Comprehensive Approach to Management of Wilt Diseases Caused by Fusarium oxysporum and Verticillium dahliae Principle Investigator Dr. Thomas R. Gordon University of California Department of Plant Pathology One Shields Avenue Davis, CA 95616 (530) 754-9893 [email protected] Co-Principal Investigators Steven T. Koike, UC Cooperative Extension Oleg Daugovish, UC Cooperative Extension Cooperators Douglas V. Shaw and Kirk D. Larson Plant Sciences Department U.C. Davis SUMMARY Our research in 2011 was directed toward the study of vascular wilt diseases caused by the soilborne pathogens, Verticillium dahliae and Fusarium oxysporum f. sp. fragariae. A central focus was on development and characterization of genetic resistance, which will make an increasingly important contribution toward management of wilt diseases in the future. Selecting for resistance to Verticillium wilt over many years has significantly increased levels of resistance to this disease, and in 2011, 63% of 61 breeding lines tested had resistance scores of 4.5 or higher (on a 1 to 5 scale, with 5 being a disease-free plant). We conducted a second year of tests in naturally infested soil to confirm the efficacy of resistance to Verticillium wilt. The results showed that ranking of cultivars based on susceptibility was essentially the same when infection occurred from exposure to inoculum in soil as when plants were root-dip inoculated. This indicates that genotypes identified as resistant by the screening procedure used in the University of California (UC) breeding program should be resistant under field conditions as well. In 2011, we continued development and implementation of a procedure to screen for resistance to Fusarium wilt. This included a comparison of inoculations with a single isolate and a mix of five isolates, and also a comparison of two different inoculum levels. Although disease was somewhat more severe in plants inoculated with the higher dose, the ranking of genotypes was similar. There was not a significant difference in results obtained with the single isolate or the mix. 9 2011 - 2012 RESEARCH PROJECTS As in past years, ‘Ventana’ and ‘San Andreas’ proved to be resistant to Fusarium wilt, whereas ‘Camarosa’ and ‘Albion’ were highly susceptible. Resistance scores for 26 breeding lines ranged from 1.0 to 5.0, with a mean of 3.3. Because grower observations suggested that soil acidification might render plants more prone to Fusarium wilt, we conducted experiments to test for an effect of pH on development of disease. Our results indicate that soil pH has at most only a weak effect on disease development, at least under controlled conditions. We continued to monitor the occurrence of Fusarium wilt and dieback caused by Macrophomina phaseolina, within California. Although Fusarium wilt has thus far been a serious problem only in Ventura County, recent finds indicate it may now also be established in the Santa Maria and Watsonville areas. Macrophomina has been confirmed to occur in all of the major strawberry production regions in the state. INTRODUCTION Historically, Verticillium wilt, caused by the pathogenic soilborne fungus, Verticillium dahliae, has been a major constraint on strawberry production in California. This disease remains a serious problem for organic strawberry growers and is of increasing concern for conventional producers where flat fumigation with methyl bromide and chloropicrin is no longer an option. When a plant suffering from Verticillium wilt dies, the pathogen produces large numbers of melanized, multi-cellular survival structures known as microsclerotia, which