Field Evaluations of Tomato Yellow Leaf Curl Virus (TYLCV) Resistant Varieties for Commercial Production Truly, Fully Integrated Project: Jari Sugano, Michael Melzer, Archana Pant, Ted Radovich, Steve Fukuda, and Susan Migita University of Hawaii at Manoa College of Tropical Agriculture and Human Resources April 2011
Background The tomato yellow leaf curl disease is a devastating viral disease of tomato (Melzer, et al, 2009) TYLCV first detected and identified in commercial tomato plantings around Oahu and Maui in 2009 Currently found in the Kona area of Hawaii
Symptoms Infected plants become Chlorotic (yellowing) Inter-veinal discoloring Stunted due to shortened internodes Leaflets curl or cup upwards at the leaf margins Reduced fruit set due to premature flower abortion
Stunted due to shortened internodes Chlorotic (yellowing) Photo credit: M. Melzer Interveinal discoloring Photo credit: M. Melzer Leaflets curl or cup upwards
TYLCV Transmission TYLCV is a vector transmitted virus It is not spread through mechanical means The main vectors are the silver leaf (Bemisia tabaci) and the sweet potato whitefly (Bemisia argentifolii) Greenhouse white fly (Trialeurodes vaporariorum) not a vector S. Bauer, USDA ARS
Objectives Screen and identify resistant varieties that can tolerate TYLCV In 2010, a replicated field trial was installed at the Poamoho Experiment station. Twelve plants were planted per replication (4 replications) Resistant varieties were solicited for this study Twelve tomato varieties were evaluated based on total marketable yield, total marketable count, grade A yield, grade A count and tolerance to the TYLCV. The University of Hawaii, College of Tropical Agriculture s tomato variety, Kewalo was selected as the control
Evaluated 12 Varieties Variety Name Type Seed Source Adonis Determinate Seminis Tygress Determinate Seminis PIK Ripe 461 Determinate Seminis Sunchaser Determinate Seminis Sunsugar (Yellow Cherry) Indeterminate Seminis Toqui Determinate Seminis Tovi Roca Indeterminate Zeraim Gedera VT-62966 Indeterminate Zeraim Gedera VT-62940 Indeterminate Zeraim Gedera Xaman (Roma Type) Determinate Zeraim Gedera Kewalo Determinate UH CTAHR Tovi Star Indeterminate Zeraim Gedera
Data Collection Harvest data was collected weekly Fruits were sorted and graded based on the Hawaii Department of Agriculture s market standards for tomato Data was analyzed with the computer software, Sigma plot
500 Results Yield (lb) 400 300 200 100 0 A VT-62940 b AB VT-62966 Adonis Tygress PIK Ripe 461 Tovi Star Total marketable yield Grade A yield Toqui Tovi Roca Sunchaser Xaman (Roma Type) Sunsugar (Yellow Cherry) Kewalo Figure 1 Total Marketable and Grade A yield of different varieties. Means followed by the same letter are not statistically significant (p<0.05). Capital letters separate the means of total marketable yield and small letters separate the means of grade A yield. Analysis conducted by. A. Pant VT-62940 and VT-62966 had the highest marketable yields followed by Adonis, Tygress, Pik Ripe 461 and Tovi Star. Indeterminate varieties such as Adonis, Tygress and Pik Ripe had the highest yield of Grade A fruit in comparison to other varieties. bc B a B a B a BC c DC bc DE bc DEF c DEF EF c cd F d
Tissue Blot to Determine Resistance Melzer utilized the tissue blot hybridization assay to identify the presence of TYLCV. The dark spots indicate the presence of virus Sunchaser, Sunsugar, and the control variety Kewalo, tested positive for TYLCV Identification of 8 resistant varieties One plant sampled in variety VT-62940 was susceptible to TYLCV (possible seed mix up)
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Timely Transfer of Research Based Information Field day showcased the different varieties to interested producers, extension agents, etc Growers are evaluating the horticultural characteristics of tolerant hybrids Applied field work has made an impact on Grower adoption Sustainability of Hawaii s tomato industry
Additional Applied Field Work Additional TYLCV and TSWV resistant varieties were obtained in 2011 Looking for double resistance Evaluate new varieties and report finding subsequent CTAHR publication or presentation Applied field testing by CTAHR and adoption of tolerant varieties by producers may lead to increased productivity and long term sustainability of the Hawaii s tomato industry
Special Mahalo to: Seminis Seed Company, Zeraim Gedera and University of Hawaii CTAHR, Agricultural Diagnostic Service Center Seed lab for donation of seeds; Poamoho Experiment Station, for field and harvest support; Steve Fukuda for overall seed / field coordination, Radovich lab for field support, data entry and tabulation, Melzer /Hu lab for field support and tissue blot tabulations.