2023 Season Dahlia Virus Testing Recap
My plan for the 2023 season was to attempt to grow a virus-free dahlia field.
My plan for the 2023 season was to attempt to grow a virus-free dahlia field. With most dahlias grown in the US being infected and with little known about the prevalence of virus transmission in dahlias, it was a moonshot, and I esteem that I landed among the stars. I started the season with 5 clean plants. I brought in stock to test, traded, tested, took cuttings and retested all spring. In May I planted ~350 cuttings in my field that were propagated from plants that had tested negative for Dahlia Mosaic Virus (DMV), Impatiens Necrotic Spot Virus (INSV), Tobacco Streak Virus (TSV), and Tomato Spotted Wilt Virus (TWSV) one or more times. I also kept about 60 dahlia cuttings to grow in my basement. I did not have high hopes for the basement plants, but if they didn’t die slow horrible powdery mildew coated deaths, it was a way to try to keep mother stock clean, especially if field transmission proved to be an issue. As of January 2024 the basement plants are still doing well. 51 of the 53 samples I sent to Agdia’s lab in the first days of the year tested negative for DMV. I will propagate my 2024 field plants from those clean basement plants. In September I culled several plants for signs of DMV. In early October I randomly sampled 10% of my field plants. No RNA viruses (INSV, TSV, TSWV) were detected. One plant of the 35 tested was positive for DMV. Subsequently, I sampled plants that were adjacent to the DMV+ plant. Those results showed multiple plants of the same cultivar to be infected and 2 additional adjacent cultivars to be infected with DMV. Testing of my basement plants in January 2024 showed the sister cuttings of the first detected infection to be positive, whereas the basement sister cuttings of the adjacent positive field plants were negative. Likewise the sister basement cuttings of the September culls, which were also adjacent to my Typhoid Mary/Trojan Horse cultivar, also tested negative for DMV. I believe that this is evidence of field transmission in these results. Also, Typhoid Mary/Trojan Horse was likely a false negative in the spring. My field is not without virus, but it was a winning first attempt.The 2023 season by the numbers:
5 – the number of clean cultivars I had in January 2023
31 – the number of clean cultivars I had in December 2023
$ 3,932.05 – the amount of money I spent on virus testing in 2023. This was my largest business expense in 2023.
2023 Lab Results