Progress 09/01/23 to 08/31/24
Outputs
Target Audience:The target audience has been hemp breeders and growers in the hemp community that are interested in hemp disease resistance. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Three graduate students have been actively engaged with this project. Students have been learning how to manage plants and pathogen cultures.They have worked with single conidial isolates, inoculated plants, rated plants for disease severity, analyzed disease data, and presented their results at professional conferences. How have the results been disseminated to communities of interest?Scientific proceedings were presented at two professional conferences and three field days. Managing Septoria Leaf Spot of Hemp, Caused by the Fungus Septoria cannabis (2024) Schwartz, JA. Gordon T., Stansell Z., and Smart CD. American Phytopathological Society Northeastern Division Meeting. Ithaca, NY 27 March 6-8, 2024. Biology, Management, and Breeding for Septoria Leaf Spot-Resistant Hemp. Schwartz, JA. Gordon T., Stansell Z., and Smart CD. American Phytopathological Society Annual Meeting. Memphis, TN July 27-30, 2024. Screening for new sources of resistance to hemp powdery mildew in diverse Cannabis sativa germplasm (2024) Vignale L. Herrmann, T, Gordon T., Stansell Z., Smart CD, Smart LB. American Phytopathological Society Annual Meeting. Memphis, TN July 27-30, 2024. USDA ARS PGRU Hemp Germplasm Laboratory Stakeholder meeting, Geneva, NY, 11 September 2024, 9:00 am to 4:30 pm Cornell University Cannabinoid Field Day, Geneva, NY, 13 September 2024, 9:00 am to 4:00 pm. What do you plan to do during the next reporting period to accomplish the goals?An additional 100 accessions will be selected for disease resistance screening of these 4 diseases during the 2025 field season. Resistant accessions selected this year will be selected for inbreeding and early generations will be tested for resistance in the 2025 field trials.
Impacts
What was accomplished under these goals?
Septoria leaf spot: One-hundred-five accessions were evaluated for Septoria leaf spot resistance in Geneva, NY. Seeds were planted in flats in a greenhouse on 15 May, where they were regularly maintained and watered. The transplants were set in the field by hand into 4 ft wide raised beds covered with plastic mulch on 30 May. Each plot consisted of 5 plants with 3 ft spacing in between plants, 3 ft spacing in between plots, and 7.5 ft spacing in between rows. The field was established in a randomized complete block design with 3 repetitions of 105 accessions. Plots were irrigated and fertigated as needed via a drip line with 24-8-16 Miracle Gro all-purpose, water-soluble fertilizer. Plastic weed cloth was applied in between rows and was supplemented with hand-weeding as needed. Inoculum was created with a single conidial isolate of Septoria cannabis collected from Geneva, NY. 100 μl/L of Silwet was added to the inoculum and a final concentration of 6.4 *10^5 conidial suspension was applied using a battery-powered backpack sprayer on 3 July. Approximately 30 mL of inoculum was applied to each plant. Symptoms were first observed 7 days post inoculation. Disease severity ratings were visually estimated on a scale of 0 to 100%. The first disease severity rating was on 10 July, and disease severity continued to be visually estimated each week until 14 August for a total of 6 ratings. Disease severity values for each accession as recorded on the last day of rating, 14 August, were uploaded to GRIN-Global, 2024_SEPTORIA_MCCARTHY01. Fourteen accessions are reported with less than 1% disease severity, and 36 accessions are reported with greater than 10% septoria severity. Four accessions report septoria severity of over 30% severity at the final evaluation point, and two accessions G 33382 and G 33635 had over 70% severity in the field trial. Powdery mildew: One-hundred-five accessions were evaluated for hemp powdery mildew resistance in Geneva, NY. Transplants were established in the field in the same way described above for Septoria leaf spot. Disease severity ratings were visually estimated on a scale of 0 to 100%. Plots were inoculated with a single conidial isolate of Golovinomyces ambrosiae, the fungus that causes hemp powdery mildew. The first disease severity rating was on 1 August 2024 and plants were assessed for disease severity every week until the last rating on 28 August 2024. More than 15 accessions were considered highly resistant with final severities below 5% and one accession G 33827 was routinely observed to have disease severity over 75%. In another field-planted sequencing trial, 418 accessions were evaluated and reported for powdery in GRIN-Global 2024-HA24-PGRU-SEQUENCING-Z1. Twenty-seven accessions are reported as less than 1% severity and 13 accessions are reported as over 90% severity on the final rating date, 25 September 2024. Downy mildew: One-hundred-five accessions were evaluated for hemp downy mildew resistance in Geneva, NY. Seeds were sown and grown to approximately 6-weeks of age. Leaf punches were taken from the plants and evaluated with a Blackbird high-throughput automated phenotyping system and rated with a neural network and though manual observation. Additionally, detached leaflets were evaluated on petri plates. All leaf tissue was inoculated with a liquid suspension of zoospores at 105 spores per ml. Rating took place every day from 5 days to 9 days post inoculation. For each accession, there were three replicates situated in a randomized complete block design for each phenotyping method. Evaluation method development is ongoing, but initial results for these controlled environment inoculations are promising. There were 15 accessions that were observed to have highly resistant phenotypes with disease severity below 5% across the rating methods. These included accessions with origins from European, Chinese, and U.S. feral lines. There were also 17 accessions that had high disease severity including G 33312 and G 33338. Fusarium head blight: One-hundred-five accessions were transplanted in Lexington, KY on 11 July 2024, in a randomized complete block design with 10 plants per plot and 3 replications for a total of 2730 plants evaluated. Transplants were planted into conventionally tilled soil using the production model typically practiced for burley tobacco production (no raised beds and no plastic) in rows spaced 1.07 m apart with 0.3 m between plants within the row. Previous research at this location has shown that Fusarium head blight (FHB) is endemic in this area, so natural inoculum was relied upon to establish disease. Fusarium disease was assessed for incidence and severity using a quantitative rating scale (Gauthier, unpublished). Ratings took place every week from 11 July to 25 September 2024, for a total of 11 ratings. Disease assessments and plant development stage were recorded. Disease ratings were generated for 88 accessions and 79 of those accessions had severity ratings of 0%. Only 9 accessions had FHB severity above 0%. G 33591, G 33296, G 33350, and G 33202 had severities above 6% while G 33342, G 33337, G 33299, and G 33200 had FHB severity above 3%. The FHB trial data has been summarized and uploaded onto GRIN-Global, 2024_FUSARIUM_HB_UKY. FHB disease severity may have been exceptionally low in 2024 due to hot temperatures and drought in Lexington this summer. A hurricane that came through on September 27th, and low FHB levels in neighboring small grains plots also complicated disease progression and rating.
Publications
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