UDSA OPMP Meeting Notes: Hymexazol  
Meeting Attendees: Julius Fajardo, USDA OPMP; Elizabeth Hill, USDA OPMP; Tom Schwartz, Senior Vice President of the Beet Sugar Development Foundation; Barry Jacobsen, Montana State University.  June 20, 2016. 
Seed:  Tiny seed, treated with many AIs (2-3 fungicides, thiram, neonics, metalaxyl) prior to receiving a protective film coating to reduce dust off.  Seeds are also a fluorescent color to deter birds from eating it.  The seed is grown in Oregon and Washington and then sent to companies to be treated, film coated, and packaged.  Seed treaters wear PPE and thus no route for human exposure during seed treatment.
Seed Cost:  ~$200/A for seed, although incorporates other chemicals.  All seed is Round-up Ready so there is a tech fee.  High cost drives growers to be very careful with seed. 
Seeding rate:  Growers aim for a uniform stand with small beets, as they have a higher sugar content and lower impurities.   There variations in seed rates depending on row width, which widely varies (mostly regionally).  For example, in Nebraska they do 36 inch rows at 40k seeds, in Montana it's typically 22-24 inch rows at 60k seeds an acre, and 24 inch rows are 50k seeds per acre.  Overall out of the 1.2 million sugar beets grown, about 70% use 24 inch rows.
Application Rate:  Varies regionally 20g/A in West, MN areas does 40 g/A. 
Targeted Diseases: Aphanomyces root rot and Pythium root rot (seedling or damping-off phase of the disease).  Aphanomyces root rot favored by wet, warm conditions while Pythium root rot is common in wet, cool temperatures.  Fusarium wilt is another targeted disease to control but drench application is not practical.
Planting:  Use precision agriculture, pelleted seed drops in furrow, press wheel comes behind. 
Protection:  4-6 weeks of seedling protection against Aphanomyces
Yield Losses:  20-30% from Aphanomyces, 100% if very susceptible stock.  Breeders try to do screening to avoid susceptible stock but inheritance is very complex for sugar beets.  Growers in Montana and Wyoming have seen yield losses from Aphanomyces drop to nearly zero when using hymexazol, although some losses still seen in ND and MN.  So far, only partial resistance of cultivars has been observed on Aphanomyces.
Alternatives:  None are available that offer efficacy.  Biocontrol agents are not effective and field performace is marginal.  Syngenta has a new product but it is not available yet (Orondis or oxathiapiprolin), and it could be years before it is available as a seed treatment.  
Losses Post Harvest:  Beets are stored in big piles for processing.  Whole fields can be rejected if Aphanomyces is present in any of the beets as it can cause rot (root rot phase of disease).  To prevent this, marginal fields with the disease can be harvested earlier but this reduces yields (easily 1,200 to 1,500 (lb? bu?) loss per acre).  Contact Larry Campbell if you'd like to learn more about storage effects of Aphanomyces. 
Literature:  Sugarbeet Research and Education Board located at www.sbreb.org/ and the Beet Sugar Development Foundation and the American Society of Sugar Beet Technologists at www.bsdf-assbt.org
Resistance:  No reports of any hymexazol resistance concerns in the sugarbeet niche market.  Current registrant is Mitsui and Sankyo originally submitted hymexazol as a reduced risk pesticide product.
