Germinating sclerotia have been observed in artificially-infested sentinel plots at the Central Oregon Agricultural Research and Extension Center (COAREC). Grass seed growers and crop consultants can assume that ergot spores are currently present in the area. Spore trap updates from COAREC (and other locations in the Pacific Northwest) will be available soon.

Sources of sclerotia include established (2nd year or older) grass seed fields with a recent history of ergot. First-year fields are not likely to be sources of inoculum unless planted with seed infested with sclerotia. However, Kentucky bluegrass stands of all ages can potentially become infected with the disease.

Only unfertilized flowers are susceptible to infection, but the ergot pathogen has a wide host range among grasses. Other hosts include cereal rye, wheat, triticale, wheatgrass, and fescues. Cereal crops and grassy weeds can serve as alternative hosts and sources of inoculum in grass seed production systems.

Some Kentucky bluegrass varieties are in the early (~boot) stages of anthesis (flowering) and may be subject to exposure to ascospores. For maximum ergot control, fungicide applications should be timed to occur at the beginning of, or immediately prior to, anthesis. Since fungicides for ergot are protective and not curative, applying earlier is better than later. Cultivars with long anthesis periods may require (an) additional application(s).

More information on fungicide options for ergot in the Pacific Northwest can be found in the Pacific Northwest Disease Management Handbook: https://pnwhandbooks.org/plantdisease/host-disease/grass-seed-ergot .

Acknowledgement: This research is funded by the Eastern Oregon Kentucky Bluegrass Working Group, the Jefferson County Seed Growers Association, the Oregon Department of Agriculture Alternatives for Field Burning Research Financial Assistance Program, the Oregon Seed Council, the Union County Seed Growers Association, and the Washington Turfgrass Seed Commission.

Ergot spore production was relatively low at all sites from June 10 through June 16, with less than 200 spores detected at HAREC, less than 350 spores detected at COAREC, and less than 5 spores detected in La Grande.

Ergot spore production significantly decreased at all sites since our last update. Between June 4 and June 9 a total of 1,788 spores were captured at COAREC in Madras (compared to 24,763 spores captured between May 29 and June 3) and a total of  184 spores were detected at HAREC in Hermiston (compared to 2,440 spores detected between May 29 and June 3). Ergot spore production has also decreased at the La Grande site, with no spores detected between June 3 and June 6.

Ergot spores are being detected on a daily basis at most of the sites. An astounding 18,000 spores were captured at the HAREC site on May 28th. Spore production has increased at the artificially-infested site at COAREC in Madras, with thousands of spores being detected every day between May 29th and June 3rd.

Protective fungicides should be applied at the onset of anthesis to protect unfertilized flowers from infection, and cultivars with prolonged flowering periods may require more than one application. Based on field observations, many cultivars of Kentucky bluegrass and perennial ryegrass are flowering in central Oregon and Hermiston, respectively.

Ergot spore counts have increased in artificially-infested plots at the Hermiston Agricultural Research and Extension Center and Central Oregon Agricultural Research and Extension Center. Spores have also been detected at the commercial production site near La Grande.

 

Protective fungicides should be applied at the onset of anthesis to protect unfertilized flowers from infection, and cultivars with prolonged flowering periods may require multiple applications. Based on field observations, some cultivars of Kentucky bluegrass and perennial ryegrass are already flowering in central Oregon and Hermiston, respectively.

It is important to remember that the spore counts presented below are intended to show daily trends in spore production and do not necessarily indicate inoculum pressure in your field(s). Spore production can vary from field to field, and inoculum pressure tends to be higher in older fields with a history of ergot in the previous season or in new fields planted next to established fields with a history of ergot.

In general, ascospore production by the pathogen is favored by:

• moderate temperatures (between 50°F and 80°F)
• high soil moisture, rainfall, and/or irrigation.
• conditions that delay or interfere with pollination, such as cool wet weather, can increase the period of susceptibility in grass seed crops.

It is recommended that growers scout fields as grass seed crops approach anthesis. Protective fungicides should be applied prior to the onset of anthesis to protect unfertilized flowers from infection, and cultivars with prolonged flowering periods may require multiple applications.

Please refer to the PNW Plant Disease Management Handbook for more information (https://pnwhandbooks.org/plantdisease/host-disease/grass-seed-ergot).

Between 0 and 31 spores have been captured at COAREC between May 11 and May 20.

Low spore counts (between 0 and 10 spores) have been observed on most days, with the exception of May 15 when 212 spores were captured.

Accumulated degree-days as of May 23 were 513 in Hermiston, OR (solid line). According to the model, most ascospores are produced in the Lower Columbia Basin when accumulated degree-days are between 414 and 727.

At this time in 2018, accumulated degree-days were 596 (dotted line).

The COAREC ergot spore trap site was set up on May 1 in one of our Kentucky bluegrass research plots. The trap is located in a second-year, 4 acre field with a history of ergot. Dr. Qunkang Cheng, Postdoctoral Research Associate, is also investigating alternative spore trapping methods for wider use in the Pacific Northwest.

Low spore counts (between 0 and 9 spores) have been observed on most days, with the exceptions of May 7 (263 spores) and May 10 (77 spores).