By KEVIN WALKER Michigan Correspondent EAST LANSING, Mich. — Researchers at Michigan State University have announced an unusually early detection of Cercospora infection in a research field of sugar beets. According to an MSU announcement June 4, the discovery was made June 1 at a research field in East Lansing at MSU’s central campus. The finding was confirmed by MSU Diagnostic Services. “We have been finding that the spores are in the air earlier this year than normal,” said Jaime Willbur, an assistant professor in the Department of Plant, Soil and Microbial Sciences at MSU. “We want growers to be aware of this and to scout for leaf spot.” The discovery was made as part of research by MSU graduate student Daniel Bublitz and Linda Hanson of the USDA’s Agricultural Research Service. Willbur, who specializes in integrated disease management in potato and sugar beet production, is also playing a role in this work. “What we found is that older beets that overwintered started to grow and were susceptible to early Cercospora infection,” she said. “Once these plants are incubated, researchers have been able to get spores to grow on the plant leaves.” Researchers use spore traps and sentinel beets in their research fields in East Lansing, and also in the Saginaw Bay area, where most of the state’s sugar beets are grown. According to Willbur, leaf spot levels are being closely monitored at this time, but she does not want to make any definitive statements about detections in the Bay area, as researchers are waiting on several scouting reports. MSU does this work in conjunction with Michigan Sugar; Hanson has been presenting findings on this research for a couple years. “We are working with the agronomists at the Michigan Sugar Company to send out the message that the weather is favorable for Cercospora leaf spot,” Willbur explained. This means warm and wet weather. Currently, beet plants have matured to the point where they have 10-12 leaves. Alternaria leaf spot, another foliar disease of sugar beet, thrives during wet, cool weather. According to the MSU announcement, the finding supports recent research indicating the presence of early inoculum in Michigan. Early Cercospora infection requires the presence of favorable environmental conditions and susceptible plant growth stage; however, the findings do suggest that inoculum is present early this season. Early leaf spot detection on overwintered sugar beets suggests that volunteer plants could be sources of early inoculum for this year’s crops, and Cercospora scouting programs should be initiated. Growers are also encouraged to use BEETcast, a Cercospora leaf spot forecasting model available through Michigan Sugar Co. BEETcast uses temperature and leaf wetness to create a disease severity value that models Cercospora growth and development. Disease management recommendations have been modified to reflect the risk of Cercospora leaf spot disease severity for the Michigan Sugar growing region. The BEETcast webpages have several tools available for users. To see the service, go online at www.michiganbeets.com |
