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Growers Successfully Managing Cercospora Leaf Spot Control in Sugarbeet (08/17/17)

Growers are working around the clock utilizing ground rigs in dry weather conditions and amply supported by aerial applicators to apply fungicides in a timely manner to manage Cercospora leaf spot (CLS) in sugarbeet.

Growers Successfully Managing Cercospora Leaf Spot Control in Sugarbeet

Growers are working around the clock utilizing ground rigs in dry weather conditions and amply supported by aerial applicators to apply fungicides in a timely manner to manage Cercospora leaf spot (CLS) in sugarbeet. CLS, caused by the fungus Cercospora beticola, is currently the most damaging foliar disease of sugarbeet in North Dakota and Minnesota. Conditions favorable for CLS include warm days above 77 F, warm nights above 60 F, and leaf wetness from dew or rainfall.

In southern Minnesota, environmental conditions favorable for CLS started in July and continued into August. Growers at the Southern Minnesota Beet Sugar Cooperative (SMBSC) have been diligent in their timely use of fungicide mixtures to control CLS. In Minn-Dak (MD) and American Crystal Sugar Company (ACSC) factory districts, CLS disease severity was low in July. Rain and dew in August have resulted in more favorable conditions for CLS and disease severity has increased significantly over the past two weeks, especially in inoculated research trials. Growers at MD and ACSC also have done a great job of containing CLS.

Growers need to continue applying fungicides to control CLS until at least mid-September or when night temperatures consistently fall below 60 F. In fields currently too wet for ground rigs, aerial applications should be used, especially in mid- to late-August because of the favorable environment for disease development coupled with the current high inoculum density.

Figure 1 below shows that CLS will cause economic damage if not controlled. Figure 2 shows that fungicide mixtures used in a rotation are controlling CLS under high inoculum pressure at Foxhome, MN.

khan.1 2

 

Mohamed Khan

Extension Sugarbeet Specialist

NDSU & U of MN

701-231-8596

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