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Northeast ND (07/30/15)

Information from the Northeast region of North Dakota.

We are nearing small grain harvest.  Pre-harvest desiccant application is just starting on early seeded acres.  The past week’s hot, humid weather has been great for row crop development.  Corn is silking and the soybeans are up to R3 development.  We are finding downy mildew on soybeans at the LREC.  Downy mildew first appears as yellow flecks scattered on the top of the leaf (see photo). Eventually, the lesions will become brown with yellow near the edges.  On the leaf underside, the fungal growth is a tan to grey look (to my eyes, it looks lavender).  This disease rarely causes economic damage. For more information please see the soybean downy mildew article in the plant pathology section of this crop and pest report.

As the canola crop loses its flowers, look for blackleg early senescing.  How is genetic resistance combatting the disease in your fields?  Factors that contribute to blackleg are temperatures in the 70s °F and extended periods of canopy wetness. The maximum ascospore discharge occurs the second year following crop growth. So if you are using a two-year rotation, there is more inoculum awaiting suitable environmental conditions than wider rotations. 

ats.lubenow.1.downy mildew

Lesley Lubenow

Area Extension Specialist/Agronomy

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