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As I stare out my window, watching rain fall, I write this short note to remind everyone to pay attention after planting for early-season seedling diseases in soybean. The cool and wet weather favors a disease like Pythium, but it is critical to make a good field assessment to determine which soybean seedling problems may be found. Often, the effects of seedling diseases is missed because symptoms are not expressed early in the season, but over the growing season, early-season soybean diseases can impact plant vigor during the reproductive stages. In the recent April 24, Wisconsin Crop Manager, Nancy Koval, Craig Grau, and I discuss the differences between seedling diseases and how to accurately diagnose them. Furthermore, updated information is now available at www.planthealth.info/seedlings_basics.html regarding soybean seedling diseases, which has information summarized across a multi-state area.

Winter wheat in much of Wisconsin is around the jointing stage.  This is an excellent time to start scouting for wheat diseases, especially those that are known to overwinter in Wisconsin like Septoria and Powdery mildew.  We have detected those two diseases in our initial scouting around the state, but their presence is highly dependent on the wheat variety.  In our scouting efforts, we have found these diseases in more susceptible varieties.  Severity of Septoria and Powder mildew is still very low at the moment.  Have a look through the April 10 Wisconsin Crop Manager for two articles that describe scouting for wheat diseases and also the decision process for understanding the risk for a disease outbreak and the use of foliar fungicides.

The last two days have lead to some very interesting findings in our wheat research plots at Arlington WI. Winterkill for the most part was limited to areas where ice was standing for several weeks (>2.5 weeks). Winterkill damage was greater in our early (9/14/07) and “normal” (9/28/07) winter wheat planting dates than in our late planted wheat (10/23/07). We hypothesize that this was due to differences in respiration rates. Growth in our early and normal planting dates was greater than we usually get in Wisconsin (main shoot and 2 to 8 tillers per plant); whereas late planted growth was about normal (main shoot emerged). Excessive fall growth would contribute to greater respiration rates thus the potential for increased winterkill under the ice.

One advantage of the winterkill this year for our program will be an assessment of variety tolerance to winterkill. In our variety trial we saw a range of 0 to 60% winterkill. This information will be reported in our 2008 Winter Wheat Variety Trials Results.

The wheat that survived (most of our research was unaffected by the winterkill) has a very good yield potential at this point in the season. Wheat planted on 9/28/07 has a tremendous tiller count. We averaged 7 tillers per plant with excellent stands. This would equate to a Feekes growth stage 3 or Zadoks growth stage 15 (five leaves unfolded) 27 (main shoot and 7 tillers). The delays in N application due to weather may prove beneficial to most WI wheat growers because our tiller counts are so high. Early N on these stands would promote lush growth on the main stem and tillers and would likely lead to higher disease incidence in this dense canopy.