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Over the weekend two issues came to my attention:

1. It appears that cereal leaf beetle has hit threshold in a few fields. Dean Volenberg noted “Seeing high densities in some fields (5 per plant) and the flag leaf is about finished off.  It is hit or miss as far as scouting, one field will have them and the next is void of any larvae and adults.  Threshold at this stage of wheat is one Cereal Leaf Beetle per plant (NDSU Extension).

 2. Also some late planted soybeans that were planted at the dry/wet soil threshold have imbibed water then desiccated. Please review my article entitled:  Variable Germination and Emergence in Soybean: Which Seeds Are Still Viable? for recommendations.

Thought I would let you know that some Nebraska soybean producers have experienced the problem of germinating seed not having enough soil moisture to complete either the germination and/or emergence process because of two reasons.   

One reason is because they planted in dry soil and hoped for a rain, which is risky.  Some producers did get a hoped-for rain, but the rain amount was only enough to wet the soil down to where the seed was placed and not enough to connect that wet layer with the moist soil another inch or two below that seed.  As a result, the seeds germinated and the radicles emerged, but because roots will not penetrate a dry soil layer, the seedlings died because rooting systems were limited to using surface water, which ultimately dried out.  This scenario forced a replanting.  A second reason was because some producers have been using cover crops for some years now even though I warned them that cover crop use WILL be definitively detrimental in a dry spring.  We have had wet springs to date, which led producers to not think about the fact that while cover crops offer all the great stuff that extension specialists have promoted, they have ONE GIANT PROBLEM – unlike fallow which can only surface dry out in dry years, cover crops put roots into the soil and act like putting blotting paper in the soil, meaning that cover crops can transpire away the stored soil water!  Well, BINGO, we got a dry spring in Nebraska this year!  Cover crop users discovered the problem this year that I warned them about every time they discussed the advantages of cover crops.  One NE Soybean Board Member actually found out that his cover crop had dried out the soil to a depth of almost 10 inches, and when he only got sufficient rain to wet the seed, it was definitely not enough to connect the wet soil surface by wetting the soil down to a deeper down moister soil depth.  Consequently, his entire field of soybeans germinated, and then died.  What’s worse for him, is that he still needed a drenching rain to eliminate that dry soil layer before he could even begin to think about replanting!  

Therefore, I have been re-urging all extension specialists in Nebraska to warn producers about this ever-so-often risky proposition of planting soybean seed into dry soil, or using cover crops temporally right up to the Round-Up burn-down before planting.  Preventing erosion is a good thing, but transpiring off critical stored water is a definitely a BAD thing.  There is no FREE LUNCH!   

– Jim

When I was out scouting early this week I noticed that many of my oat plots where showing necrosis on the leaf tips and margins (please see below image). I can honestly say I did not give it much thought as I had soybeans to spray. By Wednesday however my email, text, and phone where all buzzing about this consistent and widespread oat issue so I started to do some digging. If you look closely at the below picture you could easily write this crop injury off to our unpredictable spring environment and/or barley yellow dwarf virus (bydv). However after speaking with John Mochon who is the project manager in the oat breeding program and Scott Chapman in entomology they both vividly remember the tremendous influx of aster leaf hoppers (ALH) that arrived in early May. A follow-up conversation with Russ Groves in Entomology confirms that we experienced one the highest ALH influxes in the past decade.  Furthermore, Randy Van Haren, with Pest Pros Inc., has performed qPCR assays on populations in the Central Sands in the past 3-4 weeks with infectivity rates as high as 10-12% which is very high for this pathogen. Since I have never dealt with ALH I found a good article written by Janet J. Knodel at NDSU. She wrote “Aster leaf hoppers feed on plant sap and vector aster yellows, a phytoplasma disease that presents like BYDV. Disease symptoms will appear in 2-3 weeks (which fits with our timeline). Plants infected earlier in crop development are more susceptible to yield loss than mature crops. For example, wheat infected with aster yellows at the seedling stage will not produce kernels due to stunting. A heavy infestation of aster leafhoppers in the field also will increase the incidence of aster yellows.” Limited information exists about the susceptibility of grain crops (e.g. oats and wheat) to infection of the aster yellows phytoplasma (AYp).  Work includes oat susceptibility to AYp of Chiykowski and Wolynetz 1981, Can J. Plant Path.  And most recently Hollingworth et al. 2008 (http://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-92-4-0623). Over the next few days I will be collecting samples and working with Russ Groves to confirm if this is the potential culprit. Stay tuned… 

Article co-authored with Russ Groves, UW Entomology.

Winter wheat in southern Wisconsin is starting to head (Feekes 10.1) indicating we are ~ 7 days away from anthesis or flowering (weather dependent of course). Calendar wise this puts the WI wheat crop developmentally about 3 weeks ahead of normal. Anthesis is the last critical wheat management growth stage and accurate identification of this stage is important due to fungicide label restrictions as well as timing of fungicides for management of fusarium head scab. To better understand and identify the flowering growth stage, please check herefor an UWEX YouTube Video.

Most commercial fungicide products are only labeled through Feekes 10.5 (full heading) and others have restrictions based on days to harvest. A partial summary of these products as well as those labels for head scab please access them here. Not all products may be listed and not all products (especially some generic forms of tebuconazole) may be approved in WI. It is important to always check the label for specific use requirements.

Our prediction for Fusarium head scab is based on the Fusarium Head Blight Risk Assessment Tool (please see below). In terms of Fusarium head scab risk as of today (May 8), pockets of medium to high risk are showing up in the western portion of the state, as well as a small pocket in the eastern portion of Winnebago and Outagamie Counties. The current increase in risk is most likely a function of the weather events of the past several days. Interestingly, when we checked the May 7 forecast map and did a 24 hour prediction, it did pick up the areas in the western portion of the state, although today’s risk is somewhat higher than the forecast was. There is a chance for rain today around the state before some drying patterns move in. The risk for FHB may remain higher over the next several days. However, since we are approximately a week from flowering in the southern portion of WI, these conditions can, and will change, so we will continue to monitory and update the risk information, and management recommendations as we near flowering. 

With wheat growth and development ahead of normal in 2012, it is important to pay attention to the growth stage when determining if there is a need for the use of foliar fungicides. Active scouting is important to determine which diseases are present and either the incidence and/or severity of each disease relative to wheat growth stage. To help in understanding the efficacy of different fungicide active ingredients, the NCERA-184 (Management of Small Grain Diseases) committee reviews and updates the Fungicide Efficacy Table for Control of Wheat Diseases each year. Ratings for different active ingredients are provided and range from poor to excellent for the following wheat diseases: powdery mildew, Septoria leaf blotch, Stagonospora leaf/glume blotch, tan spot, stripe rust, leaf rust, stem rust, and head scab. These ratings are based on results and observations from trials conducted across different locations (i.e., states) and years and is meant only as a guide. It is important to read and follow the label carefully regarding application timing and recommended rates against different diseases.