Wheat in much of the country is past the growth stages that are most vulnerable to Fusarium head blight. The risk maps from earlier in the 2023 season will remain available for several months so that users can review the outcomes for this year. We hope to see you next season when these tools are reset for 2024.

--Erick DeWolf, Plant Pathologist, Kansas State University

Scab risk for susceptible varieties continues to be elevated for southwest North Dakota, pockets in the eastern third of North Dakota, and areas in northwest Minnesota. This elevated scab risk started to become apparent last week Thursday and has continued into the Fourth of July holiday. These areas with elevated scab risk continue to receive rain (sporadic amounts) with frequent morning dews, which will likely maintain a moderate to high scab risk for susceptible varieties in the coming days. However, scab risk for moderately resistant varieties will likely remain low. The wheat crop in both North Dakota and Minnesota has a wide range of heading and flowering dates this year, due to the wide range of planting dates. Therefore, make sure to actively monitor weather conditions (ie: relative humidity) as the wheat crop begins to head and flower.

Here are some comments pertaining to scab risk in last week’s NDSU Crop and Pest Report: https://www.ndsu.edu/agriculture/sites/default/files/2023-06/8%20June%2…

--Andrew Friskop, Associate Professor and Cereal Extension Pathologist, North Dakota State University

The earliest planted spring wheat has started to flower in some areas of the state and most reports have estimated that a significant amount of spring wheat and barley acreage will start heading next week. Scab risk is still low for susceptible varieties, but recent rain events across the state (and into the weekend) will likely drive up scab risk for most areas across the state. After experiencing very hot and very dry weather, cool weather has settled in with high chances of rain and higher relative humidity levels at night. If the current forecast holds true, we will expect to see scab risk increase on susceptible varieties. As a reminder, the best time to apply a fungicide in spring wheat and durum is at early-flowering or up to 7 days after onset of early-flowering. For spring barley, the best time is to apply at full-head or up to 7 days after full head emergence. In other words, we have about a 7-day window to make an effective application for scab.

--Andrew Friskop, Associate Professor and Cereal Extension Pathologist, North Dakota State University

It is trying to rain at the moment in Crookston. So far it has only really wetted the sidewalk. The forecast remains, however, hopeful for rain throughout the region. Does that mean that a 5-alarm fire for leaf diseases and or Fusarium head blight is imminent? Just like a single robin does not make spring, a single weather system does not make for widespread and economic levels of leaf diseases or Fusarium head blight. The disease forecasting that is part of the NDAWN system in the tri-state area and the National Fusarium Risk Tool are weather-based models that try to quantify how good the conditions are for individual diseases to start infections. Read more at https://blog-crop-news.extension.umn.edu/2023/06/small-grains-disease-a…

--Jochum Wiersma, Small Grains Specialist, University of Minnesota

The warm and dry conditions that existed across the state during wheat flowering have seen low risk conditions for head scab development. For a discussion on head scab management in Michigan see the following MSUE Virtual Breakfast recording https://youtu.be/I-TanpnqtEE

--Martin Chilvers, Associate Professor, Field Crop Pathology, Michigan State University

The Fusarium Head Blight Prediction Center provide daily estimates of disease risk for wheat and barley in 35 states. The map displays the probability of severe disease with red and orange areas of the map having the greatest risk. Wheat production in South Dakota, North Dakota, Minnesota, Wisconsin, Michigan and New York are the current focus of the prediction effort. The disease models currently indicate a low risk of disease for most of this area. Growers in these states should keep an eye out for weather systems that could bring rain and extended periods of high relative humidity. These weather conditions could increase the risk of disease.

Tips of using the tool: The prediction center uses a wheat growth model to focus the estimates of disease risk on areas where the crop is at or approaching the vulnerable stages of growth for Fusarium infection. Areas where the crop is too young, or is already approaching harvest are displayed as a gray color on the map.

The tool shows the disease risk for susceptible wheat varieties for today’s date. You can select earlier assessment dates by clicking on the calendar menu at the top of the risk map. Use the menu button on the upper left to active risk maps for wheat varieties with different levels of genetic resistance to Fusarium head blight.

Risk maps based on 2, 4 or 6 days of forecasted weather can help users anticipate future trends in disease risk. These maps are available by selecting the 2d, 4d and 6d buttons to the right of the calendar menu.

--Erick DeWolf, Plant Pathologist, Kansas State University

Most of the winter wheat has flowered and is entering stages of kernel fill. Scab risk was low and has remained low for susceptible varieties. This is likely attributed to the sporadic rain from pop-up showers and low relative humidity. Some of the heat and water stressed spring wheat is starting to head and the scab risk looks remain low in the coming days. Given the variation in planting dates and growing conditions, we will see a wide range of flowering in spring wheat this year.

--Andrew Friskop, Associate Professor and Cereal Extension Pathologist, North Dakota State University

Winter wheat heads have emerged from the boot nearly everywhere and many are now flowering (yellow anthers visible) in fields across New York State. This is a critical time for making a fungicide spray decision. The fungicide products Caramba, Miravis Ace, Prosaro, Prosaro Plus, and Sphaerex are each labeled on wheat in New York and are effective in suppression of Fusarium head blight (FHB) and deoxynivalenol (DON) mycotoxin contamination. An application of these fungicide products should be based on FHB risk as well as the risks of powdery mildew, rusts, and fungal leaf blotches in the upper canopy based on scouting of individual fields. There is an application window of approximately 7 days starting at beginning of flowering in which reasonable FHB and DON suppression can be expected. Though the calculated risk of FHB infection is currently low due to dry conditions, the risk level may change in following days. Also consider microenvironments near lakes, in river valleys and n ext to woods that tend to have persistent dew, and other fields that have a history of mycotoxin contamination. Check the Fusarium Risk Assessment Tool (www.w.heatscab.psu.edu/ ) and your local weather forecast frequently.

You are invited to attend Cornell’s 35th Annual Small Grains Management Field Day at Fleur De Lis Brewery in Seneca Falls on June 8. Visit https://cals.cornell.edu/2023-small-grains-managment-field-day to view the agenda and pre-register (free)!

--Gary Bergstrom, Extension Plant Pathologist, Cornell University

Flowering is finished across all counties of Maryland now, except for a few late-planted fields in the northern part of MD that may still be flowering. Currently, the risk of FHB is low in these areas and so no fungicide application is needed. For most parts, wheat is now in the grain-filling stage and should be ready for harvesting in the next couple of weeks. We experienced some showers this season, but the temperatures remained low, so symptom development in terms of bleached spikelets is limited especially if the planted variety is resistant. It is advisable to get the DON content of the harvested grain samples analyzed before taking it to the market.

This is the last FHB risk commentary of the season for MD, but feel free to contact me (email: nidhirwt@umd.edu) if you have any questions related to wheat or barley diseases any time of the year! Wish you a plentiful harvest!

--Nidhi Rawat, Small Grains Pathologist, University of Maryland

The FHB risk map is showing moderate to high risk in parts of western Nebraska. There have been significant amounts of rainfall in some areas in the region in recent weeks. In the southwest wheat is flowering or just past flowering. In the Panhandle (northwest), growth stage is at Feekes 9 to boot to just starting to head depending on the location, and therefore it is too early for infections to occur at this time. Growers in the southwest and Panhandle regions of Nebraska should monitor the weather and their wheat fields, especially irrigated fields. Additional precipitation will increase the risk of FHB in these two regions. In the eastern half of the state, wheat is past the flowering growth stage in most fields; it has been too dry in this part of the state, which has kept FHB risk low.

--Stephen Wegulo, Professor/Extension Plant Pathologist, University of Nebraska-Lincoln