Wheat fields in Kentucky are now at anthesis (Feekes 10.51) or fast approaching it. Currently, most of the state is under “low risk” for FHB for susceptible to moderately resistant varieties; however, for very susceptible varieties, some areas are in a medium to high risk, with predictions of risk to increase over the next two days. For in-season management of FHB, it is important to apply a fungicide with efficacy against FHB. The most recent edition of the “Fungicide Efficacy for Control of Wheat Diseases” publication is available on the Crop Protection Network (https://cropprotectionnetwork.org/publications/fungicide-efficacy-for-c…), which provides information on efficacy of fungicides for control of FHB and other diseases. For FHB management with fungicides, it is important to apply at Feekes growth stage 10.51 up to about 6 days after for the greatest protection against FHB.

--Dr. Carl A. Bradley, Professor and Extension Specialist, University of Kentucky

Wheat was in the boot stage in southern Indiana last week, whereas in central Indian we are around Feekes 8 as the flag leaves are beginning to emerge. As wheat heads reach complete emergence it will be important to start watch for beginning flowering. Currently Fusarium head blight (FHB) risk is low for Indiana (4/22/24). It will be important to keep an eye on this map to make an informed decision to determine if fungicides for scab are needed once wheat starts to flower.

--Dr. Darcy Telenko, Assistant Professor Extension Specialist, Purdue University

Most wheat in Tennessee is in the flowering period, the highest period for susceptibility to scab/FHB infection. While risk is estimated to be low for 'susceptible varieties', those using very old varieties should change the model to 'very susceptible' and consider the higher risk. Similarly, the scattered showers within the 10-day window recently will increase risk and might not be captured in the model. Consider protecting wheat from scab/FHB and use the fungicide efficacy table to chose the right product for your situation -https://cropprotectionnetwork.s3.amazonaws.com/cpn3002_fungicideefficac…

--Heather Marie Kelly, Extension Plant Pathologist, University of Tennessee-Entomology & Plant Pathology

Flowering continues in wheat this week across the northern half of the state of Ohio. This is the growth stage as which the crop is most susceptible to infection by Fusarium graminearum, the fungus that cases Fusarium head blight (FHB), also known as head scab. Consequently, questions are being asked about applying a fungicide to control FHB and minimize grain contamination with mycotoxins. However, according to the FHB forecasting system, the risk for head scab development has been low across the state over the past week. This is likely due, at least in part, to the cool, relatively dry conditions we have experienced in most area. The extended forecast suggests that dry (rain-free) conditions will persist over the next week or so. Remember, warm and consistently wet or humid conditions are required for FHB to develop. So, do continue to monitor the weather and use the scab forecasting system to determine if the risk for scab is increasing at the crop flowers in northern, late-plante d fields.

--Pierce Anderson Paul, Extension Plant Pathologist, The Ohio State University

Wheat in southern Indiana has started to head out and will probably start flowering (Feekes 10.5.1) in the next week. Currently the six day forecast for FHB is low for most of the state, but rain is predicted again next week. In central Indiana our wheat is at flag leaf (Feekes 9).

Wheat will be susceptible to FHB infection as it moves into early anthesis through full flower. A fungicide application may provide protection during this critical time. The updated wheat fungicide efficacy guide is a resource that can provide guidance on fungicide choice for efficacy against FHB and other diseases. It is available on the Crop Protection Network at https://cropprotectionnetwork.org/publications/fungicide-efficacy-for-c…. Continue to monitor the risk as weather changes over the next few weeks to see what happens as the rest of the state moves into that critical time period.

--Dr. Darcy Telenko, Assistant Professor Extension Specialist, Purdue University

Many wheat fields will begin going through early anthesis (flowering; Feekes growth stage 10.51) this week in Kentucky. Although rain occurred in some areas of Kentucky over the last few days, the chances for precipitation over the next few days are relatively low. Wheat continues to be susceptible to infection by the FHB pathogen beyond early anthesis, so it is important to consider making a fungicide application at Feekes 10.51 to provide protection during this critical time. The wheat fungicide efficacy guide on the Crop Protection Network (www.cropprotectionnetwork.com) provides information about which fungicide products provide the greatest efficacy against FHB and other important diseases.

--Dr. Carl A. Bradley, Professor and Extension Specialist, University of Kentucky

Head Scab Risk has Increased Across Ohio.

Due largely to rainfall, high relative humidity, and warmer temperatures over the last several days, the risk for head scab is now moderate across most of the state of Ohio, and high across the south. The risk is low in NW Ohio. This would be the time to consider applying a fungicide to control head scab and reduce the risk of grain contamination with mycotoxins as fields reach anthesis in the northern third of the state. Even fields in the lower half of the state that flowered 5-7 days ago could benefit from a fungicide application. Most of the recommended fungicides for FHB management provide similar levels of FHB and vomitoxin suppression when applied between early anthesis (Feekes 10.5.1) and early grain-fill (up to six day after early anthesis).

The recommended, and most effective, fungicides for scab and vomitoxin control are Miravis Ace, Prosaro, Caramba, Proline, Sphaerex, and Prosaro Pro. These products provide comparable levels of scab and vomitoxin suppression when applied at early anthesis or shortly thereafter. Applications made to wheat at early or full head emergence (between Feekes 10.3 and 10.5) may also suppress scab (compared to no fungicide at all), but tend to be considerably less effective against vomitoxin. Several of these fungicides are also very effective against leaf diseases, which are also on the increase in some areas. Please read product labels carefully before making an application, in particular, pay close attention to the preharvest intervals.

--Pierce Anderson Paul, Extension Plant Pathologist, The Ohio State University

Wheat is, or will soon be, flowering (Feekes growth stage 10.5.1) in parts of central and northern Ohio. Feekes 10.5.1 is the growth stage at which the crop is most susceptible to infection by the fungus that causes head scab and produces vomitoxin. However, most fields across the state are currently at low risk for head scab. This is likely because of the relatively low temperatures we have experienced over the last few days. The map indicates that the risk for head scab development is low (mostly yellow) in fields flowering today, May 26, and assessments based on 2-6 days of forecasted weather suggest that the risk will continue to be low in the western 2/3 of the state where most of the wheat is grown and moderate (specks of orange) in a few areas out east. Continue to look at the tool as more fields reach anthesis; the risk could change quickly as it warms up, particularly if the warmer weather is accompanied by high relative humidity and/or frequent rainfall.

--Pierce Anderson Paul, Extension Plant Pathologist, The Ohio State University

In Illinois, wheat will start flowering within the next few days in much of the state. We are currently experiencing temperatures in the 90s after a long period of cool wet weather. Due to these temperature swings, it may be harder than usual to predict when flowering will begin. Wheat fields should be monitored every other day for flowering and a fungicide should be applied when most of the heads are at the early flowering stage or as soon as possible afterward.

--Jessica Rutkoski, Assistant Professor, University of Illinois at Urbana-Champaign

Depending on the location and the variety maturity, wheat in Kentucky is at Feekes growth stage 10.51 (early anthesis) or beyond. Most wheat fields in the most southern areas of Kentucky would likely have been at Feekes 10.51 last week or before. Many wheat fields that are closer to southern Indiana or southern Illinois would likely be at the Feekes 10.51 stage now or soon will be. For most of the state, FHB risk is low, but there are some areas that show medium to high risk. Many of these areas showing risk are those in which wheat likely was at Feekes 10.51 last week. The risk is likely due to weather that was received last week (rainy and cooler conditions). Within the next few days, the risk map model will likely account for the very hot and sunny days that currently are occurring, which will reduce the risk of FHB greatly.

--Dr. Carl A. Bradley, Professor and Extension Specialist, University of Kentucky