Scab infection risk is likely to increase this week across the southern portion of PA as a result of increased precipitation chances. If your wheat is approaching flowering, stay alert and consider a fungicide application once flowering has begun. Miravis Ace, Prosaro, Prosaro Pro, and Sphaerex all provide very good scab suppression. The Miravis Ace label allows for earlier application than other fungicides, but best results are still achieved when application is timed after full heading in barley and flowering in wheat. If weather conditions prevent fungicide application at ideal timing, an application as soon as conditions allow will still be quite effective in reducing scab and DON production. Follow labels to determine post-harvest interval constraints for the fungicide you choose. Spray nozzles should be angled at 30 deg down from horizontal, toward the grain heads, using forward- and backward-mounted nozzles or nozzles with a two-directional spray, such as Twinjet nozzles. Add itionally, a fungicide treatment at heading using any of these products will also give you excellent control of most leaf diseases as well.

--Alyssa A. Collins, Associate Professor, Plant Pathology and Environmental Microbiology, The Pennsylvania State University

Wheat in southern Maryland (Eastern shore and the western side of the bay bridge), is mostly either flowering or finishing up flowering. Incidents of extensive stripe rust have been reported from some fields in St. Mary's County and nearby counties (Courtesy: Mr. Ben Beale). Powdery mildew is also observed in the lower canopy and is moving onto the flag leaf. In addition, leaf rust is also visible in some fields. Remember that the standard FHB fungicides (Miravis-Ace/ Prosaro/ Prosaro-Pro/ Sphaerex) should be applied at this stage, as they are also effective for controlling stripe rust, leaf rust, and powdery mildew. Strobilurin-containing fungicides should not be sprayed at this stage. Even if your wheat is just 4-6 days post-flowering, it is recommended to spray the FHB fungicides. Wheat in the northern part of Maryland is also flowering/ starting to flower now. If you have planted an FHB susceptible variety and it is flowering, you may consider applying FHB fungicides.

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

FHB risk has been high in southern Illinois since Monday. Early-planted and early-maturing wheat varieties in this region are at or near flowering. If susceptible varieties are flowering, a fungicide application may be needed to suppress FHB development. Growers should monitor fields closely and consult the FHB Risk Tool for ongoing updates.

--Boris X Camiletti, Assistant Professor, University of Illinois Urbana-Champaign

The risk of Fusarium head blight (FHB) has increased due to rains that have occurred over the last few days. Large differences in risk can be observed when choosing "Very Susceptible" to "Moderately Resistant" varieties in the FHB Risk Model. For susceptible varieties, a high risk of FHB can be observed across Kentucky, but for moderately-resistant varieties, the FHB risk is mostly low to medium, with a few spots under high risk. Wheat is generally now beyond the time where a fungicide application can be made (several days past early anthesis at this point in time), except for maybe a few exceptions with later-maturing wheat varieties. It will be important to start monitoring for symptoms of FHB in wheat fields over the next few weeks to determine if adjustments to combine fan speeds should be made, which can help blow out the lightweight "tombstone" kernels, which may have the highest levels of deoxynivalenol (DON; "vomitoxin").

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

Wheat in southern Indian is starting to head out (Feekes 10.1), therefore it is time to monitor FHB risk to make an informed decision if a fungicide application is necessary.

The current and 2 day risk map is showing a medium to high risk (orange/red) for southern Indiana, but as we dry out the 6 day risk goes drops back to low (yellow) for the whole state.

A reminder that if you chose to apply a fungicide the triazole-containing fungicides are best for FHB– see the wheat fungicide efficacy tables for more information at http://doi.org/10.31274/cpn-20190620-031

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

With the predicted showers and thunderstorms for the majority of this week, the weather is expected to be conducive for FHB. Although the FHB risk map currently shows a low risk for head scab, the real risk may escalate in the next few days, especially for the susceptible varieties. Wheat is currently in the flowering stage on the Eastern shore of Maryland, across the state of Maryland. Flowering is when yellow anthers emerge from the wheat spikes. If you have planted a susceptible variety for FHB, you may consider applying FHB fungicides.

If you are planning to apply fungicides for FHB, remember that triazole-containing fungicides (Miravis-Ace, Prosaro, Prosaro-Pro, and Sphaerex) should be used for controlling FHB. They can control other fungal pathogens like powdery mildew, rusts, in addition to scab. Strobilurin-containing fungicides should not be used at this stage. These fungicides do not need to be tank-mixed with another product for spraying. The fungicide products should be applied at the full rate recommended by the manufacturers. Aerial application at a rate of 5 gallons per acre or ground application at 15 gallons per acre with 300-350 um droplet size is recommended. Spray nozzles should be angled at 30-45 deg down from horizontal, toward the grain heads, using forward- and backward-mounted nozzles or nozzles with a two-directional spray, such as Twinjet nozzles.

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

Dry spring weather has been keeping scab risk low up to this point, however, that may be shifting in some areas of PA who have experienced persistent moist conditions since the first of the month. While the risk map is very helpful to determine average risk across large areas, it may not always reflect precise conditions that occur in pockets of wheat production that are not well-represented by weather stations. If your wheat or barley has been experiencing high humidity for a few weeks, consider a fungicide application for scab at early flowering. If you plan to spray for head scab, choose a labeled triazole-containing product (FRAC 3) like Proline, Prosaro, Prosaro Pro, Miravis Ace, or Sphaerex. Do not use a product that contains any strobilurin (FRAC 11).

--Alyssa A. Collins, Associate Professor, Plant Pathology and Environmental Microbiology, The Pennsylvania State University

Head scab risk remains low across most North Carolina wheat-growing regions, including in the scab-prone northeast corner. For wheat planted conventionally, a scab-targeted fungicide is unlikely to be profitable. However, if wheat is planted no-till behind corn and especially if the wheat variety is susceptible or moderately susceptible to scab, a fungicide may be advisable.

Optimal timing to apply a scab-targeted fungicide is early to mid-flowering, or up to a week later. The best timing for barley is about a week after 100% of heads are just emerged. Scab is not effectively managed by applications prior to flowering in wheat and full heading in barley. The most effective fungicides for scab reduction are Miravis Ace, Prosaro Pro, and Sphaerex. Do not apply strobilurin-containing products after flag leaf.

For a wheat variety's scab resistance level, find it at the NC OVT site: https://ncovt.medius.re/wheat. Look under Attributes. Scouting for scab symptoms can be done starting about 2 weeks after flowering and until the wheat starts to dry down.

--Christina Cowger, Small Grains Pathologist, USDA-ARS, NC State University

Wheat fields in Kansas are at or approaching flowering in southeast and south-central counties. The weather is currently highly favorable for FHB (scab) development in these parts of the state. It will be critical to carefully watch fields that are approaching the application window for a scab fungicide (Flowering, Feekes 10.5.1). The highest risk will be in fields of scab-susceptible varieties that are planted back into corn residue. For a reminder about the scab ratings for individual varieties, please refer to the Kansas Wheat Variety Guide: https://bookstore.ksre.ksu.edu/pubs/mf991.pdf.

For more details, please review our recent newsletter on this topic: https://bit.ly/4m3274y

--Kelsey Andersen Onofre, Assistant Professor, Wheat Extension Specialist, Kansas State University

Wheat in the Eastern Shore of Maryland is either flowering (50% of the main tillers showing yellow anthers) or will be flowering in a couple of days. This is the stage when the plants are most prone to FHB infection. Although the epidemiological models are predicting low risk currently, with the rains forecasted starting from this weekend, growers are advised to keep a close eye on the FHB risk over the coming days. In case the risk escalates, the recommended head scab fungicides are Prosaro/ Miravis-Ace/ Sphaerex or Prosaro-Pro. The applications should be made at wheat flowering or within 4-5 days after at full rates prescribed by the manufacturers. Strobilurin-containing fungicides should not be sprayed at this stage. In the northern counties, wheat is booting, and still roughly around 1-2 weeks away from flowering.

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