Nidhi Rawat and Vijay Tiwari
University of Maryland, College Park
Data from the 2024 University of Maryland small grain variety trials is now posted. Please follow the links below to download the reports. For detailed information on how to interpret variety trial data, please see this factsheet.
Nidhi Rawat, Small Grains Pathologist
University of Maryland, College Park
Wheat in Maryland has either already flowered or is finishing-up flowering. The FHB prediction maps for today and up to the next 6 days predict high FHB risk. If your wheat is still in the window for FHB fungicide application (from flowering up to the following 4-7 days) you should consider the application of FHB fungicides: Miravis-Ace, Prosaro, Prosaro-Pro, or Sphaerex. These fungicides are also effective against other fungal foliar diseases such as stripe rust, powdery mildew, and tan-spot etc. Strobilurin-containing fungicides are not recommended for application at this stage.
Nidhi Rawat, Small Grains Pathologist
University of Maryland, College Park
Wheat is mostly ending flowering across Maryland now, except for some late-planted fields. The FHB prediction map shows enhanced FHB risk. If your wheat flowered within the past 4-7 days, you are still in the window for FHB fungicide application. This season, we are also observing several foliar diseases such as stripe rust, powdery mildew, BYDV, and tan-spot in our variety trial plots. Some farmers are also reporting these issues from their fields. If you are considering the application of fungicides at this stage, use FHB fungicides: Miravis-Ace, Prosaro, Prosaro-Pro, or Sphaerex. These will control other fungal diseases, in addition to FHB, but not BYDV. For BYDV none of the fungicides can provide control, as it is a viral disease, and genetic resistance is the only real solution for it. Strobilurin-containing fungicides are not recommended for application at this stage.
Andrew Kness, Senior Agriculture Agent | akness@umd.edu
University of Maryland Extension, Harford County
This article may come a little too late for some of you depending where you are in the state; but nevertheless, here is a review/reminder. As we get into May, wheat will begin flowering and we will have to consider fungicide applications to wheat to manage Fusarium head blight (FHB), also known as head scab. FHB is the most economically important disease of wheat, causing not only yield reductions, but more seriously, grain quality issues due to the production of the mycotoxin deoxynivalenol (DON), also called vomitoxin.
The pathogen that causes FHB, Fusarium graminearum, persists in wheat, small grain, and corn residue. It infects the wheat plant through the open flower, which is why flowering is such an important management timing for quality wheat production. Fusarium graminearum requires moist conditions and moderate temperatures (59-86 °F) to initiate infection. If these conditions are met during flowering, the pathogen will infect susceptible wheat varieties and cause disease.
Management of FHB requires a layered approach of IPM practices, with the major management practices being the selection of a good wheat variety and subsequent good planting and fertility practices, plus the use of a fungicide at flowering should the environmental conditions be conducive for FHB development. The wheatscab.psu.edu map can be helpful in predicting FHB risk to wheat around flowering. Historically, this model has been over 70% effective at predicting FHB outbreaks and should be consulted when making fungicide decisions. If you decide to apply a fungicide to manage FHB, there are three important factors to consider: 1.) Timing, 2.) Application method, and 3.) Active ingredient.
As mentioned earlier, the pathogen can only infect wheat through the open flower, so you need to time your fungicide application as close to flowering, or Feekes Growth Stage 10.5.1, as possible (Figure 1). This growth stage is defined by the appearance of yellow anthers in the center of the wheat spike on at least 50% of the plants. Once this stage is reached, the application window is about 5-7 days. Some fungicide products are labelled for application as early as Feekes 10.3 (half head emergence); however, this timing is not as optimal as 10.5.1—so wait if you can.
The second factor is application method. Most of our fungicides on wheat go on with a ground sprayer. For ground applications it is important to achieve good coverage of the wheat heads, not the foliage. To do this, spray volumes should be at least 15-20 gallons/acre and you should use bi-directional spray nozzles angled forward and backwards. This combination of spray volume and angled nozzles results in thorough coverage of the wheat heads. Aerial applications should be done at 5 gallons/acre for maximum coverage.
The final consideration is fungicide active ingredient. Triazole and HDMI fungicides work best on FHB. Products include: Prosaro Pro, Prosaro, Miravis Ace, Saphaerex, Proline, and Caramba; Folicur has less efficacy than the others and Tilt is no longer effective on FHB. An added benefit is that these products will also do a good job of keeping other fungal diseases at bay during grain fill. Do not apply any group 11 (Qoi/strobilurin) fungicides such as Aproach, Headline, or Quadris after heading as these products can actually increase DON levels in the grain.
Nidhi Rawat, Small Grains Pathologist
University of Maryland, College Park
Wheat is currently flowering or will soon flower across the state of Maryland. Flowering is when yellow anthers emerge out of the wheat spikes. This is again that year, in which if you planted a resistant variety, you would be okay without spraying fungicides for controlling Fusarium head Blight (FHB risk map: top picture). However, if your planted variety is not FHB resistant, you should consider application of FHB fungicides (FHB risk map: lower picture). 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° 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, College Park
Wheat on the Eastern shore of Maryland is heading and should start flowering within a week or so. Wheat in the north-western part (Frederick, Carroll, Hartford counties) is also close to heading or has started heading. The FHB fungal pathogen infects the wheat plants at the flowering stage (when the yellow anthers emerge from the heads), which is the stage at which the application of fungicides is conducted in wheat. The FHB map currently does not show high risk, especially for a genetically resistant variety. However, keeping an eye on the forecasts and weather patterns over the next few days as your wheat flowers is recommended. 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 as well, in addition to scab. Strobilurin-containing fungicides should not be used at this stage.
Nidhi Rawat, Small Grains Pathologist
University of Maryland
Welcome to the wheat and barley heading and flowering season, Maryland! This is the first FHB risk forecast for this season from me, and I will continue to provide you with regular commentaries over the next 6-7 weeks. Wheat is some weeks away from flowering, but barley is starting/ will soon start to head, especially in the Eastern shore of the state. Unfortunately, for barley, there are no FHB-resistant varieties available so far. So, if you have planted barley, keep monitoring closely for the FHB risk over the next couple of weeks. With the rainy spell of the last week, and some more rain forecasted this week, currently, the Epidemiological models are showing elevated FHB risk over the next 6 days. So, if your barley is starting heading you might consider applying fungicides on it. If you are still some weeks away from your barley heading, keep monitoring for the risk. Remember, the best stage for applying FHB fungicides on barley is when the heads are completely out of the boots. The FHB fungicides are triazole-containing products (Miravis-Ace, Prosaro, Prosaro-Pro, Sphaerex). Do not apply strobilurin-containing fungicides after heading. Wheat is not at a stage susceptible to FHB right now.
Some barley growers from across the state reported stunting, yellowing, and death of barley plants in their fields. The most probable cause of this issue in my opinion is freeze injury. Sudden dips in temperature after the plants caught up after winter may have led to the issue. I have discussed this issue with the other regional pathologists from the US, and they also report similar issues in North Carolina, Pennsylvania, and New York. They also think it to be a result of cold injury.
Alyssa Koehler, Extension Field Crop Pathologist | akoehler@udel.edu
University of Delaware
Wheat anthesis (flowering) is underway and will be continuing for the next 1-2 weeks across the region. Up until the rains this past weekend, we have been at low FHB risk. We are currently tracking as medium-high risk for very susceptible varieties and low-medium risk for varieties with some level of resistance (Figure 1). If you are planning for wheat fungicide application, scout frequently, looking for yellow anthers in the center of the wheat head (Figure 2) to signal that flowering has begun (Feekes 10.5.1). Depending on the weather, we can usually expect flowers to start showing up on wheat heads 3-5 days after full head emergence, with cool weather this can stretch this process out to 7-10 days. Anthers can remain attached after flowering, but become a pale white. For best mycotoxin (DON) control, it is better to be at flowering or a few days beyond than to spray too early when heads are not out yet (especially those secondary tillers). Fungicide products should be applied at the manufacturers recommended rate with nozzles angled 30-45° from horizontal (30 degrees is better than 45). Nozzles angled both forward and backward or twinjet nozzles that spray in two directions give better contact with the head and increase fungicide efficacy. For ground sprays, fungicides should be applied in at least 10-15 gallons of water per acre; aerial applications are recommended at 5 gallons per acre.
Once wheat has flowered, symptoms of FHB are usually visible in 18-24 days, but cool weather can slow symptom development. Heads with FHB will have bleached florets or bleached sections of the head and may have pink growth on spikelets. Glume blotch may also be present, but typically has more of a grey appearance. You can follow these steps to assess the severity of FHB present in your field.
Seyedali Hosseinrad, Nidhi Rawat, Nicole Fiorellino, and Vijay K. Tiwari
Department of Plant Science and Landscape Architecture, University of Maryland, College Park
Fusarium head blight (FHB) is a severe fungal disease that affects small grains, wheat and barley. It is particularly problematic in regions with wet and warm springs, such as the Mid-Atlantic region. FHB is caused by several species of Fusarium, F. graminearum being the most common in the USA.
Symptoms and signs: The disease primarily attacks the wheat and barley heads, or spikes, at flowering. Early symptoms of FHB include the appearance of small, water-soaked lesions on the glumes and awns of the heads. As the infection progresses, these lesions become larger, and the spikelets (sections of the heads) become brown and dry progressively (Figure 1a, b). In particularly conducive weather conditions, the spikelets may take on a pink or reddish color due to a mass production of fungal spores called sporodochia on the glumes. The disease causes the kernels to shrink or abort, leading to reduced yield, poor-quality grain, and in severe cases, crop failure (Fig. 1 c). In addition, the fungus also produces mycotoxins, such as Deoxynivalenol (DON), which is toxic for human and animal consumption. The epidemiology of FHB is complex and multifaceted and can be influenced by various factors, including weather conditions, crop management practices, and genetic susceptibility.
Weather conditions play a major role in determining the severity of FHB in field conditions. The disease thrives in warm, wet environments and is severe in areas with high humidity and frequent rainfall. Wet weather conditions during the flowering stage of wheat development provide an ideal environment for the fungus to infect and proliferate on the developing grain heads. In particular, warm and humid weather between heading and anthesis (flowering) is highly conducive to FHB infection. Warm temperatures between 70 and 80°F are favorable for fungal growth and production of mycotoxins.
Crop management practices can also contribute to the development and spread of FHB in winter wheat. Practices such as reduced tillage and corn-wheat rotation can increase the risk of FHB infection. Reduced or no-tillage can leave plant debris on the soil surface, providing a potential source of inoculum for the fungus. At the same time, corn acts as a secondary host of the pathogen, allowing the fungal inoculum to build up in the soil over time.
Effective management of FHB in winter wheat typically involves using an integrated disease management approach that incorporates a combination of cultural, chemical, and biological control measures.
Use of FHB-resistant varieties: One of the most important cultural practices for reducing FHB infections in wheat is the selection of resistant cultivars. Several wheat varieties have been developed with genetic resistance to FHB. In fact, the UMD small grain pathology program, in collaboration with the small grain breeding program, tests upward of 60 regional commercial varieties in their misted nursery in replicated trials every year to provide growers with a robust assessment of the levels of the genetic resistance of these varieties to FHB (https://psla.umd.edu/extension/md-crops). It is highly advisable for regional farmers to refer to these ratings for making their planting decisions to reduce the severity of infections in their crops.
Due to the importance of FHB in the Mid-Atlantic region, developing FHB-resistant varieties is one of the primary goals of the MD small grain breeding program, in addition to their yield and quality. Resistance to FHB is a complex genetic trait and is influenced by a range of genetic factors. So, any breeding program targeting to incorporate a high level of genetic resistance in their varieties has to pyramid several genes toward that goal. However, a high level of genetic resistance in barley is difficult to achieve on account of the lack of resistance genes available in it.
Chemical control: The use of fungicides is a key component of FHB management in wheat and barley. Fungicides can effectively reduce the severity of infections and minimize the production of mycotoxins. Fungicides with Group 3 and 7 FRAC code ingredients have been successful in controlling FHB. FRAC group 11 fungicides should not be applied for FHB, as there are reports of them increasing DON content in the grains. Several effective chemistries with a mix of active ingredients against FHB have recently been released by manufacturers, such as Prosaro-Pro and Prosaro by Bayer, Miravis-Ace by Syngenta, and Sphaerex by BASF. All these fungicides have been tested by the UMD Small grain pathology program and are found to be equally effective when sprayed at anthesis.
In addition to the chemistry of the fungicide, the timing of spraying is very critical in managing FHB. Spraying fungicides at anthesis (when yellow anthers pop out of the wheat heads) in wheat and heading in barley is important. As weather plays a major effect in determining the severity of FHB infection, the risk of FHB can be predicted with a significant correlation with conducive weather conditions. In conjunction with the US Wheat and Barley Scab Initiative, the MD small grain program releases FHB risk commentaries for growers registered with the FHB risk prediction website (https://www.wheatscab.psu.edu/). The growers are advised to register on this website to receive the alerts on their cell phones as text messages with advice on spraying decisions for FHB.
Biological control: Some biological control agents, such as bacterial and fungal species antagonistic to FHB, are available with the claims of reducing disease severity and mycotoxin production. However, the efficacy of these biological control agents is not high yet. Researchers at UMD are testing some new promising biological products currently under development, especially for the organic growers of the region.
Crop Rotation and Tillage: Other important cultural practices include crop rotation and tillage. Planting non-host crops such as soybeans in rotation with wheat can help reduce the amount of FHB inoculum in the soil, as corn is a secondary host of the pathogen and can increase inoculum build-up in the soil for the wheat crop. Reduced tillage practices that manage crop residue on the soil surface with minimal disturbance to the soil are helpful in reducing the amount of infected crop residue on the soil surface while minimizing soil erosion and loss.
Post-harvest management: Post-harvest management practices, such as grain cleaning and drying, can help to screen the Fusarium damaged kernels that are expected to have high levels of mycotoxin contamination in the harvested grain. Cleaning equipment such as air screen cleaners or gravity tables can remove lightweight and damaged kernels. Drying grain to a moisture content of 14% or lower as soon as possible after harvest can also help minimize mycotoxin contamination. The fungus may continue mycotoxin production at high moisture conditions in storage. Proper storage conditions, such as cool and dry storage facilities, can also help to prevent mycotoxin contamination during storage.
Fusarium head blight (FHB) is a significant fungal disease affecting wheat and barley crops in the Mid-Atlantic region, causing yield and quality losses. Small grain pathology and breeding programs are working on multipronged approaches to reduce FHB impact, such as using fungicides, developing resistant cultivars, and adopting cultural practices such as crop rotation and tillage management. Also, research and innovation are crucial to ensure the region’s long-term sustainability of wheat production.
For more information:
Gillum, M., & Van Sanford, D. (2023). Understanding the Effect of Fusarium Head Blight Resistance on Agronomic Characteristics of Soft Red Winter Wheat.
Singh, L., Wight, J.P., Crank, J., Thorne, L., Erwin, J.E., Dong, Y., Rawat, N. (2021). Evaluation of application timing of Miravis-Ace for control of Fusarium head blight and DON content in wheat. Plant Health Progress. 22: 94-100.
Singh, L., Wight, J.P., Crank, J., Thorne, L., Dong, Y., Rawat, N. (2020). Efficacy assessment of a new fungicide, Miravis Ace, for control of
Nidhi Rawat, Small Grains Pathologist
University of Maryland
Flowering is finishing up across all of Maryland now, except for a few late planted fields in the northern part of MD that may still be flowering. FHB risk across the state continues to be high. So, if your wheat is currently flowering or has flowered within last 4-5 days, you can still spray FHB fungicides. I have started scouting the wheat variety trials for FHB symptoms on the Eastern shore and am already observing moderate FHB incidences in untreated plots there. The weather conditions have been conducive for FHB this season so far. If you have planted resistant varieties, the situation is expected to be better. Natural infections of leaf rust and stripe rust are also being seen sporadically. I do not expect any major losses due to these two now though. So, it’s okay not to spray any fungicide specifically for these diseases.