Tag: head scab

Managing and Scouting Fields for Fusarium Head Blight

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.

Figure 1. FHB Risk Model for very susceptible (top) and susceptible varieties (bottom) May 3, 2023 (wheatscab.psu.edu).
Figure 2. Wheat at flowering (Feekes 10.5.1) with yellow anthers visible 3-4 days after heads emerge.

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.

  1. For every 10 acres of field, randomly select one spot to survey.
  2. Keeping your line of sight above the wheat heads, walk 40-50 yards and randomly pick 10-20 heads to look at on the plant or detach and place into a bag. (Looking down may bias the heads you select).
  3. Once you have randomly collected the heads, rate the percent of each head with symptoms of FHB (bleaching or pink growth on spikelets). You can use the scale below to help calibrate your eye (next page).
  4. After you have recorded values for each head, determine the average percent FHB severity by dividing the sum of disease severities by the total number of heads collected. (Ex. You rate 10 heads with severity values: 0%, 10%, 30%, 0%, 0%, 20%, 10%, 0%, 0%, 0%. These add up to 70. 70/10 heads = 7% overall FHB severity). Higher levels of FHB are typically associated with elevated levels of DON and possible issues with yield and test weight. It is possible to have delayed or lower levels of symptoms and still have DON.
  5. Repeat this assessment as needed to get an overall rating for the field. Fields with greater than 10% FHB severity are at higher risk for yield losses or elevated DON. Fields with elevated DON should be harvested as early as possible and you may want to consider increasing combine fan speeds and shutter openings to reduce the amount of scabby kernels harvested. 

2022 Maryland Small Grain Variety Trials

Results from the University of Maryland Small Grain Variety Trials are in the tables below. To download a pdf copy of the report, click here.

University of Maryland also rates the relative susceptibility of select varieties of wheat and barley to Fusarium head blight. The results from this trial can be found here.

For questions regarding the small grain trials, contact Dr. Vijay Tiwari (vktiwari@umd.edu) or Dr. Nidhi Rawat (nidhirwt@umd.edu).

If you’d like to learn more about how to interpret variety trial data, view our fact sheet by clicking here.

Click to Download The 2022 Small Grain Variety Trials

Click to Download 2022 Wheat and Barley Disease Ratings

FHB RISK ASSESSMENT MARYLAND: 5/24/22

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.

FHB RISK ASSESSMENT MARYLAND: 5/18/22

Nidhi Rawat, Small grains Pathologist
University of Maryland

Date 5/18/2022

With the recent showers and warming weather, FHB risk in the state is increasing. Wheat in the Eastern Shore of Maryland has finished or is just finishing flowering. If your wheat has just flowered last week, and you have not sprayed FHB fungicides you can still do so, as fungicide application 4-6 days after flowering is also known to provide some control. Wheat in the Northern parts is either flowering/ will soon start flowering. The FHB risk for this part of the state (Frederick, Carroll and Harford counties) is predicted to be moderate to high, especially if the wheat variety planted is susceptible. If the planted variety is resistant, the risk is not predicted to be particularly high. The recommended stage for application of fungicides on wheat is at flowering (50% of the main tillers showing yellow anthers) or within 4-5 days of that. The fungicides effective for FHB are Prosaro-pro/ Caramba/ Miravis-Ace. 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. Strobilurin containing fungicides should not be sprayed at this stage.

Scouting Fields for Fusarium Head Blight

Alyssa Koehler, Extension Field Crop Pathologist | akoehler@udel.edu
University of Delaware

Symptoms of Fusarium Head Blight.

Wheat anthesis will be occurring over the next few weeks. So far this season we have been at low FHB risk, but we will keep a close eye on the rain events predicted over the next two weeks. Some areas are getting a bit dry, so the rain is needed, but we hope for sun after rather than multiple grey days that keep canopy moisture high. If you are planning for wheat fungicide application, scout frequently looking for yellow anthers in the center of the wheat head to signal that flowering has begun (Feekes 10.5.1). Once around 50% of heads are flowering, fungicides (Caramba, Sphaerex, Miravis Ace, Prosaro, Prosaro-Pro) are most effective when applied within a 4-5 day window. Anthers can remain attached after flowering, but become a pale white (Figure 1). Once wheat has flowered, symptoms of FHB are 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 (Figure 2) 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 level of FHB present in your field.

Figure 1. From left to right: Feekes 10.3, Anthesis; Feekes 10.5.1 (yellow anthers beginning flowering); 4 days after anthesis (white anthers post flowering). Image: A. Koehler, Univ. of Delaware.
  1. For every 10 acres of field, randomly select one spot to survey.
  2. Keeping your line of sight above the wheat heads, walk 40-50 yards and randomly pick 10-20 heads to look at on the plant or detach and place into a bag. (You don’t want to be looking down and biasing the heads you select).
  3. Once you have randomly collected the heads, rate the percent of each head with symptoms of FHB (bleaching or pink growth on spikelets).
  4. After you have recorded values for each head, determine the average percent FHB severity by dividing the sum of disease severities by the total number of heads collected. (Ex. You rate 10 heads with severity values: 0, 10, 30, 0, 0, 20, 10, 0, 0, 0. These add up to 70. 70/10 heads = 7% FHB severity). Higher levels of FHB are typically associated with elevated levels of DON and possible issues with yield and test weight. It is possible to have delayed or lower levels of symptoms and still have DON.
  5. Repeat this assessment as needed to get an overall rating for the field. Fields with greater than 10% FHB severity are at higher risk for yield losses or elevated DON. Fields with elevated DON should be harvested as early as possible and you may want to consider increasing combine fan speeds and shutter openings to reduce the amount of scabby kernels harvested.

2021 Maryland Small Grain Variety Trials

Results from the University of Maryland Small Grain Variety Trials are in the tables below. To download a pdf copy of the report, click here or visit https://psla.umd.edu/extension/md-crops/small-grains-maryland.

For questions regarding the small grain trials, contact Dr. Vijay Tiwari (vktiwari@umd.edu) or Dr. Nidhi Rawat (nidhirwt@umd.edu).

If you’d like to learn more about how to interpret variety trial data, view our fact sheet by clicking here.

Click to Download The 2021 Small Grain Variety Trials

 

 

Scouting Fields for Fusarium Head Blight

Alyssa Koehler, Extension Field Crops Pathologist
University of Delaware

Most barley has made it past flowering, with wheat fields approaching anthesis. Over the past few weeks we have remained at low risk for Fusarium head blight (FHB) http://wheatscab.psu.edu/. There have been some rain events this week, and we will keep an eye on the model over the next 1-2 weeks. The recommended stage for fungicide application is when 50% of main tillers are flowering (yellow anthers visible) until 4-5 days after. Once wheat has flowered, symptoms of FHB are 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 (Figure 1) 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 level of FHB present in your field.

Wheat infected with fusarium
Figure 1. Symptoms of Fusarium head blight on wheat. Image: A. Koehler, Univ. of Delaware.
  1. For every 10 acres of field, randomly select one spot to survey.
  2. Keeping your line of sight above the wheat heads, walk 40-50 yards and randomly pick 10-20 heads to look at on the plant or detach and place into a bag. (You don’t want to be looking down and biasing the heads you select).
  3. Once you have randomly collected the heads, rate the percent of each head with symptoms of FHB (bleaching or pink growth on spikelets).
  4. After you have recorded values for each head, determine the average percent FHB severity by dividing the sum of disease severities by the total number of heads collected.

(Ex. You rate 10 heads with severity values: 0, 10, 30, 0, 0, 20, 10, 0, 0, 0. These add up to 70. 70/10 heads = 7% FHB severity).

Higher levels of FHB are typically associated with elevated levels of DON and possible issues with yield and test weight. It is possible to have delayed or lower levels of symptoms and still have DON.

  1. Repeat this assessment as needed to get an overall rating for the field. Fields with greater than 10% FHB severity are at higher risk for yield losses or elevated DON. Fields with elevated DON should be harvested as early as possible and you may want to consider increasing combine fan speeds and shutter openings to reduce the amount of scabby kernels harvested.

 

Checklist for Fusarium Head Blight Fungicide Applications

Andrew Kness, Agriculture Agent
University of Maryland Extension, Harford County

As wheat approaches flowering, here is a final list of reminders/tips to make the most of your fungicide applications that are targeted to manage Fusarium head blight (head scab):

  • Use an effective fungicide. These include: metconazole (Caramba®), prothioconazole + tebuconazole (Prosaro®), prothioconazole (Proline®), and adepidyn (Miravis Ace®).
  • Apply an effective fungicide at the correct time. The most effective application window is from flowering (anthesis; Feekes 10.5.1) + about 5-6 days after. Late applications (4-6 days after anthesis) are better than early heading/head emergence (10.3) applications at reducing DON content in the grain.
  • Apply fungicides using the correct equipment. Ground applications should be made with 80-degree flat fan nozzles angled down from horizontal. For ground applications made at speeds over 6 mph, use a single nozzle angled forward, 30 degrees down from horizontal. For ground applications less than 6 mph, better coverage is achieved with dual forward and rearward facing nozzles, angled 30-45 degrees down from horizontal.
  • Sprayer should be operated to achieve droplet sizes of 300-350 microns.
  • Use 10-20 gallons of water per acre and keep the spray boom 8-10 inches above the crop.
  • For aerial applications: Use 4-5 gallons of water per acre. Fine to medium sized droplets (300-350 microns). Small aircraft should operate 8-10 feet above the crop; large aircraft 10-12 feet. Nozzles should be mounted to cover 65% of the aircraft’s wingspan and mounted as low as possible.
wheat at start of anthesis
Wheat at Feekes 10.5.1. Image: A. Kness, Univ. of Maryland

 

Fusarium Head Blight Risk: June 1, 2020

Nidhi Rawat, Small Grains Pathologist
University of Maryland, College Park

Fusarium head blight risk to susceptible wheat as of June 1, 2020. Visit www.wheatscab.psu.edu

Flowering is all 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 high in these areas and so FHB fungicides (Prosaro, Miravis Ace, Caramba) should be applied here. 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 will be limited. It is advisable to get the DON content of the harvested grain analyzed before taking it to the market.

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

Fusarium Head Blight Risk: May 25, 2020

Nidhi Rawat, Small Grains Pathologist
University of Maryland, College Park

Fusarium head blight risk to susceptible wheat varieties as of May 25, 2020. Image from: wheatscab.psu.edu.

Wheat is at the dough stage in the lower eastern and lower western shore of the state. Although, the map shows FHB risk to be high in this region, wheat is well past the stage of FHB infection and spray here. Several other fungal foliar diseases such as Septoria tritici blotch, Stagonospora nodorum blotch, glume blotch, and tan spot have been observed here because of the rains or overcast skies and low temperatures. In our experimental plots at Wye, we have even observed some specks of leaf rust and stripe rust diseases. However, the damage due to these diseases is not going to be substantial now, and growers in this region do not need to spray fungicides for controlling these diseases. In a normal year, now would be the time to start looking for bleached spikelets to assess FHB severity. However, due to the cold spring that we had this year, symptoms may develop late/may not be visible, and the DON content of the grains should be analyzed and considered as the sole basis of FHB losses. Up in the North, wheat has finished/is finishing up flowering. FHB risk for today appears to be low here, especially for a moderately resistant variety. Check the FHB risk map http://www.wheatscab.psu.edu/ to monitor the daily risk here. If you are worried about foliar diseases mentioned above, the triazole fungicides do an excellent job of controlling these diseases as well. Strobilurin containing fungicides should be avoided at this stage.