winter malting barley fields and nearly all winter wheat fields in New York are now past stages where fungicide application is useful. This is a good time to assess FHB symptoms in winter cereals.

Our attention in New York now switches to spring malting barley and spring wheat as these crops approach head emergence and flowering, and decisions should be made for timely application of Caramba, Prosaro, or Miravis Ace. The weather-based risk of FHB development in crops heading out this week is highly variable across the state. Be sure to check the Fusarium Risk Assessment Tool (www.wheatscab.psu.edu) and your local weather forecast frequently as your spring cereal crops approach head emergence.

--Gary Bergstrom, Extension Plant Pathologist, Cornell University

The two weather systems that brought some measurable precipitation across much of Northwest Minnesota at the end of the week allowed the risk for tan spot and leaf rust to increase to 'likely' for two consecutive mornings. And as soon as the soil surface dried up, so evaporated the risks of any initial infections of tan spot and leaf rust.

The immediate forecast does not look promising for any measurable and widespread precipitation. The disease risk model Fusarium head blight remained low over the past few days and is almost certain to remain low until at least the end of this week. Likewise, the risk for tan spot, leaf rust, and Septoria to develop will also remain low.

Fungicides do not alleviate drought stress nor can they increase yield, fungicide can only preserve the yield potential that was there. As the yield potential dwindles because of drought stress so will be the portion that can be saved with a fungicide should diseases have a chance to reach economically damaging levels yet. After all, 5% of 80 bushels is not the same as 5% of 30 bushels.

This will mean that the decision to apply a fungicide to suppress FHB and control the leaf disease will become even more difficult as the drought stress in individuals fields intensifies. The decision to consider a fungicide is now in part guided by whether the crop has still yield potential left.

This week's weather and the extended forecast are - other than the lack of precipitation - actually almost ideal for small grains. The decision to consider a fungicide at all, therefore, will be truly on a field-by-field basis and based on the yield potential that is left. That in turn is at this moment driven by how much moisture reserves are left in the soil profile to give the crop a fighting chance. The color of the crop, rather than the height, during the heat of the day, is very telling in this case: As long as you do not see that blue hue, the crop still has its toes in the water.

Meanwhile, I do ask you to continue scout for aphids as their numbers are likely to increase with the current conditions. Apply an insecticide as soon you find one or more aphids on 80% of the individual stems across the field. Do not apply an insecticide after the crop reaches anthesis.

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

The warmer temperatures and limited rainfall throughout the state have kept the FHB risk very low. The current weather conditions have also pushed spring wheat to start heading earlier than normal. Growers should keep checking the FHB prediction tool in case of weather changes for spring wheat that is yet to head.

--Emmanuel Byamukama, Assistant Professor and Plant Pathology Extension Specialist, South Dakota State University

A extremely dry spring has “pushed” the wheat and barley crop in North Dakota and there are a few reports of spring wheat starting to head in some areas of the state. Although some rainfall has been received across the state, low relative humidity and hot temperatures has lessened scab concerns for the entire state. However, small grain growth stages are extremely variable and scab risk (and weather) should be revisited as small grain crops begin to enter heading and flowering stages.

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

The conditions for disease development have further declined across the state with initial infections of the leaf spotting diseases, leaf rust, and Fusarium head blight being unlikely. I expect that the increase in dew points that are forecasted across much of the state will increase the risk of disease development only slightly and only in areas or fields that received substantive precipitation in the past week and a half or that are under irrigation.

The decision to apply a fungicide to suppress FHB in winter wheat or the earliest seeded barley and spring wheat or control crown rust in oats is a difficult one at this junction in time as the extreme heat over the weekend and the predicted daytime highs in the extended forecast do not favor grain fill and thus yield potential.

The sudden change from cold to hot weather and the application of herbicides are resulting in some weird crop responses that in some cases mimic leaf spotting diseases. Make sure that you identify the cause of these leaf spots before applying a fungicide.

Up to this point, the dew points have been low enough that nighttime temperatures stayed in the 50 and 60 across much of the state even as daytime highs soared to triple digits. This has meant that respiration during the night has stayed relatively low and not taken more photosynthate away from the developing kernels.

Meanwhile, reports of aphids and grasshoppers continue to reach me with a larger proportion of reports having numbers that warrant treatment. Scout field edges for grasshoppers and scout the whole field in the case of aphids to determine whether you are reaching economic thresholds and decide to apply an insecticide.

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

Most of the winter wheat in South Dakota is now at flowering. The predicted FHB risk continues to be low due to dry and hot conditions currently being experienced in the state. A fungicide for wheat that is at flowing would not be necessary at this time. However, it is advisable to keep checking the predicted FHB risk until wheat has completed the flowering to determine the need of a fungicide.

--Emmanuel Byamukama, Assistant Professor and Plant Pathology Extension Specialist, South Dakota State University

Head scab risk has been low across Michigan, likely driven by the exceptionally dry conditions experienced across most of the state. Flowering in our head scab trials in central Michigan (East Lansing) began May 27th. It should be remembered that best fungicide timing for head scab control occurs from flowering (10.5.1) through seven days post the beginning of flowering. Fungicides applied at this time will also assist with protection of the flag leaf and foliage from late season diseases.

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

Winter wheat in New York began flowering this week and much acreage was sprayed with Caramba, Prosaro, or Miravis Ace. There is an application window of approximately 7 days from the beginning of flowering in which reasonable FHB and DON suppression can be expected from these fungicides. The risk of FHB infection in winter wheat has increased in some areas of New York over the last few days. Check the Fusarium Risk Assessment Tool (www.wheatscab.psu.edu) and your local weather forecast frequently as your winter wheat crop approaches flowering.

--Gary Bergstrom, Extension Plant Pathologist, Cornell University

Scab infection risk is growing across the state, but especially in the West and North for all resistance classes of wheat. If your wheat in these areas is heading and approaching flowering, stay alert and consider a fungicide application. Caramba, Prosaro and Miravis Ace give good control of most leaf and head diseases, in addition to suppressing scab. Spray nozzles should be angled at 30° down from horizontal, toward the grain heads, using forward- and backward mounted nozzles or nozzles with a two directional spray, such as Twinjet nozzles.

Continue to visit wheatscab.psu.edu to use the Fusarium Head Blight Prediction Center for estimating your crop’s scab risk.

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

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. For most parts of the flowering season, we stayed relatively dry, and so far, we have not observed symptom development in terms of bleached spikelets. However, with the recent rains DON content of grains may escalate. 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!

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