Wheat Update: Stripe Rust Alert-Cold Weather-Disease Management Tools
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Collapse ▲North Carolina Stripe Rust Alert—April 8, 2024
Dr. Christina Cowger, USDA Research Plant Pathologist at NCSU & Dr. Angela Post, Small Grains Extension Specialist
Wheat stripe rust has appeared in eastern North Carolina. It was found yesterday in field plots of P26R33 in Beaufort County. Stripe rust usually blows into North Carolina from states to the south, rather than over-wintering here, and it has showed up recently in Georgia. So it is advisable to scout wheat fields on a path from South Carolina up through the North Carolina Tidewater. A stripe rust epidemic can develop much quicker than a leaf rust epidemic. If scouting reveals stripe rust in your field, a fungicide should be applied as soon as possible to preserve yield. Apply fungicides to fields containing multiple stripe rust foci first before moving on to fields with less noticeable infections. A stripe rust focus is pictured in Figure 1B, and if the epidemic is caught early enough, treatment of just the foci can prevent a broader epidemic from developing.
When choosing a fungicide, pay close attention to harvest restrictions on the label. Table 1 is abbreviated from NCERA 184 Fungicide Efficacy for Control of Wheat Diseases to include only fungicide products with an excellent stripe rust rating. The fungicides Prosaro and Folicur provide excellent protection against a stripe rust epidemic. Generic versions of the same active ingredient will provide equivalent control. These fungicides have a 30- day pre-harvest restriction so use caution when applying to fields nearing harvest. Stobilurin-only products such as Aproach and Headline are less effective when used alone after a stripe rust infection has occurred. Aproach Prima also provides excellent protection against stripe rust; however, this fungicide has a 45-day pre-harvest restriction and should only be applied to varieties that are still in boot and not yet heading. Do not apply strobilurin-containing products past flag leaf; they can increase damage if a scab epidemic occurs. As a reminder, Feekes 10.5 is heads fully emerged from the boot and Feekes 10.5.1 to 10.5.4 is the flowering stage.
Table 1. Abbreviated from NCERA-184 Fungicide Efficacy for Control of Wheat Diseases
What to Watch for Following Freezing Nights in Wheat
By Dr. Angela Post, Small Grains Extension Specialist
Most wheat in North Carolina has jointed and is approaching boot stage. Some may even be peeking heads. Prior to the boot stage wheat can withstand short durations of temperatures around 28F without considerable injury. Much of North Carolin will be under a freeze warning tonight with temperatures expected to be in the low to mid 30’s. Check your local forecast for specific details in your area. Growers should assess freeze damage as heads begin to emerge. Please use Chapter 11 of the Small Grain Production Guide: Freeze Injury in Wheat to assess any damage that may occur. I suggest scouting 7-10 days following the freezing temperatures. I still expect wheat to be tolerant of 30F for short durations unless it has reached heading. However, long periods of these temperatures can cause damage to the lower stem and weaken the stand, which results in increased lodging potential as we move through the season. Once the cold temperatures move through, I will provide an update on which locations had the greatest potential for injury.
Wheat & Barley Disease Tools
By Christina Cowger, Angela Post and Jenny Carleo
Spring’s here, and with it the need to look out for wheat and barley diseases. Here are two tools to help us monitor disease risk and, if necessary, choose a fungicide.
Fungicide Efficacy Table – this table breaks wheat fungicides into classes by mode of action (strobilurins, triazoles and combinations). Each product is rated for efficacy against the wheat diseases we are likely to encounter. Updated in March 2025.
Fusarium head blight (scab) risk tool – this is the website for scab fungicide decision-making that has long been available thanks to the US Wheat & Barley Scab Initiative, which is funded by the USDA. Some key things about scab risk:
- The tool uses your weather in the last 2 weeks to predict your risk today of a scab epidemic in your crop. Flowering is when your crop is at risk of scab infection, and when fungicides might need to be applied.
- The tool also can take into account the resistance or susceptibility of your varieties.
- Tillage and previous crop can also be important. No-till wheat with corn debris may require a scab-targeted fungicide even if the model shows low scab risk.
Subscribe here to FHB alerts by text message or email – you’ll only get them during the season when you need them. Alerts will summarize your risk and give you fungicide tips.