Issue No. 4, Article 6/April 29, 2011
Conditions Favor Fusarium Head Blight (Scab) of Wheat in Southern Illinois
The recent--and continuing--rains received in southern Illinois have made conditions very favorable for Fusarium head blight (FHB; also known as scab) of wheat. According to the online risk assessment tool, on April 27 most of southern Illinois is at medium to high risk for FHB. Only wheat fields that have headed out and are flowering are at risk of infection by the disease fungus, Fusarium graminearum. Some wheat fields in southern Illinois will likely be heading or flowering this week or next week.
Screen capture of the Fusarium Head Blight Risk Assessment Tool from April 27.
For fields that will be flowering this week, a foliar fungicide for suppression of FHB and the associated mycotoxin deoxynivalenol (DON) is recommended for fields in the medium- to high-risk areas. As I noted in issue 3 of the Bulletin, the only fungicides that provide respectable levels of FHB and DON suppression are Caramba, Prosaro, and Folicur (and other tebuconazole products). Research conducted by the University of Illinois and other universities has shown that Caramba applied at 13.5 fl oz/A and Prosaro applied at 6.5 fl oz/A are more effective at suppressing FHB and DON than Folicur applied at 4 fl oz/A (see Table 2). The highest level of FHB and DON suppression will be achieved with foliar fungicides when they are applied at Feeke's growth stage 10.5.1 (early anthesis--when anthers are beginning to extrude from the middle part of the head).
Table 2. Effectiveness of foliar fungicides for control of deoxynivalenol (DON) and head scab in wheat.
DON (% control)*
Scab (% control)*
Caramba, 13.5 fl oz/A
Prosaro, 6.5 fl oz/A
Folicur, 4 fl oz/A
Data are summarized from University of Illinois and Southern Illinois University fungicide trials conducted from 2008 to 2010 at Monmouth, Urbana, Brownstown, Dixon Springs, and Carbondale.
For fields that will flower next week, it is important to monitor the FHB risk assessment tool. If the rain stops, and sunny and dry conditions occur next week, then the risk of the disease will decrease. Visit the following link to sign up for "FHB Alerts" that can be e-mailed to you or sent as a text message to your mobile phone.
For more information about managing FHB and achieving the highest level of suppression through integrated management practices, read the article in issue 3 of the Bulletin.--Carl A. Bradley
Carl A. Bradley