1. Leaf rust of wheat. Leaf rust (Puccinia triticina syn P. recondita) has been reported and confirmed by Andy Shirley (CAE Mitchell county) in commercial wheat fields. While the incidence appears to be localized, recent weather patterns observed in the southern US can contribute to the dispersal and establishment of the disease. Additionally, favorable environmental conditions for leaf rust development are developing or are now in place in the state; THEREFORE wheat field scouting and monitoring should be implemented at this time.
If leaf rust is present in your field, this warrants a fungicide application and the options include: triazoles metconazole (Caramba) propiconazole (Tilt, Propimax) prothioconazole (Proline) prothioconazole + tebuconazole (Prosaro) tebuconazole-containing products (Folicur, others) Strobilurins azoxystrobin (Quadris) fluxastrobin (Evito) picoxystrobin (Aproach) pyraclostrobin (Headline) Mixed mode of action fluoxapyroxad + pyraclostrobin (Priaxor) flutriafol + fluoxastrobin (Fortix) propiconazole + azoxystrobin (Quilt, QuiltXcel) propiconazole + trifloxystrobin (Stratego) prothioconazole + trifloxystrobin (Stratego YLD) pyraclostrobin + metconazole (Twinline) tebuconazole + trifloxystrobin (Absolute) tebuconazole + azoxystrobin (Custodia)
When leaf rust has become established in a field, triazole fungicides tend to be most effective. Strobilurins have a more preventive activity and tend to be weaker if rust is already in the field. Remember that protection of the flag leaf is of essential importance for yield preservation. A complete list of wheat fungicides, rates and specific remarks and precautions can be found on page 60 of the 2014-15 Wheat Production Guide (http://www.caes.uga.edu/commodities/fieldcrops/gagrains/documents/2014-2015WheatProductionGuide.pdf ). Always follow product label for recommendations, precautions and restrictions. More information on identification and control of leaf rust can be found at http://extension.uga.edu/publications/detail.cfm?number=C1060
2. Powdery Mildew: Powdery mildew (Blumeria graminis; syn Erysiphe graminis) infections on wheat fields have been reported and confirmed recently across the state, especially in the southernmost part of the state. Weather has been conducive for the disease. Powdery mildew tends to diminish as temperatures consistently reach above 75ºF and RH falls below 85%. If powdery mildew progresses up the plant and is found in upper leaves (flag leaf minus 2) you might consider a fungicide application. Refer to page 9 of the 2014-15 Wheat Production Guide for wheat varieties response against powdery mildew.
3. The North Central Extension and Research Committee (NCERA-184) for the management of small grain diseases has developed an excellent guide for wheat fungicide efficacy in a table format http://www.ksre.ksu.edu/bookstore/pubs/EP130.pdf . The information is updated yearly. The 2015 table is not available yet but the data from 2014 is still valid.
4. Two new publications are now available on Wheat Leaf Rust http://extension.uga.edu/publications/detail.cfm?number=C1060 and Wheat Powdery Mildew http://extension.uga.edu/publications/detail.cfm?number=C1059