Seminole Crop E News

Agricultural News for Farmers and Agribusiness in SW Georgia

Wheat Disease

Posted by romeethredge on March 27, 2015

 Leaf rust of wheat(Puccinia triticina syn P. recondita) has been found in some area wheat fields. It’s been seen in Mitchell county and consultant Wes Briggs found some this week near the airport, here in Donalsonville.

Here’s a small spot of wheat leaf rust with some powdery mildew on the right side.

IMG_6029

 Here’s a super closeup.

IMG_6030

UGA Plant pathologist, Alfredo Martinez has this disease report. 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

3.              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.

4.              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.

5.  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

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