Southern rust has been found this past week in irrigated corn in Baldwin Co. and this week in irrigated corn fields near Columbia, AL. While not severe, a lot of corn is just tasseling due to delayed planting and will be vulnerable to severe rust damage with continued irrigation and showers.
The fields near Columbia, which range from the blister to early soft dough stage have received one application of Headline AMP and are scheduled for a second application in the next few days. Growers need to be scouting corn for rust as well as Southern corn leaf blight, which has also made an appearance in SE AL corn.
Fungicide recommendations can be found at here. With light to moderate rust pressure, the generic fungicides (i.e. generic tebuconazole) gives adequate control of southern rust on early corn (Late or double crop corn is another matter). In high yield potential fields or when heavy rust pressure is expected, the name brand fungicides do best.
In years past, Stratego YLD and Headline AMP along with Headline have lead the way. Have not had experience with Aproach, Aproach Prima, Fortix, Evito T, Priaxor, and Topguard on corn but the activity range of the a.i. fungicide component(s) should be good against rust diseases.
I have trials with the newer fungicides on irrigated corn at Gulf Coaast Research and Extesion Center (GCREC) and BARU, so we should get a good look at rust efficacy this year in these areas.
