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Southern Rust

Amy Timmerman - Extension Educator Author

09/17/2024 Added

4 Plays

Description

Southern rust in corn was confirmed last week in Nebraska.

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[00:00:00.480]This is Amy Timmerman with Nebraska Extension and this week's Extension Update.
[00:00:04.640]Southern rust in corn was confirmed last week in Nebraska, with positive cases being identified in
[00:00:10.560]local counties of Antelope and Wheeler as of yesterday, July 25, 2024. Current distribution
[00:00:16.960]patterns in fields are variable and each field should be scouted to determine whether it is
[00:00:21.280]present. Do not rely on knowledge of disease in nearby fields. Southern rust petriols can be
[00:00:27.200]orange or tan in color and are mostly produced on the upper leaf surface. The fungus is favored
[00:00:32.600]by warm temperatures around 80 degrees Fahrenheit and high relative humidity. Current and future
[00:00:39.200]weather patterns say that it is conducive for southern rust development, especially concerns
[00:00:44.880]for the upcoming week with nighttime temperatures being in the 70s and 80s with high relative
[00:00:50.020]humidities. In contrast, common rust petriols are dark brick red or cinnamon brown and usually
[00:00:56.880]large red or cinnamon brown.
[00:00:57.180]However, this year common rust has appeared more orange in coloration than normal. Do
[00:01:04.420]not just rely on color to differentiate the two types of rust. Remember that common rust
[00:01:09.880]pustules usually start on the upper leaf surface but usually push through to the bottom to
[00:01:14.940]produce more spores there as well.
[00:01:18.000]Cooler temperatures in the 70 degrees Fahrenheit are generally more favorable for common rust
[00:01:21.860]common rust so we generally see common rust development earlier in the season although
[00:01:27.290]common rust is a lesser threat to field corn production as most hybrids have genetic resistance
[00:01:32.650]to the disease fields of highest concerns are those that were planted late in the season
[00:01:38.090]and that have not begun to tassel there are several fungicides available that can be used
[00:01:43.530]to control southern rust which can be applied through chemigation or applied airily fungicide
[00:01:49.130]efficacy data can be found at cropprotectionnetwork.org this publication was compiled by the corn disease
[00:01:56.330]working group by field testing the material over multiple years and locations throughout
[00:02:01.450]the united states if you are uncertain on southern rust identification or even tar spot identification
[00:02:08.330]please reach out to me at the holt county extension office at 402-336-2760
[00:02:14.730]I have microscopes available in the office so we can easily
[00:02:18.810]verify common or southern rust by examining spore morphology and looking for spore development for
[00:02:25.290]tar spot also feel free to bring samples with you when you are visiting the Holt County Fair
[00:02:30.570]August 4th through the 10th and I'd be happy to take a look and my microscopes
[00:02:34.490]will be down there with me so we can verify any disease that you may be running into.
[00:02:38.890]This has been Amy Timmerman from Nebraska Extension.

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