Tan Spot

Overview

Tan spot, also known as yellow leaf spot, is a prevalent disease in wheat crops, especially under conditions of high humidity and frequent rainfall.

Caused by the fungus Pyrenophora tritici-repentis, which can survive in wheat residues and infect new crops, the disease manifests as tan-colored lesions on the leaves, often bordered by a yellow halo.

The disease can stress the plant during the critical stage when the wheat is determining the number of spikelets per head, leading to substantial yield losses. In severe cases, yield losses can reach 25 to 30%.

(Image Credit: Mourad Louadfel, Retired, Bugwood.org)

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How to Scout for Tan Spot

The initial step in managing tan spot is scouting. It's crucial to start scouting wheat fields for leaf diseases between growth stages 6 (jointing) and 8 (flag leaf emergence). This period is when diseases begin to manifest on susceptible varieties.

Scouting should involve randomly collecting 30 to 50 tillers from various parts of the field and looking for tan spot symptoms. If you detect tan spot in a field planted with a susceptible variety, monitor its development over the next week to decide whether to apply fungicides.

(Image Credit: Mourad Louadfel, Retired, Bugwood.org)

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How to Manage Tan Spot in Wheat with Fungicides

The decision to use fungicides should be based on several factors: the susceptibility of the variety planted, the level of disease in the field, weather conditions, and the yield potential of the field. When the disease level in the field is high on the top two leaves, fungicide application could be beneficial. However, in low disease years, fungicide applications may not be economical.

GCS Azoxy 2SC

Fungicides should be applied when one to two lesions are detected on the leaf below the flag leaf on a susceptible variety

Product image of GCS Azoxy 2SC jug

Fungicides to Manage Tan Spot in Wheat

To manage tan spot in wheat, our agronomists recommend applying GCS Azoxy or GCS Azoxyprop.

Disclaimer

© 2014 - 2024 Farmer's Business Network, Inc. All rights Reserved. The sprout logo, “Farmers Business Network”, “FBN”, “FBN Direct” are trademarks or registered trademarks of Farmer's Business Network, Inc. This content was written by Norm℠, reviewed and edited by Mikaela Tierney.

This content was generated with the assistance of Norm℠, FBN’s artificial intelligence (AI) Ag Advisor, based on a dataset of information containing general industry best practices and research. The AI model did not use specific external sources to generate this content. Our process involves using AI to aid human subject matter experts with the initial drafting and/or refinement of content.

Every product that labels TAN SPOT as a weed, pest, or disease the product can be applied against is shown below. Click any product for label and more information.
A-Zox 25SCAbsolute® 500 SCAbsolute® MaxxAcadia™ 2 SCAcadia™ 2 SCAdastrio™Aframe™Aframe™ PlusAftershock®Alterity™ 62.5 WGAlto® 100 SLAproach®Aproach® PrimaAprovia® AceAquila™ XLArius™ 250Arysta Propiconazole 41.8 EC FungicideAvaris® 2XSAvaris™ FungicideAzoxy TebAzoxyStar®Azoxystrobin SCAZterknot®AZteroid® FCAZteroid® FC 3.3Azure™ Xtra FungicideBumper®Bumper® 41.8 ECBumper® ESCaramba® fungicideCover XL (Agri Star)Crossover® ProCustodia®Delaro® 325 SC FungicideDelaro® CompleteDexter® SCDexter™ MaxDexter™ XCELDithane® F45 Rainshield® FungicideDithane® M45 FungicideElloraEquation™Equation™ SC FungicideEvito® 480 SCEvito® T FungicideFitness® FungicideFortix® FungicideFortuna™ 75 WDG FungicideGCS Azoxy 2SCGCS AzoxypropGCS Tebustrobin SCGold Rush®Headline® fungicideHeadline® SC fungicideHelmstar Plus SCKoverall® FungicideLucento™Magistrate™Manzate® MaxManzate® Pro-Stick™ (UPI)Marazo™Mazolin™MiCrop™ FungicideMiCrop™ FungicideMiravis® AceNexicor™ Xemium® brand fungicideOmni® Brand Propiconazole 41.8% ECOverrule®OxiDate® 5.0Penncozeb® 75DFPenncozeb® 80WPPPZ 41.8 Select™Preemptor® EQPreemptor™ SC FungicidePriaxor® Xemium® brand fungicideProline® 480 SCPropazPropi-Star® ECPropicon ECPropiconazole 3.6 EC FungicidePropicure 3.6FPropiMax® EC FungicideProsaro® 421 SCProsaro® Pro 400 SCProtegam® YLDProtocol®Prozio™ BWPProzio™ SCQuadris® FlowableQuilt Xcel®Quilt® FungicideRegalia®Roper® DFRoper® DF Rainshield™RustEaseSatori® FungicideSerenade® ASOShar-Shield PPZSlant™Slant™ ECSphaerex™ FungicideStratego®Stratego® YLDTarian™TebazTebuzol® 3.6FTepera™Tetraban®Tetraban® FungicideTide Propiconazole 41.8% EC FungicideTilt®Topaz® FungicideTopGuard® EQ FungicideTopguard® FungicideTrebuset™Trevo®Trevo® PTrevo® PackedTrivapro® FungicideTrivapro™ ATrivapro™ BTwinLine® FungicideVango™ WGVeltyma® fungicideVertisan®Viathon®VigilWillowood Azoxy 2SCWillowood AzoxyProp XtraWillowood Propicon 3.6ECWillowood Pyrac 2ECWillowood Tebustrobin SCXiphosin™XuviaZolera™ FX Fungicide