Sensitivity of two sugarcane rust fungi to fungicides in urediniospore germination and detached leaf bioassays

Chaulagain Bhim, Dufault Nicholas, Raid Richard Neil, Rott Philippe. 2019. Sensitivity of two sugarcane rust fungi to fungicides in urediniospore germination and detached leaf bioassays. Crop Protection, 117 : pp. 86-93.

Quartile : Q1, Sujet : AGRONOMY

Abstract : Management of brown (Puccinia melanocephala) and orange (Puccinia kuehnii) rust of sugarcane in Florida primarily relies on fungicide applications. Using two different in vitro bioassays, we evaluated the efficacy of five fungicides registered for control of these diseases. Inhibition of P. kuehnii and P. melanocephala urediniospore germination varied from 96 to 100% at 0.01–10 μg per ml of pyraclostrobin and fluxapyroxad + pyraclostrobin. However, only 48% of the P. kuehnii spores were inhibited at 10 μg per ml of fluxapyroxad. Capacity to inhibit sugarcane infection and rust uredinia formation was tested with a detached leaf bioassay where fungicides were applied at different times with respect to inoculation with P. kuehnii or P. melanocephala. When fungicides were sprayed immediately after inoculation of leaf fragments, uredinia formation of P. melanocephala and P. kuehnii was suppressed at 99–100% regardless of the fungicide, except for metconazole (36–50% reduction). Uredinia formation of P. kuehnii was also nil when all fungicides (except metconazole) were sprayed 1 or 2 days prior to inoculation. However, maximum reduction in uredinia formation was 82% and 48% when leaves were sprayed with fungicides one or two days after inoculation, respectively. Therefore, these fungicides are more efficient in preventive than curative management of sugarcane orange rust.

Mots-clés Agrovoc : Puccinia melanocephala, Puccinia, Fongicide, Efficacité

Mots-clés géographiques Agrovoc : Floride, États-Unis

Mots-clés complémentaires : Puccinia kuehnii

Mots-clés libres : Disease management, Fungicide, Puccinia melanocephala, Puccinia kuehnii, Rust, Sugarcane

Classification Agris : H01 - Protection of plants - General aspects
H20 - Plant diseases
H50 - Miscellaneous plant disorders

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

Auteurs et affiliations

• Chaulagain Bhim, University of Florida (USA)
• Dufault Nicholas, University of Florida (USA)
• Raid Richard Neil, University of Florida (USA)
• Rott Philippe, CIRAD-BIOS-UMR BGPI (USA) ORCID: 0000-0001-6085-6159 - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/594369/)

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