Response of Colletotrichum Coccodes to Selected Fungicides Using a Plant Inoculation Assay and Efficacy of Azoxystrobin Applied by Chemigation

Abstract

A plant inoculation assay was developed and used to evaluate fungicide efficacy and application timing for reduction of infection of potato stems by Colletotrichum coccodes. Incidence of infected stems treated with azoxystrobin, pyraclostrobin, fluoxastrobin, and mandipropamid + difenoconazole was significantly less than the non-treated control plants when fungicides were applied prior to inoculation. However, fungicide application after inoculation did not significantly reduce infection. Chlorothalonil and mancozeb were not effective in preventing infection by C. coccodes. Additionally, early season fungicide applications by center pivot chemigation in commercial potato fields were evaluated as a potential black dot management tactic. Below-ground stems sampled from replicated plots in commercial fields where azoxystrobin was applied by chemigation at 50 and 67 days after planting (DAP) had significantly less stem surface area covered with sclerotia at 79 DAP than the non-treated control in two of 2 years. However, the effect was not observed both years at a subsequent collection at 102 DAP and only one of 2 years at 140 DAP. Latent infections were detected in non-symptomatic plants collected from the field.Resumen Se desarrolló y utilizó un ensayo de inoculación de plantas para evaluar la eficacia y tiempo de aplicación de fungicida para la reducción de la infección en tallos de papa por Colletotrichum coccodes. La incidencia de tallos infectados tratados con azoxystrobin, pyraclostrobin, fluoxastrobin y mandipropamid + difenoconazole, fue significativamente menor que las plantas testigo no tratadas cuando se aplicaron los fungicidas antes de la inoculación. No obstante, la aplicación del fungicida después de la inoculación no redujo significativamente la infección. Clorotalonil y mancozeb no fueron efectivos en prevenir la infección por C. coccodes. Adicionalmente, se evaluaron aplicaciones de fungicidas al principio del ciclo de cultivo por quimirrigación de pivote central en campos comerciales de papa, como táctica potencial de manejo de la mancha negra. Los tallos subterráneos muestreados de lotes con repeticiones en campos comerciales donde se aplicó azoxistrobin por quimirrigación a 50 y 67 días después de la siembra (DAP), tuvieron significativamente menos área superficial del tallo cubierta con esclerocios a 79 DAP, que los testigos no tratados en dos años. No obstante, no se observó el efecto en ambos años en una colecta posterior a 102 DAP, y solo en uno de los dos años a 140 DAP. Se detectaron infecciones latentes en plantas asintomáticas colectadas en el campo.

Effect of Extended Crop Rotations on Incidence of Black Dot, Silver Scurf, and Verticillium Wilt of Potato

“…However, black dot levels were not reduced when azoxystrobin was applied at planting in a previous study (9) and incidence of black dot was observed not to be affected with an application at planting in the present study. Reductions in black dot levels were incon sistent when azoxystrobin was applied by chemigation in a previous study (21) and were inconclusive in this study. The one exception, field U5W, was rotated out of po tatoes for 15 years and had a black dot incidence of 9%.…”

Combate químico de la antracnosis de Sansevieria trifasciata var. Hahnii en un sistema de hojas separadas.

“…En términos generales, la aplicación a los 0 ddi fue más eficaz. Otros autores (Serey et al, 2007;Della-Rocca et al, 2011;Días y Latorre, 2013) también han observado, para otros patosistemas, incluidas otras especies de Colletotrichum (MacKenzie et al, 2009;Ingram et al, 2011), una mayor eficacia de fungicidas de los grupos aquí evaluados cuando se aplicaron en pre-inoculación. Sin embargo, el combate de la enfermedad se reduce conforme aumenta el tiempo que transcurre entre la aplicación del fungicida y la inoculación (Poblete y Latorre, 2001;Mondal et al, 2007).…”

Utilizing FTIR-ATR spectroscopy for classification and relative spectral similarity evaluation of different Colletotrichum coccodes isolates

“…[1][2][3] It is primarily found on Solanaceae, Fabaceae and Cucurbitaceae, and is particularly destructive as black dot disease in potatoes and anthracnose on tomatoes. 4,5 There are more than one hundred known isolates of this fungus in Israel. C. coccodes is difficult to control and it is considered as seed tuber and soilborne.…”