mefenoxam and mandipropamid

Phytophthora root rot can greatly impact citrus production worldwide, especially in newly established orchards by reducing crop yield and increasing the cost of disease management. Mandipropamid is an Oomycota fungicide that is currently registered as a soil treatment for citrus nursery container plants to manage Phytophthora root rot. In this study, we investigated the uptake of mandipropamid into citrus roots and its translocation to stems and leaves after soil application and evaluated its mobility in roots as compared to oxathiapiprolin and mefenoxam using split-root potted plants and trees in the field. A bioassay and liquid chromatography-tandem mass spectrometry were used to detect and quantify fungicides in citrus tissues, and overall, similar results were obtained using the two methods. When applied to the soil of potted, 6- to 7-month-old citrus plants using labeled rates, the majority of mandipropamid was found in root tissues (4.9 to 18.1 μg/g), but small amounts were also present in stems (0.18 to 0.32 μg/g) and leaves (0.03 to 0.22 μg/g). There was no significant increase in concentrations in all three tissues between 1 and 4 weeks after application. Concentrations in all tissues exceeded established EC

Topics: Citrus; Fungicides, Industrial; Phytophthora

Phytophthora blight is a destructive disease caused by the oomycete

Topics: Alanine; Amides; Benzamides; Carboxylic Acids; Fungicides, Industrial; Hydrocarbons, Fluorinated; Imidazoles; Morpholines; Phytophthora; Plant Diseases; Pyrazoles; Sulfonamides; Tennessee

Oxathiapiprolin is a new fungicide with extremely high efficacy against oomycete plant pathogens. Solo components oxathiapiprolin (OXPT), chlorothalonil (CHT), azoxystrobin (AZ), mandipropamid (MPD), and mefenoxam (MFX) were compared with each other and with four oxathiapiprolin pre-packed fungicidal mixtures, OXPT+CHT 1+66.7, OXPT+AZ 1+10.3, OXPT+MPD 1+8.3, and OXPT+MFX 1+3 (weight active ingredient ratio), for control efficacy of late blight induced by MFX-insensitive Phytophthora infestans strains in tomato in growth chambers and the field. Mixtures performed better than all partner fungicides alone, except OXPT. Of the four mixtures, OXPT+MFX outperformed, with the highest preventive, curative, translaminar, and systemic efficacies. In the field, OXPT+MFX was superior to other fungicides in controlling late blight epidemics induced by MFX-insensitive isolates. Its deployment in the field will combat the dominating MFX-insensitive isolates, reduce the selection pressure imposed on P. infestans and delay the buildup of subpopulations resistant to oxathiapiprolin.

Topics: Alanine; Amides; Carboxylic Acids; Drug Resistance, Fungal; Fungicides, Industrial; Hydrocarbons, Fluorinated; Nitriles; Phytophthora infestans; Plant Diseases; Pyrazoles; Pyrimidines; Solanum lycopersicum; Strobilurins