Fungicides Boscalid Research Articles

Annual Meeting, Québec, Quebec, 2006, The Canadian Phytopathological Society / Réunion annuelle, Québec, Québec, 2006, La Société canadienne de phytopathologie

Annual Meeting, Québec, Quebec, 2006, The Canadian Phytopathological Society / Réunion annuelle, Québec, Québec, 2006, La Société canadienne de phytopathologie

A NEW SEMI-SELECTIVE MEDIUM FOR THE OCHRATOXIGENIC FUNGUS ASPERGILLUS CARBONARIUS

SUMMARY Aspergillus carbonarius (Bainier) Thom. and Aspergillus niger Van Tieghem are common fungal contaminants of several commodities, including grapes. A. carbonarius is the most important, if not the exclusive, responsible for wine contamination by ochratoxin A (OTA) in Mediterranean areas. Identification of A. carbonarius is made difficult by its high similarity with A. niger, the Aspergillus species most common on grapes, as well as with other species of the section Nigri of this genus. Hence, it requires deep knowledge of fungal taxonomy. A semi-selective medium based on Malt Extract Agar amended with appropriate antibiotics (chloramphenicol and chlortetracycline) and fungicides (dichloran and boscalid) was developed in order to speed up the quantitative detection of A. carbonarius in grapes and musts and improve risk assessment of OTA contamination in wine.

新規殺菌剤ボスカリド (エメラルトDG) に関する研究

新規殺菌剤ボスカリド (エメラルトDG) に関する研究

Sicklepod (Senna obtusifolia) Control and Seed Production after 2,4-DB Applied Alone and with Fungicides or Insecticides

Experiments were conducted during 1999, 2002, and 2003 to evaluate sicklepod control by 2,4-DB applied alone or in mixture with selected fungicides and insecticides registered for use in peanut. The fungicides boscalid, chlorothalonil, fluazinam, propiconazole plus trifloxystrobin, pyraclostrobin, or tebuconazole and the insecticides acephate, carbaryl, esfenvalerate, fenpropathrin, lambda-cyhalothrin, methomyl, or indoxacarb applied in mixtures with 2,4-DB did not reduce sicklepod control by 2,4-DB compared with 2,4-DB alone. The fungicide azoxystrobin reduced control in some but not all experiments. Sicklepod control was highest when 2,4-DB was applied before flowering regardless of fungicide treatment. Seed production and germination were reduced when 2,4-DB was applied 81 to 85 d after emergence when sicklepod was flowering. Applying 2,4-DB before flowering and at pod set and pod fill did not affect seed production.

Effect of the F129L Mutation in Alternaria solani on Fungicides Affecting Mitochondrial Respiration.

Isolates of Alternaria solani previously collected from throughout the Midwestern United States and characterized as being azoxystrobin sensitive or reduced sensitive were tested for sensitivity to the Quinone outside inhibitor (QoI) fungicides famoxadone and fenamidone and the carboxamide fungicide boscalid. All three fungicides affect mitochondrial respiration: famoxadone and fenamidone at complex III, and boscalid at complex II. A. solani isolates possessing reducedsensitivity to azoxystrobin also were less sensitive in vitro to famoxadone and fenamidone compared with azoxystrobin-sensitive isolates, but the shift in sensitivity was of lower magnitude, approximately 2- to 3-fold versus approximately 12-fold for azoxystrobin. The in vitro EC50 values, the concentration that effectively reduces germination by 50% relative to the untreated control, for sensitive A. solani isolates were significantly lower for famoxadone and azoxystrobin than for fenamidone and boscalid; whereas, for reduced-sensitive isolates, famoxadone EC50 values were significantly lower than all other fungicides. Isolates of A. solani with reducedsensitivity to azoxystrobin were twofold more sensitive in vitro to boscalid than were azoxystrobin-sensitive wild-type isolates, displaying negative cross-sensitivity. All isolates determined to have reduced-sensitivity to azoxystrobin also were determined to possess the amino acid substitution of phenylalanine with leucine at position 129 (F129L mutation) using real-time polymerase chain reaction. In vivo studies were performed to determine the effects of in vitro sensitivity shifts on early blight disease control provided by each fungicide over a range of concentrations. Reduced-sensitivity to azoxystrobin did not significantly affect disease control provided by famoxadone, regardless of the wide range of in vitro famoxadone EC50 values. Efficacy of fenamidone was affected by some azoxystrobin reduced-sensitive A. solani isolates, but not others. Boscalid controlled azoxystrobin-sensitive and reduced-sensitive isolates with equal effectiveness. These results suggest that the F129L mutation present in A. solani does not convey cross-sensitivity in vivo among all QoI or related fungicides, and that two- to threefold shifts in in vitro sensitivity among A. solani isolates does not appreciably affect disease control.

Toward a structural approach to pictorial language

The challenge of the present comprehensive work was to study, from apple orchards to consumer’s plate, the influence of high- and low-temperature thermal treatments on the most frequently occurring fungicides (boscalid, captan, pyraclostrobin) and insecticides (acetamiprid, methoxyfenozide) in apples and processing factor (PF) application for more realistic dietary risk assessment in the new EFSA methodology. Dry pasteurization and canning combined with previous preliminary treatment gave PFs = 0.25–1.8 of the five active substances. Acute exposure (expressed as %ARfD) in the raw commodity was demonstrated to be 168.1% for acetamiprid in the worst case (input – highest residue) and 307.9% for boscalid in the most critical case (input - MRL), and after re-calculation for PF, decreased to 139.5% for acetamiprid in canned product and 203.2% for boscalid in pasteurized apples. These novel data may be helpful in estimating new threshold residue levels significant in food safety especially intended for children.