Kevin V. McCully1, Peter Scott2, Jacques Lavoie3 and Gilles Godbout4
Abstract: Small plot research trials and a field scale trial were established to evaluate the effect of planting potatoes into soils which were treated with Muster 75 DF herbicide the previous year. The objectives were to determine if crop injury, quality, and yields would be negatively impacted across varieties. In the small plot research trials Muster + Agral 90 was applied at 20 g/ha + 0.2% v/v (1X), and 40 g/ha + 0.2% v/v (2X) rates the previous fall. In the field scale trial Muster + Agral 90 was applied at 15 g/ha + 0.2% v/v the previous spring. Crop injury visual ratings were collected in the small plot research trials, and potato yields were collected and graded in both the small plot and field scale trials. Results from the small plot research trials indicated that final crop injury ratings, total yields, and marketable yields from the four potato varieties evaluated (Superior, Atlantic, Shepody, and Russet Burbank) were not significantly different from the untreated control. These four varieties were therefore safe to replant into soil previously treated with Muster + Agral 90 at 20 g/ha + 0.2% v/v (1X). Overall potatoes were more sensitive to the (2X) 40 g/ha Muster rate. Crop injury ratings were higher, and total yields and marketable yields were lower than the untreated control. Although crop injury was higher and total and marketable yields lower on Atlantic and Russet Burbank varieties, they were not significantly different from the untreated control. Shepody marketable yields were also not significantly different from the untreated control. Superiors were the most sensitive variety and may be at risk for yield reductions if 2x Muster rates result from over application. Results from the large field scale trial also confirmed potatoes tolerance to Muster herbicide carryover when applied at 15 g/ha rates the year previous to planting potatoes. Shepody, Russet Burbank, and Gold rush varieties all were considered very tolerant. Total and marketable yield differences between the untreated and the treated fields was considered minor. Russet Norkotah yields were much lower than the untreated control but were the result of competition from volunteer Canola and not Muster carryover.
1NB Potato and Horticulture Branch, NBDARD, Fredericton, NB E3B 5H1
2Wicklow Regional Office , NBDARD, Wicklow, NB E7L 3S4
3Grand Falls Regional Office, NBDARD, Grand Falls, NB E3Z 1G1
4Eagle Farm Ltd, Grand Falls, NB E3C 1E7