By: Peppi Laine
The efficacy of fungicides against Rhizoctonia solani was evaluated in one field trial with naturally infected seed potatoes. Pencycuron DS (pencycurom 125 g/kg) was tested with rates 100 g and 200 g per 100 kg seed potatoes and Pencycuron FS (pencycurom 250 g/kg) was tested with rates 30 ml and 60 ml per 100 kg seed potatoes. The standard treatment was Moncut 40 SC (flutolanil 449 g/l)
12.5 ml/100 kg.
The growing season 2006 was exceptionally warm and dry in whole Finland. The potato trial was planted on May 5 in Jokioinen. There were no statistically significant differences in the emergence between the fungicide treatments and the untreated control. The underground stems were assessed for the symptoms of stem canker first after the emergence and again when the rows were closing. In the first assessment, on average 37 % of the shoots per plant in the untreated plots had no stem canker (see figure 1), while the percentage of healthy shoots in plots with Pencycuron DS 200 g/100 kg was 50 % and in plots with Moncut 40 %. In the later assessments there seemed to be more healthy shoots in plots with Pencycuron FS 60 ml/100 (figure 2).
The fungicide treatments did not increase the total tuber yield (figure 3), but all the tested fungicides reduced the amount of tubers with Rhizoctonia black scurf (figure 4). All the seed treatments seemed to increase the proportion of tubers in smaller size fraction 35-55 mm. However healthy tubers in size 35-70 mm were considered as marketable yield. Seed treatments with Pencycuron DS and Moncut increased the marketable yield compared to the untreated plots (figure 5). The treatments with the liquid formulations of Pencycuron FS seemed to slightly reduce the marketable yield in tons. In the seed potato production, where smaller tuber size is desired, this does not necessarily mean economical loss.
The efficacy of fungicides against Rhizoctonia solani was evaluated in one field trial with naturally infected seed potatoes. Pencycuron DS (pencycurom 125 g/kg) was tested with rates 100 g and 200 g per 100 kg seed potatoes and Pencycuron FS (pencycurom 250 g/kg) was tested with rates 30 ml and 60 ml per 100 kg seed potatoes. The standard treatment was Moncut 40 SC (flutolanil 449 g/l)
12.5 ml/100 kg.
The growing season 2006 was exceptionally warm and dry in whole Finland. The potato trial was planted on May 5 in Jokioinen. There were no statistically significant differences in the emergence between the fungicide treatments and the untreated control. The underground stems were assessed for the symptoms of stem canker first after the emergence and again when the rows were closing. In the first assessment, on average 37 % of the shoots per plant in the untreated plots had no stem canker (see figure 1), while the percentage of healthy shoots in plots with Pencycuron DS 200 g/100 kg was 50 % and in plots with Moncut 40 %. In the later assessments there seemed to be more healthy shoots in plots with Pencycuron FS 60 ml/100 (figure 2).
The fungicide treatments did not increase the total tuber yield (figure 3), but all the tested fungicides reduced the amount of tubers with Rhizoctonia black scurf (figure 4). All the seed treatments seemed to increase the proportion of tubers in smaller size fraction 35-55 mm. However healthy tubers in size 35-70 mm were considered as marketable yield. Seed treatments with Pencycuron DS and Moncut increased the marketable yield compared to the untreated plots (figure 5). The treatments with the liquid formulations of Pencycuron FS seemed to slightly reduce the marketable yield in tons. In the seed potato production, where smaller tuber size is desired, this does not necessarily mean economical loss.
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