It was subsequently identified as being active against early and late blights in potato and tomato. Effectiveness of Sequential Applications Chlorothalonil-Zn and AzoxystrobinĪzoxystrobin is a natural fungicide originally discovered in mushrooms in the Czech Republic. Results are grouped based on comparisons.ī.
Early blight symptoms appeared within three days of last application. The last treatment was applied when p-days was between 480 and 540. All applications were started when the physiological days (p-days) reached between 350 and 450 and were spaced at 5 to 7 day intervals in August. Multiple treatment applications were used in 19, three fungicide treatments were applied, and in 2000 to 2005, there were four application dates. Multiple Application Trials (1998-2005)Īll early blight trials from 1998 to 2005 were conducted on the variety Atlantic at the UNL Panhandle Research and Extension Center, Scottsbluff, NE (Table 3). In these trials 20 plants were measured in each plot and the formula used wasĮBI= ((# plants without symptoms x 0) + (# plants with 1% infection level x 1) + (# plants with 5% x 5) + (# plants with 10% x 10) + (# plants with 25% x 25) + (# plants with 50% x 50) + (# plants with 75% x 75) + (# plants dead x 100)) / 20 (or total # plants). This number was divided by the number of plants measured to give the % of the plot showing symptoms. The general formula was the sum of the number of plants at each infection level times the infection level as a percent. It indicated the percent of each plot showing early blight symptoms. YearĮarly Blight Index (EBI) was used to compare treatment effectiveness on different reading dates.
Chlorothalonil fungicide tomato early blight trial#
Trial locations, cultivar and date of first early blight symptons (1991-1995). This may be the most accurate method to compare treatments, varieties and conditions. Based on these individual plant measurements of infection, an early blight index was calculated that depicts the percentage of the plot infected with early blight. Measurements were taken on 20 plants per plot with four plots per treatment. Effectiveness was determined weekly after application as percent of each plant that is infected with early blight at increments of 0, 1, 5, 10, 25, 50, 75, and 100% (dead). Plant Growth Regulators and Fungicide StandardsĮarly blight trials began in 1991 and were designed to evaluate the longevity of the effectiveness of a single fungicide application against early blight (Table 1).
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