A new field test for molluscicides in vegetable crops
1997
SPEISER, B.
Standard methods for assessing the efficacy of molluscicides have been developed for testing products that contain either metaldehyde or carbamates as active substances. Because these methods are not satisfactory for testing other products, a new field test has been developed. In order to maximize slug feeding activity, lettuce is grown in close proximity to a grass sward, and the experimental area is generously watered. Each experimental plot is 3 × 3 m wide and consists of an area of grass sward. The central area (1.25 × 1.25 m) of each plot is harrowed and planted with 9 lettuce seedlings. The plots are arranged in a randomized design with six replicates per treatment. The percentage of leaf area eaten is recorded twice during the first week, and later weekly. From this data, the standardized area under the damage progress curve (AUDPC) is calculated. This is the integral of leaf loss over time and gives a comprehensive overview over the time course of slug damage. At harvest, the number of marketable lettuce heads and their head weight are recorded. Some results of molluscicide trials in 1996 are given. The possibilities for adjusting plot size, choice of crop, number of replicates and number of assessment dates to personal needs are discussed.
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