Dynamics of the weed infestation with Senecio vulgaris after a single entry from seeds

Abstract

Due to a short generation time associated with a high seed production and a quick germination, which is possible throughout the year, Senecio vulgaris is especially in horticultural crops one of the most important weed species. Like all ragwort species, also Senecio vulgaris contains pyrrolizidine alkaloids which are converted in the liver to harmful substances. For this reason an accidental consumption of this species should be avoided completely. Belonging to the Compositae, chemical control of this weed species in vegetable crops, particularly in lettuce, is difficult. Based on a field-grown model experiment the emergence behavior and growth of Senecio vulgaris in leafy lettuce was studied. The first step was the contamination of the trial plots with Senecio seeds. For this purpose Senecio plants were planted at three different densities (1, 2 and 10 plants m2) in the designated plots. All plots were covered with fleece in order to prevent an unregulated dispersal of seeds. After seed maturity the fleece was removed, plants were cut into small pieces and the plant material including the seeds was incorporated into the soil. Then different leafy lettuces crops (rocket, asia green, spinach, lamb´s lettuce) were cultivated in a six-crop sequence over two years (three crop sopecies per year). The development of Senecio vulgaris and the resulting possible contamination of the lettuces with Senecio leaves was recorded. From the date of removing the fleece on seed-production a shedding of Senecio plants was prevented to avoid further contamination. Also the entry from outside the plots was excluded. Depending on the initial plant density, the 71, 55 and 216 Senecio plants m2 which emerged after the first sowing of lettuce dropped to 7, 9 and 16 plants m2 after the sixth sowing. Thus, the density of S. vulgaris plants rapidly decreased but there was still a significant potential of emerging seedlings potentially contaminating the lettuce crops after six rotations. The trial will be continued until no germination of S. vulgaris plants occurs anymore.

Keywords

• population dynamics
• salad
• seed persistence
• vegetables
• weed control