Utvecklingen hos nattskatta (Solanum nigrum L.) och dess bekämpningsbehov i konservärtsodling

Sammanfattning: Black nightshade (Solanum nigrum L.) is a major problem in gardenpea cultivations contracted by Findus AB, a Swedish food processing company. The main problem is that the nightshade berries contain solanin and, thus, are not tolerated in the marketed product, which is fresh frozen peas. In addition, berries have the same size and color as the peas and cannot be separated at the factory. Black nightshades have the last ten years become a more common weed in field grown vegetables in the southern parts of Sweden. This MSc thesis presents an experiment conducted in 2005, aiming at developing a tool for predicting the need for control of black nightshade in peas. The report includes a literature review concerning characteristics, growth and plant development of black nightshade. Also, it includes a description of the pea cultivation strategy of Findus AB. The experimental part consisted of registration of the development of black nightshade in relation to pea plants. The registrations were done in pea fields contracted by Findus AB. The study of development was conducted in fields with four pea cultivars differing in earliness. No berries of black nightshade were produced before the harvest of the two early pea cultivars. However, nightshade plants growing in fields with late pea cultivars were able to produce berries before harvest, indicating a need for an effective weed control. The data from these experiments was then compiled to form graphic presentations for each of the species. These graphs show the relationship between the development of black nightshade and peas, and can be used to predict the risk of nightshade plants producing berries before harvest of peas. As a result, the data from these graphs can assist farmers and weed assistants in determining whether or not black nightshade shall be controlled.