Einfluss verschiedener Saattermine auf den Erbsenwicklerbefall (Cydia nigricana Fabr.) in ökologischen Gemüseerbsen

Summary

The pea moth (Cydia nigricana) has developed to the most serious pest in organic green peas in recent years. In 2003 about 20 % of the contracted acreage needed to be rejected by the processing industry, due to the very low tolerance levels requiring at least 99,5 % (w/w) non affected high quality peas. The present study investigated the influence of different sowing dates on the damage level in green peas. In a small scale field experiment arranged in a complete randomized block design with four replicates three common cultivars suitable for early, mid and late sowings, namely Avola, Gonzo, Trompet, respectively, were utilized. Each variety was sown at an early and a late date, resulting in six sowing dates at total, covering the entire sowing period from mid March to mid May. Subsamples of 3 x 1,5m2/plot were harvested by threshing and pea moth related infestation was assessed as the percentage of damaged peas. Crop phenology was recorded in weekly inspections. Flight activity of male moths was monitored twice a week by pheromone traps. As a result, only the early sowing dates revealed damage levels below the required threshold of 0,5 %. Green peas sown after mid of April where increasingly affected, approaching 3-6 % damaged peas. Damage was closely related to the coincidence in time of a) flowering and the onset of maturing pods with b) the phenology of monitored pea moths. The onset of flowering did not depend only on the sowing date but also on the respective pea cultivar. As registered C. nigricana-control options are lacking as present, the described strategy of coincidence avoidance in combination with fast maturing cultivars appears to be the most suitable contribution in reducing the risk of pea moth attack in organic green peas.