The influence of cabbage stem flea beetle (Psylliodes chrysocephala (L.)) on yields of oilseed rape
1986 British Crop Protection Conference Pests and diseases Volume 2 Proceedings of a conference held at Brighton Metropole, England, November 17-20, 1986: 753-759
Damage assessment trials to investigate the effects of cabbage stem flea beetle (Psylliodes chrysocephala) on yields of winter oilseed rape are described. Results indicate that if an application of an effective insecticide is made in NovemberDecember when larval numbers are five per plant or greater, a yield response of 0.34 tonnes per ha (at 92% dry matter) can be expected and use of this population level in late autumn as a treatment threshold will avoid significant yield losses. Preliminary results also indicate that no extra yield increment is obtained from spring treatment if effective autumn control measures have been taken, even if subsequently larval numbers increase to over 13 per plant by April. In the absence of autumn control, springapplied treatment appears to give a worthwhile yield response if larval numbers in spring increase to at least five per plant or more. The possibility that incidental control of aphid vectors of beet western yellows virus can affect yield response to cabbage stem flea beetle treatments is also discussed.