Aphids

In the autumn, peach-potato aphid can transmit Turnip Yellows virus which can lead to reduced yields.  These peach-potato aphids and cabbage aphids may be found overwintering on rape, but they do not cause any feeding damage until the summer.  It is then that colonies of cabbage aphids may be seen on the stems, leaves and pods of both winter and spring rape plants.  Problems are more likely in dry summers, and an aphicide treatment is recommended if approximately 10% of flowering heads of winter rape are infested with aphids during flowering, and 5% of spring-sown rape plants infested during green-yellow bud.