Key and secondary arthropod pest population trends in apple cultivated over four seasons with no insecticides and a legume cover

Abstract

The reduced use of insecticides in apple orchards has caused many to expect secondary pests to become a serious problem. To assess the validity of this concern, we monitored arthropod populations in apple orchards cultivated with no insecticides and an alfalfa or grass cover over four seasons. Codling moths became economically injurious, while leafroller populations declined to sub-economic levels. No other species caused economic injury. Our results suggest that secondary pests may be, to some extent, pesticide induced. We did not observe any significant effect of cover treatment on arthropod populations. However, some evidence suggests that an alfalfa cover may contribute modestly to increased biological control. © Taylor & Francis Group, LLC.