EFFECT OF LARVAE OF WESTERN CORN-ROOTWORM (COLEOPTERA, CHRYSOMELIDAE) AND OF MECHANICAL ROOT PRUNING ON SAP FLOW AND GROWTH OF CORN

Little information is available on the growth response of corn, Zea mays L., to either mechanical root injury or infestation by western corn rootworm, Diabrotica virgifera virgifera LeConte. Studies were conducted in the greenhouse to determine growth and sap flow rates in corn when known proportions of the root system were damaged by mechanical root pruning and infestations of com rootworm larvae. Corn was transplanted into boxes that divided the roots into four sections. Roots in various sections were mechanically pruned or infested with 100 neonate larvae of the western corn rootworm. Sap flow was measured using a heat balance technique, and root and shoot growth were measured. Mechanical pruning of roots decreased sap flow, fresh and dry weight of stalks and roots, and plant height. Infesting roots with rootworm larvae did not significantly, affect sap flow, fresh or dry weight of stalks, or plant height. Fresh and dry weights of roots were reduced in boxes infested with rootworm larvae.