Developing fruit inhibit the regrowth of cranberry shoots after apical meristem injury by larvae ofDasineura oxycoccana(Diptera: Cecidomyiidae)

Abstract

AbstractLarvae of gall making tipworm feed on and injure the apical meristems of cranberry shoots/uprights, disrupting vegetative growth. The majority of tipworm-injured flowering uprights do not resume vegetative growth via activation of lateral axillary buds (side-shoots) before the onset of dormancy. Furthermore, growth and flowering of uprights that fail to produce side-shoots after injury may be inhibited in the following year. In cranberry, limited availability of total nonstructural carbohydrates during fruit development has been reported. Thus, competition between developing fruit and lateral axillary buds for available resources may suppress vegetative regrowth in tipworm-injured flowering uprights. We carried out deblossoming experiments in the field and greenhouse to determine if presence of developing fruit inhibited the growth of side-shoots in tipworm-injured flowering uprights. We also compared tipworm-injured flowering and vegetative uprights to determine if growth form of an upright influenced regrowth after injury. Removal of flowers from tipworm-injured flowering uprights increased the production of side-shoots in three cultivars of cranberry (Ben Lear, Howes, and Stevens). In addition, more tipworm-injured vegetative uprights resumed growth by producing side-shoots, as compared with flowering uprights (Howes and Stevens). Our results suggest that unequal partitioning of resources between developing fruit and lateral axillary buds inhibits regrowth in tipworm-injured flowering uprights of cranberry.