The biology and management of prickly paddy melon (Cucumis myriocarpus L.), an important summer annual weed in Australia

Abstract Cucumis myriocarpus is an annual cucurbitaceous summer weed infesting fallow fields and pastures. Infestation results in reduced moisture availability for winter cereal crops as well as reduced crop yields and pasture quality. The need to manage this weed is of paramount importance given its adverse effects on farming systems, biodiversity and grazing livestock and its ranking as the number one weed of importance in Australian summer fallows of grain crops. Land management practices, including movement of grazing animals and over-stocking, are potentially assisting the spread of Cucumis myriocarpus fruits and viable seed. The plant is characterized by the presence of small, ellipsoid to spherical melon fruits with spiny appendages. Each plant can produce up to 50 or more melons per plant, with each fruit containing up to 200 viable seeds. Seed is often dormant upon fruit maturity and our results under controlled environmental conditions suggest both physiological and physical factors influence dormancy. Under field conditions, seedlings can form large vines growing upto 3 m in length. Field pollination experiments suggest that this melon is mainly self-pollinated by insects, including bees, flies and wasps. Cucumis myriocarpus is generally managed by the use of various broadleaf phenoxy herbicides and systemic post-emergent products. It is found in this study that this weed established through multiple flushes of germination, hence multiple herbicidal applications coinciding with rainfall events one suggested for more efficacious management. However, rotation of infested pastures with cereal crops such as canola and wheat also results in improved control. Additional studies into the impact of soil with and physical properties, disturbance and grazing, are recommended for development of more efficacious control measures. This review discusses taxonomy, genetic variation, biology and ecology and management of this important summer annual weed.