A Simulation Model of Heterodera schachtii

A simulation model of a single sugarbeet, Beta vulgaris L., plant infected by the sugarbeet cyst nematode, Heterodera schachtii Schmidt, was developed using published information. The model is an interactive computer simulation programmed in FORTRAN. Given initial population densities of the nematode at planting, the model simulates nematode population dynamics and the growth of plant tap and fibrous roots. The driving variable for nematode development and plant growth is temperature. The sugarbeet cyst nematode, Heterodera schachtii Schmidt, is a damaging pathogen of sugarbeets worldwide (2,14). Control strategies typically include crop rotation and preplant nematicides, although some granular nematicides may be applied post- plant. Damage thresholds have been de- veloped for several geographical regions of the world. Within a given region, how- ever, damage thresholds can vary with environment and growing conditions. In- creased understanding of nematode pop- ulation dynamics as related to plant growth is important for improved management decisions regarding nematodes in agro- ecosystems. Computer simulation models have helped advance our understanding of nematode- host plant interactions (7,18,21). We report here on the development of a simulation model of H. schachtii infecting the sugar- beet, Beta vulgaris. This work was initiated in 1980, and an abstract of this work has been published (5). MODEL DEVELOPMENT The model simulates population dynam- ics of the nematode on a single sugarbeet