Development of a decision support system for managing Heterodera schahtii in sugar beet production

A decision support system, SBN-Watch, was developed to demonstrate the influence of crop rotation and the choice of sugar beets (Beta vulgaris) varieties on the sugar beet cyst nematode Heterodera schachtii Schmidt (SBN) population and sugar beets yield. The database in SBN-Watch consists of a varietal unit with five sugar beet varieties representing the three categories "Standard," "Tolerant," and "semi-tolerant." Data of minimal yield (m), tolerance limit (T), and population dynamic parameters were obtained from published commercial field trials conducted in Sweden and Denmark in 2011. Additionally, a sanitation intercrop unit with different resistant classes of white mustard (Sinapsis arvensis) and oil seed radish (Raphanus sativus) was included. The relationship between initial population (Pi) and sugar yield as well as SBN final population in soil (Pf) was calculated by two Seinhorst equations. Few data inputs are required to be entered by the user in SBN-Watch, mainly the initial population (Pi), expected sugar price and exchange rate of (sic) to SEK. The calculated reproduction factor (Rf) values using SBN-Watch corresponded well with varietal characteristics, where the standard variety Mixer had the highest (RI) values. The influence of the initial SBN population on the calculated sugar yield (tonnes ha(-1)) was generally small at Pi < 2.