Improving a pest management tool for scenario analysis of economic populations of Globodera pallida

Globodera pallida is the most damaging pest of potato in the UK. This work underpins enhancement of a well-established, web-based scenario analysis tool for its management by recommending additions and modifications of its required inputs and a change in the basis of yield loss estimates. The required annual decline rate of the dormant egg population is determined at the individual field sample level to help define the required rotation length by comparing the viable egg content of recovered cysts to that of newly formed cysts for the same projected area. The mean annual decline was 20.4 +/- 1.4% but ranged from 4.0 to 39.7% annum(-1) at the field level. Further changes were based on meta-analysis of previous field trials. Spring rainfall in the region where a field is located and cultivar tolerance influence yield loss. Tolerance has proved difficult to define for many UK potato cultivars in field trials but uncertainty can be avoided without detriment by replacing it with determinacy integers. They are already determined to support optimisation of nitrogen application rates. Multiple linear regression estimates that loss caused by pre-plant populations of up to 20 viable eggs (g soil)(-1) varies from ca 0.2 to 2.0% (viable egg)(-1) (g soil)(-1) depending on cultivar determinacy and spring rainfall. Reliability of the outcomes from scenario analysis requires validation in field trials with population densities over which planting is advisable.