1. The estimate of historical TSWV incidence that you provide for your location is used as a reference for the tool's forecasting. The tool queries weather data to compute estimates for five years in the past, the average of these estimates is adjusted based on the value you provide, and forecasts are made relative to this adjusted average. The rationale for this adjustment lies in the fact that there is variation in cultivation practice that is sure to lead to variation in TSWV incidence, and providing risk estimates relative to your history accounts for this, assuming you continue to do what you did during the time that you observed TSWV incidence in the past.
2. The effect of using Imidacloprid as a tray drench in the greenhouse has been shown to reduce late-season TSWV incidence. If you used Imidacloprid in the past, then your estimate of historical TSWV incidence reflects this. If you use Imidacloprid again during the current year, then the tool's estimate of risk will be as accurate as possible relative to the effects of Imidacloprid use. Similarly if you did not use Imidacloprid during the years that constitute your observation of historical TSWV, and you do not use it during the current year, the tool will again be as accurate as possible. In other words, the tool estimates change in weather-driven TSWV risk, assuming cultivation practice does not change.
3. A seasonal "biofix" date is used as a point in time when degree day accumulations begin. Degree day accumulations are used to describe development of organisms such as plants and thrips. For thrips, the biofix date used depends on your location. For more southeastern (generally warmer) locations, biofix is later based on the expectation that thrips enter their state of overwintering later. For more northwestern (generally cooler) locations, biofix is earlier.
4. This tool was developed using data describing TSWV incidence in tobacco. TSWV infects many other crops, and the biology underlying the epidemiology of TSWV in other crops is similar to that of TSWV in tobacco, but not the same. This tool can be reasonably used to estimate relative TSWV risk in southeastern crops other than tobacco, but it should be noted that the tool is most numerically accurate for tobacco.