JHULSACAST: A computerized forecast of potato late blight in western Uttar Pradesh*

JHULSACAST has three components, viz. i) late blight prediction models for western Uttar Pradesh, ii) a computer programme to forecast late blight (Phytophthora infestans) using the models developed for this purpose and, iii) an ‘interface’ to utilize weather data from an automatic weather station. All the three components were specifically developed for predicting late blight in western Uttar Pradesh. The models were developed by utilizing the weather data for 9 years collected at the Central Potato Research Instt. Campus, Modipuram. However, before constructing these models, some of the most popular late blight prediction models developed world over were also tested for their accuracy. Results revealed that none of them was fit enough to predict late blight accurately in western Uttar Pradesh. Two models developed one each for rainy and non rainy years are: Model 1 (Rainy year): i) measurable rain (0.1–0.5 mm) for a minimum of 2 consecutive days, ii) 5-day moving>85% RH periods≥50 hrs and iii) 5-day moving congenial temperature (7.2–26.6°C)≥105 hrs, Model 2 (non rainy years): i) 7-day moving > 85% RH period ≥ 60 hrs and ii) 7-day moving congenial temperature (7.2–26.6°C) ≥ 120 hrs. If any of the above conditions prevail for 7-consecutive days, blight would appear within 10 days.

A computer programme was written in Fox Pro to predict late blight using the above two models. The disease was successfully predicted for three consecutive years (1997–98, 1998–99, 1999–2000) using the computer programme and the above two models. An interface was also developed in Fox Pro for utilizing weather data directly from an automatic weather station.