The field experiment carried out in Winna Góra compared the efficacy of fungicide programs applied in accordance with the NegFry and Routine systems. The results of2002 validation achieved in Winna Góra showed that NegFry model forecasting the late blight occurrence is useful in Polish climatic conditions. Compared with routine treatment schemes, NegFry recommended fewer treatments without significant reduction of yield thus potato protection according to NegFry was more cost-effective than according to Routine system. Basing on these facts the NegFry decision support system can be recommended for Polish climatic conditions.

The objective of the study was to determine the effect of leaf wetness period and air temperature on development of disease symptoms caused by Puccinia recondita on winter wheat. The experiments were carried out in growth chamber at the Institute of Plant Protection in Poznań. Seedlings of a susceptible winter wheat cultivar Mikon, were artificially inoculated with urediniospores of P. recondita and incubated in temperature of 15 and 20°C. The period of duration of leaf wetness varied from 2 to 14 hours. Disease symptoms on seedlings at 20°C appeared 7 days after inoculation. Reduction of temperature to 15°C resulted in the elongation of latency period to 8 days. The relationship between leaf wetness period and disease symptoms severity was also observed. The gratest number of urediniospores in both tested temperatures were observed on plants exposed to 14 hours of leaf wetness. In temperature of 20°C 4 hours of wetness duration was enough to guarantee infection and the appearance of P. recondita pustules, whereas in 15°C at least 10 hours of wet period was needed to cause disease symptoms development. The experimental results were used to produce two equations describing relation between leaf wetness and symptoms development in tested temperatures.

Measurements of spectral reflectance from potato plants were carried out in the years 2000 and 2001 using the field radiometer CE 313 of Cimel Electronique Company. Field experiments permitted to perceive differences in the reflectance of electromagnetic radiation from potato plant cultivars Bekas and Mila as well as differences between the plants treated with fungicides providing the protection against Phytophthora infestans and the untreated plants. A differentiation of the values of vegetative indices between potato cultivars resulted from the unequal development rate of the cultivars and from their different susceptibility to Phytophthora infestans. The assessment of potato plants infection by the studied pathogen using spectral measurements agreed with the results of field inspection.

In the field experiments performed in 1999–2001 the profitability of late blight control in accordance with three decision support systems: NegFry, Simphyt and Stephan with routine fungicide program was compared. Potato protection carried out according to the recommendations of the decision support systems guaranteed higher profitability of late blight control than when potato was protected routinely. The highest profitability was recorded for susceptible variety Bekas protected according to NegFr.