Summary:

Asparagus infection with numerous pathogens very often decreases yield of spears. Efficient protection of asparagus plantation can be very difficult and sometimes even unavailable due to lack of effective plant protection agents to control of some pathogens. The choose of cultivar and field before the establishment of plantation are crucial in such cases. Irrigation has also a very considerable impact on asparagus yielding. It can influenced the diseases development too. The aim of the research was to evaluate the susceptibility of microirrigated, three German asparagus cultivars to the plants infection by pathogens.The field experiment was settled in 1998 at KruszynKrajenski near Bydgoszcz on a sandy soil. The first factor was microirrigation used in variants: W1 - non-irrigated plots (control), W2 - drip-irrigated plots, W3 - microsprinkler-irrigated plots. Irrigation doses were adequate for amount and distribution of rain-precipitation and were found out by tensiometers, too. They amounted to 195 and 113 mm for micro-sprinkler and drip irrigation, respectively. The second factor were three German cultivars of asparagus: ‘Ap', ‘Gr' and ‘SchwetzigerMeisterschuss', grown for blanched spears. Plant healthiness observations were carried out in the first 4 harvest years (2000-2004). Occurrence of root and stem rot (Fusariumoxysporumf.sp. asparagi, F. culmorum), asparagus rust (Pucciniaasparagi), grey mould (Botrytis cinerea) and Stemphylium leaf spot (Stemphyliumvesicarium) were evaluated. Percentage of infected plants on the plot and degree of plant infection were estimated at the end of the vegetation period. There was a variability of cultivars infection with pathogens. The most severe disease symptoms were observed on the ‘SchwetzigerMeisterschuss'.Cultivars ‘Ap' and ‘Gr' were significantly lower infested. Microirrigation affected a development of asparagus diseases too.Analysis of mean values showed that irrigation of asparagus increasedP.asparagioccurrence and decreasedStemphylium leaf spot development.