Plant galls being abnormal growths can alter the hypersensitive reaction (HR), a defensive mechanism that is supposed to kill pathogens, parasites and all other alien organisms, including gall-inducers. The aim of the study was to find an answer to the question, whether leaves of different size react similarly to a various number of galls of Mikiola fagi and Hartigiola annulipes. Leaves (3,179 with 7,011 galls of H. annulipes and 482 with 637 galls of M. fagi) from seven localities, including two nature reserves, were collected in western Poland in 2014. Analyses conducted as the logistic regression test showed that the HR in large leaves as reaction against H. annulipes was more often (but not statistically significant) than in small leaves. This trend was not observed in the case of M. fagi while there was no relationship between the HR and the leaf size for M. fagi. However, the linear regression test for both species showed a relationship between HR occurrence and the number of galls on the leaf blade.

   Keywords: hypersensitive reaction, galls, Hartigiola annulipes, Mikiola fagi, beech