Harmfulness of wheat leaf rust in the eastern part of forest-steppe of Ukraine

Abstract

The comparison of data obtained as a result of artificial inoculation in the period of leaf blade formation with the data received as a result of inoculating older plants in the natural infectious background shows that the drop in the weight of grains from a spike and the weight of 1000 grains depends on the degree of affect. It directly depends on the efficiency of resistance genes and on the stage of plants' development when the affect took place. So infection at an earlier stage of plants' development results in more harmful damage of the pathogen than infection at later stages. In the artificial infectious background (infection of plants in the early period of leaf flag formation) the decrease in grain weight from a spike is between 0.7–35%; weight of 1000 grain is between 0.5–13.9%. In the background of a later natural infection of the plants with a moderate development of the disease the indices of harmfulness in much lower and is between 0.9–14.5% and 0.1–5.5%, respectively. The decrease of 1000 grains weight is significantly lower as compared to the weight of grain from a spike which is obviously connected to the fact that in the lower and central deeply affected spikelets grain are not formed.