FRUIT DISORDERS, MINERAL COMPOSITION AND TREE PERFORMANCE INFLUENCED BY ROOTSTOCKS OF 'ANJOU' PEARS

Experimental sites having different rootstocks under 'Anjou' pear trees (Pyrus communis L.) were located in central Washington State near Bridgeport, Dryden, Orondo and Othello. The latter location had eight different rootstocks. Observations were made near harvest time to determine the incidence of fruit disorders, root suckering, shoot growth, fruit size and yield. Fruit and leaf samples were collected for mineral analysis. Of the eight rootstocks tested near Othello, Pyrus betulaefolia and P. ussuriensis had the highest incidence of 'Anjou' cork spot and black end (hard end). In the other locations, trees on old Home X Farmingdale (OHXF) produced fruit with less cork spot than trees on 'Barlett' or 'French' rootstocks. The fruit disorder, alfalfa greening, occurred on either 'Bartlett' seedling or 'OHXF' rootstocks. Root suckering was only a problem on 'Old Home' and 'OHXF' clonal rootstocks. Shoot growth was least for trees on 'Old Home' rootstocks at the Othello location and for trees on 'OHXF' versus 'Bartlett' rootstocks at the Orondo and Dryden locations. In 1980 at the Othello location, yield was highest on trees with P. betulaefolia rootstock and least on 'Old Home'. At other locations, yield was slightly lower on trees with 'OHXF' rootstock versus 'Bartlett' or 'French' seedling rootstocks. At the Othello location, fruit size was consistently largest on trees with French seedling rootstocks. Fruit calcium concentrations were not related to rootstocks at the Bridgeport, Dryden and Orondo locations. Potassium concentrations were relatively high in fruit cortex from trees on P. betulaefolia and low in fruit from trees on 'Old Home' rootstocks at the Othello location.