A.I. Campbell, A.F. Posnette, R. Cropley
A number of apple orchards on several different clonal rootstocks were planted 8–10 years ago in England to compare the growth, cropping and general performance of EMLA material with trees infected with several viruses and mycoplasma-like organisms.

Most of the infections reduced tree growth, crop weight and fruit size. Some of the virus treatments increased the proportion of red colour on the skin of the fruit of certain cultivars. Many of the virus effects could be modified by the application of different fertilizer treatments to the trees.

Campbell, A.I., Posnette, A.F. and Cropley, R. (1976). THE PERFORMANCE OF EMLA APPLE TREES. Acta Hortic. 67, 59-66
DOI: 10.17660/ActaHortic.1976.67.4

Acta Horticulturae