California Avocado Society 1971-72 Yearbook 55: 97-109 USE OF THE ETIOLATION TECHNIQUE IN ROOTING AVOCADO CUTTINGS

several hundred rooted cuttings from selected avocado seedlings in order to establish test plots for Phytophthora cinnamomi root rot research. These seedlings had been selected at Riverside as being more resistant to avocado root rot than the stocks currently used in commercial practice. Vegetative propagation of these selected root-stocks is necessary because seedlings of the same clones vary in their resistance to root rot (14.18). In addition, some of the selections had not fruited so seed was not available. These rootstocks could be produced either by root pieces (6) or by stem cuttings. Regeneration from root pieces in the avocado is possible, but the amount of propagating material would be limited, the operation laborious and in many cases results arc unpredictable. Stem cuttings from young avocado seedlings root quite readily (2); however, all of the selections to be used in this work were several years old and had passed beyond the young or juvenile stage. A few old clones of avocado can be rooted moderately well (10,11,16). Work in Israel suggested that rooting could be improved in some clones by the use of rooting hormones (8). Varying success has als