Effect of different Acacia acuminata variants as hosts on performance of sandalwood (Santalum spicatum) in the northern and eastern Wheatbelt, Western Australia

Abstract

Summary The effect of seven ‘jam variants’ (Acacia acuminata typical variant, A. acuminata narrow-phyllode variant, A. acuminata small-seed variant, A. acuminata/burkittii variant I, A. acuminata/burkittii variant 2, A. burkittii and A. oldfieldii) on the survival and growth of sandalwood (Santalum spicatum) was examined in two relatively low-rainfall locations, Dowerin and Morawa, in the northern and eastern Wheatbelt of Western Australia. During the course of the trial (2000–2008) the mean annual rainfall was only 326 mm at Dowerin and 259 mm at Morawa. In July 2000, seedlings from 84 families from 18 separate populations and representing each of the seven different jam variants were planted on cleared farmland at both locations. A total of 4032 host seedlings were planted at each site. At host age 2 y (April 2002), S. spicatum seeds were sown near 1807 host plants at the first site and near 1397 hosts at the second. The different jam variants were associated with clear differences in sandalwood performance at both sites. At age 1 y, mean survival of sandalwood was significantly greater near A. acuminata small—seed variant (64%) and A. acuminata narrow-phyllode variant (50–54%) than near A acuminata typical variant (21–34%). This pattern of sandalwood survival between the different jam variants was similar at age 6 y. At age 6 y, the mean stem diameter (at 150 mm above ground) of sandalwood was the greatest near A. acuminata small-seed variant within each site: 62 mm at Dowerin and 47 mm at Morawa. The mean stem diameter of sandalwood near A. acuminata typical variant was 51 mm at Dowerin and only 25 mm at Morawa. Stem borers were more common in A. acuminata typical variant than in the other jam variants at Dowerin. No borers were observed in the jam variants at Morawa. At both sites, gall rust was observed in each of the jam variants except A. oldfieldii.