Drill Grafting Application in Pistachio

Abstract

This study was conducted in Gökçebağ town

Siirt province

in a pistachio orchard comprising 40–45-year-old Siirt variety trees grafted onto Menengiç rootstock. To rejuvenate the aged trees

the drill grafting method was employed during two periods: early spring and flowering. In both applications

scions of the Siirt variety bearing two shoot buds were inserted into three trees using a drill bit with a diameter of 1-1.2 cm. Preliminary observations on May 1

2022

indicated bud sprouting in both periods. In early spring grafting

5 of 9 scions (55.5%) and 9 of 18 buds (50%) showed emergence

while in flowering-period grafting

only 3 of 9 scions (33.3%) and 3 of 18 buds (16.6%) sprouted. However

by June 6

2022

all grafts had failed

showing complete desiccation and extensive gum secretion at the graft sites. The failure was attributed to excessive gum production

intensified by the use of large-diameter drill bits

wide grafting wounds

and the presence of corky bark tissues. These factors likely prevented effective cambial contact between scion and rootstock. To improve outcomes

a second trial was initiated on March 6

2024

using younger branches and smaller drill bits (0.6-0.8 cm)

applied only during early spring. By April 17

2024

4 of 9 scions (44.4%) and 8 of 18 buds (44.4%) had sprouted. However

final checks on May 17

2024

revealed partial bud desiccation. These results suggest that gum secretion remains a major barrier to successful graft union in mature pistachio trees. Consequently

drill grafting is not a reliable method for rejuvenating old pistachio trees under these conditions

as it fails to ensure sustained cambial connectivity.