Rootstock Effects on Pistachio Trees Grown in Verticillium dahliae-Infested Soil

Area of Science:

• Plant Pathology
• Horticulture
• Agronomy

Background:

• Verticillium wilt, caused by Verticillium dahliae, is a significant disease affecting pistachio production.
• Rootstock selection is crucial for managing disease resistance and optimizing pistachio tree performance.

Purpose of the Study:

• To compare the efficacy of two interspecific hybrid pistachio rootstocks (UCBI and PGII) against standard rootstocks in managing Verticillium wilt.
• To evaluate the impact of rootstock on pistachio tree yield, growth, disease incidence, and mortality.

Main Methods:

• A 10-year field trial was conducted in soil naturally infested with Verticillium dahliae.
• Interspecific hybrid rootstocks (UCBI, PGII) were compared with Pistacia integerrima (resistant) and P. atlantica (susceptible).
• Trees were assessed for yield, growth, Verticillium wilt symptoms, mortality, and V. dahliae presence in xylem at the graft union.

Main Results:

• Trees on the (P. atlantica x P. integerrima) hybrid UCBI rootstock exhibited growth and yield comparable to P. integerrima.
• The PGII hybrid rootstock resulted in the lowest yield.
• UCBI rootstock showed significantly lower V. dahliae infection (25%) compared to P. integerrima (65%) and P. atlantica (73%) at the graft union.

Conclusions:

• The UCBI hybrid rootstock offers a promising alternative for pistachio cultivation in Verticillium dahliae-infested soils, demonstrating good yield and enhanced resistance.
• Pistacia integerrima and UCBI likely possess different mechanisms for resistance to Verticillium dahliae.
• Rootstock choice significantly influences scion vigor, infection levels, and overall pistachio nut yield in diseased environments.