P-384 - Rootstock influences hull rot of almond in Australia

In Australia, Hull rot impacts almond production due to infected nuts, while twig and fruiting spur dieback further exacerbates yield reductions in subsequent years. All growing regions of Australia are affected except Western Australia. Rhizopus sp. is the key pathogen causing hull rot in Australia, with onset occurring in January during the vulnerable stage of early hull split. Our research aims to address this challenge by focusing on effective management strategies. Assessment of an established rootstock trial demonstrated that Nonpareil grafted onto Peach Almond (P. persica x P. dulcis) rootstocks, particularly Monegro, Garnem, Hansen, and Felinem, exhibited increased hull rot susceptibility. Assessment of a planting density x rootstock trial found that Nonpareil grafted onto Barrier 1, Garnem, and Controller9.5 had similar numbers of hull rot strikes across both planting systems and may offer reliable performance regardless of planting density. Monegro, RootPac20, Controller7 and Krymsk86 had less than 10 hull rot strikes in 6.5m x 3m spacing while in 4.5m x 2m spacing, Krymsk86, RootPac40, RootPac20 and Controller6 had less than 10 hull rot strikes. Through this research, we aim to provide almond growers with effective tools and strategies to manage hull rot, ensuring sustainability and productivity of Australian almond orchards.