RESEARCH & EVENTS
Rootstocks – Informing decision making using the ABA Rootstock Project resources
Josh Fielke Industry Development Officer
FROM new plantings to replants , from clay to sand , from disease tolerance to disease susceptibility , there are no end of considerations when it comes to what rootstock is best suited to your site . Research project AL20001 – Evaluation of Potential Prunus Rootstocks – Stage 3 is the continuation of the rootstock program setup in 2011 to address these questions . This project aims to help inform decisions on rootstock selection based on observations from three separate trial sites . These trial sites were planted in 2013 at Lindsay Point , SA , in 2020 at Loxton , SA and in 2022 at Darlington Point , NSW . When deciding to plant or replant an almond orchard , the decision on which rootstock to select should be just as important as the variety . There is no one rootstock that will suit every situation and there are some key aspects that need to be considered in the decision-making process such as soil characteristics , climate conditions and management objectives . This article outlines some of the consideration when determining which rootstock is best to plant and provides reference to three documents published through the rootstock evaluation project for observations made specific to the trial site .
1 )
ABA Rootstock trial technical document - Due to the young age of two of the sites a summary has been produced for the sandy , Lindsay Point site only . This document provides each rootstocks performance at this location .
2 )
AL16006 Final Report – The final report presents detailed analysis of information collected throughout the rootstock trial sites until 2021 .
3 ) Rootstock characteristics summary .
Why use a rootstock ? Rootstocks are utilized within the almond industry to optimise almond production and to overcome
challenges that are faced due to farm climate , soil and pest situation . The majority of Australian almond production is on Nemaguard which is a peach rootstock and is easy and cheap to propagate . Hybrid rootstocks such as peach-almond provide can provide significant benefits in crop production as they produce larger trees and continue to produce good crops on the grown wood . Lastly , there are plum-almond hybrids , these are not very common in the Australian almond industry . However , these rootstocks could play a role within in the industry in harder to manage heavier soils as they are more tolerant to wet feet .
The lay of the land It is critically important to know what you are planting into , and this is where the planning needs to begin . Firstly , knowing the soil type and the variation in soil characteristics across the property assists with understanding the risk of wet feet . Wet feet can result in tree death due to lack of oxygen in the soil . This can be resulted from heavy soil types and situations that are most likely to result in soil saturation . E . g . swales ; shallow topsoil underlain by hardpan / clay layer or calcareous materials ; rising groundwater . As mentioned above , this characteristic will determine the type of prunus that is suitable for the soil . These could be one of or a combination of peach , almond , or plum . This then also needs to be correlated to the expected soil acidity or pH levels and excessive or deficient nutrient or salt levels in the soil that may be exacerbated through the soil or water application affecting plant growth . A common feature affecting almond growth is salinity either present in the soil or applied through irrigation water which can be further exacerbated by fertigation programs . This sensitivity was observed in the rootstock evaluation program , where Nemaguard and Krymsk known to be poor excluders of chloride and sodium did not perform as well as other varieties thought to be due to low levels of salinity . The amount of salt and pH level can also affect how macro and micronutrients are taken up ( Correlations ). In trials overseas it has been suggested that peach-almond hybrids , being more vigorous , often show fewer nutritional deficiencies in alkaline soils and more tolerant to salt exposure .
Soil pathogens It is important to know your nematode levels within the soil . Populations of ring , root lesion and rootknot nematodes can contribute to significant tree failures , yield losses and other issues .
Continued page 38
industry . australianalmonds . com . au
37