RESEARCH & EVENTS
Crop Doctor Len Tesoriero collects twig samples for analysis .
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From page 37 If we flip the equation and look at 320 units of nitrogen per hectare , this would supply enough nutrition to produce 3,600kg per hectare plus the tree growth requirements . If the tree crops more than this , it is likely the tree is being under supplied . From the data provided through the ABA Monterey survey that is currently open to growers producing Monterey , I have noted that the total amount of nutrient applied is not too far off the mark however we are not completely aligned in the timing of these applications against Partick Brown ' s research in the US . In most cases growers have not applied nutrients between November and January and the effect of this may need to be investigated further . When comparing incidences of Monterey leafing failure against weather station data collected through the ABA Monterey survey , consistently there was excessive rainfall during peak fertigation periods . On the year prior to symptoms being observed , between 70 % leaf out ( August 15 ) to 60 % kernel fill ( October 10 ), we saw rainfall 121 % to 474 % of the long-term average rainfall during the active growth stages . This was then followed by significant rainfalls between 60 % kernel fill ( October 10 ) and pit hardening ( November 16 ) in the year of first observations . These figures demonstrate that when there is wet weather there is a struggle to get fertigation out at the correct time , it is near impossible to catch up . The crop demands nutrition at certain crop stages and if that stage passes there will be effects on the tree , especially if the canopy is carrying a large crop . Therefore , in times of challenge , it is critical to do all you can to incrementally provide the tree with its demands as it grows and sets crop rather than rely on a number of larger applications making it harder to try to play catch up . Growers within the industry are beginning to understand the various demands of different varieties especially when it comes to irrigation . So , when we think about our orchards , do we study the various phenological stages within our orchards enough ? Consider this ; through September , crop co-efficient values ( water demand ) can change significantly within a week . If
In A Nutshell - Spring 2025 Vol 25 Issue 3
Table 1 : Calculation of nitrogen demand for a 7 – 15-year-old tree ( from ABC Nitrogen Best Management Practice WO-9743 ( almonds . com ))
Monterey is a week or two later than the Nonpareil and this is what we are targeting the irrigation at , how much of the orchard is being over watered and how could this effect their root system ? If we do not monitor the crop stage and crop co-efficient values for all varieties on our property , a decision is being made without considering all variables . There is an added complication in managing the balancing act faced by growers who only have a single ‘ A ’ system or even a dual ’ AB ’ system so are unable to adjust their watering regime to suit . In summary , the experience of Monterey has highlighted the varying nature and demands of varieties . It also highlights the benefits of installing an irrigation system that can cater to the various varieties within the orchard and the need to monitor how much water each variety uses . Balancing the crop , tree and root system is critical in maintaining the trees health to provide consistently strong crops . The ABA recently held a workshop in Griffith , NSW where we discussed the balancing demands of orchard management . One of the outcomes of this workshop will be a resource that describes the considerations that need to be made and what growers can do to best balance their orchard . This resource will become available in the near future .