Table 1: Australian almond harvest estimates versus actuals, 2011-2014.
55,605 65,336 73,008
2012 2013 2014
2011). The large 2013 crop may have been a result of a high number of fruit per spur and excessive carbon demand, thereby hindering the development of floral buds and return bloom for the 2013/14 season. Management options to alleviate this excessive demand is not well known but at the risk of generalising, it’s likely to be associated with adequate light interception and spur nutritional status. The excessive carbon demand may have also restricted the development of new vegetative spurs and floral buds, and this development may have been better served by demand driven water and fertiliser programs rather than calendar driven programs. Concerns were also raised with several growers practising deficit irrigation leading into harvest, as this period coincides with floral initiation and next season’s (2013/14) bearing potential. This was thought to be a risky practice as most orchards are planted on variable, low water holding capacity soils (sand) with drip irrigation. In many instances, particularly with a large 2013 crop, trees or even orchards may already have been stressed and this practice may have created further unwanted stresses, negatively affecting floral initiation. Furthermore, drying of the rootzone may have also made it difficult to re-establish soil water content in time for post-harvest fertiliser, leading to high electrical conductivity in the rootzone and unsuccessful plant nutrient uptake, again negatively affecting floral initiation. Deficit irrigation should be practised with caution and with the highest control. If deficit irrigation is to be practised, soil water monitoring, pressure bombs and confidence around accurate water applications are critical. The opportunity to manage a canopy for maximum year on year production is the focus of five new almond R&D projects. 2. Establishing reproductive potential The beginning of the second season (2013/14) establishes the quantity of nuts. This stage is driven by flowering, pollination and fertilisation. Some of the issues encountered in the 2013/14 season that may have reduced yield were: hull boron concentrations often lower than the critical thresholds (Nyomora et al, 1997); variable beehive quality; and sub-optimum hive placement strategies. Consequently, growers should focus their attention on: soil applications of boron supplemented with foliar sprays ground truthed by hull sampling; robust beehive auditing to ensure standards are being met; and beehives placed more evenly through the orchard to ensure optimum fruit set (Cunningham, 2014). Adverse weather conditions and inadequate management may also have compromised maximum fruit (pericarp) growth potential and limited kernel size. Again, demand driven water and fertiliser programs are essential. 3. Establishing weight potential Kernel weight is established during the second season (2013/14); beginning with kernel development, followed by dry weight accumulation. This stage is the final challenge in producing an adequate crop. The demand for resources through this stage is particularly high and is the major sink for water and nutrition. Crucially, this stage of highest
demand may have been negatively affected by high temperatures during December, January and February, leading to stomatal closure, and a decline in transpiration and carbohydrate production. Some growers reported it was difficult to meet plant water use demand due to inadequate irrigation capacity or possibly inefficient and variable system performance. Nutrient applications during the early part of this stage may have also experienced the same fate. Practising deficit irrigation at hull split to reduce hull rot was discussed and was again thought to be a risky practice as was the case with pre-harvest stress. As discussed earlier, deficit irrigation should be practised with caution and with the highest control. In addition to the factors discussed above, several other key issues were discussed by the group: • Nemaguard rootstock did not produce an adequate return crop following a heavy crop and clonal hybrid rootstocks performed better. • Non-Infectious Bud Failure (NIBF) of Carmel was raised as a serious impact with reports the 2013/14 symptoms were the most severe experienced. • Hull rot was also discussed with importance, with many growers indicating Nonpareil is continually being affected by spur decline in the lower part of the canopy where symptoms are greater. • The combination of hull rot and poor shaking efficacy was of particular concern due to the fruit being grown but not harvested. Those who re-shook, particularly Nonpareil, reported figures of approximately 300kg/ha of kernel. • Price yield was variable, not just between orchards but also within orchards. • The inability to manage rain at harvest made it difficult to harvest all the crop and at a higher enough quality. In summary, there were a myriad of topics discussed and it was difficult to isolate one or two issues that were responsible for the 2014 crop. In order for growers to determine the reasons for their low crop, they will need to examine both the 2012/13 and 2013/14 seasons in the context of the three critical stages of yield production. Nevertheless, it is reasonable to suggest many orchards have a reduced upper yield bound due to a lack of canopy size and light interception; water and nutrient programmes need to more demand based; and more of what’s grown needs to be harvested.
Kester, D.E., Martin, G.C., and Labavitch, J.M. 1996. Growth and Development. In Almond Production Manual . pp. 90-97. UC DANR Publication 3364.
Lampinen, B. 2013. Shining a Light on Canopy, Yield and Food Safety in Almond , PowerPoint presentation, University of California, Davis.
Lampinen, B., Tombesi, S., Matcalf, S., and DeJong, T. 2011. Spur behaviour in almond trees: relationships between previous year spur leaf area, fruit bearing and mortality. Tree Physiology 33(7): 700-706.
Nyomora, A., Brown, P., and Freeman, M. 1997. Fall foliar-applied boron increases tissue boron concentration and nut set of almonds. J. Amer. Soc. Hort. Sci. 122(3):405-410.