In developing countries, a significant volume of citrus products is lost in operations before, during, and after harvesting due to a lack of production knowledge, inadequate technology for harvesting, inappropriate transporting technology, and poor processing infrastructure. On the contrary, in developed countries, the loss of citrus products in the middle stages of supply chains is comparatively low, mainly due to the accessibility of advanced technologies and more efficient production, handling, and storage techniques [1
]. The citrus industry is strategic in South Africa and is the third largest horticultural industry after deciduous fruits and vegetables in terms of gross value. The country is the second largest citrus exporter in the world and accounts for 10% of global exports. Worryingly, PHLs are estimated to represent approximately 7.9% of export revenue per annum in South Africa, and therefore, it is essential to explore the causes of these PHLs [2
According to Hussein et al. [3
], differences in cultivars, production systems and scale, disease and pest management, investments in irrigation infrastructure, and handling techniques present unique PHL exposure for smallholder citrus farmers. In response, various actions were initiated by the government and private sector to reduce the vulnerability of citrus producers to PHLs in South Africa [4
]. These include PHL management training programs, government subsidies for PHL infrastructure, research, and development of cultivars, as well as innovative pests and diseases management. Experiences from other countries, including Kenya [5
], Tanzania [6
], and Ethiopia [7
], show that these efforts can be ineffective if not well integrated. Lessons from the USA also show the benefits of a transdisciplinary research-based approach to managing PHLs [8
]. However, Mashau et al. [2
] reported that the utilization of these pathways has not been possible in South Africa since not much information on the extent, diversity, and causes of citrus PHLs is documented.
To add to the PHL debate, isolated studies were conducted by Stathers et al. [9
], who examined the effects of fruit bruises on PHL without acknowledging the impact of other root causes in climatic conditions, harvesting, transporting, and storage in sub-Saharan Africa and South Asia. Mukarumbwa et al. [10
] assessed the angle of PHL management by looking at the technological implications of adopting various strategies in Zimbabwe. Their analysis missed the need to critically analyse the driving causes of the PHLs since this is important for designing loss management strategies. Kaminski and Christiaensen [11
] also explored the PHLs in fruit markets in sub-Saharan Africa using a descriptive analysis without directly measuring the extent of PHLs and the causality across the diverse driving factors. Dodd et al. [12
] reviewed PHLs management for fruits in South Africa while skipping the need for empirical evidence from recent developments in environmental factors and markets, which now place quality at the centre of purchasing decisions. Kikulwe et al. [13
] also analysed PHLs along the banana value chain in Uganda and recommended ICT investments in PHL management programs. A cross-cutting technical and economic study on Turkey’s citrus industry noted that the currently used “one size fits all” approach for managing causes of PHLs was inappropriate, hence the need for sector-specific analysis [14
]. These conflicting findings and lessons motivated this study to understand the driving factors of PHLs in the South African citrus industry.
Another critical and currently missing aspect in PHL research is accounting for weather and climate change factors. Going forward, it is essential to acknowledge that citrus PHLs are also directly influenced by preharvest factors such as climatic conditions, light, temperature, humidity, mineral nutrition, and plant growth regulators [15
]. Based on a study in Ethiopia, these climate-change-related factors have been reported to influence the overall fruit quality and suitability for storage interactively, thus increasing the PHLs [7
]. Although citrus production, harvesting, and PH handling in South Africa depend on climatic conditions, these have been manipulated using irrigation and Good Agricultural Practices (GAP) [16
]. Since the edaphic factors in the study area are assumed to be uniform, the study uses the irrigation, curling factors, pests, and diseases as variables to account for the acknowledgment that climate change and weather conditions need to be managed to reduce PHLs.
Notably, in the wake of the intertwined climate change factors of temperature, humidity, and precipitation, pests and diseases have become prevalent in the Eastern Cape province of South Africa. This has weighed in as an additional threat to citrus fruit quality and increased PHLs. Ahra et al. [17
] further asserted that another related cause of PHLs in the citrus industry was the costs of investments in climate change induced PHL management technologies. To push the “appropriate and low-cost solutions” agenda in managing PHLs, extension support services have also been targeting access to climate change information as an entry point [18
]. Regardless of all these efforts, PHLs due to social-economic, climatic, institutional, and farm level factors continue to affect South African citrus fruits marketability in high-value export markets [1
]. Because of the above observations, this study was undertaken to understand how these factors affect PHLs using provincial-level survey data in the Eastern Cape province of South Africa. The findings will aid policymakers in formulating appropriate interventions to support citrus farmers in managing PHLs that continue to threaten business viability.
2. Conceptual Framework
This study used a framework developed by the authors (Figure 1
). Numerous variations of PHL conceptual frameworks are reported in the literature. The commonality of these frameworks is that PHLs are affected by farm-specific (internal) and external factors. Guided by these frameworks, the PHLs experienced by the citrus farmer, a count, was used as the outcome variable. Socio-economic factors (e.g., age, labour, education, yield), institutional arrangements (e.g., access to credit, access to extension, access to markets), and farm factors (e.g., farm size, cultivar used, irrigation system used) were used in the modelling. External factors (e.g., tree age, government support, climate, pests and diseases, and curling factors) were additional determinants [2
]. The conceptual framework in Figure 1
shows the relationships among these variables.
The Stata package version 15 was used to run the ZIP model, where both models were specified in the sequence of running the count model and then running the model that predicts the certain zeros. The study isolated several factors based on the available literature on PHLs in the citrus industry and other related industries [3
]. Farm-specific factors such as the increase in the cost of production affect the severity of PHLs in the citrus industry. Added food safety requirements in markets and the burden of administration costs for fruit traceability have made the majority of smaller farming units unsustainable [19
]. Rising input costs for pests and diseases management and capital costs for investment in storage and climate change management infrastructure using irrigation may increase PHLs. Socio-economic factors such as extension support are provided by the Citrus Growers Association (CGA) and Citrus Research International (CRI), which identifies research priorities aimed at reducing PHLs [1
]. The adequacy of the extension remains questionable and hence the persistent high PHLs.
Additionally, increased years of education are significantly associated with reduced chances of incurring PHLs due to the ability to source and process information on managing PHLs [20
]. Institutional and technical factors are also causes of PHLs. Another citrus industry challenges are legislative requirements such as environmental laws, labour, water, and skills developments. Noncompliance with these institutional requirements may lead to PHLs on fruit quality and quantity.
Access to government grants and credit enhances farmers’ capacity to adopt PHL management technologies, leading to lower incidences of PHLs. Access to credit facilities also supports climate change management practices as well as disease and pest management due to access to resources. Likewise, increased years of experience in fruit production is associated with methods of Good Agricultural Practices (GAP) and hence less PHLs are likely to be incurred [5
]. However, an increased farmer age and a progressively higher use of seasonal labour are hypothesized to increase the probability of incurring more PHLSs [22
]. Citrus PHLs are also influenced by external preharvest factors such as climatic conditions (wet and windy weather), natural climates such as hailing, high wind velocity, heavy rainfall, fruit morphology, and chemical composition. These are difficult to manage regardless of age, experience, and access to labour [10
A detailed description of the variables used to explore the determinants of PHLs incurred by farmers is provided in Table 1
below, where five categories of essential variables were included in the model. These variables include a farmer’s socio-economic and technical characteristics, farm-specific, institutional, and external climate change, and weather-related factors.
Based on the results presented in Table 7
, climate change and weather conditions can affect the PHLs. Notable drivers are creasing, red scale, wind damage, long stem, thrip damage, and minor injuries. Citrus fruit creasing (cracking) is a preharvest physiological disorder that causes significant economic losses. It is caused not only by genetic factors but also by environmental factors (light, temperature, humidity, mineral nutrition, and plant growth regulators). Reddy et al. [15
] reported that citrus fruit creasing was affected by the highest and lowest temperatures but not by the average temperature. Sudden changes in the relative humidity during the fruit colouring period will also result in fruit creasing [3
]. Therefore, proper water management could effectively reduce the fruit creasing rate by not allowing trees to suffer severe water stress.
The red scale also affects PHLs prevalence. Therefore, the timing of fruit treatments that coincide with crawler production can be beneficial during the colder months in the cool production regions. Wind stress can also reduce the growth rate and yield, visible in fewer or no fruit on the side of the tree exposed to wind [12
]. Later in the season, young fruit is most prone to wind damage, and transverse and diagonal greyish scars become visible across the skin. If the wind is frequent and intense, a large percentage of the citrus harvest may be qualitatively downgraded or rejected. Specifically, dry winds can damage trees through leaf fall, windburn, and scorch, inevitably resulting in leaves dying and fruit scarring [11
]. Pruning is also a critical preharvest practice with effects on PHLs. Therefore, regular pruning of trees is essential as this improves airflow in the canopy, which ultimately reduces the duration of wetness and PHLs [14
From Table 8
, the effect of land tenure can be attributed to how property rights motivate investments in PHL management innovations at the farm. This shows that PHLs can be reduced if policies that clearly define property rights are implemented. Policy formulation approaches will have to go beyond the formalized channels and acknowledge the role of social bonds, structures, and the role of indigenous knowledge practices in land reallocation decisions. Kehinde et al. [37
] concurred and also suggested that targeted policy interventions must be designed to enhance access to land by clearly redefining land ownership rights and improving investment and research in PH technologies to reduce losses.
The irrigation systems are also reported as necessary in supporting the adoption of PHL-reducing innovations while focusing on best agricultural practices such as well-timed irrigation schedules and pruning. Mukarumbwa et al. [10
] reported that investment in innovative irrigation systems needed to be supported by incentives for using low-cost technology to reduce PHLs. This should also be hinged on a policy direction supporting start-up agribusinesses involved in irrigation systems design to provide low-cost and appropriate technologies. The catalytic effects of the type of labour used at the farm emanate from the observation that the reliability of labour remains a critical PHL determining factor in the citrus industry, given the nature of the supply chain cycles, which are sensitive to labour shortages. Given that labour orientations have not widely been explored in the realm of PHL, especially in the citrus industry, this study makes significant contributions to this body of knowledge. Reddy et al. [15
] alluded that labour-related PHLs were listed as a main challenge in citrus plantations and suggested the need for innovative technologies which reduce labour intensity and increase labour productivity.
The findings also showed that the current extension models in South Africa’s Eastern Cape province did not adequately accommodate labour-sensitive PHL management. Closely related to these interactions, it can also be derived from the study findings that farmers with the highest level of education were most likely to have been trained on specific techniques to reduce PHLs, as opposed to what was reported with the extension variable. A similar pattern was observed by Ngowi and Selejio [6
], who also noted the need for tailor-made functional and technical capacity-building programs along the citrus value chain activities as a possible strategy to support the relevance of training initiatives. Education becomes an immediate catalyst for adopting innovative approaches to managing PHLs. As such, there is a need for a policy that accommodates citrus production in the curriculum from the primary level.
The influence of market access shows that pre- and postharvest management practices are essential for citrus fruits to be supplied to the market in compliance with quality standards. Since markets are centralized in the study area, this makes it difficult for farmers to access them while at the same time managing transaction costs. Dodd et al. [12
] reported that there were high PHLs of citrus fruits mainly due to a lack of market access and market information among primary producers who largely depend on small producers’ associations in their localities. From a policy and operational perspective, this has pushed other individual stakeholders out of the mainstream citrus fruits supply chain functions due to perceived low long-term returns. The cultivar differences and their influence were also reported by Mashau et al. [2
]. They noted that a high PHL loss in the citrus systems due to cultivar selection left farmers with fewer options to deal with risks of increasingly high PH management costs associated with the common cultivars such as Navel.
The OR value differentials for access to credit, cultivar, and tree age implied that the major drawback was the PHLs which accounted for over 60% of the losses. These losses were triggered by different social (cultivar selection), agroecological (climate), institutional (credit), and economic (yield) constraints, which eroded the farms’ endowment and adaption to the cultivation of citrus fruits. Climatic conditions and recent changes have also negatively affected the appropriateness of cultivars such as Navels in traditionally productive areas [11
]. With limited capacity to regenerate the plantations, the farmers remain locked in the traditional cultivars, albeit increasing their exposure to PHLs. Kantaroğlu and Demirbaş [14
] also noted that the citrus production business had lost momentum through limited support from governmental and nongovernmental organizations. This has occurred mainly in secondary supply chain functions such as credit for investing in PHL management infrastructure such as irrigation and storage facilities [38
]. To cushion against these inherent risks in the citrus fruits industry, producers must design mechanisms that embrace a blend of practices anchored on self-sustaining credit schemes and an appropriate selection of cultivars.
The ZIP regression model indicated that social (e.g., education, age), economic (e.g., yield), institutional (e.g., access to markets, credit, extension) and farm specific (e.g., pruning, cultivar, irrigation) factors determined the magnitude of exposure to PHLs. In this context, it is recommended to reconfigure policies and raise the capacity to reduce the impacts of PHLs on the local and national economy. To achieve this, a tailored capacity building on good agricultural practices in citrus production, harvesting, and postharvest handling can help to reduce PHLs through the extension pillar. The production of Nova and Navel cultivars should be promoted by making these cultivars accessible and affordable for small-scale citrus farmers. Given that irrigation plays a role in PHLs, investment programs to support water-efficient drip irrigation systems need to be initiated to reduce the chances of incurring high levels of weather-related and climate-change-induced PHLs. The study’s limitations can be reduced by using a large sample size across different production regions and carrying out a comparative analysis of PHL driving factors that directly measure weather and climate change variables. This approach can also be done using panel data to support generalization and applicability over regions and time. Further comparative research may be conducted using other areas with different climatic conditions to determine whether factors causing PHLs vary across these locations.