Exploring Farmers’ Knowledge and Approaches for Reducing Post-Harvest Physiological Deterioration of Cassava Roots in Malawi

Abstract

Cassava utilisation in Malawi is negatively affected by rapid deterioration of fresh roots, primarily caused by postharvest physiological deterioration (PPD). A study was conducted to assess farmers’ knowledge and approaches used to minimize losses from PPD. Multi-stage sampling was used to identify districts, Extension Planning Areas (EPA’s) and farmers. Data were collected from 519 farmers using a structured questionnaire. Results revealed that PPD (74.0%) was the major post-harvest constraint followed by pests and diseases (62.1%). Farmers had varying knowledge levels on signs and causes of PPD. They were knowledgeable on PPD signs with 91.5% ably identifying PPD through change of pulp colour. The farmers also had moderate knowledge on causes of PPD, citing high temperature (57.6%) and over-staying of roots (56.2%) as main causes of PPD. Key methods for preventing PPD are: storage (43.0%) and piece-meal harvesting (40.4%). Only 2.6% of the farmers exploited varietal difference in dealing with PPD as some varieties (Sauti, Mpuma, Ching’amba, and Kalasa) take three to five days before showing PPD signs. Farmers’ knowledge levels and PPD preventive methods could be strengthened through: provision of training on post-harvest handling, improvement in storage and processing technologies; and application of advanced breeding techniques to exploit genetic variation in cassava germplasm.

1. Introduction

Cassava (Manihot esculenta Crantz) is the third most important source of calories in the tropics after rice and maize [1]. It is currently a food source for more than 800 million people in Africa, Asia and Latin America [2,3]. Cassava has many useful agronomic properties, such as drought tolerance and low soil fertility, which enable it to grow well in a variety of climatic conditions where few crops could survive without expensive external inputs [4]. Traditionally a famine reserve and food crop, the status of cassava is now rapidly developing into a cash crop, source of raw material for industries and forage in the main producing countries [5,6].

In Malawi, cassava is one of the most important food crops, especially in the central and northern part of Lake Malawi, where between 30 and 40% of the population depend on it as a staple food [7,8,9]. It is also used as a dietary supplement, a major part of breakfast and snacks in most parts of the country [8]. Furthermore, cassava leaves are used as a vegetable, especially in the dry season when other green vegetables are in short supply [10,11]. Fresh cassava leaves contain 17–18% protein [10]. Cassava is also an important source of income for smallholders, middlemen and sellers in various markets [7].

Malawi has registered a significant increase in cassava production over the years due to the increased area under cassava cultivation, better institutional support such as research in development of high yielding varieties, increased dependence on cassava for food security, an alternative source of income, and the improved management practices [7,9]. It is expected that production will continue to grow due to the increased support for cassava production by various actors and also because more and more farmers are becoming aware of the importance of crop diversification as a means of sustainable agricultural production and food security [7,8].

Despite the many benefits of cassava, its utilization and commercialization are limited to some extent by the short shelf life of cassava roots. Unlike other root crops, such as yam or sweet potato, once cassava is detached from the plant, it deteriorates quickly and cannot be stored under satisfactory conditions for long periods of time [12]. Primary deterioration of cassava root is also called post-harvest physiological deterioration (PPD). Essentially, PPD is a physiological defense process that is initiated at damaged sites during harvest and spreads systematically throughout the root [11,13,14]. Signs of PPD begin with blue-black to black vascular discoloration (vascular streaks) which may become visible within 24–72 h after harvest [15,16]. Most cassava varieties deteriorate within three to four days of harvest [17].

Physiological deterioration of cassava roots leads to significant quantitative and qualitative losses, which are reflected in the following: lower income for farmers and traders; threatens the constant supply for industry with fresh roots as raw material; increases market risks within the fresh cassava value chain; and it also makes cassava roots unacceptable for consumption [4,14,18,19]. The poor countries suffer greater losses, although they have capacity to absorb sub-standard products and less stringent buyer standards [4]. On average, post-harvest losses for cassava globally and Africa are estimated at 19% and 29% respectively [20]. In Malawi, cassava post-harvest losses from a combination of post-harvest deterioration and pests were estimated at 30% for the 2000–21 production season [21]. However, [22] noted that estimates for Malawi were obtained from papers that did not pass the methodological appropriateness criteria.

Complete prevention of PPD requires that cassava roots be consumed or processed immediately after harvest [23]. However, this is only practical on a small scale but not commercially. This has led to the development of technologies as well as integration of marketing activities within the cassava value chain to delay PPD [24,25]. Over the years, farmers have developed traditional methods to reduce losses from PPD such as storage in cool and humid places, processing of roots into fairly stable products and selection of cultivars with delayed post-harvest deterioration [3,26,27]. Another common way to avoid loss is to leave roots in the soil beyond the period of optimal root development, until they can be immediately consumed, processed, or marketed. The disadvantages of this practice are that the roots lose some of their starch content, palatability decreases as the roots become more fibrous and cooking times increase [26]. In Africa, there are also a number of traditional systems which provide for the conservation of cassava in pits. The use of these rudimentary techniques is not widespread because they are considered quite laborious [28].

In terms of marketing cassava roots in many developing countries, highly integrated market channels are used to ensure that farmers and traders transact as much of their perishable products. For instance in rural areas, fresh cassava roots are traditionally marketed without post-harvest treatment or protection and must therefore reach the consumer as quickly as possible before deterioration becomes apparent [11]. In addition, the quantities traded by cassava merchants are typically small. Therefore, traders buy and sell limited quantities to ensure rapid product turnover [4].

Despite the key livelihood role that cassava plays in the country’s agri-food systems, as well as documented technologies aimed at reducing PPD from other developed countries, there is limited information on PPD, its causes and prevention strategies in Malawi. This study was therefore undertaken with the aim of contributing towards cassava productivity, utilization and commercialization whilst ensuring that consumers are provided with better quality cassava roots and products. Specifically, the study elicited indigenous knowledge on PPD, its causes and methods used by farmers to deal with challenges posed by PPD in cassava value chain in the country.

2. Materials and Methods

2.1. Study Sites

The study was conducted in four major cassava growing districts in Malawi during September and October in 2020. These are: Nkhatabay, Karonga, Lilongwe and Mulanje (Figure 1). Nkhatabay and Karonga districts are located in northern part of Malawi along the Lakeshore areas where cassava is one of the major staple crops. Lilongwe district is located within the fertile plains of the central region of Malawi while Mulanje district lies within the highlands in the southern region. The targeted farmers comprised of resource poor as well as medium scale farmers whose farming conditions are diverse. These farmers encounter several production and post-harvest constraints such as pests and diseases; use of inappropriate cultural practices; shortage of clean and healthy planting material, deterioration of storage roots, low market prices, as well as unavailability of processing facilities [10].

2.2. Sampling

A multi-stage sampling approach was used in selection of districts, EPAs and farmers to participate in the study. The first stage was purposive selection of the four districts which are the main cassava growing districts in the country. The second stage was again purposive sampling of two Extension Planning Areas (EPAs) from each of the four districts based on relative importance in cassava production within the district. The final stage was random sampling of households within an EPA which was done in consultation with district agricultural extension office. Fishers formula [29] was used for estimation of proportions and determination of sample size of 384.16. A design effect of 1.35 was used to account for multi-stage clustering in the selection of target areas. This resulted in a final sample size of 519 farmers (

Table 1. Summary number of respondents interviewed per district and EPA.

District	EPA	No. of Respondents
Nkhatabay	Mpamba	23
Nkhatabay	Chintheche	43
Nkhatabay	Nkhatabay boma	55
Karonga	Vinthukutu	48
Karonga	Kaporo North	113
Lilongwe	Mkwinda	52
Lilongwe	Chitsime	62
Mulanje	Msikawanjala	55
Mulanje	Milonde	68
Total		519

Note: EPA = Extension Planning Area.

).

Fisher formula is calculated as:

$$n=\frac{Z^{2}P\left(1-P\right)}{d^2}$$

• n = sample size
• Z = value corresponding to level of confidence required (Z = 1.96 at 95% confidence level)
• P = percentage occurrence of a state or condition (50%)
• d = percentage maximum error required (d = 0.05)

2.3. Data Collection

Data were collected through formal interviews using structured questionnaires to solicit individual views on the different issues. The interviews were used to collect information such as: socio-economic data of farmers, cassava production systems, post-harvest handling practices and constraints, knowledge on signs and symptoms of PPD, causes of PPD, methods used to prevent PPD, utilization of roots affected by PPD, as well as farmers’ knowledge on variation in PPD among varieties. Farmers’ informed consent to participate in interview was sought from each individual farmer before commencement.

2.4. Data Analysis

The data collected was coded and analysed using a Statistical Package for Social Scientists (SPSS, version 22). Descriptive statistics were used to summarise the data which were presented as percentages, cross tabulations and graphs. Ranking of post-harvest constraints was done using number of counts received for each constraint which were expressed as percentage. The constraint with the highest number of counts was ranked as first and that with lowest points last.

3. Results

3.1. Socio-Economic Characteristics of Respondents/Farmers

Survey results revealed diversity in socio-economic characteristics among the farmers (

Table 2. Socio-economic characteristics of farmers by district.

Characteristic		Karonga (n = 161)	Lilongwe (n = 114)	Mulanje (n = 123)	Nkhatabay (n = 121)	Total (n = 519)
Gender	Male	34.8	79.8	27.6	28.9	41.6
	Female	65.2	20.2	72.4	71.1	58.4
Age	<20	3.7	0.0	3.3	0.8	2.1
	21–30	14.3	27.2	17.1	12.4	17.3
	31–40	32.3	32.5	20.3	20.7	26.8
	41–50	29.8	24.6	18.7	24.8	24.9
	>51	19.9	15.8	40.7	41.3	28.9
Education	Never	3.1	5.3	9.8	4.1	5.4
	Primary	64.0	72.8	74.0	72.7	70.3
	Secondary	32.3	20.2	15.4	23.1	23.5
	Tertiary	0.6	1.8	0.8	0.0	0.8
Marital status	Not Married	1.2	0.9	2.4	6.6	2.7
	Married	81.4	93.0	72.4	67.8	78.6
	Divorced	7.5	3.5	9.8	5.8	6.7
	Widowed	9.9	2.6	15.4	19.8	11.9
HH Head	Male	82.6	93.9	73.2	69.4	79.8
	Female	17.4	6.1	26.8	30.6	20.2
Years growing cassava	<5 years	9.9	42.1	15.4	5.0	17.1
	5–10 years	19.9	29.8	17.9	7.4	18.7
	11–20 years	23.6	15.8	21.1	12.4	18.7
	>20 Years	46.6	12.3	45.5	75.2	45.5

). In terms of gender, 58.4% of the farmers were female. Additionally, 78.6% of the farmers were married and 79.8% of the households were male headed. About 28.9% of the farmers were in the age category of > 51 while only 2.1% of farmers were less than 20 years old. With regard to number of years spent growing cassava, 45.5% of farmers had more than 20 years’ experience in growing cassava. Majority of farmers (70.3%) had primary education.

3.2. Cassava Pre/Post-Harvest onstraints

The major cassava pre/post-harvest constraints identified and ranked by farmers are presented in

Table 3. Cassava pre/post-harvest constraints faced by farmers.

Constraint	Karonga (n = 161)		Lilongwe (n = 114)		Mulanje (n = 123)		Nkhatabay (n = 121)		Total (n = 519)
	(%)	Rank	(%)	Rank	(%)	Rank	(%)	Rank	(%)	Rank
Inadequate capital	0.7	11	4.6	8	4.9	10	0.0	12	2.4	11
Transportation	22.0	6	18.5	7	9.8	8	36.4	5	21.7	6
Deterioration of roots	95.0	1	56.5	4	75.6	1	63.6	1	74.0	1
labour costs	0.7	12	2.8	10	0.8	11	1.7	9	1.4	12
Weevil	6.4	8	2.8	9	31.7	5	8.3	8	12.4	9
Pests and diseases	50.4	4	71.3	3	70.7	2	58.7	3	62.1	2
Animal damage	59.6	2	82.4	1	43.1	4	19.8	7	50.7	4
Theft	36.9	5	75.0	2	58.5	3	62.0	2	56.8	3
Processing/storage	19.1	7	1.9	11	0.8	12	20.7	6	11.2	10
Drying	56.0	3	0.9	12	30.1	6	36.4	4	32.7	5
Over-supply	1.4	9	47.2	5	8.1	9	0.8	10	13.0	7
Lack of markets	1.4	10	37.0	6	17.9	7	0.0	11	13.0	8

Note: % = Percentage

. Across all the four districts, 74.0% of farmers ranked PPD as the most important cassava post-harvest constraint. Furthermore, PPD was also ranked as number one constraint by farmers in three districts namely: Karonga (95.0%), Nkhatabay (63.6%) and Mulanje (75.6%). Farmers in Lilongwe ranked animal damage as their most pressing challenge followed by theft. The second constraint was high prevalence of pests and diseases such as cassava brown streak virus which in severe form could render cassava roots unusable.

3.3. Farmers’ Knowledge of PPD

Almost all the farmers interviewed had some basic knowledge of PPD. Analysis of the results (

Table 4. Farmers knowledge of signs and symptoms of deteriorated cassava roots.

Sign/Symptoms	Karonga (%)	Lilongwe (%)	Mulanje (%)	Nkhatabay (%)	Total (%)
Blue/browning	86.5	96.3	100.0	84.3	91.5
Drying/Hardening	66.0	77.8	91.1	55.4	72.2
Rotting	58.2	58.3	69.1	62.8	62.1
Change of taste	48.9	54.6	62.6	52.1	54.4
Fiberness	2.8	1.9	0.8	1.7	1.8
Smell	34.8	34.3	15.4	14.0	24.7

) revealed 91.5% of farmers were conversant with onset of primary signs of cassava root deterioration which is manifested by flesh colour change from cream/white to blue/brownish (Figure 2). Other common signs used to determine root deterioration by the farmers were hardening of the root (72.2%) and rotting of roots (62.1%).

Farmers’ response on time taken for onset of PPD signs in Karonga, Mulanje and Nkhatabay showed that it took two days for PPD signs to become visible in cassava roots, while farmers in Lilongwe indicated that signs of deterioration were clearly visible within the same day of harvesting (Figure 3). This may be attributed to the fact that more than 90% of farmers in Lilongwe grew Manyokola variety which has high dry matter content hence very susceptible to PPD.

In terms of farmers’ knowledge on the causes of PPD, farmers identified high temperature (57.6%) as the main cause of PPD in cassava roots followed closely by over-staying (56.2%) (

Table 5. Farmers knowledge on causes of post-harvest deterioration of cassava roots.

Cause of PPD	Karonga (%)	Lilongwe (%)	Mulanje (%)	Nkhatabay (%)	Total (%)
Mechanical injury	26.2	26.9	30.1	49.6	33.1
Temperature	58.2	60.2	65.9	46.3	57.6
Sunlight	46.8	60.2	75.6	15.7	49.3
Atmospheric air	0.7	0.9	0.8	2.5	1.2
Rainfall	4.3	0.9	3.3	5.0	3.4
Soil type	4.3	3.7	4.9	5.0	4.5
Pathogens	2.1	1.9	0.8	5.0	2.4
Pests	17.0	11.1	0.0	31.4	15.0
Over-staying	69.5	58.3	45.5	49.6	56.2

). The farmers explained that high temperatures accelerated onset and development of PPD. Furthermore, the farmers also noted that cassava roots that over stayed for long periods without being used or processed ended up showing signs of PPD.

3.4. Utilisation of Cassava Roots and Products Affected by PPD

Although PPD negatively affects quality of fresh cassava roots, farmers still consume partially deteriorated roots (two to three days after harvesting). A high proportion of farmers (84%) resorted to use the deteriorated roots for home consumption (Figure 4). The highest proportion of farmers consuming PPD cassava roots was in Mulanje district (98%) while the lowest was in Karonga (71%).

With regard to reasons why farmers consumed or disliked PPD affected roots or products, it was discovered that 74% of farmers consumed PPD affected cassava roots because of food shortage in their households (Figure 5a). On the other hand, farmers who did not consume PPD affected roots did so due to poor quality of the roots (35%) and also claimed that deteriorated roots are not palatable (29%) (Figure 5b).

3.5. Methods for Reducing Post-Harvest Deterioration

The study revealed that farmers used mainly local technologies to delay progression of PPD and thereby extending shelf life of cassava roots and products (

Table 6. Methods used by farmers to prevent post-harvest deterioration of cassava roots.

Control Method	Karonga (%)	Lilongwe (%)	Mulanje (%)	Nkhatabay (%)	Total (%)
Processing stable products	41.1	0.9	32.5	38.0	29.4
Storage	45.4	60.2	31.7	36.4	43.0
Piece-meal harvesting	37.6	43.5	61.8	19.0	40.4
Harvesting time	5.7	0.0	2.4	0.8	2.4
Tolerant varieties	0.7	1.9	2.4	5.8	2.6

). Commonly used local technique for delaying PPD was storage (43.0%) of cassava roots on open air, under moist condition as well as burying harvested roots in sand sprinkled with water. It was followed by piece-meal harvesting approach (40.4%).

3.6. Varietal Differences for Onset and Development of PPD

Although PPD signs may become visible as early as 24 h after harvesting cassava roots, 25.0% of farmers reported to observe varietal differences with regard to on-set and progression of PPD signs among cassava varieties (

Table 7. Farmers observing varietal differences in onset of PPD signs by district.

District	PPD Varietal Differences
	Counts	Percentage (%)
Karonga (n = 161)	51	31.7
Lilongwe (n = 114)	2	1.9
Mulanje (n = 123)	38	30.9
Nkhatabay (n = 121)	39	32.2
Total (n = 519)	130	25.0

). However, only 2.6% of farmers (Table 6) indicated to already utilize the inherent variation among cassava genotypes to deal with PPD. The farmers observed that under favourable environmental conditions, some varieties would take three to five days for visible signs of PPD to start appearing. Among the varieties mentioned to have delayed PPD were: Sauti, Mpuma, Ching’amba, and Kalasa (Figure 6).

4. Discussion

The study revealed rapid deterioration of cassava roots as one of the major post-harvest constraints for cassava in the four districts. PPD is the primary cause for post-harvest deterioration in cassava. The results are in consonance with research results by [23] who reported PPD as one of the major post-harvest constraints for cassava in Ghana. This is the case because currently, there is no effective control measure for PPD for flesh cassava roots apart from preventive approaches aimed at delaying on-set and development of PPD [16].

PPD negatively impacted utilisation and on-farm marketing of cassava roots. The study confirmed reduction of quality and palatability of roots and products made using deteriorated roots as previously reported by [11,24]. Additionally, some farmers disliked PPD affected roots as they could not properly undergo fermentation, a process used in making fermented cassava flour and doughs (Kanyakaska and Kadonoska). Apart from low quality, flour and doughs made from PPD affected roots have dark colour and an off-taste. Similar studies by [27,30] also reported significantly lower consumer acceptability for gari products prepared from deteriorated roots. Specifically the consumers disliked the odour, taste, texture and colour of the gari. Although there is remarkable quality loss in cassava roots affected by PPD, 84% offarmers were consuming partially deteriorated roots mainly due to food shortages.

Farmers displayed different knowledge levels on signs and causes of PPD. They had above average knowledge on distinguishing PPD signs as evidenced by 91.5% of the farmers were able to identify PPD by change of colour from white/cream to brown. The farmers also had challenges to articulate the other PPD signs and symptoms appropriately. The farmers displayed moderate knowledge on causes of PPD which could negatively influence strategies to prevent or delay PPD. For instance, only 33.1% of the farmers knew that mechanical damage inflicted on the roots during harvesting is the primary cause of PPD. Contrary to this knowledge, some farmers deliberately cut the ends of cassava roots to prevent PPD. A similar practice of cutting off the root ends was also observed among fresh cassava traders though their motive was to show customers the level of freshness of their roots (Personal communication with cassava vendors). On a positive note, 56.2% of the farmers correctly responded that PPD and deterioration was caused by leaving the flesh roots for some time before usage. They further pointed out that high temperatures and sunny conditions favoured the development of PPD. Knowledge of these factors that cause and influence development of PPD is crucial among farmers as it guides the farmers on local preventative methods that work by modifying the environmental conditions to extend shelf-life of fresh cassava roots [23].

Although there are wide range of technologies for preventing PPD in cassava roots, the survey results showed that farmers in the four districts predominantly use traditional methods to delay on-set and development of PDD. Example of such methods included: storage of fresh roots, piece-meal harvesting and processing into stable products. This corroborates with the findings of [22] who reported that farmers in Malawi process roots into products such as Kanyakaska, Kadonoska, and Makaka. Furthermore, [1] also reported that in Rwanda a large proportion of farmers (89.2%) resorted to storage of processed products, followed by piece-meal harvesting (71.9%) and storing the harvested roots under moist soil (53.8%). In Cameroon, more than 80% of cassava farmers embraced piece-meal harvesting and underground storage of cassava roots to prevent deterioration [27]. This practice allows farmers to adapt their harvests to household consumption and market demand. However, leaving cassava roots underground for long periods renders the roots woody and also exposes the roots to risk of being infected by soil pathogens, pests and rodents [26].

The prevalence of traditional methods for delaying PPD in developing countries reflects the subsistence level of farmers. [28] Argues that the main reasons small scale farmers use traditional storage methods are due to the fact that their methods are cheaper and easier to use. On the other hand, farmers in countries with developed cassava value chains use improved technologies for processing, drying and storage of cassava roots to prevent deterioration as well as for value addition [26]. Some of the processing technologies used include mechanical peelers, cassava graters and chippers, motorised sieves, flash dryers, solar dryers, hydraulic pressers, and hammer mills [26,27,31]. Storage techniques comprise of storage boxes lined with moist sawdust, polypropylene bags or plastic film wraps, use of waxy coatings and refrigeration [26,31,32]. Some of these technologies can be adapted for use in Malawian to catalyse transformation of the cassava value chain from subsistence to commercial sector.

The cassava value chain in Lilongwe district is entirely for fresh roots, as such only methods intended to preserve the roots in fresh form were used. Specifically, the farmers would leave the harvested roots on open cool surfaces if the roots are to be kept just for overnight. If the roots are to be kept for more than two days, they were buried under sandy soil and water sprinkled over to increase moisture as well as reduce temperature. This practice by farmers complements those in literature that recommended setting appropriate temperature, relative humidity, and limit oxygen in cassava storage rooms to inhibit the development of PPD [15,16,25,33]. Ref. [33] Reported successful preservation of cassava roots without physiological and microbiological damage for up to 28 days after harvest by storing the roots in a wooden box filled with sawdust at high relative humidity. Storage of cassava roots at high relative humidity promotes the formation of periderm layers at the wound site [33].

In terms of varietal differences in PPD, 25.0% of farmers (Table 7) indicated observing presence of variability among cassava genotypes, with some varieties taking some few days before PPD would set-in. The farmers further noted differences in progression of PPD with some varieties showing slowed development in PPD. However, only 2.6% of farmers (Table 6) utilised the varietal differences in preventing PPD. After harvesting cassava roots, the farmers would immediately process (peel and grate) roots for susceptible varieties while those deemed resistant would be processed later on. Some of the varieties that were reported to have delayed on-set for PPD include Sauti, Mpuma, Chin’gamba, and Kalasa. These varieties would take three to five days before showing visible signs of PPD. This observation concurs with reports from several authors who reported variations among varieties for PPD [12,14,17,33,34,35]. Some varieties could go up to 40 days with no visible PPD signs [14]. Notably cassava genotypes with high carotenoids levels, waxy starch and low dry matter content have been reported to have tolerance against PPD [3,14]. The four varieties enlisted by farmers as having delayed PPD in this study are all white fleshed, implying that their mechanism for PPD resistance may be attributed to dry matter content, starch type or other PPD inhibiting biochemical and not carotenoid levels.

This study confirmed that post-harvest deterioration presents a serious challenge during post-harvest handling of cassava roots which requires urgent attention of researchers and development practitioners. The results complement those in literature that effective control and preventative measures for PPD should properly integrate the following five strategies: (i) modifying storage conditions; (ii) improving processing of fresh cassava roots; (iii) selection of tolerant genotypes; (iv) pre-conditioning cassava tissue before harvesting; and (v) preventing active gene expression during storage. Some of these strategies can be combined [16,17].

5. Conclusions

The study revealed a number of post-harvest challenges being faced by cassava farmers in Malawi. Key among the challenges is rapid post-harvest deterioration of fresh cassava roots (74.0%). The study also identified differential knowledge levels among cassava farmers with regard to PPD. Farmers had above average knowledge on signs for PPD. About 91.5% of farmers identified PPD through change of flesh colour. Farmers also had moderate knowledge on causes and measures to reduce PPD. Knowledge on causes and factors influencing PPD development is crucial in designing preventative measures for PPD. Methods used for preventing PPD include: storage; peace-meal harvesting as well as processing roots into stable products. A very small proportion of the farmers (2.6%) took advantage of variation among cassava genotypes to deal with PPD. In terms of utilization of PPD affected roots, a huge proportion of farmers (84.0%) consume partially deteriorated roots due to household food insufficiency.

The study confirmed that post-harvest deterioration of cassava roots is a serious challenge for utilisation and commercialisation in Malawi. It therefore proposes the following recommendations:

• Provision of training and awareness campaigns on post-harvest handling of cassava.
• Introduction of low-cost but improved technologies to improve handling, storage, drying and processing of cassava roots at farm or community level to ensure handling of large volumes as well as maintain quality of products. Examples of such technologies that can easily be adapted to Malawi context include graters, chippers, solar dryers, hammer mills, storage boxes and polypropylene bags.
• Application of modern breeding tools to exploit existing variability in local and introduced cassava genotypes and develop varieties with durable PPD resistance.
• Scientifically verify delayed PPD in Sauti, Mpuma, Chin’gamba, and Kalasa for further effective utilization of such varieties.