Crops In Tanzania Research Articles

Characterization and chemical management of Cashew Fusarium Wilt Disease caused by Fusarium oxysporum in Tanzania

Cashew (Anacardium occidentale L.) is the present leading currency earning crop in Tanzania, generating income to over 2.5 million farmers. Despite of its importance, cashew is threatened by a new serious destructive disease called Cashew Fusarium Wilt (CFWD), which is caused by Fusarium oxysporum. The impact of the disease has reduced income at both household and national levels. The current study was conducted to characterize CFWD and investigate chemical management options for the disease. The study was conducted during the rainy and off-rainy season(s) at Tuungane-Liwale and Kitangari-Newala in Lindi and Mtwara regions respectively. Disease characterization involved field observation of the infected cashew trees, laboratory isolation and characterization of the causative agent. Chemical management involved application of azoxystrobin, carbendazim and thiophanate methyl each at a concentration of 5, 10 and 15 g of formulated product/L. Laboratory findings revealed that the causative agent of the cashew wilting symptoms is Fusarium oxysporum characterized by whitish mycelia growth, chlamydospores, macroconidia and microconidia. The tested chemical fungicides revealed significant effects on the suppression of Fusarium wilt disease and thus enhancing cashew recovery after 120 days of application. Azoxystrobin and carbendazim reduced severity and enhanced recovery. Application of azoxystrobin (15 g/L) promoted 65.2 percent recovery of cashew from 50.0 percent of disease severity and 10 g/L of carbendazim enhanced 49.4 percent of cashew recovery from 50.0 percent severity. Thiophanate methyl exhibited significant effect (P ≤ 0.05) on reducing the severity of the disease and enhancing cashew recovery whereby 15 g/L of thiophanate methyl enhanced 21.6 percent recovery from 45.0 percent severity. These findings advocate the administration of these chemicals, especially carbendazim and azoxystrobin in proper concentration for timely disease management in the affected areas. Studies to establish the effect of the applied chemicals to other biota for betterment and continued applications to combat the disease are underway.

Plant parasitic nematodes occurrence and genetic diversity of banana cultivars grown in Tanzania

The genetic diversity of bananas (Musa spp.), one of the most economically important crops in Tanzania, is underestimated with scarce reports available. In addition, cultivation of banana is severely constrained by plant parasitic nematodes (PPN). We assessed genetic diversity and population structure of 159 banana varieties from four agro-ecological zones (Northern, Southern highlands, Lake and Zanzibar islands) of Tanzania using 20 SSR markers analysed with UPGMA method. We also, assessed the PPN occurrence through isolation and counting of PPN from each banana genotype where leaf samples were collected. SSR primer pairs were polymorphic; and generated 63 distinct reproducible bands. The polymorphic information content values of each SSR marker ranged from 0.50 to 0.75 indicating high level of genetic diversity among banana varieties. The 159 banana varieties were grouped into two clusters: A and B, based on UPGMA cluster and population structure analysis. A total of 128 independent and 31 overlapping genotypes were identified. Higher kinship among genotypes was observed in cluster A compared with cluster B. Some of the clusters in A and B genotypes showed high genetic distance. The most prevalent and abundant nematode species was Pratylenchus goodeyi with a mean count of 63%, followed by Radopholus similis (31%) and P. coffeae (6%). The results from this study provides a foundation for understanding genetic variability of bananas existing in Tanzania and PPN occurrence that will be valuable information for breeding disease and pest-resistant bananas with high yield traits.

Forecasting yields, prices and net returns for main cereal crops in Tanzania as probability distributions: A multivariate empirical (MVE) approach

Maize (Zea mays L.), sorghum (Sorghum bicolor L. Moench) and rice (Oryza sativa) are essential staple crops to the livelihoods of many Tanzanians. But the future productivity of these crops is highly uncertain due to many factors including overdependence on rain-fed, poor agricultural practices and climate change and variability. Despite the multiple risks and constraints, it is vital to highlight the pathways of cereal production in the country. Understanding the pathways of cereals helps to inform policymakers, so they can make better decisions to improve the viability of the sector and its potential to increase food production and income for the majority population. In this study, we employ a Monte Carlo simulation approach to develop a multivariate empirical (MVE) distribution model to simulate stochastic variables for main cereal crops in Tanzania. Eleven years (2008–2018) of yields and prices data for maize, sorghum and rice were used in the model to simulate and forecast yields and prices in Dodoma and Morogoro regions of Tanzania for a seven-year period, from 2019 to 2025. Dodoma and Morogoro regions represent semi-arid and sub-humid agro-ecological zones, respectively. The simulated yields and prices were used with total costs and total area harvested for each crop to calculate the probable net present value (NPV) for each agro-ecological zone. The results on crop yield show a slightly increasing trend for all three crops in Dodoma region. Likewise, rice yield is expected to marginally increase in Morogoro with a decreasing trend for maize and sorghum, meanwhile, the prices for the three crops all are projected to increase for the two regions. Generally, the results on economic feasibility in terms of NPV revealed a high probability of success for all the crops in Dodoma despite a higher relative risk for rice. The results in Morogoro presented a high probability of success for rice and sorghum with maize indicating the highest relative risk, and a 2.41% probability of negative NPV. This study helps to better understand the outlook of the main cereal crop sub-sectors in two agro-ecological zones of Tanzania over the next seven years. With high dependence on rain-fed agriculture, production of main cereals in Tanzania are likely to face a high degree of risk and uncertainty threatening livelihoods, incomes and food availability to the poor households.

Avocado Production and Local Trade in the Southern Highlands of Tanzania: A Case of an Emerging Trade Commodity from Horticulture

Avocado crop in Tanzania is sparingly investigated regardless of being an important fruit commodity. This study was undertaken to explore the yield and the value chain of this crop in the country. Data were collected mainly by face-to-face interviews with 275 avocado farmers, 231 avocado traders and 16 key informants. Descriptive statistics, Chi-square test and one-way analysis of variance were used for data analysis. The average crop yield ranged from 76 to 124 kg plant−1 between regions. The average price for the farmers’ produce ranged from US$ 0.30 to 0.45 kg−1 between regions. About 72% of the farmers were dissatisfied with avocado business whereas 79% of the traders were pleased with it. A number of challenges were found hindering the development of the avocado industry in Tanzania, which in turn affects the fruit yield and the value chain. Addressing these challenges at the national, regional, district and village levels is important for improving the livelihood of Tanzanian farmers growing this crop, given the fact that a good proportion of the country’s population is employed in the agricultural sector and most of the reported challenges also affect the value chain of other crops.

Effect of fungicides used for powdery mildew disease management on African weaver ant Oecophylla longinoda (Hymenoptera: Formicidae), a biocontrol agent of sap-sucking pests in cashew crop in Tanzania

In the article above the accepted date was incorrect. The correct date is 11 September 2013.

Genetic diversity of maize accessions for maizelethal necrosis disease resistance

Maize is among the most preferred crop in Tanzania and other parts of the world. However, its production has been facing a number of challenges. Maize Lethal Necrosis Disease (MLND) is a new challenge in Eastern Africa. The control of MLND is said to be complicated as it is caused by a combination of more than one virus viz. Maize Chlorotic Mottle Virus (MCMV) and Sugarcane Mosaic Virus (SCMV). Stakeholders agree that the priority is to identify MLND resistant maize varieties. Genetic diversity provides the source of traits required against maize production challenges such as MLND. The study of genetic diversity in maize accessions often involves characterizing morphological plant characteristics as well as molecular marker techniques to study variation at DNA level. This review explores different literatures that address the importance of genetic diversity and the possibility of generating information towards obtaining potential materials against maize challenges and MLND in particular.

Assessment of sweetpotato farming systems, production constraints and breeding priorities in eastern Tanzania

Sweetpotato is an important food security crop in Tanzania. The crop is grown under diverse farming systems with very low yields. The objective of this study was to assess the present sweetpotato farming systems, farmers’ preferences, production constraints and breeding priorities in eastern Tanzania. Participatory rural appraisal was conducted in the Gairo, Kilosa and Kilombero districts of the Morogoro region and Mkuranga district of the Coast region of Tanzania. Primary and secondary data were collected using semi-structured interviews, focus group discussions and field observations. The study showed that more than 94% of the respondents depended on farming for their livelihoods. Main sweetpotato production constraints were Sweetpotato virus disease (SPVD) and pests, drought, unavailability of markets and lack of transport, low prices, inadequate extension services and postharvest losses. Preferred sweetpotato attributes included high yield, high dry matter content, tolerance to diseases and early maturity. Farmers expressed their persuasive needs towards improved extension service delivery, SPVD-tolerant cultivars, and reliable and coordinated market systems for sweetpotatoes.

Trade Impediments and Market Transaction Arrangements for Maize and Rice in Tanzania

This research paper is focused on the exploration of the impediments to beneficial trade and their resultant market transaction arrangement in maize and rice. The study therefore was confined to the following three specific objectives to first, explore perceptions and experiences on the impediments to beneficial trade among rice and maize growers and their socio-economic impacts for farmers and food security in the study area. Second, to identify production and marketing models and describe their structure, conduct and performance; and thirdly, to describe transaction costs and related impediments in the value added chain for both crops in Tanzania. Survey was done in three regions: Shinyanga region representing rice growing regions and Ruvuma and Iringa regions representing maize growing regions of Tanzania. The study involved a sample of 100 smallholder rice farmer traders and 131 maize farmer traders. This study adapted Williamsonian Transaction Costs Economics (TCE) approach (as applied in Pitelis (1993) and Furubotn et al. (2000) to identify market arrangements based on transaction costs of producing and trading in the two grain crops. Based on the observed farmers' perception and experiences with prevailing trade impediments, this study has proposed five stylized market arrangements referred to in this paper as Cereal Transaction Arrangements (CTAs). Each of these CTAs was found to have strengths and weaknesses—hence no single trade policy could be more appropriate across all CTAs. The paper recommends that the government should reduce transactions costs in CTA4 and also CTA5 which involve more progressive commercial farmers by putting in place pro-poor trade policies. Such transaction costs include cost of identifying weighing devices, constructing warehouses, corruption, levies and quantitative trade restrictions.

English

Maize is the most important food crop in Tanzania, covering 45% of the cultivated area. Maize farmers have adopted many improved maize varieties but different studies have produced different estimates of adoption rates. A survey was, therefore, conducted in 2001 to estimate the area in improved maize seed, to collect opinions regarding maize recycling, constraints to production and strategies to obtain improved maize seed. The seed sector sold an average 7,750 tons of improved maize seed per year from 1997 to 2000, but also indicate a clear negative trend in sales. While during the 1997/1998 season 9,500 tons were sold, it was reduced to 6,660 tons in the last season. Although the amount of hybrid seed sold was roughly the same for the three seasons, it was the sales of open pollinated varieties (OPVs) that decreased to less than a half in the third year. Based on an estimated national maize area of 2 million ha and a seed rate of 15 kg/ha, the estimate of the area planted with fresh improved maize seed was 26%. Considering the use of OPVs that have been recycled for two years, the area grown with improved maize seed was 46%. Drought, low prices of the produce, pests and diseases, and high input prices were mentioned by the extension officers as the most important constraints for maize production. The high costs of improved seed, poor availability and lack of knowledge were some of the reasons why farmers did not use improved seed. The major strategies farmers use to obtain improved seed were purchase from agro-dealers, recycling of their own seed, and the formation of Savings and Credit Cooperative Societies (SACCOs). Since the survey, seed sales have increased but this increase is mostly in hybrids, and has been accompanied by an increase in area , so the proportion of maize area in improved varieties remains at a low 27%. Research and development efforts should, therefore, be directed to solve the farmers’ major production constraints such as drought, lack of markets and low produce prices, and pests and diseases. Knowledge of how to obtain and grow improved varieties, including good husbandry practices, is critical in adopting improved varieties. Key words: Survey, improved maize seed, adoption rate, Tanzania.

Effect of fungicides used for powdery mildew disease management on the African weaver ant, Oecophylla longinoda (Hymenoptera: Formicidae), a biocontrol agent of sap-sucking pests in cashew crops in Tanzania

In the article above the accepted date was incorrect. The correct date is 11 September 2013.

First Report of Five Viruses Infecting Potatoes in Tanzania.

Potato (Solanum tuberosum L.) is an increasingly important food and cash crop in Tanzania (3). Potato production is concentrated in the southern highlands and mainly carried out by smallholder farmers. A certification system for seed potatoes does not exist in the country. Currently, there is little information about viruses infecting potatoes in Tanzania. In October through December 2011, occurrence of the most common, globally distributed potato viruses, Potato leaf roll virus (PLRV), Potato virus A (PVA), M (PVM), S (PVS), Y (PVY), and X (PVX) (1), was determined in 219 potato plants in 16 fields ranging from 0.2 to 1 ha. Potato crops, 1 to 3 months old, consisted sometimes of mixtures of varieties identified as Arika, Chekundu, Kagiri, Kiazi, Kikondo, Sasamka, or Tigoni by farmers, but could not be independently confirmed. The fields were located in the regions of Mbeya (Kawetele, Kikondo, Umalia, Uyole) and Rungwe (Mwakaleli) ~100 km apart in the southern highlands. Virus-like symptoms observed in most fields included yellowish-green mosaic, leaf rolling, and veinal necrosis. Symptoms in tubers were not studied. Leaves from 10 symptomatic and three symptomless plants were sampled from each field and tested by double antibody sandwich (DAS)-ELISA (1) at ARI-Uyole. Virus-specific antibodies and negative and positive controls were used according to the supplier's instructions (Science and Advice for Scottish Agriculture, Edinburgh, United Kingdom). PVS and PLRV were detected in 55% and 39% of the samples, respectively, and in all fields sampled. PVX and PVM were found in most fields and in 14% and 5% of the samples, respectively. PVA and PVY were only detected in two localities. Co-infection with PVS and PLRV was detected in 14% of the tested plants. Mixed infections involving three or four viruses were detected in 5% of the plants. A total of 20 samples, which were collected from Uyole and Mwakeleli and found to be ELISA-positive for one or several viruses, were pressed on FTA cards (GE Healthcare, Buckinghamshire, United Kingdom), transported to University of Helsinki, and analyzed by reverse-transcription PCR (2) using virus-specific primers designed to amplify the coat protein (CP) encoding region. All ELISA-positive samples tested positive by reverse transcriptase (RT)-PCR. Four and five samples ELISA-negative for PVX or PVA, respectively, were positive when tested by RT-PCR, suggesting that the actual incidence of these viruses may be higher than detected by DAS-ELISA. The PCR products from three to five samples per virus were sequenced without cloning, which reconfirmed detection of PLRV, PVA, PVS, PVX, and PVM (GenBank Accession Nos. KC866618 through KC866622, respectively) and revealed few if any differences among isolates of the viruses. The CP sequences were compared with viruses from other countries and continents (4). CP similarities suggested that viruses might have been introduced to Tanzania through potato trade or through introducing new cultivars without adequate indexing for viruses. These results suggest the need for the development of virus control schemes in potato crops, including the nascent, domestic certified seed potato production in Mbeya.

Linking Energy- and Land-Use Systems: Energy Potentials and Environmental Risks of Using Agricultural Residues in Tanzania

This paper attempts to assess whether renewable energy self-sufficiency can be achieved in the crop production and processing sector in Tanzania and if this could be accomplished in an environmentally sustainable manner. In order to answer these questions the theoretical energy potential of process residues from commercially produced agricultural crops in Tanzania is evaluated. Furthermore, a set of sustainability indicators with focus on environmental criteria is applied to identify risks and opportunities of using these residues for energy generation. In particular, the positive and negative effects on the land-use-system (soil fertility, water use and quality, biodiversity, etc.) are evaluated. The results show that energy generation with certain agricultural process residues could not only improve and secure the energy supply but could also improve the sustainability of current land-use practices.

A Preliminary Survey on Oil-bearing Crops in Tanzania

A Preliminary Survey on Oil-bearing Crops in Tanzania

Effects of planting density and drought on the productivity of tea clones ( Camellia sinensis L.): Yield responses

Tea is an important cash crop in Tanzania, contributing over US$ 45 million of annual exports and grown by over 30 000 smallholder households, and a further 10 000 people are employed by large estate producers. Over 70% of the national tea production comes from the Southern Highlands of Tanzania where expansion of tea estates under limited suitable land for tea is expected for the next two decades. Thus a client-demand driven field experiment was established in January 1993 to study and advice tea growers on the effects of plant density on the productivity and water use of young tea. The experiment comprised of two types of vegetative propagated tea plants (known as “clones”) of contrasting growth behaviour (AHP S15/10: spreading type and BBK35: erect), six plant densities (labelled D 1: 8300 plants ha −1 to D 6: 83 300 plants ha −1) and seven irrigation or drought levels (labelled I 0: un irrigated, to I 6: well irrigated condition) as the treatments. Clone AHP S15/10, with larger crop cover than clone BBK35, consistently out-yielded clone BBK35 at all densities and under both well watered and drought stressed conditions. The corresponding yields from clone BBK35 were 2620 and 5960 kg ha −1. Reciprocal of yield per plant- and asymptotic yield–density relationships were used to explain these responses to density. Yields from clone AHP S15/10 during the period of drought treatments decreased as the maximum soil water deficit increased at all densities, but there were no yield responses to drought from clone BBK35 at the low densities. The study recommends planting densities of 20 000 and 40 000 plants ha −1 for clones AHP S15/10, respectively for well irrigated conditions and a density of 20 000 plants ha −1 for both clones under un-irrigated environments.

Bacterial spot (Xanthomonas campestris pv. vesicatoria ) of tomato and sweet pepper in Tanzania

Bacterial spot of tomato (Lycopersicon esculentum) and sweet pepper (Capsicum annuum) is recorded from several countries of eastern and southern Africa, including Ethiopia, Kenya, Malawi, Mozambique and South Africa. With the growing importance of solanaceous cash crops in Tanzania, particularly tomato, it was important to confirm the findings of preliminary reports of the possible presence of the pathogen and to record it officially. It was also desirable to assess the degree of contamination of seed as potentially the most significant source of inoculum. Field surveys during the rainy seasons of 1997 and 1998 showed that bacterial spot could be found in tomato and sweet pepper fields in all the mainland vegetable regions of the northern and southern highlands, but not in Zanzibar. In fields of tomato surveyed (59 in 1997, 50 in 1998) in which bacterial spot could be seen, incidence (percentage of plants with symptoms) varied greatly between years and fields (from ,5% to .90%). In pepper, incidence was never greater than 5% (10 fields surveyed in 1997, three in 1998). Xanthomonas campestris pv. vesicatoria (Xcv) suspected from symptoms on tomato and sweet pepper fruit was confirmed by isolation on semi-selective media including Tween B (McGuire et al., 1986), followed by biochemical tests for Xanthomonas and pathogenicity tests on tomato. Although the name X. c. pv. vesicatoria remains a valid taxonomic name, it has recently been proposed for reclassification into three separate species (Jones et al., 2000). However, available data for the Tanzanian isolates are not sufficient for them to be allocated to the newly proposed taxa. In some cases, bacterial spots masked symptoms of Clavibacter michiganensis ssp. michiganensis which was also present (Black et al., 1999). For detection of Xcv in seed, extraction methods recommended for quarantine purposes were used (Anon., 1992). Using dilution plating, Xcv was found in five out of 26 samples of farmers' saved seed, was absent from 12 commercial tomato seed lots and present in two out of three commercial pepper seed lots sampled.

Agricultural performance in Tanzania under structural adjustment programs: is it really so positive?

The performances in the food and cashcrop sectors and the availability and consumption ofagricultural inputs in Tanzania during structuraladjustment programs (1986–1996) are compared withperiods prior to this IMF/World Bank backed reform.The positive developments in the first five years ofreform appear to be not sustainable. Presentlyproductivity levels per rural capita for importantfood and cash crops are declining. There are nofurther improvements in the availability andconsumption of agricultural inputs. The removal ofsubsidies on agricultural inputs from 1991 onwards iscrucial in explaining the decline in maize production,the main food crop in Tanzania. Some assumptionsbehind the reform measures are proving to be wrong.Modifications are thus needed to improve theagricultural sector of Tanzania in a sustainable way.Structural adjustment programs usually go too far inreducing the role of the government. However,government involvement might be necessary to ensure ahigher consumption of agricultural inputs and thus abetter performance of the agricultural sector inTanzania. A higher productivity in the agriculturalsector is needed in Tanzania to avoid food securityproblems in the future.

Diseases and parasitic weeds of sorghum in Tanzania: occurrence and incidence, 1986–1990

Sorghum is an important subsistence crop in Tanzania. Surveys were carried out between the 1986 and 1990 crop seasons to determine the prevalence of diseases and parasitic weeds in the major sorghum-growing areas of Tanzania. Twenty diseases of sorghum and three parastic weeds were observed. Grain moulds (several fungi), grey leaf spot ( Cercospora sorghi), anthracnose ( Colletotrichum graminicola), rust ( Puccinia purpurea), leaf blight ( Exserohilum turcicum), ladder leaf spot ( Cercospora fusimaculans), sooty stripe ( Ramulispora sorghi) and zonate leaf spot ( Gleocercospora sorghi), were economically important diseases. Striga asiatica was the most common parasitic weed in Tanzania. Ilonga in the low-altitude (⩽ 1000 m) zone and Hombolo in the mid-altitude (> 1000 m) zone were identified as locations with a high frequency of diseases and striga incidence. These locations were recommended for resistance screening against most of the leaf diseases, grain moulds and S. asiatica.

Some Newly Recorded Diseases of Minor Horticultural Crops in Tanzania

Some Newly Recorded Diseases of Minor Horticultural Crops in Tanzania