Sweet Potato Plants Research Articles

Effects of Nitrogen Level and Soil Moisture on Sweet Potato Root Distribution and Soil Chemical Properties

A culture pot experiment with sweet potato was conducted to investigate the influence of nitrogen (N) variation on fibrous root growth and storage root differentiation under two levels of soil moisture. Sweet potato plants were supplied with low N (N0, no supplemental N), medium N (N75, 75 mg kg−1), or high N (N150, 150 mg kg−1) under normal water supply (field capacity 75%) or drought (field capacity 50%) conditions. The results indicated that during storage root formation, sweet potato root biomass and storage root differentiation were greater in N75. But high N application inhibited storage root differentiation, root biomass, and morphological traits decreased sharply under drought conditions. Under normal water supply, medium N application promoted a uniform distribution of roots in the 0–30-cm soil layer, whereas excessive N application resulted in roots being distributed mainly on the surface of the soil. Water stress increased deep root growth under the N0, significantly decreased deep root growth under the N150. Under drought stress, the N75 improved the plasticity of the root system and increased Fv/Fm, qP, ETR, and PIABS, which alleviated the effect of drought stress on root growth and maintained the functioning of photosystem II. However, high N affected the pH and EC in the soil layer and was not conducive to root development. All of these results indicate an association between variation in N application and the architectural attributes of sweet potato root. This information has great importance for complete N evaluation to improve root plasticity and drought resistance in sweet potato.

INVENTARISASI DAN KARAKTERISASI PLASMA NUTFAH PERTANAMAN UBI JALAR (Ipomoea batatas L.) DI PULAU LOMBOK

Lombok Island as an area that still has a high level of food insecurity is deemed necessary to develop tuber crops such as sweet potatoes, this is to support the diversity of existing food sources. This study aims to determine: 1) sweet potato germplasm cultivated on Lombok Island; and 2) the characteristics of sweet potato germplasm on Lombok Island. This research uses a descriptive method. Inventarization is carried out by the exploration method, and using cluster analysis which is then displayed in the form of a phenogram. The results showed: 1) obtained 17 accessions of sweet potato plants spread in 4 districts of Lombok Island; 2) the accessions found consisted of accessions of Sweet Potato KLU, Honey KLU, Purple 04 KLU, Orange Lobar, White Lobar, Purple 01 Lobar, Purple 02 Lobar, Purple 03 Lobar, Ornamental Attic, Attic Yellow, Attic White, Purple 01 Attic, Purple 02 Attic, Honey Lotim, Sokan Lotim, Purple 05 Lotim, and Purple 06 Lotim; 3) the cause of the differences in the characteristics of all observed accessions is genetic factors that are supported by different growing environmental conditions. In the accession of Sweet Potato Beduk KLU and Sokan Lotim are local varieties of sweet potato from Lombok Island, so it needs to be developed to maintain local superior sweet potato varieties from Lombok Island.

Ceratocystis fimbriata Employs a Unique Infection Strategy Targeting Peltate Glandular Trichomes of Sweetpotato (Ipomoea batatas) Plants.

The infection processes of Ceratocystis fimbriata BMPZ13 (BMPZ13) was elucidated on vegetative tissues of sweetpotato plants employing light and scanning electron microscopy. Vegetative tissues infected with C. fimbriata BMPZ13 by either wounding or nonwounding inoculation methods developed typical disease symptoms, establishing black rot in stems and necrosis on buds, young leaves, and stems of sprouts, in addition to wilt on leaves and shoot cuttings, typical of vascular associated diseases. The runner hyphae of C. fimbriata BMPZ13 formed from germinated conidia were able to directly penetrate the epidermal cuticle for initial infection and invade sweetpotato peltate glandular trichomes, specialized secretory structures to store and secrete metabolites. A two-step biotrophic phase was observed with nonwounding inoculation on leaves and stems, featuring both intercellular and intracellular invasive hyphae, with the latter found within living cells of the leaf epidermis. Subsequent to the biotrophic phase was a necrotrophic phase displaying cell death in infected leaves and veins. Additionally, this cell death was an iron-associated ferroptosis, supporting the notion that iron is involved in the necrotrophic phase of C. fimbriata BMPZ13 infection. Significantly, we establish that C. fimbriata employs a unique infection strategy: the targeting of peltate glandular trichomes. Collectively, our findings show that C. fimbriata is a plant fungal pathogen with a hemibiotrophic infection style in sweetpotato vegetative tissues.

Empowerment of Farmer Group Members through The Application of Sweet Potato Cultivation Intercropping with Sweet Corn Plants in Cibeber District, Cianjur Regency, West Java

Sweet potato plants are generally planted monoculture by farmers, so that the cultivation activities in one season only focus on one commodity and no other mixed commodities. The possibility that occurs when implementing a monoculture cropping system is a failure to harvest or small production results if the plant is attacked by pests or diseases, also less optimal use of the land used. One effort to overcome this problem is the intercropping system. The purpose of this study is to describe the level of empowerment of farmer group members through the application of sweet potato cultivation intercropping with sweet corn plants, analyzing the influential factors and strategies to increase the empowerment of farmer group members through the adoption of sweet potato cultivation intercropping with sweet corn plants. The population of this study was 145 people and 61 samples were taken. Data analysis methods used are descriptive statistical analysis, multiple linear regression analysis, and Kendall's W. analysis. The results of the study show that the level of empowerment of farmer group members in the three research object villages is in the high category of 38 people or (62.30%) of the total overall respondent. The factors that influence the empowerment of farmer group members through the implementation of intercropping are external factors in extension activities. The strategy to increase the empowerment of farmer group members through the implementation of intercropping by carrying out counseling containing material about intercropping and sweet potato cultivation systems.

Empowerment of Farmer Group Members through The Application of Sweet Potato Cultivation Intercropping with Sweet Corn Plants in Cibeber District, Cianjur Regency, West Java

Sweet potato plants are generally planted monoculture by farmers, so that the cultivation activities in one season only focus on one commodity and no other mixed commodities. The possibility that occurs when implementing a monoculture cropping system is a failure to harvest or small production results if the plant is attacked by pests or diseases, also less optimal use of the land used. One effort to overcome this problem is the intercropping system. The purpose of this study is to describe the level of empowerment of farmer group members through the application of sweet potato cultivation intercropping with sweet corn plants, analyzing the influential factors and strategies to increase the empowerment of farmer group members through the adoption of sweet potato cultivation intercropping with sweet corn plants. The population of this study was 145 people and 61 samples were taken. Data analysis methods used are descriptive statistical analysis, multiple linear regression analysis, and Kendall's W. analysis. The results of the study show that the level of empowerment of farmer group members in the three research object villages is in the high category of 38 people or (62.30%) of the total overall respondent. The factors that influence the empowerment of farmer group members through the implementation of intercropping are external factors in extension activities. The strategy to increase the empowerment of farmer group members through the implementation of intercropping by carrying out counseling containing material about intercropping and sweet potato cultivation systems.

Effect of potassium fertilizer and potassium releasing bacterium (Bacillus circulans) on sweet potato plant under sandy soil conditions

The current study was executed in a newly reclaimed sandy soil at Ali Moubark farm, South Tahrir Research Station, Horticulture Research Institute, during the two successive growing seasons of 2018-2019, to rationalizing mineral potassium consumption from natural sources such as feldspar rock and potassium-releasing bacteria and its impact on quality, production and storage capacity of sweet potato cv. Abees. A Randomized Complete Block Design with four replications was used. Treatments included six levels of potassium 25, 50 and 75% of recommended dose of potassium sulphate (48% K2O) plus feldspar rock (10.6% K2O) with inoculation by potassium releasing bacteria i.e. Bacillus circulans as well as 100% recommended dose of potassium sulphate, 100% recommended dose of feldspar rock and 100% recommended dose of feldspar rock with inoculation by potassium dissolving bacteria. Results conclude that adding 50% from the recommended dose of potassium sulphate plus 50% feldspar rock with inoculation by Bacillus circulans bacteria recorded the higest values of vegetative growth (plant length per plant, number of branches per plant, leaf area and chlorophyll content), total yield, yield properties (tuber root diameter, tuber root weight, tuber root length and tuber root dry matter) and chemical centent (leaves potassium %, total carbohydrate % and tuber roots potassium %).

First record of white rot on Ipomoea batatas caused by Sclerotinia sclerotiorum in China

Collapsed vines of sweet potato (Ipomoea batatas) plants were observed in Jining fields in September 2019. In some cases, the whole plant had been killed due to the infection of crown. The size of sclerotia formed on infected tissues ranged from 0.6 to 1.5 cm in diameter. A number of sclerotia were sampled from infected fields and transferred to laboratory. After molecular assessment of the isolate SSd925 and fulfillment of Koch’s Postulates, the pathogen was identified as Sclerotinia sclerotiorum. To our knowledge, this is the first report of S. sclerotiorum on sweet potato in China.

Bioestimulante para o crescimento inicial de batata-doce

O objetivo deste trabalho foi avaliar a influência das diferentes doses do bioestimulante Raiza sobre o crescimento inicial de plantas de batata-doce. O experimento foi realizado em casa de vegetação em delineamento experimental inteiramente casualizado, com seis tratamentos e quatro repetições, no total 24 plantas. Os tratamentos (doses de bioestimulante em mililitro por planta) foram compostos por: T1, testemunha sem aplicação de bioestimulante; T2, 2 mL; T3, 4 mL; T4, 6 mL; T5, 8 mL; T6, 10 mL. Os seguintes parâmetros foram avaliados: massas de matéria fresca e seca da raiz; massas de matéria fresca e seca da parte aérea; número de folhas; comprimento de ramas; razão raiz/parte aérea; e massa foliar específica. Os parâmetros não diferiram entre si com as aplicações do bioestimulante, quanto ao crescimento inicial da batata-doce. São necessárias mais investigações, a fim de verificar a resposta da batata-doce quanto à ação do produto utilizado, especialmente quanto às dosagens.

Land evaluation of sweet potatoes with a parametric approach

Sweet potato is a food commodity that has high economic value and is an alternative staple food because of its energy and nutrition content. This study was in the form of parametric approach by assigning weights to each of the characteristics of both land and climate required for sweet potato plant growth. Climate and land suitability analysis was performed using the square root method. The results of climate suitability analysis showed that there were two periods of sweet potato plant growth, namely in November-March (S2) and March-July (S3) with a limiting factor in relative humidity (RH) and the length of the sun’s irradiation (n/N) which could not be improved. Land suitability analysis in the November-March growing period showed that there are two land suitability classes namely S3 (land units 1,2, 5 and 6) and N (land units 3 and 4). The limiting factors were soil depth, organic carbon and climate (humidity and length of sun exposure). Organic carbon is improvable by adding cover crops, soil depth with a high level of management, while climate such as relative humidity and irradiation are not manageable.

Abscisic acid phytohormone estimation in tubers and shoots of Ipomoea batatas subjected to long drought stress using competitive immunological assay.

Sweet potato (Ipomoea batatas L.), typically cultivated in temperate climates under low inputs, is one of the most important crops worldwide. Abscisic acid (ABA) is an important plant stress-induced phytohormone. Hitherto, few works analyzed the ABA function in sweet potato tissue growth. Very scarce information is available concerning the ABA role in sweet potato response to water scarcity conditions. Here, we show the ABA content variation in shoots and tubers of eight sweet potato accessions subjected to drought stress. ABA was also related to other resistance traits, such as chlorophyll content index (CCI), carbon isotopic discrimination (Δ13 C), oxalic acid (OA) and water use efficiency (WUE), to assess stress response mechanisms to water deficit between their organs. The most resilient drought-stressed sweet potato plants accumulated ABA-shoot, and significantly decreased the ABA-tuber content. ABA signaling was related to Δ13 C and CCI decrease and WUE increment, as an attempt to cope with water stress by partially closing the stomata. The partial closure of stomata could be in part due to the presence of OA-shoots, known to affect the intensity of the ABA-shoot signal in stomatal closure. Higher CCI content and minimal Δ13 C-shoot differences indicated good carboxylation fractionation, with higher Δ13 C-tuber content as an indicator of efficient tuber 13 C fixation and growth. Our work demonstrated that ABA could be used in conjunction with the other traits studied for the assessment of sweet potato whole-plant responses to environmental stresses, and thus aid the selection of the best drought tolerant genotypes for breeding programs.

Genome characterisation of a distinct species of Begomovirus causing leaf curl disease in sweetpotato [Ipomoea batatas L. (Lam)] in India

ABSTRACT A novel species of monopartite begomovirus was detected in sweetpotato [Ipomoea batatas L (Lam)] originating from the experimental field of ICAR-AICRP on Tuber Crops (West Bengal), India. The plants showed a typical upward curling of leaves symptoms and reduction in plant height and was easily transmitted through the tuber and vine cuttings of infected plant. PCR-mediated detection using specific primers confirmed the presence of begomovirus in the infected sweetpotato plants. The virus isolate was characterised genome level with 2823 nucleotide in size (GenBank accession FN432356) and designated as Sweet potato leaf curl Bengal virus (SPLCV) (India:West Bengal). The comparative analysis showed that SPLCV (India:West Bengal) clustered with distinct isolate of previously reported 35 SPLCV in the world. Six ORFs of the isolate were highly divergent from equivalent regions of other isolates. Sequence comparisons and population structure analysis of 35 SPLCV isolates revealed that SPLCV (India:West Bengal) showed 85–90% nucleotide sequence identity. Systematic examination revealed that SPLCV (India:West Bengal) isolate was shown to have a recombinant in origin. The results of the current study have uncovered the diversity and genetic structure of sweetpotato leaf curl virus and generated potentially useful information for developing management strategies for this virus.

Methyl jasmonate modulation reduces photosynthesis and induces synthesis of phenolic compounds in sweet potatoes subjected to drought

ABSTRACT Sweet potato [Ipomoea batatas (L.) Lam.] has wide adaptability to different climatic conditions. However, its yield can be affected by prolonged periods of drought. Application of exogenous jasmonates can modulate several physiological and biochemical processes, improving plant tolerance to abiotic stress. This study sought to evaluate the role of exogenous application of methyl jasmonate (MeJA) in attenuating the adverse effects of drought stress by physiobiochemical analyses and their impact during the early initiation of tuberous roots. The experimental design was completely randomized and arranged in a 2 x 2 factorial, comprised of two concentrations of a MeJA plant regulator [without (0 µmol·L-1) and with (13 µmol·L-1) application] and two water regimes (optimum and drought conditions, corresponding to a field capacity of 100 and 40%, respectively). Plants treated with MeJA showed a reduction in total leaf area and leaf dry biomass but increased adventitious root dry biomass. In addition, MeJA application in sweet potato plants affected photosynthetic performance and increased and antioxidant phenolic compounds, carotenoids, anthocyanins, and proline. The evaluated response mechanisms showed that the severity of drought was more prominent than the positive effects of MeJA, since the increases on antioxidant pigments and secondary metabolites were not sufficient to mitigate stress caused by drought, which was reflected in the reduced tuberous root production.

Pengaruh Pengaturan Komposisi Media Tanam Organik Terhadap Pertumbuhan Dan Hasil Tanaman Ubi Jalar ( Ipomoea batatas L.) Dengan Sistem Tabilampot

Sweet potatoes are an alternative source of carbohydrates that have high nutritional content. Development of sweet potato cultivation methods needs to be done to overcome the decrease of productive agricultural land due to land conversion. This study aimed to test the effect of differences in the composition of the growing media on the growth, yield, and quality of sweet potato. This study was a pot experiment using a Randomized Block Design (RBD) with 7 treatments and 5 replications. The types of treatments tested were P0: 100% soil + inorganic fertilizer; P1: 50% soil + 50% cow manure; P2: soil 50% + vermicompost 50%; P3: soil 50% + biochar rice husk 25%, cow manure 25%, P4: soil 50% + biochar rice husk 25% + vermicompost 25%, P5: soil 50% + cocopeat 25% + cow manure 25%, P6: soil 50% + cocopeat 25% + vermicompost 25%. The research results showed that the composition of the growing medium significantly affected plant growth and yield. The results of the statistical analysis showed that the treatments of P4 and P6 gave the highest growth, while the high yield of fresh weight of tubers per pot were found in the treatments P1, P2, P3, and P4 by 165.59 g, 143.38 g, 171.56 g, and 144.80 g, respectively. The highest number of tubers was found in treatment P6 by 7.66 tubers. The highest yield of dry matter was also found in treatments P1, P2, P3, and P4 by 59.91 g, 51.73 g, 59.02 g, and 48.59 g, respectively. Based on the research results, it can be recommended that the cultivation of sweet potato plants in pots can be carried out using porous growing media in a container that is sufficient and available balanced nutrients for the development of plant tubers.Keywords: Vermicompost, composition of growing media, Sweet Potatoes, Yield, Quality

PEMBERIAN HORMAX DAN NPK MUTIARA 16:16:16 PADA TANAMAN UBI JALAR ( Ipomoea batatas L.)

ABSTRACT
 The purpose of this study was to determine the effect of Hormax and NPK Mutiara (16:16:16) on sweet potato plants. The design used in this study was a Factorial Complete Randomized Design consisting of two factors. The first factor is Hormax (H) at doses of 0, 1, 3, and 5 ml per liter of water while the second factor is NPK Mutiara (16:16:16) (N) with concentrations of 0, 3.15, 6.3, and 9.45g per plant. The parameters observed were the number of crop tubers (tubers), tuber weight per plot (g), tuber weight per tuber (g), tuber weight per plant (g), wet pruned weight (g), harvest index. The last observation data were analyzed statistically and continued with a BNJ follow-up test at the 5% level. The results showed that the interaction of giving Hormax and NPK Mutiara (16:16:16) significantly affected the number of tubers per plant, tuber weight per plot, tuber weight per fruit, weight. The best treatment is in the combination of H2N2 fertilizer concentration of 3 ml/liter of water and 6.3 g / plant. The main influence of hormax is evident on the parameters of the number of tubers per plant, tuber weight per plot, tuber weight per tuber, tuber weight per plant, wet perched weight, harvest index, the best treatment of 3 ml per liter of water (H2). The main effect of NPK Mutiara fertilizer (16:16:16) is real on the parameters of the number of tubers per plant, tuber weight per plot, tuber weight per fruit, tuber weight per plant, wet perched weight, harvest index, best treatment ie 6.3 g per plants (N2).
 Keywords: Hormax, NPK, Sweet Potatoes

PENGGUNAAN AIR KELAPA DAN ASPIRIN UNTUK PRESERVASI UBI JALAR (Ipomea batatas) SECARA IN VITRO

Sweet potato is raw locally food used as an alternative staple food that important for national food security. The objective of the reseach was to achive the suitable medium for preservation of sweet potato plants by slowly growth in in vitro medium. The factorial experiment arranged in completely randomized design with the first factor was two concentrations of MS medium: MS 1 and MS 2. The second factor was several concentrations of coconut water, i.e. 0 and 15 mg/l and the third factor was several concentrations of Aspirin (0, 5, 10, 15, 20 mg/l) . The results showed that the number of green leaves and the number of internodes were affected by concentrations of medium in six weeks after planting. The MS1 medium with 0 mg/l Aspirin and 15 mg/ coconut water could produced the higher number of green leaves (8,0) and 8,5 internodes number. The MS2 + 15 mg/l coconut water and 15 mg/l Aspirin was the best medium for sweet potato preservation. Data obtained also showed that all medium containing Aspirin produced the high number of root. Keywords : Sweet potato, coconut water, Aspirin, preservation, in vitro.

Screening of Bacillus strains in biocontrol of pathogen Dickeya dadantii causing stem and root rot disease of sweet potato

ABSTRACT Outbreaks of stem and root rot disease of sweet potato caused by Dickeya dadantii recently occurred in major sweet potato planting areas in China. This study aimed to screen effective Bacillus strains in biocontrol of the bacterial soft rot pathogen. We screened plant-associated Bacillus strains capable of inhibiting D. dadantii using an in vitro overlay culture assay and an in vivo tuber slice assay. All Bacillus strains inhibited D. dadantii growth and maceration of sweet potato tubers. Two strains B. amyloliquefaciens A3 and B. velezensis A2 showed significantly higher rates of in vitro inhibition (55% and 50%) on D. dadantii growth and in vivo reduction (82% and 77%) of the maceration of sweet potato tuber slices by D. dadantii than other Bacillus strains did. They showed broad-spectrum inhibition on growth of soft rot Dickeya and Pectobacterium strains. They protected sweet potato seed tubers from infection by D. dadantii and promoted seedling growth. Their culture supernatants inhibited D. dadantii growth, swimming and biofilms and damaged D. dadantii cells. B. amyloliquefaciens A3 is more effective than B. velezensis A2 in producing surfactins, well-known lipopeptide antibiotics and biosurfactants, and inhibiting D. dadantii. Together, we developed an effective method to screen effective Bacillus strains to control the soft rot pathogen D. dadantii and screened out a strong surfactin producer B. amyloliquefaciens A3, which can be used as a reference strain for further screening of more effective Bacillus strains and to develop an agent to control the stem and root rot disease of sweet potato.

Enhanced resistance to white rot in Ipomoea batatas expressing a Trichoderma harzianum chitinase gene

Collapsed sweet potato vines observed in Hangzhou fields in September 2019 were found to be due to Sclerotinia sclerotiorum based on its morphology and ITS rDNA sequence. Here, the chitinase gene chit42 from Trichoderma harzianum was introduced into Ipomoea batatas using Agrobacterium-mediated transformation to evaluate the effect against subsequent disease severity from S. sclerotiorum. PCR analysis detected the transgene in 23 transformants with a transformation efficiency of 5.1%. RT-PCR analysis showed transgene mRNA expression in all four selected lines harboring chit42. Enzymatic tests showed a significant increase in the activity of endochitinase in extracts from leaf tissues of chit42-transgenic 75-day sweet potato lines. Virulence of three genetically different isolates was markedly reduced on leaves of 75-day-old chit42-transgenic plants compared with the controls. To our knowledge, this is the first report of S. sclerotiorum on sweet potato plants in China.

A sucrose non-fermenting-1-related protein kinase-1 gene, IbSnRK1, confers salt, drought and cold tolerance in sweet potato

Sucrose non-fermenting-1-related protein kinase-1 (SnRK1) regulates carbon and nitrogen metabolism in plants. However, its roles and their underlying mechanisms in tolerance to abiotic stresses are little known. The present study indicated that the IbSnRK1 gene was strongly induced by NaCl, polyethylene glycol (PEG) 6000, hydrogen peroxide (H2O2), cold (4 °C), and abscisic acid (ABA). Its overexpression significantly increased salt, drought, and cold tolerance in transgenic sweet potato plants. ABA, proline, and K+ contents were significantly increased, whereas malondialdehyde (MDA), Na+ and H2O2 contents and O2− production rate were significantly decreased in the transgenic plants under salt, drought, and cold stresses. Overexpression of the gene up-regulated genes involved in ABA biosynthesis, stress response, and stomatal closure; increased enzyme activities in the reactive oxygen species (ROS) scavenging system; and controlled stomatal closure under salt, drought, and cold stresses. These results show that the IbSnRK1 gene confers salt, drought, and cold tolerance in sweet potato by activating the ROS scavenging system and controlling stomatal closure via the ABA signaling pathway.

Effect of copper oxide nanoparticles on two varieties of sweetpotato plants

Little information is available on the interaction of CuO nanoparticles (nCuO) with tuberous roots. In this study, Beauregard-14 (B-14, low lignin) and Covington (COV, high lignin) sweetpotato varieties were cultivated until maturity in soil amended with nCuO, bulk copper oxide (bCuO) and CuCl2 at 25–125 mg/kg. The Cu treatments had no significant influence on chlorophyll content. Gas exchange parameters were not affected in B-14. In COV, however, at 125 mg/kg treatments, bCuO reduced the intercellular CO2 (11%), while CuCl2 increased it by 7%, compared with control (p ≤ 0.035). At 25 mg/kg nCuO increased the length of COV roots (20.7 ± 2.0 cm vs. 14.6 ± 0.8 cm, p ≤ 0.05). In periderm of B-14, nCuO, at 125 mg/kg, increased Mg by 232%, while the equivalent concentration of CuCl2 reduced P by 410%, compared with control (p ≤ 0.05). The data suggest the potential application of nCuO as nanofertilizer for sweetpotato storage root production.

Pathogenicity of fungi associated with leaf spot disease of sweet potato (Ipomea batatas L. (Lam) in Makurdi, Benue State, Nigeria

The screen house experiment was conducted to determine the pathogenicity of leaf spot fungi of sweet potato in Makurdi situated in the Southern Guinea Savannah of Nigeria. The experiment was a completely randomized design with twelve replicates. The variability in pathogenicity of four leaf spot fungi namely: Aspergillus flavus (Link), Aspergillus tamarii (Kita), Macrophomina phaseolina (Tassi), and Fusarium verticillioides (Sacc.) on sweet potato variety TIS-3164 was evaluated in the screen house using the spore suspension of the fungi at 15x 106 spores/ ml on four weeks old plants. All four isolates were pathogenic and induced necrotic symptoms on sweet potato plants. The leaf spot lesions were widest in sweet potato plants inoculated with A. tamarii (9 cm) followed by F. verticollioides (5 cm), A. flavus (4 cm) and M. phaseolina (3.20 cm). Sweet potato plants inoculated with spore suspension of the test fungi recorded significantly (P < 0.05) lower number of leaves with sweet potato plants inoculated with F. verticillioides recording the least number of leaves (30.75). At 4weeks after planting (WAP), the application of the spore suspension of A. tamarii produced significantly lower leaf area of 5.56cm2. At 4 weeks after inoculation (WAI), percentage leaf defoliation was highest on sweet potato plants inoculated with A. flavus (44.50 %) and least when sweet potato plants were inoculated with M. phaseolina (34.30 %). The inoculation of the sweet potato plants with all test fungi had no significant effect on the vine length. The study demonstrated the pathogenicity of all four test fungi on sweet potato.