Research Article

Management of Meloidogyne incognita (Kofoid & White) Chitwood and Sclerotium rolfsii Sacc. on Common Bean (Phaseolus vulgaris L.) in Field, Using Trichoderma species and Neem Cake

1Daniel Offiong Etim*, Rosemary Anietie Bassey1, Glory Akpan Bassey1 and Ndarake Eden Ini-Ibehe1

1Department of Botany, Faculty of Biological Sciences, University of Calabar, Calabar, Nigeria.

Received | May 10 2024; Accepted | Jul 29, 2025; Published | November 25, 2025

*Correspondence | Daniel Offiong Etim, Department of Botany, Faculty of Biological Sciences, University of Calabar, Calabar Nigeria. Email: [email protected]

Citation | Etim, D.O., R.A. Bassey, G.A. Bassey and N.E. Ini-Ibehe. 2025. Management of meloidogyne incognita (kofoid & white) chitwood and sclerotium rolfsii sacc. on common bean (phaseolus vulgaris l.) in field, using trichoderma species and neem cake. Sarhad Jurnal of Agriculture, 41(4): 1846-1859.

DOI | https://dx.doi.org/10.17582/journal.sja/2025/41.4.1846.1859

Keywords | Biocontrol, Common bean, Neem cake, Sclerotium rolfsii, Meloidogyne incognita Trichoderma species.

Copyright: 2025 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

P haseolus vulgaris L. is an herbaceous annual that is widely cultivated worldwide, including regions within Sub-Saharan Africa. The species (P. vulgaris) flourishes in temperate and subtropical environments, including areas in Africa, Central America, and South America. Its primary mode of cultivation pertains to the production of dry seeds, and this agricultural practice reveals a broad spectrum of variations in seed coat pigmentation and pod attributes. Dry legumes are acknowledged for their comprehensive nutrient profiles and phytochemical constituents, these are pivotal especially in connection with the role of legumes in reducing the risk of various health disorders (Camara et al., 2013). Indeed, several investigations have corroborated the effectiveness of common bean in the management of diabetes (Laleye et al., 2015) and obesity (Carai et al., 2009; Rondanelli et al., 2011). According to the Missouri Botanical Garden (2023), the most effective propagation strategy for this species involves sowing seeds in consistently moist, fertile, organically-rich, well-drained loam soil, subjected to full sunlight exposure.

P. vulgaris exhibits vulnerability to numerous pathogens that considerably diminish its agronomic productivity. The nematodes M. hapla, M. javanica, M. incognita, and the fungus S. rolfsii have been recognized as significant agents contributing to the infection of the common bean, resulting in marked reductions in growth and yield (Saka, 1990; Paparus et al., 2020). Plant-parasitic nematodes, which exhibit widespread distribution and possess a high fecundity rate, present considerable challenges in mitigating their detrimental effects on the crop, leading to extensive damage and yield losses (Luc et al., 2005). These nematodes target different parts of host plants, inducing symptoms such as wilting, chlorosis, stunted development, and gall formation in plant root system.

Likewise, Sclerotium rolfsii exhibits a broad host range, which includes potato, groundnut, soybean, sunflower, chili, tomato, P. vulgaris, cotton, lucerne, wheat, and onion, and it possesses the capacity to induce significant reductions in crop yields (Buensanteai et al., 2012). Managing S. rolfsii poses considerable difficulties in the absence of synthetic fungicides. Nevertheless, the application of synthetic pesticides not only exacerbates environmental degradation but also imposes a financial strain on rural agriculturalists in numerous developing nations, owing to the rising costs associated with these chemical agents (Bell, 2013). Recently, there has been a conspicuous transition from environmentally detrimental pesticides towards plant derived alternatives for pathogen management (Bassey et al., 2023). For example, the utilization of fungi such as T. harzianum and T. viride has become increasingly favored, alongside the development of additional plant-based pesticides aimed at controlling plant-parasitic nematodes, with the objective of mitigating the complications linked to synthetic nematicides (Bell, 2013). This present research evaluated the efficacy of two Trichoderma species, and Neem Cake (NC) in the control of M. incognita and S. rolfsii.

Materials and Methods

Experimental site and source of materials

The study was performed at Nyahasang area in Calabar municipality, located in Cross River State, located at 4.99° N latitude, 8.35° E longitude. Common bean seeds (P. vulgaris) were sourced at the Ministry of Agriculture, Cross River state, Nigeria. A stock culture of T. viride and T. harzianum was purchased in Department of Botany at the University of Calabar. The byproduct obtained during neem oil extraction, called NC was acquired from the Institute of Agricultural Research (IAR) in Zaria, Nigeria.

Sub culturing and spore count of trichoderma species

Potato Dextrose Agar (PDA) served as the culture medium for the sub-culturing of pure stock cultures of the two Trichoderma species. To quantify colony-forming units (CFU/g), the T. viride and T. harzianum were scraped and 1 gram of each species was accurately measured using an Ohaus weighing balance. The substrates measured was then placed in a beaker containing distilled water of 10 ml. This was subsequently mixed in a vortex mixer to achieve a homogeneous solution. A volume of 1ml from the diluted samples was pipetted into the hemacytometer for counting under a binocular microscope. The spore quantification of Trichoderma species followed the methodology outlined by Pitt and Poole (1981). The spore density was calculated as millions of CFU per gram of millet substrate, resultant spore numbers were utilized as inoculum loads. The quantified spore load for T. viride was 2.40 × 10⁷ CFU/g of millet, while T. harzianum recorded a spore count of 1.40 × 10⁷ CFU/g of millet.

Preparation of carrier for Trichoderma species

The method described by Sivan et al. (1984) was followed in the formulation of a substrate for Trichoderma spp. A sensitive weighing balance was utilized to measure 200g of millet grains, which were subsequently soaked in distilled water for a duration of 24 hours to facilitate fermentation prior to utilization. The grains underwent sterilization via autoclaving at 121°C for 15 minutes in a Bema bottle, and allowed to cool. Decontaminated cork borers containing mycelial discs from various T. viride and T. harzianum cultivated on PDA as pure cultures were introduced to the substrates. The substrates were incubated at ambient laboratory temperature for a period of 3 to 5 days prior to their deployment in the field for inoculation.

Application of neem cake (NC), planting of common bean seeds and inoculation of Trichoderma species

The application of NC was done at rates of 0.96 and 1.92 kg per plot, corresponding to 2 and 4 t/ha, respectively, according to the experimental design, two weeks preceding the planting; the control plots received no NC application. Three seeds of common bean were planted at a depth of 3 cm with an inter-row spacing of 50 cm and intra-row spacing of 30 cm, which were subsequently thinned to a single plant stand two weeks post-sowing, resulting in a density of 28 plants in each plot (66,667 plants/ha). One gram (1g) of various Trichoderma species was utilized for inoculation on the treatment plots, with uninoculated plots serving as the control.

Experimental design, data collection and statistical analysis

The experimental framework was established as a 3 x 3 factorial in a randomized complete block design (RCBD), replicated thrice, culminating in 9 treatment combinations and 27 experimental units or plots. Data were systematically gathered at biweekly intervals commencing three weeks post-sowing (3WAP) from eight central rows of plants. The parameters measured included: galls per plant (GPP), Mean Gall Index (MGI), root-knot disease incidence (RDI), nematode number per plant, nematode density in 250 grams of soil, incidence (%) of S. rolfsii disease and its severity index (SI), height of plants (cm), number of leaves, weight of fresh roots (g) per plant, number of pods per plant, yield of pods (t/ha), and dry weights of leaves (g) and stems (g) per plant. The acquired data were analyzed using analysis of variance (ANOVA), and significant means were evaluated through Duncan’s New Multiple Range Test (DNMRT) at a 5% level of probability.

Results

Effects of neem cake (NC), Trichoderma species and their interactions on number of galls in each plant and MGI of common bean plants naturally infested with M. incognita and S. rolfsii.

Table 1 indicates that the quantity of GPP were higher significantly (P≤0.05) in common bean specimens cultivated in unamended soils devoid of NC or Trichoderma species. A dosage increase of NC caused a significant (P≤0.05) reduction in root galling. Plants exhibiting the lowest gall count were obtained from soil enriched with 4.00 t/ha of NC. The introduction of both biocontrol agents led to significant (P≤0.05) decrease in galls, in each plant when compared to the control group.

 

Table 1: Effects of neem cake (N.), Trichoderma species (T.) and their interactions number of galls per plant and mean gall index of common bean plant naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	Number of galls per plant	Mean gall index
N00.00	66.00+8.90a	3.26+0.19a
N12.00	50.33+8.04b	2.75+0.16b
N24.00	37.22+5.93c	2.18+0.17c
Trichoderma species (T.)
T0 (control)	80.89+6.11a	3.21+0.23a
T1 Trichoderma viride	32.11+4.02c	2.33+0.20b
T2 Trichoderma harzianum	40.56+2.74b	2.65+0.15b
Trichoderma species and neem cake (Interactions)
T0N0		3.96+0.21a
T0N1		3.00+0.29a
T0N2		2.67+0.17a
T1N0		3.00+0.00a
T1N1		2.25+0.14a
T1N2		1.75+0.25a
T2N0		2.83+0.17a
T2N1		3.00+0.00a
T2N2		2.13+0.19a

 

Nevertheless, minimal gall count was recorded with the application of T. viride. In untreated plants, the average gall index was equally higher significantly (P≤0.05). The incorporation of NC into the soil markedly decreased the MGI, particularly at 4.00 t/ha. The MGI was significantly comparable in common bean plants subjected to both species of Trichoderma.

 

The interactive effects of Trichoderma species, as well as NC were significant (P≤0.05) on number of galls in each plant, as depicted in (Figure 1). The highest gall count was recorded in plants that did not receive either Trichoderma species or NC. Conversely, the combined application of treatments reduced significantly (P≤0.05) the GPP, resulting in the lowest counts. Conversely, the combined application of treatments significantly (P≤0.05) lowered the number of galls in each plant, resulting in the lowest counts.

Neem cake and Trichoderma species interactive effects on RDI (%), on nematodes per plant as well as density of nematodes in common bean naturally infested with M. incognita and S. rolfsii

Table 2 shows that the utilization on treatment using NC reduces significantly (P≤0.05) incidence of root-knot disease at an application rate of 4.00 t/

 

Table 2: Effects of neem cake (N.), Trichoderma species (T.) and their interactions on root-knot disease incidence (%), number of nematodes per plant and nematode density in 250 grams of soil of common bean plant naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	Root-knot disease incidence (%)	Number of nematodes per plant	Nematode density in 250 of soil
N0 0.00	75.00+2.08a	3356.00+697.92a	339.40+57.90a
N12.00	70.83+3.61a	1806.00+406.64b	237.90+36.46b
N24.00	61.10+3.26b	1118.00+286.73c	161.00+33.71c
Trichoderma species (T.)
T0 (control)	73.60+3.26a	3936.00+577.50a	416.20+40.52a
T1 Trichoderma viride	65.30+4.05a	1032.00+213.54c	151.00+17.25c
T2 Trichoderma harzianum	68.10+3.03a	1312.00+206.33b	171.10+20.76b
Trichoderma species and neem cake(Interactions)
T0N0	79.20+4.17a		570.00+5.77a
T0N1	75.00+7.22a		383.00+4.04b
T0N2	66.70+ 4.17a		295.70+3.18c
T1N0	75.00+ 0.00a		207.70+5.04e
T1N1	62.50+7.22a		156.00+4.93g
T1N2	58.30+8.33a		89.30+1.45h
T2N0	70.80+4.17a		240.70+5.78d
T2N1	75.00+ 0.00a		174.70+5.93f
T2N2	58.30+ 4.17a		98.00+2.31h

 

Means within a column followed by the same letter of alphabet are not significantly different from one another based on Duncan’s New Multiple Range Test (DNMRT) at 5% probability level.

 

ha, whereas the application of 2.00 t/ha NC showed statistical significance (P≤0.05) similar to the control. The application of the two T. viride and T. harzianum did not produce significant (P≥0.05) effects regarding diseases of root-knot incidence on common beans. The quantity of nematodes per plant was reduced significantly (P≤0.05) with NC application. The most substantial reduction was observed at the application rate of 4.00 t/ha. The application of Trichoderma species led to a significant (P≤0.05) reduction in nematodes per plant when compared to control (Figure 2). Plants treated using T. viride exhibited a significantly lowered the number of nematodes in each plant, in contrast to the ones treated using T. harzianum. The concentration of nematodes in the soil paralleled the trend observed in the number of nematodes per plant. Soil enhanced with 4.00 t/ha of NC significantly decreased the nematode density in the soil. The application of T. viride and T. harzianum also significantly reduced the density of nematode in the soil. Nevertheless, plants inoculated using T. viride revealed smallest nematode density in the soil.

The interaction effects of T. viride and T. harzianum, as well as NC did not yield significant (P≥0.05) effects on the disease incidence of root-knot in common bean plants. The interaction effects of the treatment applications reduce significantly (P≤0.05) the number of nematodes per plant and nematode density in the soil compared to the controls. However, the interactive effect of NC at 4.00 t/ha alongside T. viride resulted in lowered nematodes number in each plant, as well as density of nematode in the soil, in comparison to the control.

Interactive effect of neem cake, Trichoderma species on S. rolfsii disease incidence and SI of common bean infested with M. incognita and S. rolfsii

Table 3 illustrated that NC as well as Trichoderma species utilization diminishes significantly (P≤0.05) incidence of S. rolfsii disease in common bean plants. Specifically, plants treated with NC 2.00 t/ha rate exhibited significantly small (P≤0.05) incidence of S. rolfsii when compared those treated 4.00 t/ha. Regarding the Trichoderma species, common bean plants cultivated in soil enriched with T. harzianum demonstrated a significantly (P≤0.05) lower incidence of S. rolfsii than those that received T. viride. The patterns observed in the S. rolfsii disease SI for common bean plants were congruent with the findings on disease incidence, where the plants inoculated using 2.00 t/ha of NC and T. harzianum displayed reduction significantly (P≤0.05) regarding severity of S. rolfsii infection.

 

Table 3: Effects of neem cake (N.) Trichoderma species (T.) and their interactions on Sclerotium rolfsii disease incidence and Sclerotium rolfsii disease severity index of common bean plant naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	S. Rolfsii disease incidence	S. Rolfsii disease severity index
N00.00	52.41 (46.66)+ 8.28a	37.82 (37.86)+2.93a
N12.00	29.37 (26.15)+4.37c	22.49 (28.22)+1.38c
N24.00	21.43 (31.45)+3.86b	26.39 (30.81)+1.78b
Trichoderma species (T.)
T0 (control)	55.16 (47.03)+7.65a	36.37 (36.96)+3.20a
T1 Trichoderma viride	20.27 (32.38)+3.32b	27.31 (31.38)+2.17b
T2 Trichoderma harzianum	27.78 (26.85)+3.66c	23.02 (28.55)+1.73c
Trichoderma species and neem cake (interactions)
T0N0	84.52 (67.04)+3.15a	48.79 (44.30)+ 0.92a
T0N1	45.24 (34.58)+4.29cd	27.78 (31.80)+0.40de
T0N2	35.71 (39.46)+2.06bc	32.54 (34.78)+0.52bc
T1N0	32.24 (42.25)+1.98b	34.92 (36.21)+2.18b
T1N1	17.86 (24.93)+2.06e	21.03 (27.29)+0.20g
T1N2	10.71 (29.96)+2.06de	25.99 (30.64)+1.43f
T2N0	40.48 (36.69)+4.29bc	29.76 (33.06)+0.60cd
T2N1	25.00 (18.94)+2.06f	18.65 (25.58)+0.40g
T2N2	17.86 (24.93)+2.06e	20.63 (27.01)+0.53g

 

The interactive effects of T. viride and T. harzianum as well as NC regarding both the incidence as well as severity of S. rolfsii disease indicated that common bean plants devoid of both T. viride and T. harzianum and NC exhibited the highest levels of disease incidence and severity, which were statistically significant (P≤0.05). Conversely, the combined application of both treatments resulted to a reduction significantly (P≤0.05) of incidence and severity of S. rolfsii disease in common bean plants.

 

Neem cake (NC) and Trichoderma species interactive effects on height of common beans, naturally infested with M. incognita and S. rolfsii at 3, 5 and 7 at the end of planting

Table 4 indicates that NC application rate of 4.00 t/ha enhanced plant height significantly (P≤0.05) at three weeks post-sowing when compared to a rate of 2.00 t/ha and the control. T. viride and T. harzianum application did not create any statistically significant (P≥0.05) impact on plant height at three weeks post-sowing. At five and seven weeks after planting, soil amended with 4.00 t/ha of NC demonstrated a greater height significantly (P≤0.05), followed by 2.00 t/ha in comparison to the control. Soil inoculated with both T. viride and T. harzianum had similar heights at five weeks after planting. At seven weeks after planting, the inoculation of soil with both T. viride and T. harzianum caused an improvement in plant height, with the optimal height achieved when T. viride was applied. There were no statistically significant (P≥0.05) effects on plant height at three weeks after planting. Nevertheless, at five and seven weeks following planting, the tallest plants were observed in soil treated with (T1N2 and T2N2 ). Overall, plant height exhibited an increase as the duration of weeks progressed.

Neem cake (NC) and Trichoderma species interactive effects of leaves of common beans, naturally infested with M. incognita and S. rolfsii at 3, 5 and 7 at the end of planting.

Soil modified using 4.00 t/ha (Table 5) of NC increased leaf production significantly (P≤0.05) in common bean, followed by 2.00 t/ha in comparison to the control. The application of Trichoderma species did not result in any significant improvement on the number of leaves in each plant at three weeks post-sowing. At five- and seven-weeks post-sowing, soil 4.00 t/ha of NC significantly (P≤0.05) promoted leaf production in common bean plants, followed by 2.00 t/ha compared to the control. The application

 

Table 4: Effects of neem cake (N.), Trichoderma species (T.) and their interactions on plant height (cm) of common bean plant naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	3 Weeks after planting (WAP)	5WAP	7WAP
N00.00	8.84+0.13c	21.86+0.83c	39.24+0.97c
N12.00	10.58+0.14a	24.53+0.67b	45.63+0.63b
N24.00	12.00+0.11a	26.69+0.63a	49.64+0.85a
Trichoderma species (T.)
T0 (control)	10.26+0.47a	21.57+0.83b	41.98+1.71c
T1 Trichoderma viride	10.60+0.48a	25.79+0.73a	46.97+1.70a
T2 Trichoderma harzianum	10.55+0.45a	25.71+0.57a	45.57+1.21b
Trichoderma species and neem cake (Interactions)
T0N0	8.64+0.16a	18.59+0.33f	35.46+0.54g
T0N1	10.28+0.10a	21.92+0.30e	43.58+0.44e
T0N2	11.86+0.21a	24.22+0.22c	46.88+0.46cd
T1N0	8.84+0.15a	23.25+0.26d	40.92+0.38f
T1N1	10.85+0.20a	25.93+0.34b	47.50+0.72c
T1N2	12.12+0.14a	28.20+0.19a	52.48+0.52a
T2N0	9.04+0.33a	23.75+0.14cd	41.34+0.44f
T2N1	10.60+0.31a	25.73+ 0.22b	45.80+0.33d
T2N2	12.01 +0.24a	27.65+ 0.26a	49.57+0.59b

 

* Mean within a column followed by the same letter of alphabet are not significant different from one another based on Duncan’s New Multiple Range Test (DNMRT) at 5% probability level.

 

of both Trichoderma species at five- and seven-weeks post-sowing demonstrated statistically similar leaf production. Trichoderma species and NC showed no significant (P≥0.05) improvements on the leaves in each plant at three weeks post-sowing. Nevertheless, at five and seven weeks after planting, the interaction effects significantly (P≤0.05) resulted in highest leaf production in soils treated with (T2N2), next to T1N2.

Neem cake (NC) and Trichoderma species interactive effects on fresh root weight per plant, dry leaf weight per plant and dry stem weight per plant of common beans naturally infested with M. incognita and S. rolfsii.

Table 6 elucidates that significant effects was seen on Trichoderma. The most pronounced fresh root weight per plant was recorded in common bean plants that received 4.00 t/ha of NC, followed by 2.00 t/ha

 

Table 5: Effect of neem cake (N.), Trichoderma species (T.) and their interactions on number of leaves of common bean plant naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	3WAP	5WAP	7WAP
N00.00	5.22+0.15c	9.67+0.33c	11.67+0.44c
N12.00	6.11+0.11b	11.44+0.34b	13.44+ 0.34b
N24.00	6.67+0.17a	13.44+0.44a	14.89+0.59a
Trichoderma species (T.)
T0 (control)	5.89+0.20a	10.33+0.50b	11.89+0.35b
T1 Trichoderma viride	6.11+0.31a	12.33+0.78a	13.78+0.76a
T2 Trichoderma harzianum	6.00+ 0.24a	11.89+ 0.42a	14.33+0.44a
Trichoderma species and neem cake (Interactions)
T0N0	5.33+0.33a	8.67+0.33f	10.67+0.33f
T0N1	6.00+0.00a	10.33+0.33e	12.33+0.33de
T0N2	6.33+0.33a	12.00+0.00c	12.67+0.33cd
T1N0	5.00+0.00a	9.67+0.33e	11.33+0.67ef
T1N1	6.33+0.33a	12.33+0.33c	13.67+0.33bc
T1N2	7.00+0.00a	15.00+0.00a	16.33+0.33a
T2N0	5.33+0.33a	10.67+0.33de	13.00+0.58cd
T2N1	6.00+0.00a	11.67+0.33d	14.33+0.33b
T2N2	6.67+0.33a	13.33+0.33b	15.67+0.33a

 

compared to control group. Plants that were not treated with Trichoderma species exhibited greater fresh root weight when compared to plants treated with the biocontrol agents. The dry leaf weight in each plant demonstrated significant (P≤0.05) variations in common bean plants treated with different rates of NC and Trichoderma spp. The highest dry leaf weight per plant was achieved when the soil was modified with 4.00 t/ha of NC. Conversely, T. viride yielded a dry leaf that was significantly (P≤0.05) compared to the control. The dry stem weight per plant exhibited a trend consistent with that of the dry leaf weight per plant. Soil enriched with 4.00 t/ha of NC exhibited the highest dry weight per plant, followed by the 2.00 t/ha application. Regarding Trichoderma spp., T. viride manifested significantly (P≤0.05) highest dry stem weight per plant.

These interactive effects were significant (P≤0.05) regarding fresh root weight in each plant. The maximum fresh root weight per plant was attained by T0N0, followed closely by T1N2. The interactive effect was significant (P≤0.05) concerning dry leaf weight of each plant. The greatest, yet statistically similar dry leaf weights were achieved by common bean plants treated with T0N2, T1N1, T1N2, and T2N2. Furthermore, the interactive effects on dry stem weight were equally significant (P≤0.05). Nevertheless, greatest dry stem weight was obtained from plants in T1N2 treatment group.

Neem cake (NC) and Trichoderma species interactive effects on number of pods per plant and pod yield t/ha of common beans naturally infested with M. incognita and S. rolfsii

Table 7 and Figure 3 revealed the number of pods in each plant were significant (P≤0.05) in NC, as well as Trichoderma species enriched plants, when put side by side with control group. A greater pods per plant numbers were observed when the soil was amended using 4.00 t/ha of NC, in comparison to the control. Plots inoculated with either species of Trichoderma exhibited a pod count that was significantly (P≤0.05) greater with reference to the control. The pod yield was equally significant (P≤0.05) in plants cultivated in soil modified with 4.00 t/ha of NC. Soil amended with 4.00 t/ha of NC significantly yielded the highest pod yield, followed by 2.00 t/ha, when compared to the control. Both biocontrol agents significantly (P≤0.05) yielded greatest pod production relative to control, with plants treated with T. viride demonstrating the

 

Table 6: Effects neem cake (N.), Trichoderma species (T.) and their interactions on fresh root weight per plant, dry leaf weight per plant and dry stem weight per plant of common bean naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	Fresh root weight per plant	Dry leaf weight per plant	Dry stem weight per plant
N00.00	27.47+1.94c	33.74+2.93c	134.10+12.66c
N12.00	30.28+0.68b	43.55+1.67b	189.80+14.43b
N24.00	31.32+0.49a	48.53+1.09a	211.90+17.09a
Trichoderma species (T.)
To (control)	32.63+0.72a	35.64+3.61c	121.20+9.47c
T1 Trichoderma viride	28.88+1.55b	46.65+1.84a	213.70+13.60a
T2 Trichoderma harzianum	27.57+0.91c	43.52+1.52b	200.90+12.61b
Trichoderma species and neem
Cake (Interactions) T0N0	35.04+ 0.84a	22.07+0.34d	84.10+1.23g
T0N1	32.31+0.38b	38.30+0.54c	134.30+2.62f
T0N2	30.53+0.53c	46.57+ 0.46a	145.10+2.51ef
T1N0	22.98+0.99e	40.35+ 0.47bc	163.80+3.15d
T1N1	30.66­+0.28c	49.61+ 0.64a	220.50+ 3.01c
T1N2	33.01+ 0.47b	50.00+3.20a	256.80+2.21a
T2N0	24.39+ 0.42e	38.80+ 0.20c	154.50+3.36de
T2N1	27.88+ 0.57d	42.74+0.5b	214.50+ 13.07c
T2N2	30.43+0.50c	49.03+ 0.88a	233.80+ 4.28b

 

 

Table 7: Effects neem cake (N) Trichoderma species (T) and their interactions on number of pods per plant and pod yield of common bean plant naturally infested with M. incognita and S. rolfsii.

Neem (t/ha)	Number of pods per plant	Pod yield t/ha
N00.00	8.56+0.50c	10.13+0.64c
N12.00	11.00+0.55b	14.65+1.01b
N24.00	12.22+0.52a	18.24+1.10a
Trichoderma species (T.)
T0 (control)	8.67+0.58b	10.78+0.91c
T1 Trichoderma viride	11.78+0.66a	16.77+1.34a
T2 Trichoderma harzianum	11.33+0.47a	15.47+1.29b
Trichoderma species and neem
Cake (interactions) T0N0	6.67+0.33a
T0N1	9.00+0.58a
T0N2	10.33+0.33a
T1N0	9.33+0.33a
T1N1	12.33+0.33a
T1N2	13.67+0.33a
T2N0	9.67+0.33a
T2N1	11.67+0.33a
T2N2	12.67+0.33a

 

highest pod yield. The interaction effects indicated no significant influence (P≥0.05) on the quantity of pods per individual plant. Conversely, the interaction effects on pod yield t/ha revealed a statistically significant enhancement (P≤0.05), with highest pod yield t/ha observed in plants subjected to treatment T1N2.

 

Discussion

The results of this investigation indicated that the inoculation of T. viride and T. harzianum, with NC into common bean plants infested with M. incognita and S. rolfsii exhibited a synergistic effect. Natural field infestations by both pathogens led to pronounced root galling in common bean plants, an increased nematode population per plant, an increased incidence of root-knot disease, and an increase in nematode density within the soil. The significant degree of galling observed in common bean plants may be linked to environmental factors, particularly given that the soil utilized in the field trials had a notable sand content. Previous studies have indicated that nematode activity is amplified in soils characterized by elevated sand proportions (Agu, 2008; Olewe, 2005). The findings of this investigation align with the observations made by Kim et al. (2016), that reported that galls are more prevalent on soil composed entirely of sand compared to those with lower sand content.

The incorporation of fungicides and nematicides into soil amendments has been documented as highly effective in controlling soil-borne fungi and nematodes, as well as enhancing soil fertility. Nonetheless, these chemical agents are not environmentally sustainable, prompting the exploration of biocontrol and eco-friendly alternatives as viable strategies for enhancing crop performance via soil amendments (Tanimola, 2008). These organic fertilizers are typically regarded as facilitators of improved crop performance due to several properties inherent to them, such as their capacity to function as nematicides (Sukul, 1992; Kimpinski, 2003), their role in augmenting soil nutrient content, enhancing physical and chemical soil properties, and stimulating the activity of predators and parasites that target phyto-parasitic nematodes (Nico, 2004; Hungalle, 1986). Based on observations from field experiments, the utilization of NC and Trichoderma species obviously contributed to reduce galls formation, and the gall index in common beans infected with M. incognita. It is conceivable that these fungi produced substances with lethal properties, thereby mitigating the galls induced by M. incognita.

Notably, the gall index decreased from an extremely vulnerable level in untreated soil to a resistant level within soils modified utilizing NC, as well as biocontrol agents. Additionally, these populations of nematode per plant, the density of nematode within the soil, as well as reproduction factor of nematode was lowered significantly resulting from the incorporation of neem and Trichoderma species into the soil. These results align with previous studies by various authors indicating the addition of neem compost and Trichoderma species effectively reduces root galling in addition to population of nematode within both roots as well as soil caused by M. incognita, hence, promoting common bean cultivation (Atungwu et al., 2009; Chimbekujwo and Neher, 2001; Radwan et al., 2012).

Neen cake exhibited greater efficacy at 4.00 t/ha compared to 2.00 t/ha in terms of lowering of galls formation and the number of nematodes in the soil. Akhatar and Mahmood (1995), stated that NC comprises phenolic compounds, tannins, flavonoids, and a variety of chemicals including salanin, thironemonie, and azadirachtin, which possess nematicidal properties at specific concentrations. This finding is in line with earlier reports on the bioactivity of neem leaves and seed extracts against several pathogens (Del Serrone and Nicoletti 2013). In the field trial, it was noted that treatment with NC exerted a substantial suppressive effect on S. rolfsii at a dosage of 2.00 t/ha, in contrast to the higher rate of 4.00 t/ha. Given the complexity of the additional nutrients present in the field, it is plausible that treatment with 2.00 t/ha of NC facilitated a more rapid and effective synergy with other soil nutrients, thereby enhancing the control of S. rolfsii relative to the higher application rate of 4.00 t/ha.

T. harzianum outperformed T. viride in terms of reducing the incidence of S. rolfsii disease and the associated disease SI within the field environment. According to the findings reported by Eziashi et al. (2007), T. harzianum exhibits antagonistic properties against S. rolfsii through the production of various bioactive compounds, including viridian, glotoxin, gliotoxin, glioviridin, dermin, and trichodermin. The increased release rate of these bioactive substances by T. harzianum into the soil could elucidate the enhanced efficacy observed against S. rolfsii compared to T. viride. The synergistic effects of NC combined with Trichoderma species proved to be more potent in the management of S. rolfsii disease incidence and severity during the field experiment. It is conceivable that NC facilitated the release of nematicidal compounds or organic matter that interacted proficiently with the antagonistic attributes of Trichoderma species, thereby inhibiting the proliferation of S. rolfsii.

In the present investigation, there was a notable improvement in both growth and yield of common bean in soils that were either fortified with NC or inoculated with species of Trichoderma, in comparison to the unamended control groups. The crops treated with NC demonstrated greater plant height, with the most notable effect observed at the higher application rate of 4.00 t/ha, measured within 3, 5, as well as 7 weeks then the planting were just concluded. It therefore implies NC enriches soil fertility, which may explain the increase in both plant height and pod yield (t/ha), as nutrients are gradually released into the growing environment. This result supports the observations of Krishnaray et al. (2018) and Madhuri et al. (2021), who found that NC boosts plant height and pod production in tomato plants. Similarly, Olabiyi et al. (2016) reported a significant improvement regarding the plant height of common bean following neem compost application. Consistent with these findings, Eifediyi et al. (2013) also noted an increase in common bean plant height following NC treatment.

At the 3-week after planting (WAP), the inoculation of the soil with Trichoderma species did not demonstrate any statistically significant effects on plant height in the experimental field. This lack of effect could be linked to the short duration when these observations were made. Comparable results were observed by Olabiyi et al. (2016), where the application of T. harzianum did not yield a significant effect on the height of common beans relative to the untreated controls. The optimal height of common bean plants was recorded when the soil was treated with T. viride in conjunction with NC at the rate of 4.00 t/ha. This finding corroborates the research of Olabiyi et al. (2016), who noted that the combination of T. viride with organic amendments promoted vigor and growth of common bean plant. The fresh root, dry leaf, and dry stem weights of common beans in this investigation were found to be superior in soils that were enriched with neem and the biocontrol agents, when compared to the unamended plots.

Conclusions and Recommendations

The investigation identified a synergistic relationship between T. viride and T. harzianum, with NC. The degree of galling and basal stem rot exhibited a marked increase when the two pathogens were simultaneously inoculated compared to their individual inoculation. The study demonstrated that the combination of T. viride and 4.00 t/ha of NC was the most effective in managing M. incognita and S. rolfsii in the cultivation of common bean plants. Treatment significantly lowered gall formation, nematode populations, and disease incidence. T. viride outperformed T. harzianum in reducing pathogen impact, with treated common bean plants showing enhanced growth, and yielding the highest pod production (21.08 t/ha). The above findings outline integration of biocontrol agents as well as organic amendments for efficient pest management in common bean plant. Upcoming studies have to ascertain long-term treatments effects as well as their usability across various agro-ecological zones.

Acknowledgements

The authors are grateful to Dada Adeleke, for playing significant role in the isolation of S. rolfsii used in this study.

Novelty statement

The research has highlighted the potential application of NC and native isolates of Trichoderma species cultivated on millet as a strategy for controlling the disease complex affecting common beans, which is induced by M. incognita and S. rolfsii. Integrating organic amendments and beneficial microorganisms is a promising strategy for managing the disease complex affecting common beans.

Author’s contribution

Daniel Offiong Etim: Designed the study, performed the statistical analysis, wrote the protocol and wrote the first draft of manuscript.

Rosemary Anietie Bassey and Glory Akpan Bassey: Managed the analysis of the study.

Ndarake Eden Ini-Ibehe: Managed the literature searches. All authors read and approved the final manuscript.

Generative AI or AI assisted technology statement

The authors declare that no Genrative AI was used in the creation of this manuscript.

Conflict of interest

The authors have no conflict of interest.

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