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J Nematol
J Nematol
jofnem
jofnem
Journal of Nematology
0022-300X
2640-396X
Sciendo

39221106
jofnem-2024-0033
10.2478/jofnem-2024-0033
Research Paper
Evaluation of nematicides for Meloidogyne enterolobii management in sweetpotato
Chen Jingwei
Ma Jukui
Gao Fangyuan
Tang Wei
Yang Dongjing
Zhang Chengling
Liang Zhao
Xie Yiping
Sun Houjun sunhouj1980@163.com

Xuzhou Institute of Agricultural Sciences of Jiangsu Xuhuai Area, Key Laboratory of Biology and Genetic, Improvement of Sweetpotato of Ministry of Agriculture and rural affairs, 221131, Xuzhou, Jiangsu
This paper was edited by Michael Mccarville.

24 8 2024
3 2024
56 1 2024003319 3 2024
© 2024 Jingwei Chen et al., published by Sciendo
2024
Jingwei Chen et al., published by Sciendo
https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Abstract

Sweetpotato is an important crop whose roots are consumed by people worldwide. Meloidogyne enterolobii stands out as a highly deleterious variant among the species of root-knot nematode that causes significant damage in sweetpotato. In the present study, the activity of four nematicides against M. enterolobii was assessed both in vitro and in growth cabinet experiments. After 48 hours of exposure, fluopyram and cyclobutrifluram had a greater negative effect on the motility of M. enterolobii second-stage juveniles (J2s) compared to fluensulfone and hymexazol, with respective median effective concentration (EC50) values of 0.204, 0.423, 22.335 and 216.622 mg L−1. When M. enterolobii eggs were incubated for 72 hours at the highest concentration of each nematicides, the inhibitory hatching effect of cyclobutrifluram (2.5 mg L−1), fluopyram (1.25 mg L−1) and fluensulfone (80 mg L−1) surpassed 85%, whereas hymexazol (640 mg L−1) was only 67%. Similar results were observed in growth cabinet experiments as well. The disease index (DI) and gall index (GI) were significantly decreased by all four nematicides compared to the control. However, the application of hymexazol did not yield a statistically significant difference in the egg masses index compared to the control, a finding which may be attributed to its potentially limited penetrability through the eggshell barrier. Overall, this study has demonstrated that all four nematicides effectively suppress M. enterolobii in sweetpotato, and this is the first report on the nematicidal activity of cyclobutrifluram and hymexazol against M. enterolobii.

Keywords

cyclobutrifluram
hymexazol
fluopyram
fluensulfone
Meloidogyne enterolobii
sweetpotato
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pmc1. Introduction

Sweetpotato (Ipomoea batatas (L.) Lam., family Convolvulaceae) is widely cultivated in tropical and warm temperate climates and is the seventh most widely cultivated food crop in the world and the sixth most widely cultivated food crop in China, but its production is limited by various biotic constraints including plant parasitic nematodes (8,11). Meloidogyne enterolobii (syn. mayaguensis) stands out as a highly deleterious variant among the species of root-knot nematode (RKN) that causes significant damage in sweetpotato (11,17,21,37). This is largely attributable to the damage inflicted upon sweetpotato tubers by nematode infection, resulting in reduced crop quality and diminished marketability (21).

In the United States, M. enterolobii was first reported in Puerto Rico in 1988 (27). It has since spread and has been reported in North and South Carolina (5,29,39). More recently, M. enterolobii was found in eight North Carolina counties: Johnston, Harnett, Sampson, Wayne, Greene, Wilson, Nash and Columbus (39,35,32). Sweetpotato production areas in the Carolinas have been particularly hard hit by the introduction of M. enterolobii, which has spread relatively quickly in sweetpotato production areas (30). In 2014, M. enterolobii on sweetpotato was reported in Guangdong Province, China (11). Subsequently, in 2022, root-knot nematode infections of sweetpotato by M. enterolobii was also reported in Guangxi province, China (15). Guangxi Province is the largest sweetpotato producer in south China and the third top producing region in the whole country. Thus, M. enterolobii, an important emerging nematode, is a growing threat to sweetpotato agriculture both in the United States and China.

Historically, broad spectrum soil fumigants (e.g. methyl bromide), organophosphates (e.g. aldicarb) and carbamates (e.g. oxamyl) have been used to control various soilborne pests that threaten crop productivity, including plant parasitic nematodes (40). Driven by the phase-out of environmentally and human-health hazardous traditional chemistries, the past 15 years have witnessed the development of innovative nematicides with significantly reduced toxicity to vertebrates (36). These include fluopyram, fluensulfone and cyclobutrifluram, which have a trifluoro (3-F) group in the chemical structure (36).

Fluopyram was first developed for crop use as a fungicide and was shown later to be effective against plant parasitic nematodes. Fluopyram can inhibit the function of succinate dehydrogenase, an enzyme that is essential to the mitochondrial respiratory chain (6,31). Fluensulfone was registered by the US Environmental Protection Agency (EPA) for use on cucurbit and fruiting vegetables in 2014 (20). Fluensulfone was shown to reduce root infection and plant parasitic nematodes penetration into plants (24,26). This compound is a unique nematicide with a mode of action distinguished from anticholinesterases and macrocyclic lactone (18,23). Cyclobutrifluram strongly affects the survival and fertility rates of Caenorhabditis elegans by decreasing the number of germ cells (12). Furthermore, it has been proven by a genetic approach that cyclobutrifluram also inhibits the function of the mitochondrial succinate dehydrogenase complex (12). However, research on its effectiveness against root knot nematodes has not been reported. Hymexazol is used as a broad-spectrum fungicide for treating soil-borne diseases due to its high efficiency and low cost (19). It was also used to control complex infestations of plant pathogenic nematodes and fungi (9). However, just like fluopyram which started out as a fungicide, it is unclear whether hymexazol also have an inhibitory effect on the growth and development of plant parasitic nematodes.

Synthetic non-fumigant nematicides have shown considerable efficacy in glasshouse and field trials (33,34,38), but different plant parasitic nematodes do not share equal sensitivity to these compounds. For instance, in vitro incubation studies with fluensulfone have shown similar results, with Aphelenchoides besseyi, A. fragariae, Bursaphelenchus xylophilus and Ditylenchus dipsaci showing tolerance to fluensulfone exposure, while Pratylenchus penetrans and Xiphinema index showed sensitivity to this compound (22). This research aims to assess the efficacy of four nematicides in controlling M. enterolobii on sweetpotato, and to explore the potential of introducing new nematicides for managing the nematode infections in sweetpotato.

2. Materials and Methods

2.1. Nematodes

The population of nematode used in this study was originally isolated from black nightshade (Solanum nigrum) in Lufeng county (22°55′57.44″N, 115°33′10.31″E), Guangdong Province, China (7). Based on the morphological, molecular analyses of mtDNA cytochrome c oxidase I (COI) and D2-D3 regions of 28S rDNA and detection using species-specific primers, the nematode was identified as M. enterolobii. M. enterolobii was maintained on potted sweetpotato (Ipomoea batatas (L.) Lam ‘Long 9’) plants in a growth cabinet for three months prior to use. Eggs of M. enterolobii were extracted from infected roots of sweetpotato with 0.5% sodium hypochlorite solution(Hussey & Barker, 1973). The whole infested root systems were put into 500 mL screw-top flasks and shaken in 0.5% sodium hypochlorite solution for 5 min prior to being washed with water over a No. 500 sieve (25 μm) and transferred to the beaker with about 30 mL of water. To obtain second-stage juveniles, the egg suspension was poured over a Baermann funnel and incubated in sterile water for 5 days at 28°C. Emerging J2s were collected daily by a sieve, and only those collected on the fifth day of incubation were used in the experiments.

2.2. Chemicals

Cyclobutrifluram [45% suspension concentrate, SC] was obtained from Syngenta group China and Fluopyram [41.7% suspension concentrate, SC] was provided by Bayer Crop Science, Greater China. Fluensulfone [40.0% emulsifiable concentrate, EC] was obtained from ADAMA Agricultural Solutions Ltd, Beijing, China. Hymexazol [70.0% water power, WP] was obtained from Weifang Huanuo Biotechnology Co., Ltd., Weifang, China.

2.3. Effect of nematicides on nematode motility

To determine the effect of nematicide concentration on J2s motility of M. enterolobii, a 24-well microplate motility assay was performed. In the preliminary phase, we first conducted a pre-experiment to determine the approximate range of EC50 for each chemical. Based on the result of the preliminary experiment, we designed distinct application rates for each chemical accordingly. Plate wells were filled 1ml aqueous solutions of cyclobutrifluram at 2.5, 1.25, 0.63, 0.31 and 0.16 mg L−1, Fluopyram at 1.25, 0.63, 0.31, 0.16 and 0.08mgL−1, Fluensulfone at 80, 40, 20, 10 and 5 mgL−1, and Hymexazol at 640, 320, 160, 80 and 40 mg L−1, or tap water (control; PH 7.3). Approximately 100 J2s suspended in 10 μL of tap water were introduced into each well. At 48 h post inoculation, 25 μL of mol L−1 sodium hydroxide (NaOH) was added to the appropriate wells as an irritant to distinguish between motile and immotile nematodes (8). Percent motility was recorded 30 seconds after the addition of the NaOH using a stereoscope (Nikon SMZ745). Each treatment was replicated three times, and all experiments were conducted twice.

2.4. Effect of nematicides on egg inhibitory hatching rate

To determine the effect of nematicide concentration and exposure time on eggs hatching of M. enterolobii, a 24-well microplate egg hatching assay was performed. The treatment concentration of cyclobutrifluram was 2.5, 0.63 and 0.16 mg L−1; Fluopyram was 1.25, 0.31 and 0.08 mg L−1, Fluensulfone was 80, 20 and 5 mg L−1, and Hymexazol was 640, 160 and 40 mg L−1. Eggs were exposed to tap water (PH 7.3) as the control. Approximately 100 eggs suspended in 10 μL of tap water were introduced into each well. At 24, 48 or 72 h post inoculation, the number of hatched nematodes in each treatment was observed and counted by a stereomicroscope. Each treatment was replicated three times, and all experiments were conducted twice. Inhibitory hatching rate (IHR) was calculated for each nematicide treatment using the following formula: IHR=number of hatched nematodes in control − number of hatched nematodes in treatmentnumber of hatched nematodes in control × 100%

2.5. Growth cabinet nematicide efficacy trial on sweetpotato

A growth cabinet experiment was conducted to assess the impact of applying nematicides at the recommended dosage on the reproductive capacity of M. enterolobii infecting sweet potato root systems. In simple terms, 20 cm wide square pots were filled with 1.5 L of dry heat sterilized sandy loam soil, which was augmented with organic peat. The control group consisted of pots inoculated with M. enterolobii but not treated with any nematicides. Three days after the sweetpotato seedlings (‘Long 9’) were transplanted, nematodes were inoculated into the potted soil. Each pot was inoculated with 1000 J2s of M. enterolobii. Nematicide treatments were applied to each pot except for fluensulfone, which was applied 3 days prior to planting to avoid phytotoxicity issues. Each treatment was as follows: (1) Cyclobutrifluram (0.03 mL pot−1), (2) Fluopyram (0.03 mL pot−1), (3) Fluensulfone (0.2 mL pot−1), (4) Hymexazol (1 mg pot−1), and (5) Nema+ (nematodes with no nematicide). Each treatment consisted of three replicates, each containing six sweetpotato plants, with one 15 cm tall sweetpotato seedling per pot. All experiments were conducted twice. Pots were watered as necessary throughout the experiment to maintain adequate soil moisture. After 50 days of growth in a temperature-controlled growth cabinet set at 28±1°C with 12 hours of light per day, the experiment was terminated.

A disease measurement was obtained in the pot experiments. The first was disease incidence, which was the number of diseased plants out of the total number of plants in each replicate and was reported on a percentage basis. The sweetpotato seedlings whose root systems exhibited visible galls were identified as diseased plants. The root gall index (GI) was calculated as the number of root galls on an individual plant divided by the total weight of the plant roots, and then multiplied by 100. The egg mass index (EMI) was calculated as the number of egg masses on an individual plant divided by the total weight of the plant roots, and then multiplying the result by 100. The GI and EMI can effectively reflect the nematode's reproduction status in plant and the severity of damage to the plant. Counting egg masses was performed using a stereoscope. A disease severity was determined by rating the roots on each plant on a 0 to 5 scale (Zhou et al., 2016), in which 0= less than 10% root-knot; 1= very slight root-knot, between 11%–20%; 2= obvious root-knot, percentage was between 21%–50%; 3, percentage was between 51%–80% root-knot; 4, percentage was between 81%–90% root-knot; 5= root knots exceeded 91%. A disease index (DI), whose values ranged from 0 to 100 was calculated for each nematicide treatment using the following formula: DI=Σ(the number of diseased plants in the pot × rating i)total number of plants in the pot× 5×100

Where i is 1–5.

2.6. Data analysis

Analysis of variance was performed on data from individual experiments using IBM® SPSS® Statistics (Version 20). Data were subjected to analysis of variance (ANOVA) and following significant results, means were separated according to the Student's Protected LSD tests. A significance level of α = 0.05 was used in all analyses. Median effective concentration (EC50) values for each nematicide were calculated by probit analysis of the nematodes' motility after 48h of incubation.

3. Results

3.1. In vitro nematicidal activity of four nematicides on nematode motility

Non-motile J2s of M. enterolobii did not recover their motility after NaOH was add to the wells, indicating that cyclobutrifluram, fluopyram, fluensulfone and hymexazol were nematicidal. The EC50 (48h) for cyclobutrifluram, fluopyram, fluensulfone and hymexazol was 0.423, 0.204, 22.335 and 216.622 mg L−1, respectively (Table 1). Based on the J2s motility assays, J2s of M. enterolobii were more sensitive to fluopyram and cyclobutrifluram than fluensulfone and hymexazol.

Table 1: Toxicity of Cyclobutrifluram, Fluopyram, Fluensulfone, Hymexazol to second stage juveniles of M. enterolobii (48h).

Chemicals	Regression	Slope SEa	EC50 (mg L−1)	95% confidence interval	Pb	χ2	
Cyclobutrifluram	0.425+1.137X	0.144	0.423	0.318~0.537	0.318	3.521	
Fluopyram	0.76+1.101X	0.132	0.204	0.157~0.256	0.191	4.748	
Fluensulfone	−1.408+1.044X	0.189	22.335	17.393~28.908	0.351	3.273	
Hymexazol	−3.664+1.569X	0.152	216.622	182.532~259.864	0.989	0.123	
a slope standard error.

b P-value.

3.2. Effect of nematicides on egg inhibitory hatching rate

After incubating M. enterolobii eggs in each of the nematicide treatments, the inhibitory hatching rate of eggs increased over time at the same concentration, and it also increased with concentrations at same time point (Fig. 1). Incubating M. enterolobii eggs in each nematicide concentration for 24 hours resulted in inhibitory hatching rate of 67.19%, 72.53%, 76.39% and 49.90% for cyclobutrifluram (2.5 mg L−1), fluopyram (1.25 mg L−1), fluensulfone (80 mg L−1) and hymexazol (640 mg L−1), respectively. After incubating M. enterolobii eggs in each nematicide concentration for 48 hours, inhibitory hatching rates were observed as follows: cyclobutrifluram (2.5 mg L−1)- 88.28%, fluopyram (1.25mg L−1)- 83.81%, fluensulfone (80 mg L−1)- 88.08% and hymexazol (640 mg L−1)- 63.51%. Following an incubation period of 72 hours, inhibitory hatching rates were recorded as cyclobutrifluram (2.5 mg L−1)-90.73%, fluopyram (1.25mg L−1)- 96.78%, fluensulfone (80 mg L−1)-87.45% and hymexazol (640 mg L−1)-67.39%. The highest concentration among all tested nematicides after 72 hours of exposure showed that cyclobutrifluram, fluopyram and fluensulfone achieved an inhibitory hatching effect exceeding 85%, while hymexazol only reached a rate of 67%.

Figure 1: Inhibitory hatching rate of Meloidogyne enterolobii after 24h, 48h, and 72h of exposure to varying concentrations (A) cyclobutrifluram, (B) fluopyram, (C) hymexazol, and (D) fluensulfone in a 24-well microplate egg hatch assay. Bar values represent means ± standard error of three replicates. Treatments within the same experiment, connected by the same letter, were not significantly different according to the Protected LSD (α = 0.05).

3.3. Growth cabinet nematicide efficacy trial on sweetpotato

In the growth cabinet studies conducted on sweetpotato infected with M. enterolobii, all the nematicide treatments exhibited lower disease incidence compared to the control, except for hymexazol. Among these treatments, fluopyram demonstrated the lowest disease incidence (50%), which was significantly different from the control (100%) (Table 2). However, each nematicide treatment resulted in a significantly lower DI of sweetpotato compared to the control. The ascending order of DI under each treatment was as follows: fluopyram (7), cyclobutrifluram (13), fluensulfone (25) and hymexazol (38). Cyclobutrifluram and fluopyram showed significantly difference from the other treatments. Similarly, the GI of sweetpotato under each nematicides was significantly lower than that of the control. The ascending order of GI was as follows: fluopyram (64), cyclobutrifluram (69), fluensulfone (157) and hymexazol (238). Cyclobutrifluram and fluopyram were significantly different from other treatments. The EMI of sweetpotato in each of the nematicide treatments was significantly lower than the control except for hymexazol. The EMIs of sweetpotato under each treatment were fluopyram (36), cyclobutrifluram (51), fluensulfone (150) and hymexazol (238) in ascending order, with cyclobutrifluram and fluopyram being significantly different from other treatments.

Table 2: Control efficiency of four kinds of nematicides on sweetpotatos infected by Meloidogyne enterolobii under greenhouse conditions.

Treatment	Disease Incidence (%)	DIa (0–100)	GIb	EMIc	
Cyclobutrifluram	78 ± 5.3d ab	13 ± 0.8d	69 ± 5.0d	51 ± 1.5c	
Fluopyram	50 ± 19.5b	7 ± 2.7d	64 ± 2.2d	36 ± 9.6c	
Fluensulfone	83 ± 0.0ab	25 ± 1.6c	157 ± 10.0c	150 ± 11.0b	
Hymexazol	100 ± 0.0a	38 ± 2.4b	238 ± 21.1b	238 ± 20.7a	
Control	100 ± 0.0a	46 ± 4.2a	313 ± 19.6a	256 ± 26.4a	
a–c DI, disease index; GI, gall index; EMI, egg masses index.

d Values are means ± standard error. Any means within the same column not connected by the same letter are considered significantly different according to Protected LSD (α = 0.05).

4. Discussion

M. enterolobii is one of the species of root knot nematode that is a growing threat to sweetpotato agriculture in China and the United States. Combinations of management, including crop rotation and use of resistant cultivars, are not completely efficient and searching for new nematicides constantly is needed (4). Assessing nematicidal activity using plant bioassays evaluates more points of possible nematode inhibition, whereas in vitro assays only evaluate a small component of the infection process (e.g. hatching or motility). In the present study, we demonstrated that cyclobutrifluram had high nematicidal activity against M. enterolobii in vitro, and application of cyclobutrifluram significantly reduced DI and nematode reproduction in sweetpotato plants infected by the parasites. Meanwhile, we also found that hymexazol had nematicidal activity against M. enterolobii, but the effect was significantly lower than cyclobutrifluram, fluopyram and fluensulfone. The current study is the first report of the nematicidal activity of cyclobutrifluram and hymexazol against M. enterolobii in sweetpotato.

More recently, cyclobutrifluram has been developed as a targeted solution for plant parasitic nematodes. Its chemical structure is similar to fluopyram and fluensulfone (36). Cyclobutrifluram effectively reduced the survival rates of C. elegans by inhibiting the function of the mitochondrial succinate dehydrogenase complex (12). In field management applications for plant parasitic nematodes, cyclobutrifluram significantly decreased the number of nematodes per gram of soybean roots and leads to a yield increase in certain cultivars compared to treatments with only abamectin (28). Moreover, cyclobutrifluram did not exhibit any phytotoxic effects on soybean seeds and seedlings (28). The aforementioned outcomes align with the findings derived from our independent research. Results from motility and inhibitory hatching bioassays indicated that cyclobutrifluram negatively affected J2s and eggs of M. enterolobii. In vitro, cyclobutrifluram had a high toxicity to J2s of M. enterolobii with a median effective concentration (EC50) of 0.423 mg L−1 after 48h of exposure. The highest concentration of cyclobutrifluram used in incubating M. enterolobii eggs for 72 hours resulted in an inhibitory hatching effect exceeding 90%. During the growth cabinet experiments involving sweetpotato subjected to M. enterolobii, cyclobutrifluram significantly reduced the DI, GI and EMI compared to the control.

Of the four nematicides tested, fluopyram had a stronger negative impact on M. enterolobii compared to fluensulfone. These findings align with previous research by Watson (37). However, a contrasting result was reported by Alam (2) in a growth cabinet experiment, where oxamyl and fluensulfone were found to be the most effective nematicides in suppressing nematode eggs hatching, followed by fluopyram. This discrepancy could be attributed to varying sensitivity of geographically distinct populations of the same species towards the same nematicide. Notably, Oka and Saroya (24) observed a more than 10-fold difference in median lethal concentration (LC50) among the M. incognita populations after 17 hours of exposure to fluensulfone.

Hymexazol was employed for management of complex infestations caused by plant pathogenic nematodes and fungi (9). In light of this, we postulated that hymexazol could hold potential as a nematicide. Also noteworthy is the fact that hymexazol showed nematicidal efficacy against M. enterolobii. This was not the first time that a fungicide was investigated for its effect on plant parasitic nematodes (9). Carbendazim was reported to possess some nematicidal activity (14) and pentachloronitrobenzene was proven to suppress M. incognita (1). However, the effectiveness of hymexazol against M. enterolobii was comparatively lower than other fluorinated nematicides, particularly in terms of its effect on inhibiting egg hatching rates. When M. enterolobii eggs were incubated with the highest concentration of 640 mg L−1 hymexazol for 72 hours, the inhibitory hatching effect reached only 67%. In growth cabinet experiments, no significant change in the EMI was observed when hymexazol was used. This may be attributed to its potentially limited penetrability through the eggshell barrier.

Prolonged use of a single nematicide can result in resistance of nematode, which poses challenges in managing root knot nematode (16). To promote the healthy development of sweetpotato agriculture, it is important to diversify the nematicides used to manage M. enterolobii. In this study, fluorinated nematicides and hymexazol have shown the potential to suppress M. enterolobii on sweetpotato when applied at the recommended rate. Further studies should be conducted to investigate the efficacy of nematicides for management of M. enterolobii on sweetpotato under field conditions, as well as to explore the molecular mechanisms of cyclobutrifluram and hymexazol in suppressing M. enterolobii.

Acknowledgments

This work was supported by CARS-10-Sweetpotato and Foundation of the Key R&D Program (Modern Agriculture) of Xuzhou City (C22087).
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References

[1] Adams JR Rodriguez-Kabana R King PS The nontarget effects of pentachloronitrobenzene on plant parasitic and free living nematodes Nematropica 1979 9 110 122 doi: https://doi.org/10.1007/s10658-019-01770-7
[2] Alam MS Khanal C Rutter W Roberts J Non-fumigant nematicides are promising alternatives to fumigants for the management of Meloidogyne enterolobii in tobacco Journal of Nematology 2022 54 20220045 doi: https://doi.org/10.2478/jofnem-2022-0045. 36457364
[3] Becker JO Ploeg A Nuñez JJ Multi-year field evaluation of fluorinated nematicides against Meloidogyne incognita in Carrots Plant Disease 2019 103 2392 2396 doi: https://doi.org/10.1094/PDIS-03-19-0489-RE. 31318644
[4] Bennett AJ Bending GD Chandler D Hilton S Mills P Meeting the demand for crop production: the challenge of yield decline in crops grown in short rotations Biological reviews 2012 87 52 71 21631700
[5] Brito JA Powers TO Mullin PG Inserra RN Dickson DW Morphological and molecular characterization of Meloidogyne mayaguensis isolates from Florida Journal of Nematology 2004 36 232 240 19262811
[6] Burns AR Luciani GM Musso G Bagg R Yeo M Zhang Y Caenorhabditis elegans is a useful model for anthelmintic discovery Nature communications 2015 6 7485 doi: https://doi.org/10.1038/ncomms8485.
[7] Chen J Gao F Ma J Yang D Zhang C Tang W 2023 First report of Meloidogyne enterolobii infecting Solanum nigrum in China Plant Disease 2023 107 4035 doi: https://doi.org/10.1094/PDIS-07-23-1316-PDN.
[8] Chen SY Dickson DW A technique for determining live second-stage juveniles of Heterodera glycines Journal of Nematology 2000 32 117 121 19270956
[9] Dernoeden PH Krusberg LR Sardanelli S Fungicide effects on Acremonium endophyte, plant-parasitic nematodes, and thatch in kentucky bluegrass and perennial ryegrass Plant Disease 1990 74 879 881 doi: https://doi.org/10.1007/s10658-019-01770-7
[10] Elling AA Major emerging problems with minor Meloidogyne species Phytopathology 2013 103 1092 1102 doi: https://doi.org/10.1094/pdis-07-23-1316-pdn 23777404
[11] Gao B Wang RY Chen SL Li XH Ma J First report of root-knot nematode Meloidogyne enterolobii on sweetpotato in China Plant Disease 2014 98 702 702 doi: https://doi.org/10.1094/pdis-09-13-0953-pdn
[12] Heydari F Rodriguez-Crespo D Wicky C The new nematicide cyclobutrifluram targets the mitochondrial succinate dehydrogenase complex in Caenorhabditis elegans Journal of Developmental Biology 2023 11 39 doi: https://doi.org/10.3390/jdb11040039 37873747
[13] Hussey R Barker K A comparison of methods of collecting inocula of Meloidogyne spp., including a new technique Plant disease reporter 1973 57 1025 1028
[14] Jaffee BA McInnis TM Effects of carbendazim on the nematophagous fungus Hirsutella rhossiliensis and the ring nematode Journal of Nematology 1990 22 418 419 19287739
[15] Jia L Wu H Wang Y Li H First report of the root-knot nematode Meloidogyne enterolobii on sweetpotato in guangxi province, China Plant Diease 2022 106 1308 doi: https://doi.org/10.1094/pdis-08-21-1793-pdn.
[16] Kammerer CL Harmon PF Crow WT Reduced sensitivity to Fluopyram in Meloidogyne graminis following long-term exposure in Golf Turf Journal of Nematology 2023 55 20230048 https://doi.org/10.2478/jofnem-2023-0048. 38026550
[17] Karssen G Liao J Kan Z van Heese EY den Nijs LJ On the species status of the root-knot nematode Meloidogyne mayaguensis Rammah & Hirschmann, 1988 Zookeys 2012 181 67 77 doi: https://doi.org/10.3897/zookeys.181.2787.
[18] Kearn J Ludlow E Dillon J O'Connor V Holden-Dye L Fluensulfone is a nematicide with a mode of action distinct from anticholinesterases and macrocyclic lactones Pesticide Biochemistry and Physiology 2014 109 44 57 doi: https://doi.org/10.1016/j.pestbp.2014.01.004 24581383
[19] Ma X-p Chen J-s Du X-h A continuous flow process for the synthesis of Hymexazol Organic Process Research & Development 2019 23 1152 1158 doi: https://doi.org/10.1021/acs.oprd.9b00047
[20] Morris KA Langston DB Davis RF Noe JP Dickson DW Timper P Efficacy of various application methods of fluensulfone for managing root-knot nematodes in vegetables Journal of Nematology 2016 48 65 71 doi: https://doi.org/10.21307/jofnem-2017-010 27418698
[21] Nielsen L Sasser J Control of root-knot nematodes affecting Porto Rico sweetpotatoes Phytopathology 1959 49 135 140 doi: https://doi.org/10.1094/pdis-07-23-1316-pdn
[22] Oka Y Nematicidal activity of fluensulfone against some migratory nematodes under laboratory conditions Pest management science 2014 70 1850 1858 doi: https://doi.org/10.1002/ps.3730 24452922
[23] Oka Y From old-generation to next-generation nematicides Agronomy 2020 10 1387 doi: https://doi.org/10.3390/agronomy10091387.
[24] Oka Y Saroya Y Effect of fluensulfone and fluopyram on the mobility and infection of second-stage juveniles of Meloidogyne incognita and M. javanica Pest management science 2019 75 2095 2106 doi: https://doi.org/10.1002/ps.5399 30843368
[25] Oka Y Shuker S Tkachi N Nematicidal efficacy of MCW-2, a new nematicide of the fluoroalkenyl group, against the root-knot nematode Meloidogyne javanica Pest management science 2009 65 1082 1089 doi: https://doi.org/10.1002/ps.1796 19488996
[26] Oka Y Shuker S Tkachi N Systemic nematicidal activity of fluensulfone against the root-knot nematode Meloidogyne incognita on pepper Pest management science 2012 68 268 275 doi: https://doi.org/10.1002/ps.2256 21842527
[27] Rammah A Hirschmann H Meloidogyne mayaguensis n. sp. (Meloidogynidae), a Root-knot nematode from Puerto Rico Journal of Nematology 1998 20 58 69
[28] Ribeiro DR Efficacy of a novel nematicidal seed treatment against Pratylenchus brachyurus and Heterodera glycines in soybean University of São Paulo 2020 doi: https://doi.org/10.11606/D.11.2020.tde-19062020-111333
[29] Rutter WB Skantar AM Handoo ZA Mueller JD Aultman SP Agudelo P Meloidogyne enterolobii found infecting root-knot nematode resistant sweetpotato in South Carolina, United States Plant Disease 2019 103 775 775 doi: https://doi.org/10.1094/pdis-08-18-1388-pdn
[30] Rutter WB Wadl PA Mueller JD Agudelo P Identification of sweetpotato germplasm resistant to pathotypically distinct isolates of Meloidogyne enterolobii from the Carolinas Plant Disease 2021 105 3147 3153 doi: https://doi.org/10.1094/pdis-02-20-0379-re 33599516
[31] Schleker ASS Rist M Matera C Damijonaitis A Collienne U Matsuoka K Mode of action of fluopyram in plant-parasitic nematodes Scientific Reports 2022 12 11954 doi: https://doi.org/10.1038/s41598-022-15782-7 35831379
[32] Schwarz T Li C Ye W Davis E Distribution of Meloidogyne enterolobii in eastern North Carolina and comparison of four isolates Plant Health Progress 2020 21 91 96 doi: https://doi.org/10.1094/php-12-19-0093-rs
[33] Silva JDO Loffredo A da Rocha MR Becker JOJJoP Efficacy of new nematicides for managing Meloidogyne incognita in tomato crop Journal of Phytopathology 2019 167 295 298 doi: https://doi.org/10.1111/jph.12798.
[34] Talavera M Thoden TC Vela-Delgado MD Verdejo-Lucas S Sánchez-Moreno S The impact of fluazaindolizine on free-living nematodes and the nematode community structure in a root-knot nematode infested vegetable production system Pest management science 2021 77 5220 5227 doi: https://doi.org/10.1002/ps.6563 34275187
[35] Thiessen L Impact of guavar oot knot nematode internal quarantine on tobacco and field crops in NC [Internet] Raleigh NC State Extension 2020 Available from: https://ipm.ces.ncsu.edu/2018/10/impact-of-guava-root-knot-nematode-internalquarantine-on-tobacco-and-field-crops-in-nc-ipm/
[36] Umetsu N Shirai Y Development of novel pesticides in the 21st century Journal of Pesticide Science 2020 45 54 74 doi: https://doi.org/10.1094/pdis-02-20-0379-re 33132734
[37] Watson TT Sensitivity of Meloidogyne enterolobii and M. incognita to fluorinated nematicides Pest management science 2022 78 1398 1406 doi: https://doi.org/10.1002/ps.6756 34897953
[38] Watson TT Noling JW Desaeger JA Fluopyram as a rescue nematicide for managing sting nematode (Belonolaimus longicaudatus) on commercial strawberry in Florida Crop protection 2020 132 105108 doi: https://doi.org/10.1016/j.cropro.2020.105108
[39] Ye WM Koenning SR Zhuo K Liao JL First report of Meloidogyne enterolobii on cotton and soybean in North Carolina, United States Plant Disease 2013 97 1262 1262 doi: https://doi.org/10.1094/pdis-03-13-0228-pdn
[40] Zasada I A Halbrendt JM Kokalis-Burelle N LaMondia JA Mckenry M Noling JW Managing nematodes without methyl bromide Annual review of phytopathology 2010 48 311 328 doi: https://doi.org/10.1146/annurev-phyto-073009-114425
[41] Zhou L Yuen G Wang Y Wei L Ji G Evaluation of bacterial biological control agents for control of root-knot nematode disease on tomato Crop protection 2016 84 8 13 doi: https://doi.org/10.1016/j.cropro.2015.12.009.
