Management Of Plant Parasitic Nematodes Research Articles

Phytochemical Volatiles as Potential Bionematicides with Safer Ecotoxicological Properties.

The management of plant-parasitic nematodes (PPNs) still relies on traditional nematicides that threaten the environment and human health. Novel solutions are urgently needed for PPN pest management that are effective while safeguarding non-target organisms. Volatile phytochemicals belong to a structurally diverse group of bioactive metabolites that are believed to hold safer environmental characteristics than synthetic pesticides. Nonetheless, not many studies have analysed the potential environmental benefits of shifting to these novel bionematicides. In the present study, 20 phytochemical volatiles with reported nematicidal activity were compared to traditional pesticides using specific parameters of environmental and human health safety available on applied online databases and predicted in silico through specialised software. Overall, the reviewed nematicidal phytochemicals were reportedly less toxic than synthetic nematicides. They were predicted to disperse to the air and soil environmental compartments and were reported to have a lower toxicity on aquatic organisms. On the contrary, the synthetic nematicides were reportedly toxic to aquatic organisms while showing a predicted high affinity to the water environmental compartment. As alternatives, β-keto or fatty acid derivatives, e.g., aliphatic alcohols or ketones, showed more adequate properties. This study highlights the importance of complementing studies on nematicidal activity with a risk assessment-based analysis to allow for a faster selection of nematicidal phytochemical volatiles and to leverage the development and implementation of bionematicides.

Chitin-enriched insect frass fertilizer as a biorational alternative for root-knot nematode (Meloidogyne incognita) management.

Root-knot nematodes (Meloidogyne spp.) are serious pests of most food crops, causing up to 100% yield loss. Nevertheless, commercial nematicides are costly and harmful to the environment. While the nematicidal potential of crustacean and synthetic chitin has been demonstrated globally, research on the potential of insect-derived chitin for nematode control has received limited attention. Here, seven chitin-fortified black soldier fly frass fertilizer extracts (chFE) were assessed for their suppressiveness of Meloidogyne incognita and impacts on spinach growth in comparison with a commercial nematicide using in vitro and in vivo bioassays. The performance of chFE and control treatments was assessed by determining their effects on nematode egg hatchability; infective juvenile (J2) mortality and paralysis; number of galls, egg masses, and J2s per plant; and spinach root and shoot biomass. In vitro results showed that chFE and commercial nematicide suppressed nematode egg hatchability by 42% and 52%, respectively, relative to the control (sterile distilled water). Up to 100% paralysis was achieved when M. incognita J2s were exposed to either chFE or commercial nematicide. Further, the J2 mortality achieved using chFE (95%) was comparable to the value achieved using commercial nematicide (96%); in all treatments, mortality increased with exposure time. Similarly, up to 85% suppression of gall development was achieved when spinach plants were grown in soil drenched with chFE; up to 79% reduction in egg mass formation and 68% suppression of J2 development in the root system were achieved using chFE. Also, chFE application significantly increased spinach root and shoot biomass by 54%-74% and 39%-58%, respectively, compared to commercial nematicide. Our findings demonstrate the nematicidal potential of chFE and its benefits on crop production. Thus, chFE could be considered as a promising multipurpose, regenerative, and cost-effective input for sustainable management of plant-parasitic nematodes and enhancement of crop yield.

Plant-parasitic nematodes associated with Panicum maximum and Mimosa hirsutissima in a pasture field

Pastures and weed plants can host plant-parasitic nematodes of economic importance, with the limited yield of pastures representing a continuous challenge for agriculture, especially in the lower Jequitinhonha Valley in southeastern Brazil, where dairy and beef cattle play a crucial role in the local economy. From this perspective, this study aimed to provide information on the population density of plant-parasitic nematodes associated with Panicum maximum cv. Mombaça and Mimosa hirsutissima, weed species commonly found in pasture areas cropped with this grass in the municipality of Almenara, MG, in the Jequitinhonha Valley region of southeastern Brazil. Soil and root samples were collected from the field and placed in plastic bags, which were labeled and taken to the laboratory for nematode extraction. Nematode population densities were estimated in a Peters counting slide under a light microscope, and genera identification was based on morphological traits. In rhizosphere soil (100 g) of P. maximum cv. Mombaça, the highest population densities were observed for Helicotylenchus sp. (3,999), followed by Tylenchus sp. (1,191), Meloidogyne spp. (939), and Pratylenchus sp. (544). In roots (1 g), on the other hand, the highest values corresponded to Pratylenchus sp. (19.6) and Meloidogyne spp. (15.5). However, in rhizosphere soil of M. hirsutissima, the highest population densities were recorded for Tylenchus sp. (2,072), Helicotylenchus sp. (1,883), Pratylenchus sp. (751), and Meloidogyne spp. (307). In contrast, in the roots, the highest values were observed for Meloidogyne spp. (6.9), Tylenchus sp. (4.4), and Pratylenchus sp. (2.7). These findings are essential to take decisions on the management of plant-parasitic nematodes.

A Deep Learning-Based Decision Support Tool for Plant-Parasitic Nematode Management.

Plant-parasitic nematodes (PPN), especially sedentary endoparasitic nematodes like root-knot nematodes (RKN), pose a significant threat to major crops and vegetables. They are responsible for causing substantial yield losses, leading to economic consequences, and impacting the global food supply. The identification of PPNs and the assessment of their population is a tedious and time-consuming task. This study developed a state-of-the-art deep learning model-based decision support tool to detect and estimate the nematode population. The decision support tool is integrated with the fast inferencing YOLOv5 model and used pretrained nematode weight to detect plant-parasitic nematodes (juveniles) and eggs. The performance of the YOLOv5-640 model at detecting RKN eggs was as follows: precision = 0.992; recall = 0.959; F1-score = 0.975; and mAP = 0.979. YOLOv5-640 was able to detect RKN eggs with an inference time of 3.9 milliseconds, which is faster compared to other detection methods. The deep learning framework was integrated into a user-friendly web application system to build a fast and reliable prototype nematode decision support tool (NemDST). The NemDST facilitates farmers/growers to input image data, assess the nematode population, track the population growths, and recommend immediate actions necessary to control nematode infestation. This tool has the potential for rapid assessment of the nematode population to minimise crop yield losses and enhance financial outcomes.

Pre-treatment with Dazomet enhances the biocontrol efficacy of purpureocillium lilacinum to Meloidogyne incognita

BackgroundMeloidogyne incognita greatly restricts the production of protected vegetables in China. Application of biocontrol agent Purpureocillium lilacinum is an important practice to control the nematode; however, instability usually occurs especially in heavily infested field. This study aimed to illustrate the high efficiency of P. lilacinum agent with fumigant Dazomet in vitro.ResultsP. lilacinum YES-2-14 showed strong parasitic and nematicidal activities to M. incognita. Pre-treatment with Dazomet significantly enhanced the biocontrol effects of the fungus. After fumigation with Dazomet at a dosage of 7.5 mg kg− 1 soil, parasitism of YES-2-14 on M. incognita eggs increased by more than 50%. Meanwhile, when P. lilacinum fermentation filtrate treated following Dazomet fumigation at 10 and 20 mg kg− 1 soil, the mortalities of second-stage juveniles (J2s) increased by 110.2% and 72.7%, respectively. Both Dazomet and P. lilacinum significantly reduced the penetration ability of J2s to tomato roots. When P. lilacinum filtrate used alone, the J2s penetrating into the young roots decreased by 48.8% at 4 dpi; while in the combined treatment, almost no J2 was detected within the roots at 4 dpi and the number of knots reduced by more than 99% at 45 dpi, indicating a synergistic effect of the biocontrol fungus and fumigant.ConclusionsPre-treatment with Dazomet greatly increased the biocontrol efficacy of P. lilacinum to M. incognita. This research provides insight into the efficient management of plant parasitic nematodes and effective use of biocontrol agents.

Nematode-Suppressive Potential of Digestates to Meloidogyne incognita and Heterodera schachtii.

Management of plant-parasitic nematodes uses host plant resistance, crop rotation, cultural methods, and nematicide applications. Host plant resistance is tedious to develop, and crop rotation and cultural methods are challenging to use. Environmental and human health concerns render sole reliance on chemical nematode suppression nonsustainable. Previously, digestate from anaerobically fermented maize silage suppressed Heterodera schachtii in Beta vulgaris crops. Here, seven digestates were investigated for nematode suppressive potential: liquid dairy manure digestate (LDMD), liquid dairy manure digestate with ammonia removed (LDMDA-), food waste digestate (FWD), liquid food waste digestate with ammonia removed (LFWDA-), liquid food waste digestate (LFWD), food waste hydrolysate from the Renewable Energy Anaerobic Digester (HREAD), and food waste hydrolysate from the South Area Transfer Station in Sacramento (HSATS). In a red radish (Raphanus sativus) bioassay with H. schachtii, digestates were amended at rates of 0.02, 0.11, 0.57, and 2.86 ml per 100 cm3 of soil. At a rate of 2.86 ml, all amendments except LDMDA- and LFWDA- significantly reduced juvenile root penetration compared with the infested control. In a greenhouse watermelon (Citrullus lanatus) bioassay with Meloidogyne incognita, amendments FWD, LFWD, HREAD, and HSATS as well as LDMD (less effectively) at 2.86 and 5.76 ml per 100 cm3 of soil significantly reduced egg masses per root system compared with the nontreated, nematode-infested control. In a microplot experiment with M. incognita and red radish, in the treatment amended with LFWD at 2.37 ml per 100 cm3 of soil, marketable yields were improved by approximately 50% over the nontreated control and were comparable with those in the treatment with the nematicide Reklemel. In a second microplot experiment with M. incognita and watermelon, treatments that contained LFWD at rates of 3.55 ml per 100 cm3 of soil had transient numerical effects of initial nematode suppression that were not maintained throughout the 3-month growth period. The results of these studies demonstrated that digestates FWD and LFWD consistently expressed some nematode-suppressive capacity.

Synthesis, Nematicidal Evaluation, and the Structure-Activity Relationship Study of Aurone Derivatives.

Plant-parasitic nematodes (PPNs) are one of the major threats to modern agriculture. Chemical nematicides are still required for the management of PPNs. Based on our previous work, the structure of aurone analogues was obtained using a hybrid 3D similarity calculation method (SHAFTS, SHApe-FeaTure Similarity). Thirty-seven compounds were synthesized. The nematicidal activity of target compounds against Meloidogyne incognita (root-knot nematode, M. incognita) was evaluated, and the structure-activity relationship of synthesized compounds was analyzed. The results showed that compound 6 and some of its derivatives exhibited impressive nematicidal activity. Among these compounds, compound 32 bearing 6-F showed the best in vitro and in vivo nematicidal activity. Its lethal concentration 50% after exposure to 72 h (LC50/72h) value was 1.75 mg/L, and the inhibition rate reached 97.93% in the sand at 40 mg/L. At the same time, compound 32 also exhibited excellent inhibition on egg hatching and moderate inhibition on the motility of Caenorhabditis elegans (C. elegans).

Two strains Neocosmosporastercicola (Sordariomycetes, Nectriaceae) with high nematicidal activity, isolated from the cysts of Globodera sp. (Heteroderidae) in China.

Plant-parasitic nematodes (PPNs) are significant pests that result in considerable economic losses in global crop production. Due to the high toxicity of chemical nematicides, there is a need to develop new strategies for nematode control. In this context, nematophagous fungi may offer a viable option for biological control. Two fungal strains (GUCC2212 and GUCC2232) were isolated from cysts of Globodera sp., identified as Neocosmosporastercicola. The fungal filtrates of the strains were evaluated for their nematicidal activity against three species of PPNs: Aphelenchoidesbesseyi, Bursaphelenchusxylophilus and Ditylenchusdestructor. The fermentation filtrates of two strains exhibited substantial toxicity towards the evaluated nematodes, with mortality rates reaching up to 100% within 72 h. Concurrently, N.stercicola also demonstrated predatory and parasitic behavior. The eggs of Globodera sp. were parasitized by the two strains. N.stercicola represents a newly recorded species in China and a novel nematophagous species. In conclusion, the two strains of N.stercicola show promise as biocontrol agents for PPNs management.

Nematicidal Activity of Natural Products against Root-knot Nematode: A Review

Phylum Nematoda is the most abundant group among the metazoans. Root-knot nematodes (Meloidogyne spp.) are a serious threat to agrarian plants worldwide. RKN is among the most predominant spp. which affects a variety of plants and vegetables. It is challenging for farmers to manage these nematodes. The usage of nematicides is an efficient means of management of plant-parasitic nematodes. The continuous use of chemical nematicides can cause augmentation in cases of nematode resistance. In order to fulfill the requirement of modern sustainable agriculture along with safe environment and human health, there is need to switch over to natural remedies to control RKNs. Lately, many research studies have been carried out to isolate product from natural resources and evaluate their nematicidal activity against these nematodes. The present review provides a summary of nematicidal activity of the naturally derived substances against Meloidogyne incognita over the past few years.

Metabolites and chemical agents in the plant roots: an overview of their use in plant-parasitic nematode management

Summary Plant-parasitic nematodes are devastating phytopathogens that cause substantial economic losses in the agricultural sector. There are numerous management measures available to reduce the threat posed by plant-parasitic nematodes. One of the most effective management strategies is the use of synthetic chemical nematicides. However, many of these chemicals negatively impact the environment and health of non-target organisms, so there is great urgency for finding new environmentally safe and sustainable approaches for managing plant-parasitic nematodes. Plant roots release numerous metabolites that possess defensive properties; thus, it is imperative to understand the root-regulated interactions among plants and nematodes that form the basis for managing plant-parasitic nematodes. The present review focuses on the root metabolites and chemical agents that serve as attractants, repellents, stimulators, or inhibitors for nematodes. They influence plant resistance by modifying plant physiology to resist nematodes and can also inhibit nematode growth and development by secreting antinematode chemicals. The ultimate goal of this review is to focus mainly on the current state of knowledge on the interaction between plant roots and the potential of these compounds in management of plant-parasitic nematodes.

Soil Solarization: A safe, affective and practicable technique for the management of plant-parasitic nematodes

Soil Solarization: A safe, affective and practicable technique for the management of plant-parasitic nematodes

Exploiting Plant-Phytonematode Interactions to Upgrade Safe and Effective Nematode Control.

Plant-parasitic nematodes (PPNs) bring about substantial losses of economic crops globally. With the environmental and health issues facing the use of chemical nematicides, research efforts should focus on providing economically effective and safe control methods. The sound exploitation of plant-PPN interactions is fundamental to such efforts. Initially, proper sampling and extraction techniques should be followed to avoid misleading nematode data. Recent evolutions in plant-PPN interactions can make use of diverse non-molecular and molecular approaches to boost plant defenses. Therefore, PPN control and increasing crop yields through single, sequential, dual-purpose, and simultaneous applications of agricultural inputs, including biocontrol agents, should be seriously attempted, especially within IPM schemes. The use of biologicals would ideally be facilitated by production practices to solve related issues. The full investment of such interactions should employ new views of interdisciplinary specialties in the relevant modern disciplines to optimize the PPN management. Having an accurate grasp of the related molecular events will help in developing tools for PPN control. Nonetheless, the currently investigated molecular plant-PPN interactions favoring plant responses, e.g., resistance genes, RNA interference, marker-assisted selection, proteinase inhibitors, chemo-disruptive peptides, and plant-incorporated protectants, are key factors to expanding reliable management. They may be applied on broader scales for a substantial improvement in crop yields.

Identification and Management of Plant Parasitic Nematodes Associated with Walnut (Juglans Regia L.) in Abbottabad

Purpose: Phytonematodes known as the hidden enemies of plants and crops are potential pest of walnut trees in Abbottabad, KP Pakistan. Methods: Soil samples from walnut trees were collected from different localities were processed by using Bearmann funnel techniques. Several nematode species were identified including Meloidogyne incognita, Helicotylenchus dihystera, Psilenchus hilarulus, Tylenchus sp. and Helicotylenchus vulgaris. Findings & Practical implication: Management of plant parasitic nematodes by using castor oil cakes (8kg/tree), cow dung (8 kg/tree) and duck manure (8kg/tree) showed that population was declined after application. Plant growth and yield was also improved. Data plotted in histogram graphs and t-test showed that p values were found significant. Conclusion: The mean and S.D values of initial population, 3 month, 6 month and 12 month for castor oil cakes are 116 ± 1.2, 84 ± 1.0, 60 ± 1.0, 42 ± 0.6, for cow dung 127 ± 5.7, 110 ± 2.4, 87 ± 2.4, 73 ± 1.3 and for duck manure 108 ± 2.4, 92 ± 1.0, 69 ± 0.5, 45 ± 1.0. Keywords: Phytonematodes, walnut, castor oil, cow dung, duck manure.

On-Farm Evaluations of Nonfumigant Nematicides on Nematode Communities of Peach.

Experiments were established to evaluate the efficacy of currently available nonfumigant chemical and biological nematicides against nematode communities in peach orchards in two different geographic regions of South Carolina: the Upstate and Ridge. The treatments included sole or mixed application of two chemical nematicides (oxamyl and fluopyram) and a biological nematicide (Majestene) plus an untreated control. Ring nematode and lesion nematode were predominant in Upstate and Ridge orchards, respectively. Fluopyram was the most effective nematicide in the Upstate orchard, and it reduced plant-parasitic nematodes by 69% relative to the untreated control at 3months postapplication. Similarly, fluopyram and oxamyl suppressed 74 to 87% of plant-parasitic nematodes in the Ridge orchard at 2months postapplication. Significant effects of Majestene on plant-parasitic nematodes was not observed. Mixed applications of nematicides were also effective in suppressing plant-parasitic nematodes although the suppressions were not always significant from sole applications or the control. The chemical nematicides significantly reduced free-living nematodes in the first 2months following their applications in the Ridge orchard, the reductions ranging from 60 to 79% relative to the control. However, free-living nematode populations quickly rebounded to the highest level in 3months following the nematicide applications. Free-living nematode communities in the Upstate orchard did not experience any significant effects of nematicides until 4 months following nematicide application; at that time there was a 60 to 68% decline in populations. Results from this study suggest that the nonfumigant nematicides can only provide a short-term management of plant-parasitic nematodes in peach.

Distribution and Prevalence of Plant-Parasitic Nematodes of Turfgrass at Golf Courses in China.

Simple SummaryPlant-parasitic nematodes (PPNs) are one of the most important pests to cause infectious diseases on turfgrass. Numerous studies have been conducted on PPNs associated with turfgrass worldwide. However, little published research is available on PPNs associated with turfgrass in China. Information on the occurrence, distribution, diversity, and dominant species of PPNs associated with turfgrass in different regions of China is limited, making it challenging to design suitable management practices for control. In this study, we assessed morphological characteristics and utilized molecular methods to identify PPNs from turfgrass soil samples. The purpose of this study was to determine the species, distribution, incidence, and diversity of PPNs associated with turfgrass at golf courses in North, East, and South China (NC, EC, and SC, respectively). The results provide valuable information for the management of PPNs on turfgrass in China.We sampled 127 turfgrass soil samples from 33 golf courses in NC, EC, and SC for plant-parasitic nematodes (PPNs). PPNs were extracted from soil samples using the shallow dish method and were identified at the genus or species levels with a combination of morphological and molecular methods. The results revealed 41 species of nematode belonging to 20 genera and 10 families. Nine genera are new records of PPNs associated with turfgrass in China. The PPNs show strong geographical distributions. Of the 20 genera, Helicotylenchus, Paratrichodorus, Hoplolaimus, Meloidogyne, Hemicriconemoides, and Mesocriconema showed higher infestation and frequency, and most of these genera had numbers in soil samples above established damage thresholds. Four golf courses had soil samples with PPNs > 30%, indicating the potential for nematode damage. The biodiversity indices H’, SR, J’, λ, and H2 showed significant differences among different regions and turfgrass species; H’, SR, J’, and H2 were significantly higher in EC than in NC and SC, while λ was lowest in EC. Creeping bentgrass had the highest H’, SR, J’, and H2 and the lowest λ in comparison with seashore paspalum and hybrid bermudagrass. These findings provide baseline information on the occurrence of turfgrass-associated PPNs in China, and have important implications for the effective management of PPNs causing damage on turfgrass.

Vertical Distribution of Plant-Parasitic Nematodes in Sweet Potato.

Plant-parasitic nematodes (PPN) are harmful pests that have become a severe threat to crop production worldwide. Diversity of PPN at horizontal and spatial scales influence the effectiveness of control strategies. This study evaluated the vertical distribution of PPN genera at 0 cm to 30 cm and 30 cm to 60 cm in sweet potato fields in Central, Manyatta, and Nembure regions of Embu County, Kenya. A significant region × depth interaction was observed for Tylenchus. For all the other nematode genera, there were no significant variations in the abundance at 0 cm to 30 cm and 30 cm to 60 cm depths. However, Helicotylenchus, Meloidogyne, and Scutellonema occurred in greater numbers at both depths in all regions. Shannon and Simpson diversity indices were higher at 0 cm to 30 cm depth while Pielou’s evenness was similar at both depths in the three regions. Diversity partitioning of genus richness, Shannon, and Simpson diversities across all regions at 0 cm to 30 cm, indicated that β component contributed 61.9%, 35.6%, and 22.6% of γ diversity, respectively. Coinertia analysis indicated a significant covariation between nematode genera and soil properties. The results show that management of PPN in sweet potato fields should be targeted at soil depths that are not less than 60 cm.

Extracts and purified substances of Cabralea canjerana inhibit hatching and extracts of Schinus terebinthifolius kill juveniles of meloidogyne incognita

Nematicidal substances have been identified from plants and are potentially useful for the management of plant-parasitic nematodes. Cabralea canjerana, (Meliaceae) and Schinus terebinthifolius (Anacardiaceae) produce bioactive compounds during their secondary metabolism and little is known about the effect of such substances on plant-parasitic nematodes. In the present study, we assessed the effect of aqueous and ethanolic extracts of C. canjerana and S. terebinthifolius at 1% (m:v) and purified substances from C. canjerana (gedunin, ocotillone, cabraleadiol, a mixture of ocotillone + cabraleadiol and a mixture of shoreic acid + eichlerianic acid) on hatching and mortality of Meloidogyne incognita juveniles. Aqueous extracts of C. canjerana fruits and seeds reduced hatching by 70.3 to 95.7%. Aqueous extracts of S. terebinthifolius fruits killed 42.8 to 77.1% of juveniles. The purified substances of C. canjerana inhibited the hatching of M. incognita from 57 to 90% and did not increase the mortality of juveniles. Therefore, C. canjerana extracts and its purified substances reduce M. incognita hatching and aqueous extracts of S. terebinthifolius kill J2 of this nematode.

Nematode assemblages, food web indices and metabolic footprints in maize-pigeon pea agro-ecosystems

Pigeon pea (Cajanus cajan L.) and maize (Zea mays L.) are important food crops in developing countries due to their multiple benefits. However, their production is constrained by plant-parasitic nematodes (PPN) which cause significant yield losses. Understanding the nematode-based soil food web structure in maize-pigeon pea agro-ecosystems will allow sustainable PPN management by improving soil health. This study explored nematode community assemblages, indices and metabolic footprints in maize-pigeon pea agroecosystems in Mbeere South, Embu County, Kenya. Soil samples were collected from Gachuriri, Irabari, Kanduu, Kangeta, Kangungi, Kaninwathiga, Karimari and Mutugu regions. The recovered nematodes were identified to the genus level. There were 41 nematode genera across the eight regions. Longidorus spp., Heterocephalobus spp., Cervidellus spp., Mesorhabditis spp. and Mononchus spp. differed significantly across the regions. Meloidogyne spp., Scutellonema spp., Rotylenchulus spp. and Pratylenchus spp. were the most prevalent genera although their abundance was not statistically different across the regions. Using the structure and enrichment indices, soil food web in Irabari was degraded, whereas the other seven regions were structured. The main energy channel of organic matter decomposition in the studied regions was dominated by fungivores. There were no differences in metabolic footprints expect for bacterivore footprint. The occurrence of Hoplolaimus spp. and Xiphinema spp. showed a negative correlation with N, C, Mg and Na. This work provides useful insights into the maize-pigeon pea nematode soil food web structure and function which can be used in improving their yields and soil health.

Production of Purpureocillium lilacinum and Pochonia chlamydosporia by Submerged Liquid Fermentation and Bioactivity against Tetranychus urticae and Heterodera glycines through Seed Inoculation.

Pochoniachlamydosporia and Purpureocillium lilacinum are fungal bioagents used for the sustainable management of plant parasitic nematodes. However, their production through submerged liquid fermentation and their use in seed treatment have been underexplored. Therefore, our goal was to assess the effect of different liquid media on the growth of 40 isolates of P. lilacinum and two of P. chlamydosporia. The most promising isolates tested were assessed for plant growth promotion and the control of the two-spotted spider mite (Tetranychus urticae) and the soybean cyst nematode (Heterodera glycines). Most isolates produced > 108 blastospores mL−1 and some isolates produced more than 104 microsclerotia mL−1. Microsclerotia of selected isolates were used to inoculate common bean (Phaseolus vulgaris L.) seeds in greenhouse trials. All fungal isolates reduced the T. urticae fecundity in inoculated plants through seed treatment, while P. chlamydosporia ESALQ5406 and P. lilacinum ESALQ2593 decreased cyst nematode population. Purpureocillium lilacinum was more frequently detected in soil, whereas P. chlamydosporia colonized all plant parts. Pochonia chlamydosporia ESALQ5406 improved the root development of bean plants. These findings demonstrate the possibility of producing submerged propagules of P. chlamydosporia and P. lilacinum by liquid culture, and greenhouse trials support the applicability of fungal microsclerotia in seed treatment to control P. vulgaris pests.

Effect of differential addition of water on mobility of fluopyram in two different soils of Kerala

ABSTRACT Fluopyram, a pyridyl ethyl benzamide broad-spectrum fungicide and nematicide, used for the management of plant parasitic nematodes and soil-borne fungi, is recommended for use in crops like tomato, potato and tobacco. Fluopyram being a pesticide used for drenching soil, there is every possibility of it getting leached down with water, ultimately leading to contamination of waterbodies. An experiment was conducted to study the downward movement of fluopyram in laterite and red loam soils in Kerala, India. Fluopyram and fluopyram benzamide, each at150 µg, were loaded separately on top of the respective soil column and were eluted separately with 20, 40, 80 and 160 mL each of water equivalent to 50, 100, 200 and 400 mm rainfall. It was observed that 76.84% and 74.85% of fluopyram and 73.48% and 64.24% of fluopyram benzamide were confined to the top 0–10 cm soil with application of 20 mL water in laterite and red loam soil, respectively. More than 50% of fluopyram and fluopyram benzamide were detected in the top 0–10 cm layer of soil with the application of 40 and 80 mL water. With the application of 160 mL water, considerable reduction in the concentration of both compounds was observed and the residues moved beyond 30 cm. Leaching of residues was more in laterite soil than in red loam soil, and they are in direct relation to the volume of water applied and the residues moved beyond 30 cm depth with 160 mL water.