Reduced Nematode Populations Research Articles

Maize Response to Sole and Combined Effects of Nitrogen and Nematode Stresses

Crops grown on the field or in phytotrons are faced with different biotic stresses including plant-parasitic nematodes (PPNs) and abiotic stresses such as drought and poor soil fertility (low nitrogen levels). In this study, the interactive responses of a low-nitrogen tolerant variety LNTP-YC6 and a regular variety BR-9928-DMRSR to Pratylenchus zeae under four nitrogen-levels: no amendment; [T0], low nitrogen [100kgN/ha NPK; T1], optimum nitrogen [200kgN/ha NPK + Urea; T2] and compost [10t/ha; T3] were investigated. The treatments were arranged in a 2 x 4 factorial fitted into randomised complete block design (RCBD) with four replicates. Data were collected on growth parameters (plant height and stem girth), yield components (number and weight of cobs), lesion score (LS), final nematode population (FNP) and reproductive factor (RF). Low nutrient stress in combination with nematode infection generally reduced maize growth and yield. Growth parameters of BR-9928-DMRSR variety were generally high while yield parameters of LNTP-YC6 variety were significantly greater than in BR-9928-DMRSR variety. However, T2 and T3 improved growth and yield of both maize varieties compared to T0, with T2 being superior to T3. Meanwhile, T3 reduced FNP more than T2. FNP (107.65) and RF (1.3) of P. zeae on LNTP-YC6 variety and with T3 was significantly low compared to T2 (178, 3.34), T0 (188, 3.6) and T1 (217, 5.0). In all the parameters considered, LNTP-YC6 outperformed BR-9928-DMRSR variety. In conclusion, soil amendment with optimum rate of nitrogen and compost reduced nematode population and enhanced maize growth, while low nitrogen in combination with nematode stress reduced maize yield.

Mineral composition of beetroot treated with potential elicitors and inoculated with Meloidogyne javanica

BackgroundThe root-knot nematode Meloidogyne javanica can infect beetroots, causing extensive damage to this food crop. As chemical and genetic control tactics have shown limited efficacy, new strategies are needed to improve the integrated management of this parasite. This study assessed the influence of potential defence elicitors and M. javanica infection on the mineral composition of beetroot. Plants were treated with acibenzolar-S-methyl (ASM), citrus biomass, or a mannanoligosaccharide-based product (MOS) and inoculated with 1000 eggs and second-stage juveniles of M. javanica. At 60 days after inoculation, beetroot plants were harvested and evaluated for nematode population density, vegetative growth, and mineral content.ResultsAll potential elicitors reduced nematode population density in beetroots (p ≤ 0.10) and improved the vegetative parameters of inoculated plants (p ≤ 0.05), except shoot fresh weight. Some minerals were found to be negatively affected by treatments, particularly calcium, whose levels were consistently lower in treated plants. On the other hand, M. javanica inoculation increased magnesium, iron, manganese, zinc, and copper contents in beetroots. However, the latter mineral (Cu content) of inoculated plants was positively influenced by MOS and ASM.ConclusionPotential elicitor treatments did not improve the mineral composition of beetroot, but were effective in reducing nematode population density. Plants inoculated with M. javanica had higher mineral levels. However, gall formation decreases the commercial value of the crop and might render it unsuitable for commercialisation. M. javanica-infected beetroots may be used for nutrient extraction or sold to food processing industries.

Use of acibenzolar-S-methyl and other novel products for the management of Aphelenchoides fragariae on ornamental plants in glasshouse and commercial conditions

Several chemical, biopesticide and elicitor treatments were evaluated on healthy plants inoculated with leaf and bud nematodes (Aphelenchoides fragariae). Aphelenchoides fragariae is a major threat to ornamental plant production worldwide, and its management poses a great challenge due to its wide host range of herbaceous, ferns and woody plants. Commercially available products containing spirotetramat, abamectin, azadirachtin and the elicitor of plant defences, acibenzolar-S-methyl (ASM), were assessed for their ability to reduce the multiplication of A. fragariae inoculated on two plant species: Anemone hupenhensis (Japanese anemone), and Buddleja davidii (Buddleja).Treatments were applied individually and in combination with ASM in a spray programme. All treatments consistently showed a significant reduction of nematode multiplication in treated plants compared to the control. Programmes of ASM with spirotetramat, abamectin or azadirachtin had significantly lower nematode populations on both plant species compared to the untreated plants. In Buddleja plants, a programme using spirotetramat + ASM had a 97% reduction of the A. fragariae population over the control (ROC) while ASM, spirotetramat, abamectin, azadirachtin, ASM + abamectin and ASM + azadirachtin caused between 78 and 94% ROC. On Japanese anemone, the highest nematode ROC (95%) was obtained with the spirotetramat + ASM programme, while other treatments (ASM, spirotetramat, abamectin, azadirachtin, ASM + abamectin and ASM + azadirachtin) had a range of 80–94% reduction of A. fragariae over the control.Management of plants infested by leaf and bud nematodes may prove challenging; however, all the treatments investigated demonstrated a significant reduction in nematode population in Buddleja and Japanese anemone, indicating that they have significant potential as effective alternatives to manage A. fragariae in ornamental plants. The potential of ASM alone or in programmes with other actives is discussed in relation to their use in the management of A. fragariae.

Biofumigation efficacy of spider plant (Cleome gynandra L.) accessions on nematode control in tuberose (Polianthes tuberosa L.)

Tuberose (Polianthes tuberosa L.) is a perennial summer flower grown by smallholders in Kenya for export. However, its production and export volumes have declined drastically due to nematodes infestation. This study evaluated the effect of Cleome gynandra accessions on nematode management on tuberose. Experiment was conducted at the Horticulture Research Field, Egerton University, Kenya using a randomized complete block design with four replications. The treatments were: five accessions of C. gynandra namely ‘Simlaw’, ‘Egerton’, ‘Taastrup’, ‘PS’ and ‘IP8’, applied at 6 kg/m2 and compared with Brassica napus, solarization and untreated control. Data was collected on growth and yield parameters, nematode infestation and quality of tuberose. Data collected was subjected to analysis of variance at p≤0.05 and means separated using Tukey’s test. Biofumigation with Cleome gynandra accessions helped to reduce nematode population by 34%, gall numbers by 83% and galling index by be 96% when compared with the control. Use of biofumigation helped to improve plant height and leaf number of tuberose by 16% and 87%, respectively, when compared with the control. Use of biofumigation helped to improve spike length by 32%, marketable spikes by 80%, and flower yield by 90% and reduced nonmarketable spikes by 95% when compared with the control. Based on the above results, use of Cleome gynandra accessions and other biofumigants such as rape seed can be used to manage nematodes and improve growth, yield and quality of tuberose.

Integration of Arbuscular Mycorrhizal and Nematode Antagonistic Fungi for the Biocontrol of Root Lesion Nematode Pratylenchus zeae Graham, 1951 on Sugarcane

To study the integration of two Arbuscular mycorrhizal fungi (AMF) Glomus fasciculatum and G. mosseae and three nematode antagonistic fungi viz., Arthrobotrys oligospora, Purpureocillium lilacinum (= Paecilomyces lilacinus) and Pochonia chlamydosporia on sugarcane cv. 86032 to manage root lesion nematode Pratylenchus zeae, an experiment was conducted under potted condition. Increased shoot and root growth was observed due to either individual or combined inoculations of bioagents than nematode alone control plants. Among the treatments, G. fasciculatum + A. oligospora combination recorded maximum shoot weight followed by G. fasciculatum + P. lilacinum. Reduction in P. zeae population recorded in all the bioagents inoculated plants compared to nematode alone control. The nematode reduction was more when antagonistic fungi were combined with AMF and the nematode reductions in roots was ranged between 50 and 77%. Among the AMF and antagonistic fungi combinations, maximum reduction in nematode population (77%) was recorded with G. fasciculatum + A. oligospora. Compatible association between AMF and other nematode antagonistic fungi observed. There was an increased mycorrhizal colonization recorded in combined treatments of AMF and antagonistic fungi than AMF alone. Integration of AM fungus G. fasciculatum with nematode antagonistic fungus A. oligospora appears to be a potential combination for the control of root lesion nematode P. zeae management in sugarcane.

THE ROLE OF SOIL MOISTURE REGIME IN ENHANCING BIOFUMIGATION EFFICACY AGAINST Meloidogyne Incognita (KOFOID ET WHITE) CHITW. ON TOMATO

Anaerobic soil disinfestation (ASD), through anaerobical decomposition of organic matter in the soil is currently recommended for the control of soil borne pests including nematodes. A greenhouse trial was conducted aimed to assess the efficacy of different soil moisture regimes i.e. field capacity (FC), saturation (SA) and flooding (FL) with and without forage radish (FR) biomass addition on suppressing of root knotnematodes (Meloidogyne incognita) in tomato plant growing soil. The trial was laid out as 7 treatments in 4 replicates in completely randomized design (CRD) pots. In addition to the six treatments of soil moisture regimes with and without fodder radish, vydate, as synthetic chemical nematicide was used as positive control treatment. However, FC soil moisture regime without fodder radish served as negative control treatment. pH, redox potential (Eh) and oxygen diffusion rate (ODR) were measured in the soil in one-week interval during 4 weeks of fodder radish decomposition period before tomato seedlings (cv. Elysa) transplanting. Root knot nematode population (Meloidogyne incognita), reproductive factor and galling index were determined 12weeks after transplanting. Tomato crop growth parameters including plant length, fresh and dry plant weights and fruit fresh weights were also recorded. Obtained data revealed that both pH, Eh and ODR in the soil during 4 weeks of fodder radish decomposition period dramatically declined under soil flooding with fodder radish green manure treatment. Flooding the soil with fodder radish significantly reduced nematode population, reproductive factor and galling index values. The treatment was comparable to that obtained with vydate application treatment and was finally reflected on improvement of all studied tomato growth attributes.

Fluopyram Suppresses Population Densities of Heterodera glycines in Field and Greenhouse Studies in Michigan.

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, causes significant damage to soybean production annually. Fluopyram is a fungicide commonly used in soybean seed treatments intended to control soilborne fungal pathogens; however, recent studies have also suggested inhibitory effects on SCN. We examined the effects of a fluopyram seed treatment, ILeVO, on SCN reproduction, sudden death syndrome (SDS) development, and yield in a 3-year field study. Overall, fluopyram had a significant effect on yield (P = 0.046) and end-of-season SCN eggs and second-stage juveniles (Pf, P = 0.033) but no significant effect on SCN reproduction (Rf) or SDS disease index (P > 0.05). Post hoc tests indicated that fluopyram increased yield and suppressed SCN quantities. However, Rf was consistently greater than 1 whether or not the seed was treated with fluopyram, indicating that SCN populations were still increasing in the presence of fluopyram. A follow-up greenhouse study indicated that fluopyram reduced SCN relative to nontreated controls, as observed in the field, but only reduced SCN DNA within roots of a susceptible cultivar. These results indicate that fluopyram can suppress SCN quantities relative to nontreated seed but may not successfully reduce nematode populations without the use of additional management strategies.

Eco–friendly management of Meloidogyne javanica in chickpea (Cicer arietinum L.) using organic amendments and bio–control agent

Root–knot nematodes (Meloidogyne spp.) are the sedentary endoparasites that cause severe yield losses in chickpea. Chemical nematicides are widely used to control root–knot nematodes. These toxic chemicals pollute the soil and water environments and affect human health. The present study aimed to identify a potential bio–organic approach of management of M. javanica in chickpea. A two–year field experiment (2013–2015) was conducted to evaluate the efficacy of organic amendments (neem cake, neem seed powder and vermicompost), bio–control agent (Trichoderma harzianum), and chemical nematicides (carbofuran 3G, carbosulfan 25DS) for managing M. javanica in chickpea. The population of M. javanica in control treatment was 6.6 infective juveniles cc−1 soil. Organic amendments and bio–control agent reduced nematode population considerably in comparison to control treatment. Results showed that root galls and gall index were reduced in all the treatments over control, and the maximum reductions were observed in carbofuran 3G and neem cake treatments. Neem cake and carbofuran 3G reduced the root galls by 59% and 62% and gall index by 45% and 58% over control. Neem cake, carbofuran 3G and carbosulfan 25DS treatments resulted in the higher yield of chickpea over control treatment, which was primarily attributed to an increase in plant biomass and number of pods per plant. Chemical nematicides reduced the nodulation as compared to other treatments. Hence, neem cake could be an alternative to toxic chemical nematicides and recommended as eco–friendly management of M. javanica in chickpea.

Efficacy of chemical and biological nematicides in the management of Meloidogyne paranaensis in Coffea arabica

Coffee crop is of high importance to the Brazilian agriculture, but plant-parasitic nematodes, especially the root-knot nematode Meloidogyne paranaensis, can reduce the productivities of coffee plants. The management of nematodes in coffee is done mainly with the use of resistant plants and chemical and biological nematicides, mainly in large-scale farms. Nevertheless, there is scarce information about the efficacy of available nematicides and new molecules in the control of root-knot nematodes in coffee. Thus, the objective of the present work was to evaluate the efficacy, under greenhouse conditions, of four chemical (cadusafos, carbofuran, fluopyram, and fluensulfone) and two biological (Purpureocillium lilacinum and Trichoderma harzianum) nematicides and one organo-mineral compost in the control of M. paranaensis, the main nematode species for Paraná coffee production. For this, coffee plants of the cultivar Mundo Novo with four to five pairs of leaves were transplanted to 3.6 L-capacity plastic pots and inoculated with 1,000 eggs of M. paranaensis; noninoculated plants were used as control. Nematicide treatments at the recommended dosages by manufacturers were done soon after the transplant and inoculation or 60 days after. Evaluations were done 120 days after the inoculation on the basis of nematode reproduction factor (RF) and number of nematodes per gram of root (Nema/g). Additionally, the development of plants was measured by the variables plant height, fresh top weight, and fresh root weight. The results showed that the best nematicides to reduce nematode population were fluensulfone and fluopyram, with 99% and 100% reduction of the nematode RF, respectively. Carbofuran and cadusafos, although controlled the nematode, caused phytotoxicity to coffee plants. Biological nematicides were not effective in the reduction of the nematode population, but the application of P. lilacinum provided better development of plants. These results have high relevance, as they demonstrated the effect of chemical molecules and biological agents, both in M. paranaensis-infected plants and in noninfected plants; with this information, growers can choose products with a higher nematicidal effect and that allow better plant development for use in infested fields.

Management of root-knot nematode, Meloidogyne incognita infesting fig under field conditions

A statistically designed field experiment with ten treatments including an untreated control replicated thrice in Randomized Block Design was conducted in root- knot nematode infested fig (cv. Poona fig) orchard. All the treatments were significantly superior over an untreated control in reducing root- knot nematode population, number of root galls and egg masses and increasing the yield of fig. However, soil application of carbofuran 3G at 2 kg a.i./ha was found to be most effective in reducing root-knot nematode population (53.66%), number of root galls (50.19%) and number of egg masses (45.36%) at intermediate stage and increasing the fruit yield of fig (37.85%) with 1:17.79 ICBR at termination. This treatment was followed by the treatment of phorate 10 G at 2kg a.i./ ha. The reduction in root- knot nematode population, number of root galls and egg masses and increase in fruit yield recorded in this treatment were 49.46, 50.11, 42.31 and 28.19%, respectively with 1: 33.64 ICBR. While, at termination stage, the treatment of Phule Trichoderma plus at 20 kg/ha was found to be most effective in reducing nematode population (40.36%), number of root galls (37.08%) and number of egg masses (41.02%) and increasing the fruit yield of fig (13.54%) with 1: 11.20 ICBR. This was followed by the treatments with rest of the biocontrol agents. The reduction in root- knot nematode population, number of root galls and number of egg masses and increase in fruit yield of fig recorded in these treatments ranged from 32.03 to 38.50, 29.31 to 36.00, 31.90 to 35.97 and 11.54 to 20.75%, respectively with 1: 9.80 to 1: 20.04 ICBR.

Rhizophere engineering with beneficial microbes for growth enhancement and nematode disease complex management in gherkin (Cucumis anguria L.)

Major studies on root knot nematode (Meloidogyne incognita) tend to focus on the nematode alone, but with not much attention to its synergistic association with bacterial or fungal pathogens co-inhabiting the crop rhizosphere. Nematodes pave the way for easy entry of these pathogens inside the host roots, forming a disease complex that causes enormous yield loss. Greater knowledge on the interaction of fungal and nematode pathogens is required to find better solutions for sustainable management of the nematode diseases complex. Hence, this research was designed to study the interaction between M. incognita and Fusarium oxysporum f. sp. melonis and evaluate the consortia formulation of biocontrol agents (BCA) Trichoderma viride IIHR TV-2 and Bacillus subtilis IIHR BS-21 against nematode-fungal diseases complex in gherkin (cv. Ajax). Nematode-fungus interaction studies revealed that inoculation of M. incognita 15 days earlier to fungus showed maximum wilt incidence (96.81%) than fungus alone (85.29%), revealing their synergistic association. Under in vitro, cell free culture filtrates of T. viride IIHR TV-2 and B. subtilis IIHR BS-21 showed significant antagonism ovicidal, larvicidal and fungicidal action. Both the BCA strains were found compatible with each other (91.84%). Under field conditions, seed treatment (20 ml kg−1) and subsequent soil application of vermicompost (2 t ha−1) enriched with BCA consortia (5 l) before planting, followed by monthly application at 1 t ha−1 showed maximum increase in the plant growth parameters and reduction in nematode population in soil (66.37%), roots (62.45%) and per cent wilt incidence (42.56%) compared to untreated plants. Marketable gherkin yields also increased by 34.42% over the control. These results emphasize the efficacy of vermicompost enriched with microbial consortia in managing pathogen complexes and can be included as promising component in integrated nematode and disease management for gherkin and other horticultural crops.

Nematode Management in the Strawberry Fields of Southern Spain

(1) Background: Spain is the sixth strawberry producer in the world, with about 6500 ha producing more than 350,000 tons, and an annual commercial value about 390 million €. Stunted and dead strawberry plants are frequently associated with plant-parasitic nematodes, but nematode diseases have not been characterized to date in the country. (2) Methods: A poll on the perception of the impact of nematodes on strawberry production was carried out by face-to-face interviews with farm advisors. In addition, nematological field surveys were carried out at the end of the growing season in 2017 and 2018 to determine prevalence and abundance of plant-parasitic nematodes in strawberry crops. The host suitability to Meloidogyne hapla of seventeen strawberry cultivars and the tolerance limit to M. hapla at progressively higher initial population densities (Pi) were assessed in pot experiments in a growth chamber. Comparison of the relative efficacies of several soil disinfestation methods in controlling nematode populations (M. hapla and Pratylenchus penetrans) was carried out in experimental field trials for twelve consecutive years. (3) Results: Meloidogyne spp., Pratylenchus penetrans, and Hemicycliophora spp. were the main plant-parasitic nematodes in the strawberry fields in South Spain. Root-knot nematodes were found in 90% of the fields, being M. hapla the most prevalent species (71% of the fields). A tolerance limit of 0.2 M. hapla juveniles per g of soil was estimated for strawberry, and currently cropped strawberry cultivars did not show resistance to M. hapla. Nematode population densities were reduced by more than 70% by soil fumigation with 1,3-dichloropropene, dazomet, dimethyl-disulfide, and methyl iodide. The efficacy of metam-sodium in reducing nematode populations was about 50% and that of chloropicrin, furfural, and sodium-azide, less than 40%. Combination of solarization with organic manures (biosolarization) reduced soil nematode populations by 68–73%. (4) Conclusions: Plant-parasitic nematodes (Meloidogyne, Pratylenchus, and Hemicycliophora) are widely distributed in the strawberry fields of Southern Spain. Strawberry is a poor host for M. hapla with a tolerance limit of 0.2 J2 per g of soil, and low population increases in cropping cycles of 7–8 months. Strawberry cultivars show a range of susceptibility and tolerance to M. hapla, but no resistance is found. Nematodes are effectively controlled by chemical fumigation of soils, but soil biosolarization is equally effective, and therefore, can be proposed as a sustainable alternative for pathogen control in strawberry cultivation.

Effect of Coffee Silver Skin and Brewers' Spent Grain in the Control of Root-knot Nematodes.

SummaryPlant parasitic nematodes (PPN) are important pests of numerous agricultural crops especially vegetables, able to cause remarkable yield losses correlated to soil nematode population densities at sowing or transplant. The concern on environmental risks, stemming from the use of chemical pesticides acting as nematicides, compels to their replacement with more sustainable pest control strategies. To verify the effect of aqueous extracts of the agro-industry waste coffee silverskin (CS) and brewers’ spent grain (BSG) on the widespread root-knot nematode Meloidogyne incognita, and on the physiology of tomato plants, a pot experiment was carried out in a glasshouse at 25 ± 2 °C. The possible phytotoxicity of CS and BSG extracts was assessed on garden cress seeds. Tomato plants (landrace of Apulia Region) were transplanted in an artificial nematode infested soil with an initial population density of 3.17 eggs and juveniles/mL soil. CS and BSG were applied at rates of 50 and 100 % (1L/pot). Untreated and Fenamiphos EC 240 (nematicide) (0.01 μL a.i./mL soil) treated plants were used as controls. Reactive oxygen species (ROS) and chlorophyll content of tomato plants were estimated during the experiment. CS extract, at both doses, significantly reduced nematode population in comparison to the untreated control, although it was less effective than Fenamiphos. BSG extract did not reduce final nematode population compared to the control. Ten days after the first treatment, CS 100 %, BSG 50 % and BSG 100% elicited the highest ROS values, which considerably affected the growth of tomato plants in comparison to the untreated plants. The control of these pests is meeting with difficulties because of the current national and international regulations in force, which are limiting the use of synthetic nematicides. Therefore, CS extracts could assume economic relevance, as alternative products to be used in sustainable strategies for nematode management.

ADVANCED STUDIES ON SOME ENDOPHYTIC MICROORGANISMS AND PLANT EXTRACTS TO CONTROL ROOT-KNOT NEMATODES

In this study four different plants were used i.e. Moringa, Cabbage, Cassia and Chinaberry at different forms, concentrations and depths. The four plants under study used as chopped leaves as bio-fumigants. Results revealed that moringa at 4%. The lowest effect recorded with cassia 1%. The four plants were used as achopped leaves at 4% at three depths 5, 15, 30 cm against nematodes. Results revealed that the depth of 15 cm the best one in reducing the nematode population. the different four plants used as a leaves powdr at 1,2 and 4% of soil weight. Moringa at 4% the effective one in reducing nematode population. Using seeds powder of moringa and cabbage at different doses 1,2, and 4% of soil weight. Moringa seeds powder at 4% gave the highest effective one on reducing root-knot nematodes. Moringa oil was used to manage root-knot nematodes at different concentrations and different application types. Results showed that soil drench the effective typy in managing the nematode population at 2%. The four plants were used also with three different solvents under laboratory and greenhouse conditions. Results showed that moringa ethanol extract was the effective one either in vitro or in vivo . Eleven isolates of bacterial and six of fungal isolates were isolated from cabbage and moringa roots and seeds , identified and evaluated against root-knot nematodes under laboratory and greenhouse conditions .Results found that the all bacterial and fungal isolates appeared effectiveness against egg hatching and larvae mortality in vitro and nematode population in vivo. The integrated pest management carried out by using the effective treatment from each experiment to manage root-knot nematodes under greenhouse conditions. Results found that all treatments reduced all nematode parameters. Trichoderma spp. plus Bacillus cereus appeared a promising in managing root-knot nematodes

Sustainable alternatives to 1,3-dichloropropene for controlling root-knot nematodes and fungal pathogens in melon crops in Mediterranean soils: Efficacy and effects on soil quality

The control of agricultural pests is key to maintain economically viable crops. Increasing environmental awareness, however, is leading to more restrictive European policies regulating the use of certain pesticides due to their impact on human health and the soil system. Given this context, we evaluated the efficacy of three alternatives to the soil fumigant 1,3-dichloropropene (1,3-D), which is currently banned in Europe: two non-fumigant nematicides [oxamyl (OX) and fenamiphos (FEN)] and the soil fumigant dimethyl disulfide (DMDS). We analysed the efficiency of these pesticides against root-knot nematodes and soil fungal pathogens (determined by qPCR) as well as the soil biological quality after treatments application (estimated by enzyme activities). Among treatments, 1,3-D and DMDS significantly reduced nematode populations. FEN was more effective in sandy soil, while OX had no effect in any soil. OX and FEN had no effect on fungal pathogens, whereas DMDS reduced the abundance of Rhizoctonia solani and Fusarium solani at the root level in clay-loam soil. Soil quality decreased after treatment application but then recovered throughout the experiment, indicating the possible dissipation of the pesticides. Our findings support DMDS as a potential sustainable alternative for controlling root-knot nematodes and fungal pathogens due to its effectiveness in both studied soils, although its negative impact on soil biological quality in sandier soils must be taken into account.Main finding of the work. DMDS is a reliable alternative to 1,3-D for controlling agricultural pest but its inhibitory effect on soil enzyme activities varied according to the soil characteristics.

Management of plant parasitic nematodes in Okra by Bio-fumigation

A pot culture study was carried out to assess the effect of two bio-fumigants viz. Cabbage and Cauliflower leaves on plant parasitic nematode population infecting okra. The experiment resulted in reduction of root knot nematode (40.7%), lance nematode (40.8–80.1%), spiral nematode (49.1–79.7%) and stunt nematode (40.8–81.3%) with improvement of plant growth parameters like shoot length (23.3–54.6%), root length (14.1–46.5%), fresh shoot weight (28.4–81.9%), fresh root weight (22–38.7%), dry shoot weight (11.6–85.7%) and dry root weight (24–39%) of okra plant as compared to untreated control. Both cabbage and cauliflower leaves were found to be at par with respect to reduction of nematode population and enhancement of plant growth parameters. However, Cabbage leaf @ 88 g/kg soil (5.0 kg/m2) exhibited better performance in all above aspects. It reduced the population of root knot nematode, lance nematode, spiral nematode and stunt nematode by 50%, 52.4%, 61.2% and 50.9%, respectively. The enhancement of shoot length, root length, fresh shoot weight, dry shoot weight, fresh root weight and dry root weight to the tune of 49.3%, 46.5%, 79.3%, 78.5%, 38.7% and 39.5%, respectively were observed with this treatment.

Cloning of the defense gene PlchiIII and its potential role in the biocontrol of Pratylenchus coffeae nematodes and Meloidogyne incognita eggs in Musa

Abstract A wide range of crops such as bananas and plantains are devastated by plant parasitic nematodes that affect the root system, leading to impaired plant growth and production. In this scenario, the chitinase gene was isolated from the nematode-resistant cultivar of Pisang lilin. The amplified target gene was cloned into pET28a encoding 323 amino acid residues, which shares a high degree of homology with acidic class III chitinase in Musa acuminata, and the product was transformed into E. coli BL21 strain for protein expression. Using affinity chromatography, the recombinant chitinase was purified as a protein of 29 kDa with an optimal activity at pH 7.0. The purified chitinase was capable of degrading the chitin present in the exoskeleton layer of root lesion nematodes (Pratylenchus coffeae) and in the eggshells of root-knot nematodes (Meloidogyne incognita), as well as significantly influencing its development and mortality. Bioassay was performed under in vitro conditions. In root lesion nematodes, 100% mortality was recorded at concentrations of 0.2 µg/mL and 0.15 µg/mL on the 3rd and 5th days, respectively, whereas the egg-hatching rate was inhibited by 100% at concentrations of 0.2 µg/mL and 0.01 µg/mL on the 1st and 5th days, respectively. The results of this study suggest that the PlchiIII gene can be used as a plant-based microbial agent in the biocontrol of nematodes would help in reducing nematode population and increase the yield of banana.

Enhancement of nematicidal potential through cloning and expression of chitinase gene from Bacillus subtilis subsp. Subtilis BTN7A strain.

A gene encoding chitinase from B. subtilis has been isolated after optimization of PCR conditions. It was cloned with two different prometers, T7 promoter of the pJET1.2/blunt cloning vector and the SP6 promoter of pGEM®-T Easy vector. After transforming E. coli DH5α, two transformants were selected, CHI-NRC-4 from the first vector and T-CHI-NRC-6 from the second vector, and used for further studies. The complete CDS sequence of chitinase gene was determined and submitted to GenBank with the accession number KX268692.1. Culture supernatants of E. coli (CHI-NRC-4) and E. coli (T-CHI-NRC-6) were investigated for their inhibitory effect on M. javanica egg hatch under laboratory conditions. Result showed up to 96% inhibition in egg hatching due to both E. coli transformants as compared to control which reflect the same expression efficiency of both used prometers. A greenhouse experiment was carried out to evaluate the nematicidal effect of culture supernatants of the two transformts E. coli (CHI-NRC-4) and E. coli (T-CHI-NRC-6) against M. javanica infected eggplant. Obtained results showed a significant reduction in nematode population in soil and roots and enhancement in eggplant growth parameters as compared to control.

Can arbuscular mycorrhiza fungi and NPK fertilizer suppress nematodes and improve tuber yield of yam (Dioscorea rotundata ‘cv’ ewuru)?

Poor soil fertility and nematodes limit yam tuber yield and quality. Arbuscular mycorrhizal fungi (AMF) and fertilizers may suppress nematodes and improve yam productivity. We evaluated the extent AMF and fertilizer suppressed nematodes and improved yam performance. Tuber weight, mycorrhizal colonization of roots and nematode populations were evaluated with eight treatments; Control (No amendments), 90-50-75, kg N- P 2 O 5 -K 2 O ha -1 (NPK), (AMF) (2g/kg soil), nematodes (5000 juvenile/pot), and their combinations. Tuber weight was higher in NPK+AMF and NPK+nematode treatments than AMF+nematode. NPK+AMF improved tuber weight by 17.5% and 32% compared with sole NPK or AMF respectively. Compared with control, nematodes did not reduce tuber weight but, AMF+nematode reduced it by 49.4%. NPK reduced AMF colonization of roots and reduced nematode population on tuber, in roots and soil by 34%, 42.6% and 41% respectively. NPK+AMF treatment was superior to either NPK or AMF in improving tuber yield while NPK was superior to AMF in suppressing nematodes in roots, soil, and tuber.

Effect of different inocula of Rotylenchulus reniformis and their management with botanicals on Sunflower

The results revealed that the plants inoculated with 10 and 100 nematodes (J4) were similar in growth as compared to check treatment. However, gradual loss in plant growth parameters was observed with increase in inoculum levels. This showed that Rotylenchulus reniformis was found pathogenic to the sunflower crop which adversely affected the growth. For the management of nematode five plants leaves namely neem, marigold, dhatura, oak, and lantana were evaluated for the nematicidal properties against R. reniformis. When plants extracts (S/8 &S/16 dilutions) were put around sunflower crop in pots, resulted an increase in shoot length, max. being in dhatura leaves extract. Similarly, a significant increase of shoot and root weights were also observed. However, maximum reduction of nematode population was noticed in neem and marigold leaf extracts.