Nematode Damage Research Articles

Nematode Damage to Plantain (Musa spp. AAB-Group) at Flowering as Affected by Paring and Organic Mulch in Southwestern Nigeria

The experiment investigated the effects of paring, oil palm bunch refuse and sawdust mulches on the flowering of mother plant, development of suckers, and the establishment, population and damage dynamics of plant parasitic nematodes on plantain cultivar Agbagba in Southwestern Nigeria. A multifactorial experiment was laid out in a randomized complete block design. Above-ground plant growth parameters were measured at flowering of mother plants. Twenty-two months after planting (MAP), mats were sampled to assess nematode population densities, root and rhizome damages. Results of this study showed that paring and mulching gave complementarily effect on early flowering of plants, improved root production and the extent of benefit was dependent on the type of mulch material used. Pared plants produced fewer suckers at flowering than the non- pared plants, had healthier roots and lower root infections associated with plant parasitic nematode damage. Oil palm bunch refuse was superior to the sawdust mulch in enhancing plant growth, root health and suppressing nematode population densities. In an integrated pest management context therefore, paring coupled with mulching is recommended to boost plantain production.

Transgenic Nicotiana tabacum cultivar Samsun plants carrying the wild sugar beet Hs1pro1 gene have resistance to root-knot nematodes

Nematodes are the principal animal parasites of plants, causing annual crop losses of more than US$100 billion worldwide. Conventional control measures against nematode infection include toxic nematicide application to soil, crop rotation practices, and classical breeding approaches. However, due to the limitations of each technique, biotechnology presents itself as an effective alternative in nematode control. To date, several resistance genes against nematodes have been cloned. One such gene, Hs1^{pro1}, cloned from wild sugar beet, Beta procumbens, shows resistance to the cyst nematode Heterodera schachtii. Recent studies showed that Hs1^{pro1} has a broad target pathogen range. In this study, we transformed Nicotiana tabacum cultivar Samsun plants with the Hs1^{pro1} gene and assayed transgenic plants for nematode resistance. Our analysis suggests that compared to wild-type plants, Hs1^{pro1}-carrying transgenic plants are more resistant to 2 different root-knot nematode species, Meloidogyne incognita and Meloidogyne javanica. The results in this study support previous findings of the broad host range of Hs1^{pro1} and are promising in terms of the genetic engineering of economically important susceptible crop plants such as potato and tomato against nematode and secondary damage from other soil-pathogen damage.

Influences of a radish and sweet potato continuous ridge use system on root-knot nematode damage to sweet potato

Influences of a radish and sweet potato continuous ridge use system on root-knot nematode damage to sweet potato

Lauric acid in crown daisy root exudate potently regulates root-knot nematode chemotaxis and disrupts Mi-flp-18 expression to block infection

Tomato (Solanum lycopersicum) crops can be severely damaged due to parasitism by the root-knot nematode (RKN) Meloidogyne incognita, but are protected when intercropped with crown daisy (Chrysanthemum coronarium L.). Root exudate may be the determining factor for this protection. An experiment using pots linked by a tube and Petri dish experiments were undertaken to confirm that tomato-crown daisy intercropping root exudate decreased the number of nematodes and alleviated nematode damage, and to determine crown daisy root exudate-regulated nematode chemotaxis. Following a gas chromatography-mass spectrometry assay, it was found that the intercropping protection was derived from the potent bioactivity of a specific root exudate component of crown daisy, namely lauric acid. The Mi-flp-18 gene, encoding an FMRFamide-like peptide neuromodulator, regulated nematode chemotaxis and infection by RNA interference. Moreover, it was shown that lauric acid acts as both a lethal trap and a repellent for M. incognita by specifically regulating Mi-flp-18 expression in a concentration-dependent manner. Low concentrations of lauric acid (0.5-2.0mM) attract M. incognita and consequently cause death, while high concentrations (4.0mM) repel M. incognita. This study elucidates how lauric acid in crown daisy root exudate regulates nematode chemotaxis and disrupts Mi-flp-18 expression to alleviate nematode damage, and presents a general methodology for studying signalling systems affected by plant root exudates in the rhizosphere. This could lead to the development of economical and feasible strategies for controlling plant-parasitic nematodes, and provide an alternative to the use of pesticides in farming systems.

An Aegilops ventricosa Translocation Confers Resistance Against Root-knot Nematodes to Common Wheat.

Root knot nematodes (RKN; Meloidogyne spp.) cause severe losses worldwide to a wide range of crops. Crop rotations with resistant hosts can be used to control losses, but the wide host range of RKN limits this option. In this study, we found that the wheat cultivar Lassik is resistant to several isolates of the RKN species M. incognita and M. javanica, including those that can reproduce on tomato with the resistance gene Mi-1. Comparison of near-isogenic lines of wheat showed that the wheat resistance gene(s) is localized within a segment of the short arm of chromosome 2N from Aegilops ventricosa (Zhuk.) Chennav translocated into common wheat (Triticum aestivum L.) chromosome arm 2AS and is associated with a highly significant decrease in RKN eggs in the roots. This RKN resistance gene has been assigned the name Rkn3. While wheat itself is tolerant of RKN infection, a microplot experiment coupled with tomato bioassays showed less RKN root galling in the tomato samples grown in soil from the previous microplots including RKN resistant wheat varieties than in those including a susceptible wheat isogenic line. This result suggests that rotation with Rkn3 resistant wheat cultivars has the potential to be a valuable component of nematode management for crops that are highly susceptible to nematode damage and for which alternative strategies are limited.

Rhizospheric biological weapons for growth enhancement and Meloidogyne incognita management in Withania somnifera cv. Poshita

Withania somnifera L. (Family Solanaceae) is an angiospermic medicinal herb, well recognized for the immense therapeutic potentials of its roots containing several withanolides. W. somnifera is also a susceptible host for southern root knot nematode, Meloidogyne incognita. The nematode infestation in roots causes serious crop losses in terms of yield and chemo-pharmaceutical quality of this medicinal herb. In the present study, influence of five rhizospheric microbes, namely Bacillus megaterium (ATCC No. 14581), Pseudomonas fluorescens (ATCC No. 13525), Trichoderma viride (MTCC No. 167), Paecilomyces lilacinus (PDBC PL55) and Glomus intraradices was studied for the management of M. incognita in W. somnifera cv. Poshita under greenhouse conditions. All rhizospheric microbes, except G. intraradices, displayed nematicidal potentials via ovicidal and larvicidal actions in vitro and, resulted in significant improvement in plant growth parameters. The rate of nematode damage to W. somnifera was directly proportional to M. incognita (number of J2) population.

English

A survey of plantain farms was conducted in April 2012 at four locations in two districts of Ghana. The purpose was to identify plant parasitic nematodes (PPN) associated with plantain production in Ghana. The locations were Adomakokrom and Kenyasi in the Brong Ahafo, Adanwomase and Mpobi in the Ashanti region. Demographic and sociological data of farmers, plantain root lesion scores, PPN populations per 200 cm3 soil and 5 g plantain roots were analyzed. Nematode damage to root at Adomakokrom, Adanwomase, Mpobi and Kenyasi were 50, 75, 75 and 50%, respectively. Five nematode species were recovered from the rhizosphere of plantain. The nematodes were in the order of importance; Pratylenchus coffeae, Meloidogyne spp.,Rotylenchulus reniformis, Radopholus similis and Helicotylenchus multicintus. High populations ofP. coffeae (803/200 cm3), H. multicintus (292/200 cm3) and R. reniformis (343/200 cm3) were extracted from soil samples at Adomakokrom, Adanwomase and Adanwomase respectively. Four parasitic nematodes; Meloidogyne spp., P. coffeae, R. reniformis and R. similis were extracted from plantain roots. Root populations were higher compared with soil samples. For sustainable plantain production in Ghana, an efficient management option must be devised.   Key words: Ghana, integrated pest management, Musa spp., plant parasitic nematodes.

Pathogenicity and damage potential of five species of plant-parasitic nematodes on plantain (Musa spp., AAB genome) cv. Agbagba

The pathogenicity of five plant-parasitic nematode species, Radopholus similis, Pratylenchus coffeae, Helicotylenchus multicinctus, Hoplolaimus pararobustus and Meloidogyne spp., commonly recorded from banana and plantain in West and Central Africa, was assessed on plantain (Musa spp., AAB genome) cv. Agbagba in Nigeria. The pest status of H. pararobustus was demonstrated for the first time in addition to H. multicinctus, while the importance of P. coffeae and R. similis was further confirmed. In addition, the study further demonstrated the contribution of nematodes to weakened pseudostems (stems) and stem snapping during periods of low water availability, in the absence of weevil damage. Through a series of experiments, the nematode damage potential was evaluated in 20 l pots, 70 l microplots (halved oil drums) and a field experiment over four crop cycles. In pots only a combination of four species (without H. pararobustus) led to greater root necrosis than the non-inoculated control, while R. similis reduced root mass. In microplots most crop growth parameters were similar across treatments, except root necrosis, which was higher for all nematode treatments than on control plants and more severe on P. coffeae roots than for other nematode species. In the field trial heavy storms disrupted data collection. Plant stem snapping, however, was greater for all nematode treatments compared with controls. Nematode damage indices such as feeder root health and root necrosis were higher in all nematode treatments and consistently so for R. similis and P. coffeae over the first two cropping cycles. Mean bunch weight of harvested plants was lower for all nematode treatments than controls; between 33.3% and 50.8%, even for first cycle mother plants, and consistently lower across crop cycles.

Spatial and temporal dynamics of Meloidogyne minor on creeping bentgrass in golf greens

Meloidogyne minor, first reported on potatoes in the Netherlands in 2004, is an emerging nematode pest in Europe. It damages turfgrass, particularly creeping bentgrass (Agrostis stolonifera) grown on sandy soils such as those of golf greens. However, little is known of the nematode's life history and pathology. In this study, the spatial and temporal distribution of M. minor on a creeping bentgrass green in Ireland was determined over a 15 month period. Cores were taken on transects across yellowing patches of grass caused by nematode damage. Second‐stage juveniles (J2) were absent from the soil from November to February, when soil temperatures were below 10°C. Both galls and egg masses were present throughout the year but were more abundant in late summer and early autumn. More J2, galls and egg masses were present in the top 10 cm of soil than at a depth of 11–20 cm. The nematode population tended to decrease as distance from the centre of the yellow patches increased. The diameter of visual symptoms (yellow patches) was also recorded over the 15 months. The mean diameter of five sampled patches increased from 23·7 cm in June 2003 to 45·2 cm in August 2004. There were 158–193 galls per 100 cm3 soil at the margin of the visible infested area, indicating that this could be the threshold level for visible symptoms.

Effects of rhizobacteria on parasitism by Meloidogyne ethiopica on grapevines

Meloidogyne ethiopica is one of the most important plant-parasitic nematodes affecting vines in Chile and is very aggressive and difficult to control. This study evaluated 16 strains of rhizobacteria, originally isolated from roots of grapevines, for their effects on parasitism and nematode damage to potted vine plants. The antagonistic effect of rhizobacteria was assessed by treating 2-month-old plants of cv. Chardonnay in 3-l pots with a suspension containing 1 × 106 cfu ml−1 of the bacteria and 1,000 nematode eggs. After 6 months of growth, the plants were cut and root and canopy weights, nematode populations and root damage determined. The effect of rhizobacterial culture filtrate on hatching of nematode eggs was also assessed in vitro. Seven strains of rhizobacteria proved effective in inhibiting damage or reproduction of the nematode. These were strains of Serratia marcescens, Comamonas acidovorans, Pantoea agglomerans, Sphingobacterium spiritivorum, Bacillus mycoides, Alcaligenes piechaudii and Serratia plymuthica. A further three strains, of Bacillus megaterium, P. agglomerans and Pseudomonas savastanoi, significantly increased root weight, but did not decrease nematode damage or population density. The supernatant of all strains significantly decreased hatching of juvenile nematodes after 24 h of immersion, with isolates of P. putida and B. megaterium being the most effective.

REACTION OF PSIDIUM ACCESSIONS TO THE MELOIDOGYNE ENTEROLOBII ROOT-KNOT NEMATODE

The presence of the root-knot nematode, Meloidogyne enterolobii, in guava commercial orchards in many Brazilian states has caused severe loss to growers. 146 guava and aracazeiro (wild guava) accessions were evaluated in a greenhouse and nursery in order to find resistant accessions to be used as rootstock for commercial guava cultivars. In the greenhouse, 15 to 20 cm tall plants were inoculated with 10,000 nematode eggs, in a randomized complete design with an unequal number of replications. Under field nursery conditions, after seed germination, the plants were transferred to plastic bags with nematode contaminated soil. Five months after inoculation, the greenhouse accessions were evaluated for nematode damage. The nematode reproduction factor (RF) was estimated and the accessions classified as resistant or susceptible. The plants grown in the field nursery were visually evaluated for the presence of root galls one year after transplanting to plastic bags. A total of 66 Psidium, including 14 aracazeiro and 52 guava accessions, were evaluated under field nursery conditions. Two aracazeiros were classified as resistant, and another segregated for nematode tolerance under nursery conditions. All the guava accessions were susceptible in both evaluation conditions. Among the 20 aracazeiro accessions evaluated in the greenhouse, three were resistant to the nematode (RF<1) and 9, collected in the state of Rio Grande do Sul, were immune (RF=0). After further investigation performed among some resistant aracazeiro accessions collected in southern Brazil, sub-tropical region, poor plant development was observed in the northeastern Brazilian semi-arid region and low grafting compatibility with commercial guava cultivars. The current strategy to overcome this guava pest includes developing interspecific Psidium hybrids among resistant aracazeiros and susceptible guava to obtain hybrids with adequate plant height and stem diameter, highly compatible when used as rootstock for commercial guava cultivars.

Combining effects of soil solarization and grafting on plant yield and soil-borne pathogens in cucumber

Combining effects of soil solarization and grafting on soilborne pathogens, plant height and yield in cucumber were compared in a greenhouse of Bati Akdeniz Agricultural Research Institute located in Antalya in 2008 fall season. The experiment was set in split plot design containing; 1, 2, 4 and 5 months soil solarization (MSS), and non-solarized control plots (NSC) on which grafted Maximus F1+ Bergama F1 and non-grafted Bergama F1 were grown. Almost all of plants grown in non-solarized plots were infected with root-knot nematodes with severe root damages; however, only a few plants were affected by this nematode in 4 and 5 month solarized plots with very slight root galls. No resistance to root-knot nematodes was observed in both grafted and non-grafted plants. Almost half of the plants grown on non-solarized control plots were infected with Fusarium oxysporum f. sp. cucumerinum with relatively slight disease symptoms. In conclusion, combining solarization with grafting significantly promoted early flowering time, plant vigor, early and total yields and reduced nematode and fusarium wilt damages in this study.

Cloning arginine kinase gene and its RNAi in Bursaphelenchus xylophilus causing pine wilt disease

Since Bursaphelenchus xylophilus causes serious losses in pine forestry, new ways of controlling this nematode damage are urgently needed. Arginine kinase (AK) is a phosphotransferase, which plays a critical role in cellular energy metabolism in invertebrates. It is only present in invertebrates and may be a suitable chemotherapeutic target in the control of this pest. RNA interference (RNAi) technology has been developed in biological science in recent decades as a powerful tool to silence the target gene function in the post-translational status. In this study, one AK gene, BxAK1 (GeneBank accession No. EU853862) was firstly cloned, and then its functions were identified by RNAi technology. Results show that the full-length cDNA of the BxAK1 gene contains 1206 base pairs and an 1086 bp open reading frame encoding 361 amino acids. The length of the BxAK1 genomic coding region contains 2430 bp consisting of four introns of 421, 117, 475, and 268 bp respectively, and five exons of 57, 207, 309, 360, and 215 bp respectively. A dsRNA targeting BxAK1 was constructed and tested for its RNAi effect on B. xylophilus by soaking bioassays. RNAi not only significantly increased the mortality of B. xylophilus, but also greatly reduced its fecundity and fertility. These results suggest that RNAi targeting BxAK1 may be an effective approach for controlling nematode pests.

Seed treatment and soil drench with dl-β-amino butyric acid for the suppression of Meloidogyne javanica on tomato

Due to the recent environmental concerns, increasing amounts of research have been diverted to investigating natural products for the control of nematodes. dl-β-Amino butyric acid (BABA) could play a part in limiting nematode damage to plants. In this study, different concentrations of BABA were used as soil drench and seed treatment to determine if they can control Meloidogyne javanica on tomato. In an in vitro test, BABA did not impair mobility of second-stage juveniles of the nematode but 10 and 25 mg/l concentrations reduced hatch. Both of the application methods tested (drenching soil and/or pre-treating seeds with 25 mg/l of BABA) for the treatment of nematode infested tomato plants reduced the numbers of galls and egg masses by 82 %; nematode reproduction rates on these plants were reduced to one and, compared with untreated control plants, final nematode density was decreased by nearly 87 %. Increasing BABA concentrations of the treatment solutions to 200 and 500 mg/l resulted in further reduction in nematode damage and reproduction on treated plants, although the differences between the concentrations were not significant. Compared with untreated tomato, gall and egg mass production were decreased by an average of 92 %, and reproduction rates were held below one by both the 200- and 500-mg/l BABA rates. When seeds pretreated with 25 mg/l were also soil drenched with three BABA concentrations, the effects were slightly greater than when each method was used alone. Treated plants showed slight improvement in growth and weight.

AŞI UYUŞMA DÜZEYİ BELİRLENMESİNDE KULLANILAN FORMÜLLERİN FARKLI ÜZÜM ÇEŞİT-ANAÇ KOMBİNASYONLARINDA KARŞILAŞTIRILMASI

Vitis vinifera L. cultivars have to be grafted on American grape rootstocks due to phylloxera and nematode damages, which makes it obligatory to determine their graft compatibility in a vineyard. For this purpose, any of four formulae developed by Perraudine, Branas, Spiegel-Roy & Lavee and Onaran was inconclusive to reliably determine the compatibility of a scion/stock combination. Therefore, it is needed to compare these results with values of pruning weight, yield and quality analyses obtained from a long-term grape growing. In addition, they have to be supported by histological and biochemical analyses.

EPPO Workshop on Meloidogyne chitwoodi and Meloidogyne fallax (2011‐03‐08): importance for potato production and experience of management in EPPO countries

Prior to the meeting of the Panel on Phytosanitary Measures for Potato in 2011, a one-day workshop on Meloidogyne chitwoodi and Meloidogyne fallax was held. Several additional experts, including nematologists, attended the workshop. The objectives were to review current knowledge on these Meloidogyne nematode pests; to share experiences of dealing with outbreaks; and to consider what further work, if any, should be undertaken by EPPO. There were four presentations by experts followed by discussions of several key issues. The conclusions of the workshop are presented. Meloidogyne nematodes are extremely polyphagous, difficult to detect and difficult to eradicate. In view of the regulatory status of both M. chitwoodi and M. fallax, there is a need for more systematic surveillance of these nematodes in the EPPO region to investigate their distribution and the feasibility of phytosanitary measures for the longer term. The participants at the EPPO workshop concluded that, based on current knowledge, M. chitwoodi and M. fallax do not pose a major threat for potato production. However, to promote awareness and surveillance, a national regulatory control system is needed to assist countries in taking action in case these nematodes are found. The experiences shared during this workshop will be used to develop a National Regulatory Control System for M. chitwoodi and M. fallax (EPPO PM 9 Standard). Mr Niere (Julius Kuhn-Institut, DE) gave a general introduction to Meloidogyne nematodes with emphasis on M. chitwoodi and M. fallax. Root-knot nematodes are the most important group of plant parasitic nematodes. In 1949, the first five species were described by B. Chitwood; by 2009, nearly 100 species had been described. The decreasing use of nematicides, coupled with more intensive host cropping systems, may explain why these nematodes have become a more prominent problem for growers. Meloidogyne nematodes are extremely polyphagous and damaging and have a worldwide distribution. The origin of these nematodes is not known. The species that have traditionally been recognized as major pests are M. incognita, M. arenaria, M. javanica and M. hapla. New species are emerging, however, including M. enterolobii, M. paranaenis, M. fallax, M. chitwoodi and M. minor, which also pose a major threat. Meloidogyne species are especially damaging in tropical regions for numerous vegetable crops, and can cause complete loss of harvest. Root-knot nematodes damage root systems and can induce the formation of galls, thereby weakening root systems, but rarely cause plant death. Necrotic lesions can also occur in the cortex. In

Nematodes as a Limiting Factor in Potato Production in Scandinavia

Plant parasitic nematodes associated with potato feed on roots and/or tubers. About 70 species, representing 24 genera, have been reported from potato. Since nematodes attack underground plant parts, there are no reliable foliar symptoms to show that nematodes may be the major cause of poor growth and reduced tuber yields. Potato roots damaged by nematodes may show lesions, abnormal proliferation of lateral roots, emerging white females and brown cysts. Nematode attacks may render plants vulnerable to other pathogens, so disease caused by microorganisms may have nematodes as an etiological component. Therefore, nematode damage may often have been attributed to other factors. In Scandinavia, potato cyst nematodes (Globodera rostochiensis and Globodera pallida) are by far the most important nematodes on potato. In Norway, the cost of compensations schemes due to imposed statutory regulations of potato cyst nematodes may some years exceed the compensation for any other pests or diseases organism in agriculture. Other important nematodes include root lesion nematodes (Pratylenchus spp.), stubby root nematodes (Trichodorus spp. and Paratrichodorus spp.), and potato rot and stem nematodes (Ditylenchus spp.). Root knot nematode Meloidogyne hapla is considered less important. Meloidogyne chitwoodi and Meloidogyne fallax are not known to be present in Nordic countries. In the control, crop rotations using non-host crops, alternating susceptible and resistant potato cultivars, are an important control measure. However, the use of resistant potato cultivars requires knowledge of the species and pathotypes present in the field.

Integriertes Nematodenmanagement in Fruchtfolgesystemen mit Zuckerrüben

Für das integrierte Nematodenmanagement spielt die Entwicklung moderner Methoden und Techniken zur Befallsermittlung und Schadensprognose eine zentrale Rolle. Effizientere Verfahren zur Erfassung von Nematoden aus der Bodenprobe, zusammen mit einer vereinfachten Bodenprobenahme und der Nutzung von berührungslosen Messverfahren zur Lokalisierung und Abgrenzung von Flächen mit erhöhtem Befallsrisiko, liefern Perspektiven für eine verbesserte Schadensprognose. Ein deutlich geringeres Vermehrungsrisiko von Heterodera schachtii durch den Anbau von Raps im Vergleich zum Anbau von Zuckerrüben ist gegeben, wenn eine rechtzeitige Bekämpfung von Ausfallraps erfolgt. Der Einsatz nematodentoleranter Zuckerrübensorten bietet eine erhöhte Ertragssicherheit auf hohem Ertragsniveau. Zum kurz- und langfristigen Vermehrungspotenzial von H. schachtii durch den Anbau solcher Sorten besteht bislang noch wenig Erfahrung. Das Potenzial für die Entwicklung biologischer Bekämpfungsansätze lässt sich erhöhen, wenn komplexe Phänomene, wie die Suppressivität von Böden, besser verstanden werden. Aussichtsreiche Verfahren, wie die Biofumigation, müssen noch weiterentwickelt werden, damit sie unter den Bedingungen der Anbaupraxis eine Wirkung gegen Nematoden erwarten lassen.

Amendment of soil with African marigold and sunn hemp for management of Meloidogyne incognita in selected legumes

Field experiments were conducted in 2008 and 2009 in the tropical rainforest zone of Nigeria to investigate the effects of amendment of soil with seedlings of African marigold ( Tagetes erecta) and sunn hemp ( Crotalaria juncea) incorporated singly in plots on Meloidogyne incognita and yield of cowpea and soybean. The experimental field, which was naturally free of plant-parasitic nematodes, was inoculated with chopped roots of M. incognita race 2-infected Celosia argentea roots and planted to tomato to increase M. incognita population at the site. Eight week-old marigold seedlings were incorporated in cowpea or soybean field and eight week-old sunn hemp seedlings were also incorporated in cowpea or soybean field. At the ends of the experiments, M. incognita population densities were significantly higher in control plots than those of the plots amended with marigold or sunn hemp with correspondingly higher grain yield in the amended plots in both cowpea and soybean fields in both years. A significantly higher population of the nematode and consequently, lower yield was associated with cultivar Ife Brown than cultivar Ife Bimpe of cowpea for each treatment whereas in soybean cultivars, the pattern was not definite. Also twelve seedlings of marigold or sunn hemp per plot incorporated into the soil produced significantly higher grain yield in cultivar Ife Brown of cowpea and cultivar TGX 1440 of soybean compared to six seedlings per plot. The results of this study suggest that incorporating marigold or sunn hemp in M. incognita-infected cowpea or soybean field has potentials to suppress M. incognita population and reduce nematode damage on yield of the associated leguminous crops.

Biological control of Meloidogyne javanica by Trichoderma harzianum BI and salicylic acid on Tomato

In this study, Trichoderma harzianum BI was evaluated for its capacity to reduce the incidence and pathogenicity of the root-knot nematode Meloidogyne javanica on tomato. Culture filtrates of T. harzianum BI at different concentrations, (standard, 1:1, 1:10, and 1:100) were studied. In vitro studies revealed that hatching of M. javanica eggs were inhibited by the culture filtrates and this inhibition was positively correlated with increase in the concentration of culture filtrates. Parasitism of M. javanica eggs by T. harzianum BI ranged from 21% in control to 84% in antagonistic fungi. T. harzianum BI reduced nematode damage to tomato in vivo, too. Treatment of the soil with the antagonistic fungi and salicylic acid clearly improved nematode control when applied jointly or alone. The antagonistic fungi and salicylic acid were further tested for their ability to induce production of defense related enzymes in tomato. Earlier and increased activities of soluble peroxidase (SPOX) was observed in T. harzianum BI and salicylic acid treated tomato inoculated with M. javanica. Thus, the present study shows that in addition to direct antagonism, induction of defense-related enzymes involved in peroxidase pathway contributed to enhance resistance against invasion of M. javanica in tomato. Key words: Biological control, Meloidogyne javanica, Trichoderma harzianum BI, peroxidase.