Nematode Control Measures Research Articles

Farmer knowledge, management practices and occurrence of tomato root knot nematodes in Kenya

Root-knot nematodes (RKNs) (Meloidogyne spp.) is a major constraint to tomato (Solanum lycopersicum L.) production in sub-Saharan Africa; yet there is low adoption of recommended nematode control measures in regions like east Africa due to inadequate farmer knowledge about the pest and associated diseases. The objective of this study was to assess farmers’ knowledge status, and intensity of damage of root-knot nematodes and their management practices in Kenya. A survey was conducted in Kenya, during February to August 2021; using a semi-structured questionnaire administered to 282 randomly selected household heads of actively growing tomato farmers, at two elevations in three counties. Most farmers (98.9%) could not identify the disease precisely. They mostly attributed its symptoms to moisture stress and nutrient deûciencies. Most farmers (63%) practiced mono-cropping; while only 4.3% of farmers amended soils with manure. Respondents preferred growing RKN susceptible tomato varieties, mainly Rio-Grande, Cal J, Onyx and Kilele FI. A total of 92% expressed willingness to shift to RKNs resistant varieties, if recommended varieties match their desirable characteristics. Majority of the respondents lacked knowledge on nematode characteristics and its associated disease control. A total of 37.9% of the respondents did not use control measures against the RKNs. There was high disease incidence, severity and galling index in the surveyed areas.

Impact of the genetic diversity of three cyst nematodes on the effectiveness of root exudates to induce hatching

Cyst nematodes are sedentary endoparasites of plants which cause important economic losses worldwide. New nematode control measures are needed since the removal of effective chemical nematicides from the market due to their negative impact on environment and human health. Induced hatching of second-stage juveniles in the absence of host plant using root exudates, also named “suicide hatching”, could be a sustainable alternative method to reduce nematode population densities in infested soils. Unfortunately, biocontrol methods are often less effective in agricultural fields than in laboratory or greenhouse and this could be due to, among other reasons, a different susceptibility of nematode populations to root exudate stimulation. Testing this intra-specific variability would help to anticipate any drop in the efficiency of this new biocontrol strategy. A selection of root exudates from different plant species, maximizing the hatching level highlighted in a previous study, was tested on the hatching of representative populations of the genetic diversity for Globodera pallida, Heterodera schachtii and Heterodera carotae. Results showed significant differences between populations for given nematode species but not correlated with the genetic structure. Overall, root exudates tested provide a high level of hatching of these three nematode species. Surprisingly, the root exudate from broccoli induces hatching of European populations of the potato cyst nematode G. pallida.

First Report of the Hop Cyst Nematode, Heterodera humuli, in Two Counties of the Yakima Valley Region, WA, USA.

Cyst nematodes are ranked as the second most damaging plant-parasitic nematode genus of crops worldwide (Jones et al. 2013). The hop cyst nematode, Heterodera humuli, has been reported to cause up to 38% reduction in dry hops per bine (Hay and Pethybridge 2003). America is the top hop producing country worldwide, with 75% of production occurring in Washington state, with the majority of this production occurring in the Yakima Valley region (USDA, 2019). In late 2019, 30 soil samples from 15 different fields were collected from the hop cvs. HBC 394, HBC 369, and YCR 14. Nematodes were extracted using an adapted centrifugal floatation method (Jenkins 1964) from 100 cc subsamples of soil. Twenty of these samples contained at least one cyst and 23 contained at least one juvenile. Body length of juveniles (n = 5) averaged + standard deviation 377.62 ± 4.76 μm which is consistent with H. humuli juvenile body measurements (Sen 1968). Three samples from Yakima County and two from Benton County were identified to the species level using sequences from the internal transcribed spacer (ITS) region of the 5.8S gene. The sequences (GenBank accession numbers MT840678 to MT840682) were amplified using forward primer 5.8S-F (5'-GTGATTCCATTCACCAHCTACCTG-3'), and reverse primer 5.8S-R (5'-TTCGCACTAATTATCGCAGTTGG-3'). Sequence comparison with available ITS (5.8S) sequences in GenBank using BLAST showed 99.85% identity to H. humuli for all five samples. Because COI sequences of H. humuli are not available, to provide an additional marker for species identification, we amplified the COI sequences by using (forward primer Hete-COI-F (5'-TTTGGDCAYCCHGARGTTTATGTT-3'), and reverse primer Hete-COI-R (5'-AYWGTAAAAAGGRRAATAAAACC-3') for these samples. Four COI sequences (GenBank accession numbers MT840683 to MT840686) were obtained. These COI sequences will be used to identify future H. humuli samples. To confirm pathogenicity, eight 1-gal pots were filled with a 90:10 play sand to potting soil mixture and one hop rhizome cv. 'Centennial' was planted in pots and maintained in a greenhouse. After above ground plant growth was observed, half the pots were inoculated with hand-picked H. humuli cysts from Yakima soil samples at a density of 10 cysts/100 cc of soil. The life cycle of H. humuli in potted experiments is 40 days (McNamara and Mende 1995). Forty-five days after inoculation, plant measurements were recorded and nematodes extracted from five 100 cc soil samples per pot as described above. Soil samples revealed that H. humuli populations had an average Reproductive Factor (RF = final nematode population/initial nematode population) of 2.08. Five cysts were crushed to determine eggs/cyst, which yielded an average of 101 eggs/cyst. Young infected hops lacked vigor, with all replicates stunted both in bine height and leaf length compared to healthy controls. Bine heights were reduced by an average of 40.4% in pots inoculated with H. humuli compared to control plants (P = 0.0016). Distribution of hop cyst within the United States is limited to the top four states for hop production: Washington, Oregon, Idaho and Michigan (Cobb 1962; Sen and Jensen 1967; Hafez et al. 2010, Warner and Bird, 2015). In 1962, Cobb reported H. humuli in Pierce County, Washington, but it had not been reported in Benton County and Yakima County until now. This is a significant finding that has the potential to impact the Washington state hop industry, valued at $475.7 million in 2019 (USDA, 2019). Due to the lack of known effective nematode control measures, the discovery of H. humuli in the major hop-growing region of Washington warrants concern.

私達の線虫研究の歩み－IPM 研究と防除手段30年の転変－

私達の線虫研究の歩み－IPM 研究と防除手段30年の転変－

Sustainable management of root knot nematode, Meloidogyne incognita by humic acid in Chilli (Capsicum annuum)

The possibility of using Potassium humate as an environmentally friendly nematode control measures and improved crop yield was tested under field conditions in chilli. Humic acid products are powerful fungal stimulant and biological benefits in relation to nematode management. Two g of potassium humate/kg soil was found to be effective in reducing the gall index and nematode population. All the dosage of potassium humate had a significant effect in terms of nematode reduction. It was observed that potassium humate at 20 kg/ha recorded highest yield with minimum soil population. Potassium humate reduced the nematode infestation by 33.3% and increased the yield by 60.9%.

The trade-off between farmers' autonomy and the control of parasitic gastro-intestinal nematodes of sheep in conventional and organic farms

Farmers value autonomy in the management of their farm. Amongst organic farmers especially, autonomy is thought to contribute to the success of the farm. Wider integrated farming systems however oppose such autonomy by making farm management decisions remotely. One of the greatest threats to the success of meat sheep farms is the presence of parasitic gastrointestinal nematodes. This study questioned whether a greater level of farmer autonomy could be correlated to the better control of the gastrointestinal nematode infections and whether this could be associated with farmer specific health beliefs. Data was collected across 36 meat sheep farms with similar climatic variables but with different beliefs and attitudes to health care in farming. These farms fell within three groups: French organic, French conventional and Algerian conventional farms. Information regarding farmers' health beliefs and their level of autonomy in management was gathered using questionnaires to address autonomy in the following variables: agriculture production, husbandry, feed, therapeutics, commercialization, and farmers' education. The intensity of gastrointestinal nematode infections was also measured on each of these farms using faecal egg counts on composite sheep samples. Statistical and correlation analyses of autonomy variables to gastrointestinal nematode infection intensities were carried out. The results showed farmer autonomy was not associated with better gastrointestinal nematode control in any of the three groups of farms studied. Greater level of autonomy in husbandry and therapeutics specifically were associated with greater levels of infection. Farmers across the 36 farms studied were unanimously concerned about the threat gastrointestinal nematodes present to their flocks. Yet their current knowledge was clearly not sufficient to control infections irrespective of their health beliefs. This paper makes suggestions to facilitate communication with farmers and to improve the integration of gastrointestinal nematode control measures.

Breeding and usage of sugar beet cultivars and hybrids resistant to sugar beet nematode Heterodera schachtii

Heterodera schachtii Schmidt, 1871 is one of the most economically important pests of sugar beet (Beta vulgaris L.) worldwide. It is also widespread in most sugar beet growing regions in Ukraine causing serious yield reduction and decreasing sugar content of sugar beet in infested fi elds. An advanced parasitic strategy of H. schachtii is employed to support nematode growth, reproduction and harmfulness. In intensive agriculture systems the nematode control measures heavily rely on nematicides and good agricultural practice (crop rota- tion in the fi rst place). But alternative strategies based on nematode resistant sugar beet cultivars and hybrids are required as none of nematicides approved for the open fi eld application are registered in Ukraine. Here we review the achievements and problems of breeding process for H. schachtii resistance and provide the results of national traditional breeding program. Since the beginning of 1980s fi ve sugar beet cultivars (Verchnyatskyi 103, Yaltuschkivska 30, Bilotcerkivska 45, BTs-40 and Yuvileynyi) and seventeen lines partly resistant or toler- ant to H. schachtii have been obtained throughout targeted crossing and progenies assessment in the infested fi elds. The further directions for better utilization of genetic sources for nematode resistance presented in na- tional gene bank collection are emphasized. There is a need for more accurate identifi cation of resistance genes, broader application of reliable molecular markers (suitable for marker-assisted selection of nematode resistant plants in the breeding process) and methods for genetic transformation of plants. Crop cash value and national production capacity should drive the cooperation in this fi eld. Knowledge as well as germplasm exchange are thereby welcomed that can benefi t breeding progress at national and international level.

Nematode Management in Potatoes (Irish or White)

Nematode species and population levels, incidence of soil-borne diseases and insects, soil moisture at field preparation time, and the intended market for the potatoes can all affect the choice of nematode control measures. Growers should use a combination of as many different kinds of control measures as feasible, since none provides perfect protection for the crop. This 7-page fact sheet was written by J.W. Noling and published by the UF Department of Entomology and Nematology, December 2012.
 http://edis.ifas.ufl.edu/ng029

Botanical nematicides in the mediterranean basin

Achieving food sufficiency in a sustainable manner is a major challenge for farmers, agro-industries, researchers and governments. Amongst agricultural pests supressing crops, root-knot nematodes (Meloidogyne spp.) represent possibly the world’s most damaging one, the control of which has been mainly based on chemical nematicides. In the recent years the environmental, food safety and animal welfare issues pose the need for alternative nematode control measures. Screening naturally occurring compounds in plants, involved in the complex chemical-mediated interactions between a plant and other organisms in its environment, can provide with innovative nematode control measures that can be safely used in integrated pest management programs. The Mediterranean Basin is an area where various soils and climatic conditions allow a vast plant biodiversity providing with chemical botanicals of significant nematicidal potency. This is a review on the Mediterranean botanicals that can control Meloidogyne spp.

The history of plant and soil nematology in Australia and New Zealand, with particular reference to the contributions of six pioneering nematologists

In an era of rapid technological advancement, it is easy to overlook those who established the knowledge base that underpins today’s research programs. This paper traces the history of plant and soil nematology in Australia and New Zealand and recognises six pioneers who contributed significantly to its development, namely N. A. Cobb, R. C. Colbran, H. R. Wallace, A. F. Bird, J. M. Fisher and W. C. Clark. Collectively, these scientists described many unique and economically important nematodes, advanced our understanding of the biology and ecology of both plant-parasitic and free-living species, laid the foundation for many of the nematode control measures that are in use today and also contributed to the development of the discipline of nematology at an international level.

Status of weeds as reservoirs of plant parasitic nematodes in banana fields in Martinique

During a survey of the nematodes associated with weeds in banana fields in Martinique, 41 weed species in 37 genera from 20 plant families were collected to extract nematodes from the roots. Results of this survey showed that 24 weed species were hosts of Radopholus similis, 23 were hosts of Helicotylenchus spp., 13 were hosts of Pratylenchus spp., 13 were hosts of Hoplolaimus seinhorsti, 29 were hosts of Meloidogyne spp. and 24 were hosts of Rotylenchulus reniformis. The presence of the burrowing nematode was more consistently found within three families, the Euphorbiaceae, Poaceae and Solanaceae. In some weed species such as Caladium bicolor, Commelina diffusa, Echinochloa colona and Phenax sonneratii, the levels of nematodes recovered were similar to, or greater than the numbers recovered from Musa roots. These results clearly show that certain weeds can be significant reservoirs of plant parasitic nematodes including R. similis in banana fields. This information is crucial in devising appropriate nematode control measures for use with rotation crops or fallow before re-planting banana fields with nematode free planting material.

New strategies for the control of plant-parasitic nematodes

New nematode control measures are required due to the likely removal of effective nematicides from the market because of increasing concerns of possible effects on human health and the environment. Biological control, organic and inorganic soil amendments, naturally occurring nematicides, induced resistance, interruption of host recognition and transgenic plants will be a part of integrated management of plant-parasitic nematodes in the near future. The paper reports work carried out in Israel on these topics.

Modeling the alfalfa stem nematode in irrigated alfalfa

An alfalfa growth simulation model, modified to incorporate the impact of the alfalfa stem nematode and include an economic analysis component, is reported. The modified model was calibrated for Colorado growing conditions and used to evaluate nematode control measures and determine the optimal time for alfalfa replacement when fields are infested with the alfalfa stem nematode. The results indicate that planting nematode-resistant varieties increases returns from nematode-infested alfalfa fields. Nematode control activities implemented at the proper time can extend the economic life of an alfalfa stand. Planting a non-host crop in the fifth year of production also increases returns.

A survey of nematode control measures used by milking goat farmers and of anthelmintic resistance on their farms

Forty-seven milking goat herds, located throughout New Zealand, were surveyed for anthelmintic usage and for gastrointestinal nematodes resistant to anthelmintics. Most farmers (62%) followed a predetermined drenching programme and usually (68%) had a policy of alternating between drench families. Alternation was generally within the farming year. Kids were on average being drenched 12.5 times during their first year (range 2-34). Does aged greater than one year were all being drenched at the same frequency (average 13.4, range 2-34) irrespective of age. On each of the 47 farms, a group of goats was treated with a benzimidazole (BZ) drench (oxfendazole, OFZ, at 4.5 mg/kg on 36 farms and thiabendazole, TBZ at 66 mg/kg on 11 farms); a second group was treated with a "cell membrane depolarizing" (CMD) drench (levamisole, LEV, at 8 mg/kg on 35 farms and morantel citrate, MOR, at 10 mg/kg on 12 farms); a third group remained untreated as controls. Faecal egg counts and larval cultures were done before dosing and one week later. Faecal egg count depressions of <80% were taken as being suggestive of anthelmintic resistance. On this basis resistance was found on 79% of farms surveyed. Resistance to BZs alone occurred on 36% of farms, resistance to CMDs alone on 4% and resistance to both on 38% of farms. On 23% of farms one or other of the drenches was without any apparent effect and on one farm both of the drenches tested failed to reduce the egg counts. Post-drenching larval cultures showed Trichostrongylus, Haemonchus and Ostertagia to be the most prevalent genera remaining after drenching with BZ on 14,11, and 8 farms, respectively. After drenching with LEV Ostertagia was the dominant species on 10 farms, Trichostrongylus on 2 and on one farm the two genera were equally common. Following treatment with MOR Trichostrongylus was the dominant species on 3 farms, Haemonchus on 2 and on one farm Trichostrongylus and Ostertagia were equally common. There was a positive association between drenching frequency and the presence of resistance on farms. Possible interpretations of this association are discussed.

A survey of nematode control measures used by sheep farmers and of anthelmintic resistance on their farms Part 2: South Island excluding the Nelson region

Forty-three randomly selected farms located throughout South Island, excluding the Nelson region, were surveyed for anthelmintic usage and for sheep nematodes resistant to anthelmintics. Most farmers had used both benzimidazole and non-benzimidazole broad-spectrum drenches on their properties in previous years. Sheep were being drenched, on average, 5.6 times within their first year of life but much less frequently thereafter. Commercial interests played the dominant role in helping farmers formulate their drenching policies. On each farm 24 numbered ewe replacement lambs, born during the spring of 1980, were sampled for faeces at the beginning of the trial to provide material for egg counts and larval cultures. The lambs were weighed and divided into three groups of eight. One group received thiabendazole (TBZ) at 66 mg/kg, the second levamisole (LEV) at 8 mg/kg while the third remained untreated as controls. All were resampled 4 to 10 days later. On 32 (88%) of the 40 farms where drenching trials were successfully carried out during autumn 1981, the faecal egg count depression (FECD) following treatment with either drench was 100%. On one farm TBZ was less than 100% effective as gauged by FECD. LEV proved to be less than 100% effective on 7 farms. On one farm the FECD was less than 80%, on 2 between 90% and 95% and on 4 between 95% and 99%.

A survey of nematode control measures used by sheep farmers and of anthelmintic resistance on their farms. Part 1. North Island and the Nelson region of South Island.

Abstract Fifty four randomly selected farms, located throughout the North Island and the Nelson region of South Island, were surveyed for anthelmintic usage and for sheep nematodes resistant to anthelmintics. Information on anthelmintic usage was recorded on a standardized questionnaire. Most fanners had used both benzimidazole and non- benzimidazole broad spectrum drenches on their properties in previous years. Sheep were being drenched, on average, 7 times within their first year of life but much less frequently thereafter. Commercial interests played the dominant role in helping farmers formulate their drenching policies. On each farm 24 numbered ewe replacement lambs were sampled for faeces at the beginning of the trial to provide material for egg counts and larval cultures. The lambs were weighed and divided into three groups of eight. One group received thiabendazole (TBZ) at 66 mg/kg, the second levamisole (LEV) at 8mg/kg while the third remained untreated as controls. All were resampled 4 to 10 da...