Potato Fields Research Articles

Reserves of potato field

Reserves of potato field

Development of 'Poroshiri', a chip processing potato variety with golden cyst nematode and common scab resistance.

Golden cyst nematodes have threatened the cultivation of 'Toyoshiro', a major potato variety used for chip processing in Japan. Common scab is a soilborne disease that occurs in potato fields worldwide. To solve these problems, we crossed two US varieties and selected a clone that showed a slightly higher marketable yield and a significantly higher yield rate, compared with 'Toyoshiro', and had good chip processing quality, extreme resistance to cyst nematodes, and moderately high resistance to common scab. This clone was named 'Poroshiri'; it is the first variety released from the Calbee Potato breeding program.

Development characteristics of underground pests of root vegetable and potato crops

The present article delves into a comprehensive examination of the species composition of pests prevalent within fields cultivating root vegetables and potatoes. Through systematic scrutiny, the study reveals the presence of pest representatives spanning three distinct classes, six genera, eleven families, and twenty-nine species within a potato field subject to repeated cultivation. Among these discerned species, a detailed analysis is focused on sixteen varieties of subterranean pests originating from four distinct genera. Concurrently, the research encompasses a decade-long assessment of the prevalence of subterranean autumn and exclamatory moths, facilitated by the use of pheromone traps. Over this span, observations indicate that the occurrence of autumn moths reached a count of 4.4 units, with spring moths totaling 1.1 units. Additionally, the study delves into the developmental attributes of root vegetables and potato crops, garnering insights into their growth patterns and characteristics. The culmination of this research brings about tangible and applicable insights. The acquired findings not only contribute to the knowledge regarding the pests affecting these agricultural sectors but also furnish practical recommendations and suggestions for enhancing production practices. The article not only underlines the significance of understanding the intricacies of pest dynamics but also reinforces the need for informed agricultural management practices to mitigate their impact and bolster crop productivity.

Efficacy of Various Biopesticides against Red Ant (Dorylus orientalis Westwood) in Potato Field

Red ant (Dorylus orientalis Westwood) is the most destructive insect pest of potato tubers in the field in Nepal. A field experiment was conducted at Bhatkada, Dadeldhura district, Nepal in 2020 to determine the efficacy of various biopesticides and chemical insecticide on red ants. The plot size in this experiment was 106.7 m2. Five treatments viz. Chlorpyriphos 20% EC (2 mL L-1 water), Banmaara (2 kg plot-1), Cow urine (2 L 6 L-1water plot-1), Agave (25 g tuber-1) and Control (no treatment) were evaluated in randomized complete block design with four replications. The data on plant height and the number of leaves were taken at 45, 60, and 75 days after planting (DAP). The data on slightly and severely infested tubers were taken after harvesting of potato. The results showed that Chlorpyriphos treated plots gave the lowest values of traits viz numbers of slightly infested tuber (91,500 ha-1), severely infested tubers (12,500 ha-1), weights of slight infested tubers (7,700 kg ha-1) and severely infested tuber (1,130 kg ha-1). Among the botanical pesticides, Agave treated plots provided the second lowest values of numbers of slightly infested tuber (145,500 ha-1), severely infested tubers (37,400 ha-1), weights of slight infested tubers (13,400 kg ha-1) and severely infested tuber (3,110 kg ha-1). The results showed that the Agave treatment provided the highest marketable yield (50,900 kg ha-1). Thus, Chlorpyriphos and Agave could be used to efficiently protect potato tubers from red ant in potato field.

Diversity of plant-parasitic nematodes in potato fields at different altitudes in Probolinggo District, East Java, Indonesia

Abstract. Prada AP, Pratiwi GNC, Wagiyana. 2022. Diversity of plant-parasitic nematodes in potato fields at different altitudes in Probolinggo District, East Java, Indonesia. Cell Biol Dev 6: 61-67. Plant parasitic nematodes (PPNs) are microorganisms sensitive to environmental conditions. Therefore, plant parasitic nematode diversity in a field may affect the decision of effective management tactics. This study aimed to assess the diversity of plant parasitic nematodes in potato fields at three different altitudes. The study was carried out in Probolinggo District, East Java, Indonesia. The sampling area was divided into three groups based on altitude variations, namely 1,008 m asl., 1,413 m asl., and 1,875 m asl. Soil samples were collected randomly in a zigzag pattern. Samples were collected from 20 points across each field at a depth of 20-30 cm below the soil surface. Each sub-sample included up to 500 g of soil. The white head tray method extracted nematodes from 500 g of soil from each subsample. After characterizing the extracted nematodes, the absolute density and dominance values were determined. The results revealed variations in the three areas with different altitudes. The total number of plant-parasitic nematodes (PPN) discovered on the field at an altitude of 1,008 m asl. was 57.00 ± 16.43. Furthermore, at an altitude of 1,413 m asl., the total number of PPNs discovered is 41.67 ± 10.98. The total number of nematodes on the field at an altitude of 1,875 m asl. was 50.50 ± 12.60. The findings of this study also indicated that Meloidogyne sp. was the genus with the highest population on the field, at an altitude of 1,008 m asl. On the other hand, Pratylenchus sp. is the most abundant nematode in the field between 1,413 and 1,875 m asl. An identical situation also occurred with the nematode dominance values in the three fields studied.

Occurrence of the sweet potato hornworm <em>Agrius convolvuli</em> (Lepidoptera: Sphingidae) in the Haut-Katanga province, Democratic Republic of the Congo

Agrius convolvuli (Lepidoptera: Sphingidae) is a pest that feeds on young sweet potato leaves causing severe plant defoliation. This study was designed to report for the first time on the occurrence of the pest in the Haut-Katanga province in DR Congo. Survey and observations were conducted during the growing season in ten cities of the Haut Katanga province to detect the presence of A. convolvuli. Fifty-two sweet potato fields were inspected during the season. Larvae and pupae were collected in each city and reared in the laboratory at the University of Lubumbashi, DR Congo. Results revealed that the pest occurs in the province with Lubumbashi and Kasumbalesa being the most highly infested with 18.80±11.36 and 18.71±8.13% of infestation, respectively. The highest number of larvae per field and per plant was recorded in Lubumbashi alone with 18.80±8.04 and 3.80±1.48, respectively. Classification of sweet potato leaf damage indicated that Kasumbalesa, Sakania and Lubumbashi had high levels of damage. Positive relationships were observed between infestation rate and number of larvae per field (R2=0.3069; t=4.705; p<0.0001) but also between infestation rate and number of larvae per plant (R2=0.4478; t=6.368; p<0.0001). The findings of the current study suggest that A. convolvuli could be a potential threat to sweet potato production in the Haut-Katanga province.

Bias in sex ratios and polyandry rate in reproduction of Leptinotarsa decemlineata

The Colorado potato beetle (CPB, Leptinotarsa decemlineata Slechtd.) is an invasive pest with economic importance worldwide. Sex ratios during egg-hatching and a frequency of polyandry in single-female families were analysed to clarify the reproduction strategy of CPB, which was still known only in fragments. 1296 just hatching 1st instar CPB larvae were collected from 19 single-female families, of which 13 were random families collected from potato fields and 6 were families produced by laboratory farming of naturally fertilised females. All larvae were analysed to detect a sex using a qPCR-based method and to detect polymorphisms in genotypes of 9 microsatellite (SSR) markers. The bias in sex ratio in favour of females was confirmed using linear mixed-effects model in both experimental groups of families: field collections (F = 36.39; P = 0.0001) and laboratory farming (F = 13.74; P = 0.0139). The analysis of diversity in microsatellites proved the polyandry in all progenies as 73% of analysed segregation patterns did not match with the patterns expected for full-sib progenies; on average per locus, 46% of allelic and 49.7% of genotype ratios showed irregular segregation. Both findings contribute toward understanding CPB success rate as an invasive species, as the preferential bearing of females with polyandry has a great potential to keep fitness of progenies, to maintain and operate population diversity, and to accelerate the reproduction of the pest.

Ultra-High-Resolution UAV-Based Detection of Alternaria solani Infections in Potato Fields

Automatic detection of foliar diseases in potato fields, such as early blight caused by Alternaria solani, could allow farmers to reduce the application of plant protection products while minimizing production losses. UAV-based, high resolution, NIR-sensitive cameras offer the advantage of a detailed top-down perspective, with high-contrast images ideally suited for detecting Alternaria solani lesions. A field experiment was conducted with 8 plots housing 256 infected plants which were monitored 6 times over a 16-day period with a UAV. A modified RGB camera, sensitive to NIR, was combined with a superzoom lens to obtain ultra-high-resolution images with a spatial resolution of 0.3 mm/px. More than 15,000 lesions were annotated with points in two full size images corresponding to 1250 cropped tiles of 256 by 256 pixels. A deep learning U-Net model was trained to predict the density of Alternaria solani lesions for every pixel. In this way, density maps were calculated to indicate disease hotspots as a guide for the farmer.

Black Plastic Film Mulching Increases Soil Nitrous Oxide Emissions in Arid Potato Fields

Black plastic film mulching is a common practice for potato production in the arid area of Northwest China. Many studies have reported the significant positive effect of black plastic film mulch on potato harvest, while the effect of black plastic film mulch treatment on soil nitrous oxide (N2O) emissions is still unclear. As a consequence, this study aimed to examine the effect of black plastic film mulch treatment on N2O emission from arid upland potato fields. With the static chamber-gas chromatography method, soil N2O emissions were measured. The results showed that black plastic film mulching treatment significantly increased cumulative soil N2O emissions by 21-26% compared with non-mulched treatment. Cumulative N2O emission positively correlated with soil temperature, soil moisture, soil CO2 concentration, and amoA-AOB abundance. This study indicated that black plastic film mulching, mainly through increasing soil temperature and soil moisture, increasing soil carbon dioxide (CO2) concentration, and promoting the abundance of nitrification-related functional gene of amoA-AOB, regulated N2O emissions. This study also highlighted that the specific soil environment under black plastic film mulch is conducive to N2O emissions and lay the foundation for settling the contradiction between food production and greenhouse gas mitigation in upland soils. The negative effects of black plastic film mulching on the environment should be considered in future applications in food production.

Identification of three new ‘Candidatus Liberibacter solanacearum’ haplotypes in four psyllid species (Hemiptera: Psylloidea)

Eleven haplotypes of the bacterium, ‘Candidatus Liberibacter solanacearum’, have been identified worldwide, several of which infect important agricultural crops. In the United States, haplotypes A and B are associated with yield and quality losses in potato, tomato, and other crops of the Solanaceae. Both haplotypes are vectored by potato psyllid, Bactericera cockerelli. Recently, a third haplotype, designated F, was identified in southern Oregon potato fields. To identify the vector of this haplotype, psyllids of multiple species were collected from yellow sticky cards placed near potato fields during two growing seasons. Over 2700 specimens were tested for ‘Ca. L. solanacearum’ by polymerase chain reaction. Forty-seven psyllids harbored the bacterium. The infected specimens comprised four psyllid species in two families, Aphalaridae and Triozidae (Hemiptera: Psylloidea). Nucleic acid and/or amino acid sequence analysis of the ‘Ca. L. solanacearum’ 16S ribosomal RNA, 50S ribosomal proteins L10/L12, and outer membrane protein identified three new haplotypes of the bacterium, designated as Aph1, Aph2 and Aph3, including two variants of Aph2 (Aph2a and Aph2b). The impact of these new haplotypes on solanaceous or other crops is not known. The vector of ‘Ca. L. solanacearum’ haplotype F was not detected in this study.

Ground-Penetrating Radar Full-Wave Inversion for Soil Moisture Mapping in Trench-Hill Potato Fields for Precise Irrigation

In this paper, we analysed the effect of trench-hill soil surface on ground-penetrating radar (GPR) full-wave inversion for soil moisture measurement. We conducted numerical experiments by modelling the trench-hill surface using finite-difference time–domain (FDTD) simulations. The FDTD simulations were carried out with the open-source software gprMax, using different centre frequencies, namely, 150 MHz, 250 MHz and 450 MHz. The gprMax source/receiver for each centre frequency was calibrated, respectively, to transform the FDTD radar signal to normalized Green’s functions for wave propagation in multilayered media. The radar signals and inversion results of the three different frequency ranges are compared. The FDTD Green’s functions of the trench-hill surface with a flat surface are also compared. The results show that the trench-hill surface only slightly affects the inversion when frequency is lower than 190 MHz, which agrees with Rayleigh’s criterion. Field measurements were performed as well, using a prototype radar mounted on an irrigation robot. The low-frequency antenna was calibrated over a large water plane. The optimal operating frequency range was set to 130–190 MHz. TDR measurements were performed as well for comparison. The results demonstrated promising perspectives for automated and real-time determination of the root–zone soil moisture in potato fields, and thereby for precise and automatic irrigation.

Factors modulating home range and resource use: a case study with Canarian houbara bustards

BackgroundThe home range of an animal is determined by its ecological requirements, and these may vary depending on many intrinsic and extrinsic factors, which are ultimately driven by food resources. Investigating the effects of these factors, and specifically how individuals use food resources within their home ranges is essential to understand the ecology and dynamics of animal populations, and to establish conservation measures in the case of endangered species. Here, we investigate these questions in the Canarian houbara bustard, an endangered subspecies of African houbara endemic to the Canary Islands.MethodsWe analysed GPS locations of 43 houbaras in 2018–2021, using solar GSM/GPRS loggers provided with accelerometers. We assessed (1) the variation in their home range and core area with kernel density estimators in relation to several intrinsic and extrinsic factors and (2) their foraging habitat selection.ResultsHome ranges were smallest during the breeding season (November–April), when rains triggered a rapid growth of herbaceous vegetation. Displaying males and nesting females had smaller home ranges than individuals not involved in reproduction. Both sexes used almost exclusively non-cultivated land, selecting low density Launaea arborescens shrublands, pastures and green fallows as foraging habitats. Heavier males used smaller home ranges because they spent more time displaying at a fixed display site, while heavier females moved over larger areas during the mating period, probably visiting more candidate mates. During the non-breeding season (May–October), both sexes showed larger home ranges, shifting to high density shrubland, but also partly to cultivated land. They selected sweet potato fields, green fallows, alfalfas, orchards and irrigated fields, which offered highly valuable food resources during the driest months of the year.ConclusionsOur study shows how Canarian houbara, originally a desert-dwelling species that uses mostly shrublands and pastures, has developed the necessary adaptations to benefit from resources provided by current low intensity farming practices in the study area. Maintaining appropriate habitat conditions in the eastern Canary islands should constitute a key conservation measure to prevent the extinction of this endangered houbara subspecies.

Weed Detection in Potato Fields Based on Improved YOLOv4: Optimal Speed and Accuracy of Weed Detection in Potato Fields

The key to precise weeding in the field lies in the efficient detection of weeds. There are no studies on weed detection in potato fields. In view of the difficulties brought by the cross-growth of potatoes and weeds to the detection of weeds, the existing detection methods cannot meet the requirements of detection speed and detection accuracy at the same time. This study proposes an improved YOLOv4 model for weed detection in potato fields. The proposed algorithm replaces the backbone network CSPDarknet53 in the YOLOv4 network structure with the lightweight MobileNetV3 network and introduces Depthwise separable convolutions instead of partial traditional convolutions in the Path Aggregation Network (PANet), which reduces the computational cost of the model and speeds up its detection. In order to improve the detection accuracy, the convolutional block attention module (CBAM) is fused into the PANet structure, and the CBAM will process the input feature map with a channel attention mechanism (CAM) and spatial attention mechanism (SAM), respectively, which can enhance the extraction of useful feature information. The K-means++ clustering algorithm is used instead of the K-means clustering algorithm to update the anchor box information of the model so that the anchor boxes are more suitable for the datasets in this study. Various image processing methods such as CLAHE, MSR, SSR, and gamma are used to increase the robustness of the model, which eliminates the problem of overfitting. CIoU is used as the loss function, and the cosine annealing decay method is used to adjust the learning rate to make the model converge faster. Based on the above-improved methods, we propose the MC-YOLOv4 model. The mAP value of the MC-YOLOv4 model in weed detection in the potato field was 98.52%, which was 3.2%, 4.48%, 2.32%, 0.06%, and 19.86% higher than YOLOv4, YOLOv4-tiny, Faster R-CNN, YOLOv5 l, and SSD(MobilenetV2), respectively, and the average detection time of a single image was 12.49ms. The results show that the optimized method proposed in this paper outperforms other commonly used target detection models in terms of model footprint, detection time consumption, and detection accuracy. This paper can provide a feasible real-time weed identification method for the system of precise weeding in potato fields with limited hardware resources. This model also provides a reference for the efficient detection of weeds in other crop fields and provides theoretical and technical support for the automatic control of weeds.

ОБОСНОВАНИЕ И ОПРЕДЕЛЕНИЕ ПАРАМЕТРОВ БОРОЗДООБРАЗОВАТЕЛЯ КАРТОФЕЛЕСАЖАЛКИ

Furrow formation is one of the most labor-intensive operations in potato cultivation technology. The article discusses the justification and determination of furrower parameters of the potato planter. Analytical dependences of the height of the junction point of the disks and the width of the furrow bottom are obtained, taking into account the technological parameters, its design features and the physical and mechanical properties of the soil. Potatoes are planted in the usual way. The main row spacing in our country is 70 cm. However, in areas of high humidity and in irrigated areas, wide-row planting with a row spacing of 90 cm is used. In some areas of the European part, in arid areas, potatoes are planted with a row spacing of 60 cm. By the time of harvesting, the potato field has a ridged appearance, obtained as a result of hilling, where the height of the ridges is 11…20 cm. The angle of the row seed drills is that the vanishing point of the coulter rises above the bottom of the furrow by 6.3 cm. With an increase in the angle of entry of the coulter into the soil from 2° to 11°, the depth of the coulter travel increases. At angle values from 3° to 8°, the stroke depth approaches the optimum (12…18 cm).

Gene Flow of Phytophthora infestans Between Refuse Piles, and Organic and Conventional Potato Fields in Southern Flevoland, The Netherlands

Gene Flow of Phytophthora infestans Between Refuse Piles, and Organic and Conventional Potato Fields in Southern Flevoland, The Netherlands

Using the SCOPE model for potato growth, productivity and yield monitoring under different levels of nitrogen fertilization

Most applications of remote sensing in agricultural crop monitoring use multispectral imaging techniques, but with upcoming hyperspectral missions, the opportunity arises to better estimate pigment absorption and crop structure by exploiting the full solar reflective spectrum. In this study, we demonstrate how hyperspectral time series can be used with the Soil Canopy Observation of Photochemistry and Energy fluxes (SCOPE) model to estimate crop yield variability among fields, crop varieties and nitrogen treatments generically, i.e. without a calibration with in situ , data. Field experiments were conducted in two potato fields in the Netherlands between May and September 2019. The fields were planted with five varieties of potato, under three nitrogen fertilization treatments. By fitting the model to the full VNIR-SWIR spectrum of measured hyperspectral reflectance, we retrieved the model input parameters of Leaf Area Index (LAI), leaf chlorophyll content (Cab) and leaf water content (Cw) and simulated the photosynthesis throughout the season using data of local Automatic Weather Stations (AWS). Statistical analysis of measured and retrieved traits of LAI, Cab and canopy water content showed that two fields responded differently to the treatments, exhibiting fewer classes than were expected based on the experimental design. Potato yield, which was estimated as the sum of photosynthesis flux multiplied by the harvest index of 0.64, correlated with the measured tuber dry weight with R 2 0.36 and RMSE 2.5 t ha −1 . This study demonstrates that even in the absence of crop or variety specific information, hyperspectral reflectance and local weather data ingested into SCOPE can explain a substantial part of the observed variability in yield among fields. • Time series of hyperspectral canopy reflectance were recorded in two potato fields. • The variation in traits was created by nitrogen fertilization treatments. • SCOPE model retrieved plant traits contained information about treatments. • SCOPE-simulated accumulated photosynthesis correlated with the final dry yield. • SCOPE model is more generic than dimensionality reduction methods.

The prevalence of recombinant strains of potato virus Y in the East Kazakhstan region.

The eastern region of Kazakhstan is an important territorial district producing seed potatoes. Since 2022, the region has been divided into the Abay region (administrative center in Semey city) and the East Kazakhstan region (administrative center in Ust-Kamenogorsk city). One of the largest elite seed farms producing potatoes is East Kazakhstan Agricultural Station LLP (Ust-Kamenogorsk). Potato Virus Y (PVY) was reported as problem for the production of Solanum tuberosum L. in Kazakhstan more than 25 years ago, however, over the past 5 years the spread of recombinant strains of PVY has become more serious problem (Loebenstein, Manadilova 2003). The purpose of this study was to find out the prevalence of PVY strains in the fields of the eastern region of Kazakhstan, including the fields of elite seed farm and commercial potato fields of the Glubokovsky district for the period from 2020 to 2021. Previously, the presence of recombinant strains (PVYN, PVYNTN, PVYN-Wi, PVYO) was shown in the west of Kazakhstan (Khassanov et al. 2020), but there is no data on the variety of PVY strains in the east region of Kazakhstan. Considering the geographical remoteness of these regions by more than 2000 km, the study of the prevalence of PVY in the fields of Kazakhstan needs to be supplemented with new data. PVY strains show a range of symptoms in different potato cultivars. The most damaging of these symptoms is tuber necrosis (Karasev and Gray 2013) associated with PVYNTN and some other recombinant strains. The pathogenesis of a viral infection of the PVYN strain and its recombinants is associated with the development of severe necrotic lesions of the tuber material, because of which yield losses can reach 60% (Chikh-Ali at al., 2020). In July 2021 leaf samples of 240 plants of two local regional potato varieties (Tavria and Izolda) were randomly selected to study PVY strains circulating in seed potatoes. 120 samples of the Tavria variety (seed material of the Elita class) and 120 samples of the Izolda variety (seed material of the Elita class) grown on seed potato fields of the East Kazakhstan Agricultural Experimental Station (GPS: N50.03324°, E82.53346°) were tested for the presence of potato viruses (PVA, PVS, PVM, PLRV, PVY) using commercial ELISA test systems (Russian Potato Research Center, Russia). In most samples (43 leaf samples), PVY is identified in the presence of a number of other potato viruses, mainly with PVM and PVS viruses. In order to type of PVY recombinant strains, samples containing PVY monoinfection have been selected. According to the results of ELISA, 21 PVY monoinfection positive samples have been detected: 14 plants of the Tavria variety, 7 plants of the Izolda variety. Serotype analysis using anti-rabbit polyclonal antibodies (Bioreba Ag, Switzerland) specific for PVYO, PVYC and PVYN serotypes identified PVYO serotype in 14 samples of the Tavria variety and in 7 samples of the Izolda variety, PVYN serotype in 2 samples of the Tavria variety and in 2 samples of the Izolda variety. All 21 PVY-positive samples were tested for strain by reverse transcription polymerase chain reaction (RT-PCR) using the strain-specific primers described by Chikh Ali et al. (2010). The products of PCR analysis showed the presence of bands characteristic of the recombinant N:O strain, 853, 633, and 441 bp - in 17 samples and characteristic of the NTNa strain, 1307, 633 and 441 bp in 4 samples. After determining the results of the analysis of leaf material samples, PVY-infected plants were removed from the soil and the tuber material was visually analyzed for signs of necrosis. According to the results of visual diagnostics, the symptoms of tuber necrosis were found in 80% of cases of infection with recombinant strains of PVYNTNa. In terms of severity, the symptoms of tuber necrosis were identical in both strains and caused to the damage of 35-50% of tubers on each plant of the Tavria and Isolda varieties, which indicates the absence of resistance to these recombinant strains. As is known, at present, many potato varieties have strain-specific resistance to PVYO (Funke at al. 2017). However, N:O and NTNa recombinant strains are the most difficult to develop resistance (Green et al. 2017). This is the first report on the Tavria and Izolda potato varieties as a susceptible host to recombinant strains of PVYN:O and PVYNTNa. Over the past five years, recombinant strains PVYN:O and PVYNTNa were introduced in two regions of Kazakhstan. In this regard, research and development of effective strategies to reduce the spread of recombinant strains PVYN:O and PVYNTNa in Kazakhstan, is particularly relevant. The authors declared no conflicts of interest. Funding: research was carried out within the framework of the scientific project "Development and implementation of innovative technology aimed at imparting antiviral resistance to crop varieties", funded by the Ministry of Education and Science of the Republic of Kazakhstan, Individual registration number (IRN): AP08052163.

First detection of the potato cyst nematode (Globodera rostochiensis) in a major potato production region of China.

The potato cyst nematodes (PCN) Globodera rostochiensis and Globodera pallida are the very important quarantine nematode pests of potato [Stone 1973]. Both species cause serious potato tuber yield losses. These species are subjected to strict quarantine regulations in many countries (EPPO 2017). G. rostochiensis was detected in Sichuan and Yunnan province, China in 2022 (Jiang et al. 2022). A survey for cyst nematodes in potato fields was conducted in Guizhou Province from 2018 to 2020. A total of 200 samples, including roots and soil, were collected from 40 potato fields in Hezhang (N27 06.145, E104 39.153) and Weining (N26 50.541, E104 09.885) counties in Guizhou Province, China. The Cobb decanting and sieving method was used to isolate cysts and J2s from the soil samples (Southey 1986). The potato roots were stained with acid fusion to observe cyst development. Morphological and molecular analyses indicated that 27 (13.5%) of the samples contained G. rostochiensis. The cyst density ranged between 1-85 cysts per 100 cm3 of soil and a mean density was 15 cysts per 100 cm3 soil. The smoothly rounded cysts were in brown and golden color, and the terminal cone was absent and circumfenestrate. The key morphometrics of cysts (n=20) were 695 ± 26 (685-757) μm in length excluding neck and 690 ± 30 (668 to769) μm in width; the number of cuticular ridges between anus and vulval fenestra was 16.3 ±2.1 (14 to 18); fenestral length was 15.1 ± 2.1 μm (13.18 to 19.27); distance from anus to the edge of fenestra was 61.12 ± 8.9 (49.22 to76.27) μm; and Granek's ratio was 4.54 ± 0.8 (3.97-5.26). The key morphometrics of J2 (n = 20): 468.0 ± 20.1 (427 to - 521) μm in body length, 20.58 ± 0.7 (20.2 to 21.8) μm in stylet length, 43.9 ± 5.6 (40.3 to 53.9) μm in tail length, and 23.1 ± 1.8 (21.77 to 25.32) μm in hyaline region length. The cyst and J2 morphologies were consistent with those of G. rostochiensis (Subbotin et al. 2010, EPPO 2017). Genomic DNA was isolated from cysts (n=20). DNA extraction was performed in a volume of 20 μl containing 3 μl 10× PCR buffer, 3 μl Proteinase K (600 μg μl-1), 14 μl distilled water and a single cyst was added and ground in an ice bath as described by Ou et al. (2008). The internal transcribed spacer (ITS) regions were amplified using the universal primers: rDNA1 (5'-TTGATTACGTCCCTGCCCTTT-3') and rDNA2 (5'-TTTCACTCGCCGTTACTAAGG-3') (Fleming 1998 ), and the 28S rDNA-D2/D3 regions were amplified using the primers: D2A (5´-ACAAGTACCGTGAGGGAAAGTTG-3´) and D3B (5´-TCGGAAGGAACCAGCTACTA-3´) (Subbotin et al. 2006). After the brackets at the beginning and end of the sequences were closed-up, the ITS rDNA sequences (GenBank Accession No. MZ042367 and MZ042368) showed 99.66% - 99.92% identity to G. rostochiensis sequences available in GenBank (FJ212166.1, GQ294513, FJ212164.1 and KJ409617.1). Sequences from the 28S region (GenBank Accession No. MZ057597 and MZ057598) were 99.23% - 99.74% similar to those of G. rostochiensis isolate from Slovakia (KJ409625.1), Italy (KJ409631.1) and United Kingdom (KJ409633.1). We used species specific primers ITS5（5'-GGAAGTAAAAGTCGTAACAAGG-3'）and PITSr3 (5'AGCGCAGACATGCCGCAA-3') to amplify the product (Bulman & Marshall 1997; EPPO 2017). A single 434bp fragment was obtained from Hezhang and Weining populations. A host test for the Hezhang and Weining populations were performed by inoculating 1,000 eggs per plant of varieties Qingshu 9, Huize 2 and Hezuo 88 grown in the pots containing 800 cm3 of sterilized soil (soil: sand ratio was 3:1), and four replications were tested in greenhouse under 16 h light, 22°C in the day and 8 h dark in the night. At 90 days post inoculation, 32.6 ± 7, 31.2 ± 8, and 29.5 ± 8 females and cysts were extracted from the infected roots and soils of the varieties Qingshu 9, Huize 2 and Hezuo 88, respectively. No females and cysts were observed on the control plants. The trial indicated that potato cultivars Qingshu 9, Huize 2 and Hezuo 88 are hosts for the Hezhang and Weining populations of Globodera rostochiensis. To the best of our knowledge, this is the first detection of potato cyst nematode Globodera rostochiensis in Guizhou Province, China.

Soil ingestion, a key determinant of exposure to environmental contaminants. The case study of chlordecone exposure in free-range pigs in the French West Indies.

Ingested soil may expose free-range animals to environmental pollutants. In pigs, soil ingestion is few described whereas their burrowing behaviour suggests that it could be high. Although highly productive pigs are generally reared indoor, free-range farming is increasing in view of ethical considerations for animal welfare and is a common practice for subsistence agriculture systems. The experiment lasted 8 weeks (2 for adaptation, 6 for measurements) with 24 growing pigs of Guadeloupean Creole (CR) or Large White (LW) breeds. Pigs were assigned to 3 outdoor treatments: high pasture HP (>60 days of regrowth), low pasture LP (35 days of regrowth), and sweet potato SP (sweet potato field). Titanium (soil marker) and chromium (faecal output marker) contents of faeces, vegetation and soil samples were used to estimate individual daily soil ingestions. The average, 10th and 90th percentiles were 440, 200 and 726 g of dry soil per 100 kg body weight, respectively, without significant differences between the 3 outdoor treatments or the 2 breeds but with a significant period (i.e. week of measurements) × treatment interaction (P < 0.001). In the French West Indies, animals may be exposed to chlordecone (CLD), a very persistent organochlorine insecticide. Simulations of CLD tissue contamination due to ingestion of contaminated soil were carried out and compared to the maximum residue limit. These results show that grazing management needs to be adapted to effectively limit soil ingestion by pigs and the impact of a contaminated environment on the sustainability of pig systems.

Association of phytoplasmas with a new disease of potato crops in cundinamarca, Colombia

Cundinamarca is the major potato producer region in Colombia. Potato growers first reported the presence of new symptoms affecting commercial potato fields in Cundinamarca as far back as 2012. These included foliage yellowing, curling on the upper leaf side and purple margins, occasionally with purple coloration of the underside veins, excessive shoot proliferation, abnormally short or long internodes and abnormal leaf development. Plants had a distorted pattern of growth suggesting a possible phytoplasma cause. Phytoplasmas were detected by nested PCR of the phytoplasma 16S rRNA gene and we confirmed the presence of ‘Candidatus Phytoplasma asteris’ (group 16SrI) and ‘Candidatus Phytoplasma fraxini’ (16SrVII) by RFLP and sequencing of samples from commercial plots. Of 152 symptomatic and non-symptomatic potato plants tested, 33.5% were positive for one of the identified phytoplasmas or both (mixed infections). Phytoplasmas were also observed by electron microscopy in symptomatic plants. Both phytoplasmas were transmitted in tubers produced by infected plants and by the insect vector Exitianus atratus (Hemiptera: Cicadellidae) to healthy test potato plants. Daughter plants from infected tubers and the healthy plants inoculated via the insect vector developed the same symptoms observed in field grown potato plants, in single and mixed infections of both phytoplasmas. Our results confirm the presence of a new disease of potato in Cundinamarca, Colombia, which we named yellowing and rolling-leaf phytoplasma (fitoplasma del amarillamiento y enrrollamiento de hojas).