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Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agriculture includes the production of crops, animals, aquaculture, fisheries, and forests for both food and non-food use. The primary factor in the rise of sedentary civilization among humans was agriculture, which allowed people to live in cities by producing surpluses of food from the farming of domesticated species. Uncertainties in the Agricultural Sector directly imply a steep decline in every other aspect of any society. The Agronomical Products, be they raw vegetables, or produced fruits, are all prone to Parasites and Microorganisms. In this research, we will focus on Solanum Tuberosum, and its disease Early Blight, of which, Alternaria Solani is a Causal Vector. For the detection of Early Blight in Potato Leaves, we will make use of the Image Segmentation Technique, based on Spectral Clustering, with Normalized Laplacian Cuts. The model works by segmenting, or rather segregating the affected part of the Potato leaf from the unaffected part, resulting in the formation of a few clusters, based on which the affected leaves can be classified from the healthy leaves. Though the model is a parametrized model, the results have been explored for different values of the parameters, σ i , and σ x that correspond to the varying configuration of the Gaussian Kernel. The efficiency of the Proposed Model have been compared with existing Image Clustering Models, like, Fuzzy C-means Clustering, Agglomerate Clustering, etc. [ABSTRACT FROM AUTHOR]

Breast cancer is one of the most diagnosed neoplasms worldwide, especially in women. The disease occurs due to genetic variations that modify cell behavior in various cellular aspects, increasing proliferation and preventing cell death among them. Breast cancer presents an average response rate to conventional treatments of between 50% and 60%, given that in the long term, it may present natural or tumor-acquired resistance ar. Diets that include foods that contribute to enhance the molecular mechanism of anti-tumoral medications or stop the development of tumor recurrence, could be important in improving patient survival. Among foods with antitumor biological activities such as antiproliferative or antioxidant activity, those with high phenolic content and a purple color have gained prominence in recent years. In the present research, it has been found that purple and pink-colored Chilean native potato genotypes possess high concentrations of total phenolic content and anthocyanins. The results showed that the potato extract modified the antioxidant response of breast cancer cells. Additionally, three high-pigmented potatoes induce significant cell death in two different breast cancer cell lines. As a molecular mechanism, the extract with high anti-tumoral activities can modulate the gene expression of Bax and Bcl-2 , both associated with cell death. In summary, the results demonstrate the important biological activities of native potato genotypes on breast cancer cell viability. It is important to highlight the great biomedical potential of these potatoes, which could be cultivated extensively, be used worldwide for nutrition and may be an excellent complementary option for patients undergoing breast cancer treatments. [ABSTRACT FROM AUTHOR]

New strategies for protecting crops from aphid attacks must be developed. The present study aimed to examine the effect of cis -Jasmone (CJ), an activator of plant defense, on potato plants. Plants were sprayed with an exogenous application of CJ at 12, 24, and 48 h; and the green peach aphid, Myzus persicae Sulzer, and its parasitoid, Aphidius gifuensis, were used to evaluate the tri-trophic interactions of the aphids, parasitoids, and plants. In this work, we examined that the adult M. persicae produced fewer nymphs on CJ-treated plants at 12, 24, and 48 h than on control plants. Furthermore, M. persicae nymphs that fed on CJ-treated plants at 48 h had a lower mean relative growth rate (MRGR). Moreover, the intrinsic rate of population increase (r) was significantly lowered in CJ-treated plants at 12, 24, and 48 h. CJ-treated plants at all time durations showed considerably less settlement of aphid than control plants. In the olfactometer bioassay, the parasitoid exhibited a prolonged duration in the arm treated with volatiles from CJ-treated plants at 12, 24, and 48 h in comparison to the control. Moreover, the salicylic acid and jasmonic acid marker gene expression levels were significantly upregulated by CJ-treatment. Surprisingly, aphids raised on CJ-treated potato plants showed higher transcriptional levels of detoxifying enzymes. The findings of this research will provide new insights into the possible applications of important volatile components like cis -jasmone in integrated pest management systems, in addition to enhancing our comprehension of the ways in which plant volatiles affect the crop community. • cis -jasmone exposure reduces the efficiency of M. persicae at different time durations 12, 24 and 48h. • cis -jasmone influences the preference of A. gifuensis and enhance parasitoid performance at different time durations 12, 24 and 48h. • Aphid settlement was decreased and parasitoid settlement was increased at potato plants treated with cis -jasmone at different time durations 12, 24 and 48h. • cis -jasmone treatment upregulates the expression of defense-related genes in potato plants and detoxification genes in M. persicae at different time durations. [ABSTRACT FROM AUTHOR]

[Display omitted] Nitrogen resulting from the mineralization of organic fertilizers is of great importance in organic farming and depends greatly on the type of fertilizer used. Two tests (incubation and pot test) were conducted on poor organic matter soil to assess mineralization and N release from different organic sources. The objective of the first test was the study of the mineralization under incubation conditions of four organic fertilizers commonly used doses (worm-compost: 5 t ha−1; compost: 5 t ha−1; sheep manure: 30 t ha−1; fishmeal: 3,5 t ha−1), while that of the second test was the study in pot experiment of the effect of adding worm-compost (0, 5, 10 and 15 t ha−1) and fishmeal (0, 1.75 and 3.5 t ha−1) on N mineralization, and growth and yield of potato. During incubation, N mineralized from the four organic fertilizers tested differ significantly. The maximum N mineralization apparent rates (NMAR) were 62.3%, 38%, 30% and 18%, for fishmeal, compost, worm-compost and sheep manure, respectively. At the end of the incubation, an N immobilization was observed for worm-compost and compost and was attributed to a C/N increase. For the pots test, the use of fishmeal had a significant effect on leaf number, plant height, plant dry matter, aerial nitrogen uptake, tuber number and tuber yield, while the addition of worm-compost had an effect, on leaf number and tuber yield only. The combination of these two fertilizers (10 t ha−1 of worm-compost and 1.75 t ha−1 of fishmeal) generated at harvest a maximum of underground N uptake (2.96 g plant−1; 123 kg ha−1) and total N uptake (3.26 g plant−1; 136.5 kg ha−1). This was favored by NMAR of 71% and 64.3% for fishmeal and worm-compost, respectively, generating the optimal yield (554.4 g plant−1; 23.1 t ha−1). [ABSTRACT FROM AUTHOR]

Potatoes produce two major steroidal glycoalkoids α-solanine and α-chaconine that comprise about 95% of all the glycoalkaloids in the potatoes. Under the stressful conditions production of glycoalkaloids get amplified that can lead to toxic symptoms in humans, particularly when taken in excess of 200–400 mg in adults and 20–40 mg in children. Toxicity may lead number of neuro-metabolic disorders due to anticholinesterase activity and also cause cell membrane disturbance ultimately affecting the digestion and metabolism. Minimizing these glycoalkaloids in potato tubers is crucial to reduce toxicity. Based on the previous reports suggesting α-solanine as a significant inhibitor of acetylcholinesterase, in this study we have analyzed the interaction of α-solanine, with acetylcholinesterase using computer-based docking and molecular-dynamic simulations. Our findings from docking studies with acetylcholinesterase showed a high docking score (−16.630 kcal/mol) for α-solanine, while molecular dynamics simulation suggested that α-solanine forms stable protein-ligand interactions with acetylcholinesterase. After having confirmed interaction through the docking and simulation results, we attempted to suppress the α-solanine level through suppression of the Solanidine galactosyltransferase (sgt1) gene that catalyzes solanidine to α-solanine conversion during the biosynthesis of α-solanine using the CRISPRi/dCas9-KRAB tool. Through CRISPRi/dCas9-KRAB, we intended to specifically target reducing the α-solanine level without disturbing the cellular concentration of α-chaconine. Our developed transgenic potatoes with suppressed sgt1 gene showed low α-solanine and unchanged α-chaconine levels, while nutritional analysis showed no significant changes compared to untransformed plants. • Computer based simulation and molecular dynamics studies suggest that α-solanine interacts with acetylcoline esterase resulting minimal hydrolysis acetylcholine thus interference with neural relay system i.e. acetylcholine mediated transmission of impulse. • Application of CRISPRi/Cas9 tool to suppress sgt1 is quite precise in suppression of α-solanine without any compensatory alteration in α-chaconine level. • Insignificant alteration in the α-chaconine level in the tubers enable plants to sustain moderate level of abiotic stresses. [ABSTRACT FROM AUTHOR]

Potatoes are grown in Israel twice a year, in autumn and spring, contributing over $300 million to the state's economy in 2022. In both seasons late blight caused by the oomycete Phytophthora infestans is a major threat to yields. Fungicides are the most important means to control P. infestans. The classical fungicides mancozeb and chlorothalonil were banned by the regulator while mefenoxam, cymoxanil and infinito, suffer of reduced field efficacy. The new OSBPI fungicide oxathiapiprolin solo provides excellent control of the disease by foliar or soil applications but its proneness to resistance development enforces its application in mixtures with fungicides with a different mode of action. In three field trials done in Israel during 2021–2023, oxathiapiprolin solo and seven oxathiapiprolin-premixed fungicides were applied to potato crops Sifra or VR808 at early season. Plants were thereafter inoculated with mixed genotypes of P. infestans , sensitive and resistant to mefenoxam, and disease progress was monitored along 35 days after inoculation. All oxathiapiprolin products provided excellent control of the disease all along the season, significantly better than the fungicides mancozeb, mefenoxam, cymoxanil, ranman or infinito. Disease control was dependent on the dose applied, the proportion of oxathiapiprolin in the mixture, the partner fungicide, and the experiment. At the recommended dose of 0.1 % (50 g/ha in 500 L), the mixtures with mefenoxam or mandipropamid were more effective than the mixtures with chlorothalonil or azoxystrobin. At 0.2 %, all seven mixtures were highly effective all along the season. Tuber yields were significantly higher in plots treated with oxathiapiprolin mixtures as compared with control fungicide-free plots. Monitoring assays done along the season failed to detect oxathiapiprolin-insensitive mutants of P. infestans in all three trials, including plots treated with 0.2 % oxathiapiprolin solo (MIC = 0.3 ppm ai). We conclude that a single preventive application of oxathiapiprolin-based fungicides to potato crops at early season can provide effective control of late blight under heavy pressure of P.infestans for as long as 5 weeks without selecting for insensitive mutants. • Late blight of potato caused by the oomycete Phytophthora infestans is a major threat to yields. • Fungicides are the most important means to control P. infestans. • A single preventive application of oxathiapiprolin-based fungicides to potato crops at early season can provide effective control of late blight. Under heavy pressure of P.infestans for as long as 5 weeks without selecting for insensitive mutants. • Tuber yields were significantly higher in plots treated with oxathiapiprolin-based fungicides as compared with control fungicide-free plots. [ABSTRACT FROM AUTHOR]

The goal of the research is to determine the effect of pretreated poultry manure and irrigation on the yield and quality of potatoes (Solanum tuberosum) grown in fields located on the southern steppe of the Republic of Bashkortostan. Field experiments were repeated every three years. During vegetation, potato leaves and tubers were studied at the full blossom, leaves' decay, and potato harvest. The results showed that applying pretreated poultry manure at the rate of 120 t/ha favored higher tuber weight both on the rainfed and irrigated plots (from 0.23 to 0.82 kg/plant and from 0.24 to 1.02 kg/plant, respectively). On the rainfed and irrigated plots where poultry mature was not applied (control fields) the tubers' weight ranged from 0.08 to 0.31 kg/plant and from 0.16 to 0.50 kg/plant, respectively. Upon application of 40 t/ha of manure, under irrigation, the highest marketable value of tubers was 78%. On the rainfed plots the same value was 72% when applying poultry manure at a dose of 120 t/ha. Soil moisture monitoring showed that the potatoes did not get adequate water during the growing season. When the soil moisture on irrigated plots was 70% less than its minimum water capacity, potato plantings were watered. [ABSTRACT FROM AUTHOR]

Background: The Plant U-box (PUB), ubiquitin ligase gene, has a highly conserved domain in potato. However, little information is available about U-box genes in potato (Solanum tuberosum). In this study, 62 U-box genes were detected in the potato genome using bioinformatics methods. Further, motif analysis, gene structure, gene expression, TFBS, and synteny analysis were performed on the U-box genes. Results: Based on in silico analysis, most of StU-boxs included a U-box domain; however, some of them lacked harbored domain the ARM, Pkinase_Tyr, and other domains. Based on their phylogenetic relationships, the StU-box family members were categorized into four classes. Analysis of transcription factor binding sites (TFBS) in the promoter region of StU-box genes revealed that StU-box genes had the highest and the lowest number of TFBS in MYB and CSD, respectively. Moreover, based on in silico and gene expression data, variable frequencies of TFBS in StU-box genes could indicate that these genes control different developmental stages and are involved in complex regulatory mechanisms. The number of exons in U-box genes ranged from one to sixteen. For most U-box genes, the exon–intron compositions and conserved motifs composition in most proteins in each group were similar. The intron–exon patterns and the composition of conserved motifs validated the U-box genes phylogenetic classification. Based on the results of genome distribution, StU-box genes were distributed unevenly on the 12 S. tuberosum chromosomes. The results showed that gene duplication may possess a significant role in genome expansion of S. tuberosum. Furthermore, genome evolution of S. tuberosum was surveyed using identification of orthologous and paralogous. We identified 40 orthologous gene pairs between S. tuberosum with Solanum lycopersicum, Oryza sativa, Triticum aestivum, Gossypium hirsutum, Zea maize, Coriaria mytifolia, and Arabidopsis thaliana as well as eight duplicated genes (paralogous) in S. tuberosum. StU-box 51 gene is one of the important gene among other StU-boxes in S. tuberosum under drought stress which was expressed in tuber and leaf under drought stress. Furthermore, StU-box 51 gene has the highest expression levels in four tissue-specific (stem, root, leaf, and tuber) in potato as well as it had the highest number of TFBS in promoter region. Based on our results, StU-box 51 can introduce to researcher to utilize in breeding program and genetic engineering in potato. Conclusions: The results of this survey will be useful for further investigation of the probable role and molecular mechanisms of U-box genes in response to different stresses. [ABSTRACT FROM AUTHOR]

Sustainable agriculture is an integrated system based on ecological principles, providing society's present food needs, without compromising the ability for current or future generations to meet their needs. In this system, organic and biological fertilizers and bio-pesticides are used to maintain nutrients in the soil, control weeds and pests, and increase biodiversity. The present study aimed to evaluate some traits of Solanum tuberosum following the application of chemical, organic, and biological fertilizers. This study was conducted as a factorial experiment based on randomized complete block design in three replications in two agricultural years of 2017 and 2018. The first factor was chemical/organic fertilizers at five levels (No fertilizer, 100% Urea, 66% urea + 33% Manure, 33% urea + 66% Manure and 100% Manure) and the second factor was tuber inoculation with biological fertilizers at four levels (No bacteria, Azospirillum , Pseuidomonas , Azospirillum + Pseudomonas). The results showed that the combined application of Pseudomonas with 66% urea + 33% manure resulted in the highest protein (1861.6 kg/ha) and biological (140.69 t/ha) yields in the first year. While in the second year the highest biological yield (108.65 t/ha) was achieved by the application of Pseudomonas with 100% urea. The highest tuber protein content (7.05%) and nitrate content (93.45 mg/kg) were obtained by the application of Azospirillum + Pseudomonas with 100% manure in the second year. Although the positive effect of biological fertilizers, especially Pseudomonas , has been shown on potato characters, the use of biological fertilizers alone cannot completely replace the chemical fertilizers. Therefore, sustainable agriculture can be achieved by the implementation of integrated plant nutrition using urea, manure, and biofertilizers. [ABSTRACT FROM AUTHOR]

This study was carried out in Isparta, Turkey during 2011 and 2012 crop seasons to determine the effects of sulphur doses (0, 20, 40, 60, 80 and 100 kg ha-1) and sulphur application methods (S1: application on seedbed during planting, S2: broadcast on soil before planting and S3: foliar application) on yield and quality of potato. Results of the study showed that S applications significantly increased tuber number per plant, number of large tubers, tuber yield per plant and total tuber yield. The highest increase was observed from 40-60 kg ha-1 applications doses. Tuber number per plant, tuber yield per plant and total tuber yield increased by 11%, 13.7% and 14.6% compared to control, respectively. Sulfur fertilization improved tuber quality as well. Dry matter, starch and protein contents significantly increased with the S fertilization, while reducing sugar contents decreased. [ABSTRACT FROM AUTHOR]

Background: Potato (Solanum tuberosum L.) is one of the most important food crops in the world. Pathogens remain as one of the major constraints limiting potato productivity. Thus, understanding of gene regulation mechanism of pathogenesis-related genes such as glucan endo-1,3-beta-glucosidase is a foundation for genetic engineering of potato for disease resistance and reduces the use of fungicides. In the present study, 19 genes were selected and attempts were made through in silico methods to identify and characterize the promoter regions, regulatory elements, and CpG islands of glucan endo-1,3-beta-glucosidase gene in Solanum tuberosum cultivar DM 1-3 516 R44. Results: The current analysis revealed that single transcription start sites (TSSs) were present in 12/19 (63.2%) of promoter regions analyzed. The predictive score at a cutoff value of 0.8 for the majority (84.2%) of the promoter regions ranged from 0.90 to 1.00. The locations for 42% of the TSSs were below −500 bp relative to the start codon (ATG). MβGII was identified as the common promoter motif for 94.4% of the genes with an E value of 3.5e−001. The CpG analysis showed low CpG density in the promoter regions of most of the genes except for gene ID102593331 and ID: 102595860. The number of SSRs per gene ranged from 2 to 9 with repeat lengths of 2 to 6 bp. Evolutionary distances ranged from 0.685 to 0.770 (mean = 0.73), demonstrating narrower genetic diversity range. Phylogeny was inferred using the UPGMA method, and gene sequences from different species were found to be clustered together. Conclusion: In silico identified regulatory elements in promoter regions will contribute to our understanding of the regulatory mechanism of glucan endo-1,3-beta-glucosidase genes and provide a promising target for genetic engineering to improve disease resistance in potatoes. [ABSTRACT FROM AUTHOR]

Background: Potato (Solanum tuberosum L.) is one of the most important food crops in the world. Pathogens remain as one of the major constraints limiting potato productivity. Thus, understanding of gene regulation mechanism of pathogenesis-related genes such as glucan endo-1,3-beta-glucosidase is a foundation for genetic engineering of potato for disease resistance and reduces the use of fungicides. In the present study, 19 genes were selected and attempts were made through in silico methods to identify and characterize the promoter regions, regulatory elements, and CpG islands of glucan endo-1,3-beta-glucosidase gene in Solanum tuberosum cultivar DM 1-3 516 R44. Results: The current analysis revealed that single transcription start sites (TSSs) were present in 12/19 (63.2%) of promoter regions analyzed. The predictive score at a cutoff value of 0.8 for the majority (84.2%) of the promoter regions ranged from 0.90 to 1.00. The locations for 42% of the TSSs were below −500 bp relative to the start codon (ATG). MβGII was identified as the common promoter motif for 94.4% of the genes with an E value of 3.5e−001. The CpG analysis showed low CpG density in the promoter regions of most of the genes except for gene ID102593331 and ID: 102595860. The number of SSRs per gene ranged from 2 to 9 with repeat lengths of 2 to 6 bp. Evolutionary distances ranged from 0.685 to 0.770 (mean = 0.73), demonstrating narrower genetic diversity range. Phylogeny was inferred using the UPGMA method, and gene sequences from different species were found to be clustered together. Conclusion: In silico identified regulatory elements in promoter regions will contribute to our understanding of the regulatory mechanism of glucan endo-1,3-beta-glucosidase genes and provide a promising target for genetic engineering to improve disease resistance in potatoes. [ABSTRACT FROM AUTHOR]

Potato (Solanum tuberosum L.) under Mediterranean climate may be affected by internal brown spot, non-pathogenic disorder of flesh tissues leading to a dramatic depreciation of tubers. Its aetiology is still clarifying; however, some abiotic stressors, such as the high temperatures, heat and drought are noticed as crucial factors exacerbating the physiological decline. With the aim of escaping the potato growth stages most prone to the physiopathy, shortening cropping cycle by KCl-induced potato canopy desiccation was experimented on two field trials. Experimental field treatments were two consecutive KCl foliar applications, respectively at thirty and twenty days before harvesting, at 113 and 75 g L−1, that were compared to the water-sprayed control. Salt solution spraying injured above-ground parts ending potato's growth early reducing incidence of tuber internal browning, on average, between 30% and 50% at low and high KCl concentration, respectively. The non-sensitive cultivar Agria proved the most productive, whereas Ricciona di Napoli resulted strongly defected by the physiopathy. Under low-irrigation regime, IBS occurrence was reduced of about 39%. The reduction of the transpiration flow and growth cycle likely decreased internal brown spot under KCl vine desiccation, as well as the role of KCl on tuber ripening dynamics cannot be overlooked. [ABSTRACT FROM AUTHOR]

Among various biotic stresses, potato virus Y (PVY) is one of the most economically important pathogen deteriorating the quality and yield of cultivate potato (Solanum tubersosum L.). Precise identification and characterization of PVY in potato tubers is a crucial step for international trade and selection of seed potato for healthy plant material. Nevertheless, PVY genome has high degree of genetic variability and thus detection and classification of isolates is a challenging task. During this study, the genetic variability of PVY was investigated in five different regions of Saudi Arabia. In total, 184 plant leaf samples were collected from Haradh, Qassim, Al-Ahsa, Hail and Wadi Al-Dawasir regions and subjected to PVY specific ELISA assays. The PVY infection rate was ranging from 36.36% in Hail region to 94.47% in the Qassim region, respectively. The strain specific ELISA assay showed that 10.32% of samples were tested positive for PVYN strain while, average rate of PVY infection was 55.98% in all collected samples, respectively. Total RNA was isolated from 25 ELISA positive samples and subjected to RTPCR using degenerate primers for PVY. The amplicons were sequenced and the partial coat protein (CP) sequence of 23 samples were 99.2-100% identical to the recombinant PVY strains SYRII, SYRIII and 261-4, respectively. While, two isolates showed highest nucleotide (nt) sequence identity at 99. 7% to pyyN-Wi recombinant strain. The full-length genome of one isolate was completely sequenced using next generation sequencing, which showed 99.4-99.5% nt sequence identity with pyySYRIII reported from Syria (AB461454) and Saudi Arabia (KP793715), respectively. The results further support the findings that SYRIII strain has been broadly spreading in the Middle East and thus, potato producers in these regions must be well aware of this spreading epidemic in the potato fields. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Verticillium dahliae is a soil-borne vascular pathogen difficult to control, especially after the phasing out of several fumigants. Where resistant varieties are not available, Verticillium wilt (VW) is controlled through an integrated approach. Chemical control has been extensively studied, but often does not provide a satisfactory protection level. Recently, thiophanate-methyl (TM), the sole benzimidazole currently on the market, has been registered for the use in soil applications. We evaluated the efficacy of TM against V. dahliae in in vitro , greenhouse and field experiments. We confirmed that TM is one of the most effective fungicides against V. dahliae in in vitro tests (EC 50 = 0.006 μg mL−1). In a greenhouse experiment, soil drenching with TM (0.073 or 0.146 mL plant−1, corresponding to 0.65 or 1.3 L ha−1) reduced the incidence of VW of artichoke, but not the symptoms severity or vascular browning. In pot-grown potato, TM (at 5.6 or 11.2 mg plant−1) completely suppressed the disease and promoted plant growth. In one field trial, a high dose of TM (2.1 L ha−1) only delayed VW progress, but did not affect yield losses. In a second field trial, with a more severe V. dahliae attack, no significant disease control was observed following TM applications, neither by foliar spray nor by chemigation. We concluded that TM is effective against V. dahliae , but it can provide only a partial VW control when the disease pressure is not too high. However, the results obtained in the field trial emphasize the need for further trials under different levels of inoculum pressure and with different application protocols. • In vitro , thiophanate-methyl (TM) is highly effective against V. dahliae. • In pot trials, TM delayed artichoke Verticillium wilt (VW) and suppressed potato VW. • In field trials, TM delayed potato VW but did not affect yield losses. [ABSTRACT FROM AUTHOR]

Abstract Thrips tabaci (Lindeman) is an important polyphagous pest, and vector of Tomato spotted wilt virus responsible for sporadic, but devastating epidemics in potato. T. tabaci shows significant preferential differences between potato cultivars that may be important for field resistance. To investigate the role of visual cues in host choice we tested colour preference using two-choice assays. Thrips tabaci showed a significant preference for mid-green over red, blue, and white coloured cards, a preference for both light-green and mid-green over dark-green, and light-green over yellow, but no preferential difference between mid-green and yellow, and between light-green and mid-green. Analysis of the spectral reflectance of potato cultivars differing in thrips preference, revealed significant differences within the 400–700 nm wavelengths. In most cases cultivars preferred by T. tabaci had lighter green foliage and higher reflectance at 552 nm, and thus colour preference may be important for host selection. Oviposition choice of T. tabaci for potato cultivars was determined from counts of larvae and unhatched eggs from leaf disks under choice and no-choice conditions. In contrast to the colour choice experiments, onion thrips showed oviposition preference for cultivars with darker green foliage and lower reflectance at 552 nm. Graphical abstract Unlabelled Image Highlights • In this study we demonstrate that T. tabaci responds to visual colour cues. • Thrips tabaci shows a preference for mid-green over red, blue, and white • Thrips tabaci has preference for light and mid-green over dark-green, and light-green over yellow. • Potato cultivars preferred by T. tabaci had lighter green foliage hues. • In contrast, T. tabaci showed oviposition preference for cultivars with darker green foliage. [ABSTRACT FROM AUTHOR]

Abstract Field experiments were carried out in 2016 and 2017 to integrate cultivar resistance into the TOMCAST model to control early blight on potato crops. Four potato cultivars (cvs. Agata, Sava, Oleva and Kuras), which varied for their level of resistance to early blight were used for the experiments. Fungicide (fungicide schedule) was applied as follows: an untreated; a standard treatment, in which fungicide application started at 50% row closure; and three different TOMCAST (tomato forecaster) treatments, in which fungicide application started at 330 physiological days (P-days) and subsequent sprayings were done at either 15, 20 or 25 TOMCAST threshold according to temperature and leaf wetness. The relative area under the disease progress curve (rAUDPC), rate of infection and final severity of early blight were used to quantify the intensity of early blight on the potato crops. Moreover, disease progress curves (DPCs) were constructed to compare the development of early blight on the cultivars. Analysis of the DPCs, rAUDPC, rate of infection and final severity of early blight showed that both fungicide application and cultivar resistance were important in suppressing the development of early blight. Fungicide application significantly reduced the rAUDPC, rate of infection and final severity of early blight on the potato crops in the treated plots compared to the untreated plots. TOMCAST-15 was the most effective TOMCAST threshold for controlling early blight on all the tested cultivars. For cv. Kuras, with a high level of resistance, the control of early blight by the TOMCAST thresholds was very good and comparable to the standard treatment. Therefore, we concluded that lower TOMCAST thresholds should be used for susceptible cultivars. However, for cultivars with a good level of resistance, a higher TOMCAST threshold could be used to control early blight effectively. Highlights • Cultivar resistance and fungicide are both important for controlling early blight. • TOMCAST threshold can be adjusted according to level of resistance of potato cultivars to early blight. • TOMCAST 15 was the safest threshold to control early blight effectively on all the cultivars. • For cultivars with a higher level of resistance, higher TOMCAST thresholds were able to control early blight effectively. [ABSTRACT FROM AUTHOR]

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archivos Latinoamericanos de Nutrición is the property of Sociedad Latinoamericana de Nutricion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The most important viral diseases in potato crops are PVY and PLRV, and they are efficiently transmitted by numerous aphids being Myzus persicae and Macrosiphum euphorbiae , the most important. These vector aphids are highly polyphagous and are widely distributed; and since PVY and PLRV have a broad host range there can be a wide diversity of plants hosting vector aphids, and/or being reservoirs of the viruses, in the community of plants associated with potato crops. Here, we searched for plants growing in the areas adjacent to potato crops in Salta, Argentina, to find plants that represent a risk for potato crops for being hosts of aphid vectors and/or reservoirs of PLRV and PVY. We found 34 plant species belonging to 16 families hosting aphids, from these 11 plant species were reported as hosts for PVY and/or PLRV. Also, we found 27 aphid species and 18 of them have been reported as vectors for PLRV and/or PVY. Three aphid species were found on most plants; M. persicae, M. euphorbiae and Aphis gossypii. Altogether, we found 95 plant-aphid associations in potato fields, of which 16 are newly recorded plant-aphid associations. These new associations likely arose from the great diversity of plants hosting a great diversity of aphids reported as vectors of PLRV and PVY, in a changing and dynamic agricultural ecosystem. The results that we present have implications for PLRV and PVY control in potato and other related crops. • The appearance of novel plant-aphid associations in potato fields can play a role in the crop's sanity. • Novel plants-aphid associations may arise in changing and dynamic agricultural ecosystems. • The emergence of novel plant-aphid associations is probably due to the expanding distribution of the species involved. • Novel plant-aphid associations risky for the control of PLRV and PVY were found in potato fields. [ABSTRACT FROM AUTHOR]

Liriomyza huidobrensis (Blanchard) is an emerging pest of potatoes in Korea. Host selection is crucial for the survival of leafminer as immatures have limited mobility and selection is often influenced by the host quality. A potato choice made by leafminer is guided by cultivar characteristics. To determine the effects of potato cultivars on the life variables of leafminer, a feeding preference of adult leafminer was examined by offering a choice of 21 different potato cultivars: ‘Superior’, ‘Hongyeong’, ‘Seohong’, ‘Chuyeong’, ‘Chudong’, ‘Jinseon’, ‘Bangul’, ‘Saebong’, ‘Jowon’, ‘Goun’, ‘Jopung’, ‘Hongseon’, ‘Dejima’, ‘Atlantic’, ‘Jayeong’, ‘Namseo’, ‘Chubake’, ‘Haryeong’, ‘Jeseo’, ‘Oryun’, and ‘Minseo’. The preference and performance of adult leafminer were varied significantly among cultivars. L. huidobrensis showed a preference for the Goun cultivar. Adult showed poor performance toward less attractive and poor in quality cultivars such as cv. Oryun. There was a significant relationship between choice and performance, and between plant morphology and performance. The results suggest that higher preference and performance of L. huidobrensis on cv. Goun and least on cv. Oryun might be governed by morphology as well as chemical attributes of potato cultivars. These variables estimated in this study can serve as a basis for selecting potato cultivars with resistant characteristics and can be applied as a pest management tool for leafminers at minimal costs. However, field experiments are needed to obtain concrete information about leafminer behavior relative to potato cultivars. [ABSTRACT FROM AUTHOR]

RNA interference is a defense response against virus multiplication. The goal of this paper was to test if expressing virus-specific shRNAs against potato virus Y (PVY) could confer resistance against PVY in potatoes. The recombinant binary vectors consisted of short hairpin RNA (shRNA) transgenes, expressed under the CaMV35S promoter, directed against the conserved portion of the potato virus Y (PVY) coat protein gene. To provide the shRNA a particular shape and stability in vivo , stem and loop sequences from a microRNA (miR403; an active regulatory microRNA in potato) were included with the siRNA sequences. The shRNA constructs were delivered into the “Cardinal” potato variety using Agrobacterium , and transgenic status was confirmed by polymerase chain reaction (PCR) and Southern blot. Compared to wild-type plants inoculated with PVY, expression of PVY coat protein mRNA, as assayed by reverse transcriptase (RT)-PCR, was reduced to 0.05% in shRNA1-transgenic potato lines and 22% in shRNA4-transgenic lines. In addition, via northern blots, the maximum accumulation of the transgene-specific siRNA was observed in shRNA1 transgenic plants, less was observed in shRNA4-transgenic lines, and the least amount was detected in control plants, which correlates with silencing of the PVY coat protein gene. Conclusively, by simultaneous RNA silencing, shRNA1-transgenic plants were found to be almost immune to PVY infection compared with shRNA4-potato plants. Therefore, the expression of virus-specific shRNAs is a novel, effective, and predictable approach to engineer resistance against PVY. [ABSTRACT FROM AUTHOR]

Induction of acquired resistance activates defense-related genes. Current study aimed to (a) initiate potato acquired resistance to the Early Blight disease caused by Alternaria solani through treating potato plants with low and repetitive doses of 2,4-dichlorophenoxy acetic acid (2,4-D), abscisic acid (AB), and hydrogen peroxide (H 2 O 2 ) and (b) test the success of the use of the chemical inducers along with the application of fungicides. Potato cultivars Nicola and Spunta were treated once per wk for 6 wk and challenged 1 wk later by in the control of A. solani . Results showed that peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenoloxidase (PPO) enzyme activities and gene regulation were significantly increased after 1 d of infection and lasted for more than 15 d. The 2,4-D and H 2 O 2 inducers significantly increased both enzyme activities and gene expression of PAL, PPO, and POD for more than 15 d post inoculation. PAL was the most increased at the enzyme activity and gene expression levels. Incorporation of such in-expensive treatments might reduce management costs and reduce the environmental pollution. [ABSTRACT FROM AUTHOR]

Abstract: Use of host plant resistance is an essential component of integrated management of Thrips tabaci Lindeman. The present research was designed to screen five commercial cultivars of potato, namely Agria, Kondor, Morene, Diamant and Savalan, and two breeding lines 397082-2 and Khavaran for their susceptibility to thrips infestation and for their mean relative plant growth rate (MRGR) and crop yield in an experimental field (not frected with insecticides) and a control field (chlorpyrifos frected) in the Ardabil region of Iran in 2011 and 2012. Thrips populations were assessed by visual inspection on potato leaves. At harvest time, the percentage of leaf area damaged by thrips infestation was assessed on leaves of the tested genotypes. All adults of phytophagous thrips collected in the experimental field were T. tabaci. In both years the mean numbers of thrips adults and larvae were lowest on Savalan cultivar among the tested genotypes. The mean damage index was also lowest on Savalan in both years and the MRGR and the mean yield were greatest in Savalan in the control field. Moreover, in thrips-infested plants, the lowest percentage of MRGR loss and the lowest percentage of yield reduction were observed in Savalan (3.7% and 5.8%, respectively). Of the genotypes tested, Savalan is the most resistant host and has potential for use in the sustainable management of T. tabaci on potato. [Copyright &y& Elsevier]

Abstract: Nutrients such as boron, nitrogen and calcium stimulate the production of phenols. This research focuses on the role of calcium in increasing phenol metabolism in potato peels and the ensuing tuber resistance to soft rot pathogens was investigated. Two field experiments were conducted at the University of Zimbabwe campus plots in 2008 and 2009 summer seasons. Sprouted tubers of cv. BP1 were planted in plots treated with different fertilizer combinations. The treatments were: 1) compound S (7N: 21P: 8K) + ammonium nitrate (34 %N) 2) compound D (7N: 14P: 7K) + calcium nitrate (19 Ca: 15.5N) 3) compound S + calcium nitrate and 4) compound D + ammonium nitrate. The harvested progeny tubers were inoculated with Pectobacterium carotovorum subsp. brasiliense. Calcium amendment increased the activities of enzymes (phenylalanine ammonia-lyase, polyphenol oxidase and peroxidases) involved in the metabolism of phenolics and total soluble phenols. Calcium amendment significantly reduced (P < 0.05) the maceration effect of P. carotovorum subsp. brasiliense in tuber tissues. Chlorogenic acid, caffeic acid and calcium, but not ferulic acid content were significantly higher (P < 0.05) in plants grown in calcium treated plots. Calcium positively and significantly correlated with polyphenol oxidase (PPO), phenylalanine (PAL) and peroxidase (POD), while chlorogenic and caffeic acid showed a positive relationship with POD and PPO. Calcium amendment significantly reduced maceration symptom caused by the bacteria (P < 0.05), resulting in smaller decayed zone diameters on inoculated tubers from calcium-treated plots. This study shows that soil amendments of calcium increase concentration of calcium, caffeic and chlorogenic acid in tuber peels and also reduces maceration effect of pectinolytic pathogens. Reduced maceration could be due to increased levels of caffeic and chlorogenic acid which have antimicrobial properties. [Copyright &y& Elsevier]

Early blight, caused by Alternaria solani, and brown leaf spot, caused by a number of small-spored Alternaria spp. including Alternaria alternata sensu stricto , Alternaria arborescens, and Alternaria tenuissima, are observed annually in all midwestern potato production areas. However, Alternaria spp. have developed reduced sensitivity and/or resistance to many single-site mode of action fungicides such as quinone outside inhibitor (QoI; FRAC group 11), succinate dehydrogenase inhibitor (SDHI; FRAC group 7), and anilinopyrimidine (AP; FRAC group 9). Mean in vitro sensitivity EC 50 values (effective concentration where fungal growth is inhibited by 50%) of A. alternata (n = 16) , A. arborescens (n = 3) , A. tenuissima (n = 5) , and A. solani (n = 58) in response to the AP fungicides pyrimethanil and cyprodinil and the phenylpyrrole (PP) fungicide fludioxonil were determined via mycelial growth assays. Significant fungicide by isolate interactions were observed for all Alternaria spp. evaluated in vitro, indicating reduced-sensitivity of some isolates to individual fungicides. EC 50 values for three non-baseline A. solani isolates collected in 2010, 2011 and 2013 were within the baseline for all three fungicides. A significant correlation was observed between pyrimethanil and cyprodinil EC 50 values among A. alternata isolates, but no relationship was observed with the other fungicides or in A. solani. In greenhouse evaluations, a significant loss of disease control was observed for some non-baseline A. solani isolates, and this was more pronounced in the AP fungicides, pyrimethanil and cyprodinil. No significant correlation was observed between in vitro EC 50 value and area under the dose response curve based on greenhouse assays, likely due to the limited number of isolates evaluated. Further research is needed to determine if these reductions affect control of early blight and brown leaf spot in potato under field conditions. Results from this study indicate that fludioxonil and cyprodinil are potentially good additions into fungicide rotation programs or as co-pack chemistries for control of leaf spot diseases and fungicide resistance management. • AP and PP fungicides remain effective on potato early blight/brown spot pathogens. • Cross-sensitivity between pyrimethanil and cyprodinil in baseline A. alternata. • Significant loss of disease control seen for some non-baseline A. solani isolates. • Fludioxonil and cyprodinil are good candidates for addition to a potato IPM program. [ABSTRACT FROM AUTHOR]

Abstract: Early blight, caused by the fungus Alternaria solani and brown leaf spot, caused by Alternaria alternata, are important diseases of potato crops in Idaho. In recent years growers have reported a reduction in efficacy of fungicides traditionally used in the past decade to control early blight. In 2009, a collection of A. solani 39 isolates were screened for resistance to azoxystrobin, pyraclostrobin, boscalid and famoxadone. Fungicide sensitivity testing was done using spiral plate dilution gradients. Results showed that of 39 isolates screened, all were resistant to azoxystrobin and three were resistant to boscalid. None were resistant to pyraclostrobin or famoxadone. In summer 2010, more isolates were collected (9 A. alternata and 26 A. solani) and the survey was expanded to include more fungicides with four different modes of action that targeted succinate dehydrogenase (SDH), methionine biosynthesis, mitochondrial respiration and multi-site contact activity. New isolates of A. solani and A. alternata were also collected from two additional sites. The results showed that 57% of the isolates were resistant to boscalid as well as an average of 63% of the isolates being resistant to the strobilurin fungicides. Seven and 15% of isolates were resistant to penthiopyrad (an SDH inhibitor), and pyrimethanil (a methionine biosynthesis inhibitor), respectively. However, none of the isolates were resistant to fluopyram (an SDH inhibitor) or a mixture of fluopyram and pyrimethanil. Although there appears to be cross resistance developing in Alternaria spp. to some of the new SDH inhibitors like penthiopyrad, others such as fluopyram are still showing limited to no resistance development in Alternaria spp. in Idaho. [Copyright &y& Elsevier]

In this article, the authors focus on a study related to the use of uridine diphosphate N-acetylglucosamine (UDP)-N-acetylglucosamine: dolichol phosphate-N-acetylglucosamine-phosphotransferase (GPT) gene as a marker during potato transformation. They inform that GPT transformation is stable with high reproducibility. They mention that growth and tuber production in GPT-transformed plants are higher than in wild-type plants.

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Abstract: The objective of this study was to evaluate the reaction to late blight of two potato cultivars in response to nitrogen (N) management under field and in Vitro conditions. In Balcarce trial a reduction in phenols with the addition of excess N was found. Despite the reduction of the concentration of phenols no differences in the relative area under disease progress curve (rAUDPC) were observed between N levels. In Tafí del Valle, the rAUDPC denoted an interaction between cultivar and N level. In Frital, the N0 showed lower rAUDPC than N optimal (Opt) and N excessive (Exc) treatments. In contrast, no differences in rAUDPC between N levels on Pampeana were found. In the detached leaf test, no significant differences between N levels were observed in the threshold of severity of disease and the lesion growth rate. In conclusion, excessive N fertilization did not increase the susceptibility to late blight in this study. [Copyright &y& Elsevier]

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Abstract: Potato (Solanum tuberosum L.) is globally the fourth largest staple crop after rice, wheat and maize. China is the largest potato producer worldwide, accounting for 26.3% and 22.2% of the global total area and yield, respectively. Viral diseases have been a limiting factor for sustainable production of potato in China. This article provides update and comprehensive information on the most important viruses, their effect on yield and their control in China. Meristem culture is currently the most widely used technique for production of virus-free potato plants and these plants are used as nuclear stock for the production of certified seed tubers. Although a significant increase in tuber yield has been achieved using certified seed potatoes, lack of application of a national seed potato production scheme has hindered progress. Conventional breeding using virus-resistant cultivars introduced from other countries as parents has already led to the production of Chinese cultivars. Use of virus-resistant wild Solanum species and genetic transformation techniques will provide new virus-resistant varieties in the future to further enhance control of potato viruses in China. [Copyright &y& Elsevier]

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Abstract: Potato tuber blight caused by Phytophthora infestans accounts for significant losses of tubers in storage. Despite research on infection and management of tuber blight, there is paucity of information on the prediction of the occurrence tuber blight or modelling of tuber infection by P. infestans under field conditions. A tuber blight prediction model was developed in New York in experiments conducted using cultivars Allegany, NY101, and Katahdin in 1998 and 1999. This model was validated using data collected from the potato cultivar Snowden in field experiments in Laingsburg, Michigan from 2000 to 2009. In both New York and Michigan experiments, disease was initiated by artificial inoculation of cultivars with a US-8 isolate of P. infestans. Mean leaf area affected ranged from 0 to 94% at New York, and 0 to 93% at Michigan. At New York and Michigan, mean tuber blight incidences ranged from 1 to 40% and 0 to 15%, respectively. In the validation of the model using data collected at Laingsburg, Michigan, the model correctly predicted tuber blight incidence in 7 out of 9 years. Comparison of observed with predicted values indicated that slopes of the regression line between observed and predicted germination and infection data were not significantly different (P > 0.3547). Correlation coefficient between observed and predicted values was high (r 2 > 0.65) and the coefficient of variation of the residuals of error was about 12%. Although inoculum availability is assumed in the model, incorporation of relationships of inoculum density, propagule survival in soil, and tuber blight incidence would greatly improve the prediction of tuber blight under field conditions. [Copyright &y& Elsevier]

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Abstract: The aphids Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (Hemiptera: Aphididae) are responsible for yield reduction in potato (Solanum tuberosum) production by direct phloem feeding and by spreading viruses. Breeding resistant traits from Solanum chomatophilum into the potato germplasm provides alternative means to control aphid infestations. Integrated pest management strategy, using plant resistance, benefits from the characterization of the resistance and of its impact on aphid biology. Our objective was to characterize the resistance of S. chomatophilum by assessing the effects of accessions, plant parts on aphid performance, and by assessing the impact of the resistance factors on different aphid developmental stages and on alate morph production. Detailed aphid performance was obtained by measuring fecundity, survival, percentage of nymphs that reached adult moult, and population growth using whole plant and clip cage experimental designs. Accession and plant physiological age, but not aphid developmental stage, influenced all life-history parameters, except for alate morph production which was not induced on the resistant accessions. Plant part influence was independent of plant species and accession. Both experimental designs resulted in congruent resistance levels at the accession level for each of the two aphid species, supporting the use of any of them in S. chomatophilum resistance screening. PI243340 was resistant to both aphid species, while PI365324 and PI310990 were also resistant to M. euphorbiae and M. persicae, respectively. [Copyright &y& Elsevier]

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The article presents a study on the role of intraspecific genetic diversity on disease management of agricultural crops using the potato late blight in Peru. The study intends to develop a simple model pertaining to the effects of host diversity that can provide a better understanding on the effects of host diversity. It provides a comparison on the impact of host diversity on potato late blight diversity between the shorter and longer season region.

Abstract: In potato production systems of the high Andes, Andean potato weevils of the genus Premnotrypes and Rhigopsidius are the most important potato pests. The adults are flightless insects that migrate to potato fields during the potato-growing season, where the larvae damage a high proportion of the tuber harvest. We tested the hypothesis that plastic barriers established at field borders at sowing time are effective management tools to stop Andean potato weevil migration into potato fields, with a consequent reduction in Andean potato weevil tuber damage. In addition, we studied the effect of barriers on carabids, which represent an important insect family in the Andes and are natural enemies of Andean potato weevils. The studies were carried out in 21 on-farm experiments in two villages in the Central Highlands of Peru. The effect of plastic barriers was compared to farmers'' practice, consisting of 1–4 insecticide applications per potato-growing season, in participatory research in fallow–potato and potato–potato rotation systems in which the Andean potato weevil Premnotrypes suturicallus Kuschel is endemic. Plastic barriers proved to be highly effective in stopping weevil migration. In screen house experiments only a small proportion (13%) of weevils was able to escape from plastic heights of 25cm. A height of 50cm could not be overcome, which was the height used in the on-farm field experiments. The combination of plastic barriers with pitfall traps installed close to the plastic significantly increased the number of Andean potato weevil catches, and proved an effective technology for mass trapping of Andean potato weevil adults. Plastic barriers also affected and increased the number of carabids, mainly of the genus Blennidus, in the pitfall traps. The proportion of carabids was 4–5 times higher in the location in which a lower number of Andean potato weevils and damaged tubers were observed. The results suggest that carabids are important predators of Andean potato weevils. The plastic barriers effectively reduced Andean potato weevils-caused potato tuber damage at harvest. Compared to the farmers'' practice of using insecticides, the barriers were equally effective in fallow–potato rotation systems. In potato–potato rotation systems the combination of plastic barrier with one application of insecticide was superior to farmers'' practice using 3–4 insecticide applications. The costs for plastic barriers were calculated to be equivalent to two or three insecticide applications per hectare. Plastic barriers are proposed as a new effective component for Integrated Pest Management of Andean potato weevils. [Copyright &y& Elsevier]

The article presents a case study which identifies the anti-herbivore traits in agricultural plants. The study involves the role of trichomes against a sap-feeding insect, the leafhopper, on potato. It also explores two different types of costs, the allocation costs focusing on the relationship of trichomes and yield, and the costs that involve trade-offs with alternative strategies.

Copyright of Agro Sur is the property of Universidad Austral de Chile, Facultad de Ciencias Agrarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Wireworm control has become a major pest management concern for potato growers in the United States. Studies were conducted from 2002 to 2005 on the Eastern Shore of Virginia to identify the species complex of wireworms and timing of injury to potatoes, and to evaluate the efficacy of various soil-applied insecticides alone or in combination for wireworm control. The cornfield wireworm, Melanotus communis (Gyllenhal), was the dominant species found in potato fields accounting for roughly 80% of individuals collected. Conoderus lividus De Geer and Conoderus vespertinus (Fabricius) comprised the remaining 20% of wireworm specimens found. Wireworms were most apparent on or near potato seed pieces in late April, and were detected less frequently near potato plants over time as the season progressed into July. Most wireworm damage to potato tubers, however, occurred late in the potato crop season (after mid-June). There was a significant positive relationship between tuber size and percentage of wireworm damage. In general, the longer tubers remained in the ground, the higher the percentage of wireworm injury. Results from several insecticide efficacy experiments in potatoes showed that fipronil, imidacloprid, thiamethoxam, and bifenthrin applied to the soil at planting provided similar wireworm control (50–80%) to that of the organophosphate standards, phorate, and ethoprop. Combinations of imidacloprid or thiamethoxam with fipronil or bifenthrin did not enhance the efficacy of any one of them used alone. The aforementioned products provide much needed alternative insecticide modes of action for wireworm control in potatoes and perhaps other crops in the future. [Copyright &y& Elsevier]

Abstract: Reduced sensitivity to quinone outside inhibitor (QoI) fungicides conferred by the presence of the F129L mutation was identified in Alternaria solani isolates collected in Nebraska in 2000 and in isolates collected from the Midwestern states of Minnesota and North Dakota in 2001. Over 4200 isolates of A. solani collected over a 5-year period from 2002 to 2006 from 11 potato-producing states were evaluated for the presence of the F129L mutation utilizing azoxystrobin spore germination assays and real-time PCR. From this population, 96.5% of isolates were determined to have reduced sensitivity to QoI fungicides and/or to contain the F129L mutation. In addition to Midwestern states of Minnesota, Nebraska and North Dakota, A. solani isolates containing the F129L mutation were collected from Colorado, Michigan and Texas in 2003, Wisconsin in 2005, as well as from the Western United States including Idaho, Washington and Wyoming in 2005 and Oregon in 2006. The detection of these isolates in areas outside the Midwest suggests that the F129L mutation is stable and present under conditions that are less conducive for the pathogen and where it is under less selection pressure by QoI fungicides. Competitive fitness tests confirm that, while isolates of A. solani with the F129L mutation had a decrease in in vitro percentage germination compared with wild-type isolates, F129L mutant isolates produced higher disease severity in greenhouse trials than wild-type isolates. Field trials were performed in central Minnesota and central North Dakota in 2000 and 2001 when the A. solani population was dominated by wild-type isolates as well as in 2002, 2003, 2005 and 2006 when F129L mutant isolates dominated. These trials support in vitro and greenhouse results indicating that the F129L mutation has affected the field performance of all QoI fungicides. Field trial results suggest that these fungicides do not provide improved disease control over standard protectant fungicides such as chlorothalonil and mancozeb. [Copyright &y& Elsevier]