Cabbage Fields Research Articles

Estimating Soil Moisture Distributions across Small Farm Fields with ALOS/PALSAR

The ALOS (advanced land observing satellite) has an active microwave sensor, PALSAR (phased array L-band synthetic aperture radar), which has a fine resolution of 6.5 m. Because of the fine resolution, PALSAR provides the possibility of estimating soil moisture distributions in small farmlands. Making such small-scale estimates has not been available with traditional satellite remote sensing techniques. In this study, the relationship between microwave backscattering coefficient (σ) measured with PALSAR and ground-based soil moisture was determined to investigate the performance of PALSAR for estimating soil moisture distribution in a small-scale farmland. On the ground at a cabbage field in Japan in 2008, the soil moisture distribution of multiple soil layers was measured using time domain reflectometry when the ALOS flew over the field. Soil moisture in the 0–20 cm soil layer showed the largest correlation coefficient with σ (r = 0.403). The σ values also showed a strong correlation with the ground surface coverage ratio by cabbage plants. Our results suggested that PALSAR could estimate soil moisture distribution of the 0–20 cm soil layer across a bare field and a crop coverage ratio when crops were planted.

Viruses infecting Brassica crops in the Black Sea Region of Turkey

ABSTRACTIn Turkey, cabbage is the most economically important member of the genus Brassica. Samsun, located in the Black Sea Region is the greatest cabbage producing area in Turkey. Surveys were done to determine the distribution of viruses in cabbage cultivated areas in 2012–2014. According to the results of field observations, characteristic virus symptoms were observed on some cabbage plants. The average percentages of symptoms-affected plants were recorded as 2–20% in the visited fields. A total of 535 leaf samples were collected from cabbage fields and tested for the presence of Turnip mosaic virus (TuMV), Cauliflower mosaic virus (CaMV), Cucumber mosaic virus (CMV), Turnip yellow mosaic virus (TYMV), and Beet western yellows virus (BWYV) by double-antibody sandwich Enzyme-linked immunosorbent assay (DAS-ELISA) using virus-specific polyclonal antiserum. The ELISA results revealed that 8.1% and 6.9% of these samples were infected with TuMV and CaMV, respectively. The TuMV+CaMV mixed infection ratio was 2.1%. However, CMV, TYMV, and BWYV were not detected. This is the first comprehensive study of viruses on Brassica crops in the Black Sea Region of Turkey, the most important centre for cabbage production in Turkey.

Studies of the effects of imidacloprid and deltamethrin insecticides on the biology of Pieris brassicae (Linn.) on cabbage

The present investigation was conducted during Rabi season of 2011 to see the effect of imidacloprid and deltamethrin insecticides on the biology of Pieris brassicae (Linn.) on cabbage at experimental field of the Department of Plant Protection, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh. The larvae of Pieris brassicae were collected from cabbage field in the month of January and February 2012. They were kept in jars measuring 25 x15 cm and provided fresh cabbage leaves as food for larvae. These jars were kept in B.O.D chamber at 24.5 oC and 70±10 per cent relative humidity. Fresh cabbage leaves were dipped in 0.05 per cent aqueous solution of, imidacloprid and deltamethrin and dried at room temperature by keping in the experimental jars. Fifteen third instar larvae in a batch of five were allowed to feed on them for 24 hours. Survivorship and expectancy of the life was greatest in the beginning of the age and decreased gradually with the advancement of the age in the all treatment including control. The expectancy was minimum (17.18) when P. brassicae was treated with imidacloprid while maximum in the untreated individuals (25.83). The mortality of P. brassicae was significantly high in the early instars as compared to late instars in both treated and untreated individuals. How to view point the article : Khan, Hadi Husain, Ansari, M. Shafiq, Hasan, Fazil, Ahmad, Salman and Danish, Mohd. (2016). Studies of the effects of imidacloprid and deltamethrin insecticides on the biology of Pieris brassicae (Linn.) on cabbage. Internat. J. Plant Protec., 9(1) : 313-321.

Adaptation strategies for mitigating agricultural GHG emissions under dual-level uncertainties with the consideration of global warming impacts

Agriculture plays a central role in maintaining food security and achieving sustainable development for human society. It is a challenge for the agricultural sector to mitigate greenhouse gas (GHG) emissions and maintain agricultural production. However, dual-level uncertainties exist in the processes of agricultural GHG accounting and emission reduction management. In this research, an integrated approach for identifying adaptation strategies in agricultural GHG emission reduction management was developed through incorporating life cycle analysis (LCA) of agricultural production into a general mathematical programming model. This approach strengthened the applicability of LCA and the comprehensiveness of programming models in generating agricultural adaptive actions under different GHG emission restriction targets. Also, dual-level uncertainties of LCA and adaptation management can be effectively addressed. A case study was proposed to illustrate application of the approach in Dalian City, China. The results indicated that farming patterns in eight districts would change significantly. The total area of maize fields would account for the primary proportion (i.e., 40–45 %) in its agricultural sector. Rice, peanut and cabbage fields would be the minor contributors in terms of GHG emissions. In addition to effective rainfall (i.e., [156, 259] mm/ha), a certain amount of water would be supplied for agricultural irrigation to maximize the city’s agricultural yields. Compared with other agricultural crops, rice fields would need the largest amount of irrigation water (i.e., [153.72, 277.98] Mt) to meet the requirements of local government plans.

Dispersal of sugar beet cyst nematode (Heterodera schachtii) by water and soil in highland Chinese cabbage fields

사탕무씨스트선충(Heterodera schachtii)은 전세계적으로 십자화과 작물에 심각한 경제적 손실을 유발시키는 선충으로 2011년 우리나라의 고랭지 채소 재배지에 최초 발생이 확인되었다. 고랭지 배추 재배지에 사탕무씨스트선충에 의한 피해가 증 가하고 있는 실정이나 피해 확산에 대한 실제적 원인 규명이 없어 본 연구에서는 고랭지 배추 재배지에서 작업화와 작업차량, 물을 통한 사탕무씨스트선충의 확산 가능성을 구명하기 위하여 수행하였다. 사탕무씨스트 선충 감염지에서 작업 할 경우 신발 에 묻은 흙에 사탕무씨스트선충이 존재하였는데 부착 된 씨스트선충의 수는 지역별로 차이가 있었다. 사탕무씨스트선충에 감염된 배추 밭 농로를 주행 한 차량의 바퀴에서도 사탕무씨스트 선충의 부착이 확인 되었다. 고랭지 배추 재배지에서 배추 수확 시 사용하는 굴삭기의 궤도에서는 41kg의 흙이 부착되었으며 장거리 수송용 5톤 트럭의 바퀴 네 개에서도 223.7g의 흙이 채취 되어 수확 작업 시 다량의 사탕무시스트선충이 부착될 수 있음을 확인 할 수 있었다. 강우 시 사탕무씨스트선충 감염 포장에서 작업할 경우를 가정하여 관주량별(2, 4, 8Lㆍm-2)에 따른 작업화 부착 흙 양과 사탕무씨스트선충 부착량을 조사한 결과 관주량 이 많을수록 장화에 부착되는 흙의 양은 많았으나 사탕무씨스트선충의 밀도는 차이가 없었다. 강우 시, 사탕무시스트선충 감 염지에서는 유거수를 통해 사탕무씨스트 선충이 이동하였다. 우리나라 고랭지 배추 재배지에서 신규 도입 선충인 사탕무씨스 트선충은 작업자의 작업화와 수확 작업에 이용되는 굴삭기와 차량의 바퀴 및 물을 통해 확산이 이루어 질 수 있음을 구명하였 다. 따라서 사탕무씨스트선충 감염지역에서는 작업자의 개인 위생과 작업 차량에 대한 토양 제거를 통해 감염 확산을 막아야 할 것으로 판단된다.

Effects of Synthetic Insecticides and Crude Botanicals Extracts on Cabbage aphid, Brevicoryne brassicae (L.) (Hemiptera: Aphididae) on Cabbage

The study was conducted to evaluate the insecticidal action of two new chemical insecticides and three locally available botanicals. These materials were evaluated for their efficacy against cabbage aphids, Brevicoryne brassicae (L.), under laboratory and field conditions. The laboratory result revealed that Lambda Cyhalothrin (Triger 5 E.CTM) and Emamectin benzoate (Cutter 112 E.CTM) were non-significant difference from the standard check within 1 day after application. The field results showed between the new insecticides, Triger 5 E.CTM and Cutter 112 E.CTM were non-significant difference from that of the standard check (Diazinon 60% E.CTM) at both locations (Guder and Mutulu) within three days after application. Extracts of neem (Azadirachta indica) seed, Hop bush (Dodonae angustifolia) fresh leaf and Lemon grass (Cymbopogon citrates) gave positive performance under laboratory while the efficacy percent were decline at both field locations on field. Azadirachta indica seed, Dodonae angustifolia and Cymbopogon citrates were given 59.48, 57.16 and 52.50 at Mutulu and 53.92, 37.26 and 62.72 at Guder location mortality percent, respectively, after 3rd day observation in first spray. The obtained results revealed that all tested materials were exhibited mortality rate action against cabbage aphids. Powdered neem seed, Dodonae angustifolia fresh leaf and leaves of Cymbopogon citrates caused moderately mortality percent against cabbage aphid within 3 days after applications. Higher damage and low yield were observed in control and botanicals application. This study indicated that the two insecticides Cutter 112 E.CTM and Triger 5 E.CTM and botanicals could be recommended as an alternative management option of Brevicoryne brassicae (L.) in Ethiopia.

Impact ofBacillus thuringiensisBerliner var.kurstakiApplication on Population Densities ofPlutella xylostellaL. (Lepidoptera: Plutellidae), and Its Dominant Parasitoid,Cotesia vestalisHaliday (Hymenoptera: Braconidae) and the Implications on Cabbage Yield

Cotesia vestalis Haliday (Hymenoptera: Braconidae) is a solitary koinobiont endoparasitoid that causes high larval mortality of Plutella xylostella L. (Lepidoptera: Plutellidae) on Brassica crops in South Africa. Many farmers use prophylactic and curative microbial insecticides such as Bacillus thuringiensis (Berliner) var. kurstaki (Btk) to minimise damage caused by P. xylostella on their crop. Bacillus thuringiensis formulations are widely adopted based on them not having a direct effect on parasitoids, which then assumes that they complement each other in pest management. We investigated parasitism of P. xylostella by C. vestalis in cabbage fields treated with Btk and assessed the implications on cabbage yield. Populations of P. xylostella and C. vestalis were monitored for 12 weeks in each of the four growing seasons in Btk-treated and control plots at Alice, Eastern Cape, South Africa. Plutella xylostella densities and levels of parasitism were lower in the Btk-treated plots. Consistent with low infestation, damage in Btk-treated cabbage was significantly lower than in the control.

Biodiversity enhancement and utilization – Pest control in brassicas

In cabbage fields parasitoid wasps ( Hymenoptera ) use the eggs or larvae of pest butterflies and moths for their own reproduction, ultimately killing them, playing an important role in the biological plant protection strategy. An efficient way to promote this parasitoids in the crop field is to provide them with flower strips as well as companion plants, e.g. cornflower ( Centaurea cyanus ), that will provide them with food (nectar) and shelter. Between 2007 and 2010 we conducted experiments to test the olfactory attractiveness of different flowers as well as the influence of their nectar on the regulation of the cabbage moth ( Mamestra brassicae ) as well as on the lifespan and parasitation performance of its antagonists (egg and larval parasitoids). Keywords: functional biodiversity, cabbage, flowering plants, natural enemies

Dissipation kinetics of emamectin benzoate and lufenuron residues in cabbage grown under field conditions.

Residue analysis of emamectin benzoate and lufenuron in cabbage matrices and soil was developed using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and ultra high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with 1% acetic acid in acetonitrile (v/v) or 1% acetic acid in acetonitrile/water (5:1, v/v) and cleaned up by dispersive solid-phase extraction. Mean recoveries and relative standard deviations (RSDs) in all samples ranged 87.8-100.0 % and 3.6-12.6% for emamectin benzoate and 87.8-104.8 % and 6.2-11.5% for lufenuron, respectively. The validated method was used to evaluate the dissipation rate of emamectin benzoate and lufenuron in cabbage and soil as well as the residual levels in harvested cabbage and soil at different preharvest intervals (PHI). The half-lives of emamectin benzoate and lufenuron were 1.08-2.70 and 1.74-5.04 days in cabbage, and 1.42-4.01 and 0.94-6.18 days in soil, respectively. The terminal residues were below the China maximum residue limits (MRLs) at 3 days for emamectin benzoate (0.1 mg kg(-1)) and European Union MRLs at 5 days for lufenuron (0.5 mg kg(-1)), which suggested that 5 days could be recommended as the PHI for the commercial formulation of emamectin benzoate and lufenuron application in the Chinese cabbage field.

경남지역 밭 잡초 발생분포 및 군락변화

본 연구는 경남지역의 밭에서 발생하는 잡초의 분포현황을 조사하기 위하여 수행하였다. 보리 재배지에서는 21과 55종, 마늘 재배지 22과 56종, 양파 재배지 19과 47종, 배추 재배지 26과 68종, 감자 재배지 22과 54종, 고구마 재배지 25과 62종, 고추 재배지 29과 87종, 옥수수 재배지 28과 79종, 콩 재배지 29과 84종이 발생되었다. 작목별 우점하는 초종은 보리 재배지 뚝새풀 20.7%, 마늘 재배지 황새냉이 12.3%, 양파 재배지 좀명아주 18.7%, 배추 재배지 쇠비름 8.1%, 감자 재배지 좀명아주 13%, 고구마 재배지 바랭이 12.6%, 고추 재배지 바랭이 12.6%, 옥수수 재배지 11.3%, 콩 재배지 바랭이 13.2%로 발생되었다. 동작물 재배지에서는 뚝새풀, 황새냉이 및 좀명아주가, 하작물 재배지에서는 바랭이, 쇠비름, 깨풀이 가장 문제시 되었다. 이러한 잡초 발생 정보는 경남지역 밭잡초 관리방안 수립에 기여할 것으로 판단된다. This study was conducted to provide basic information for weed control by surveying the occurrence of weed species in upland crop fields in Gyeongnam province of Korea. The result of this survey, 55 weed species 21 families in barley fields, 56 weed species 22 families in garlic fields, 47 weed species 19 families in onion fields, 68 weed species 26 families in Chinese cabbage fields, 54 weed species 22 families in potato fields, 62 weed species 25 families in sweet potato fields, 87 weed species 29 families in red pepper fields, 79 weed species 28 families in corn fields, 84 weed species 29 families in soybean fields. The most dominant weed species in upland crop fields of Gyeongnam province were Alopecurus aequalis var. amurensis 20.7% (barley fields), Cardamine flexuosa 12.3% (garlic fields), Chenopodium ficifolium 18.7% (onion fields), Portulaca oleracea 8.1% (Chinese cabbage fields), Chenopodium ficifolium 13% (potato fields), Digitaria ciliaris 12.6% (sweet potato fields and red pepper fields) and Digitaria ciliaris 11.3% (corn fields), 13.2% (soybean fields). This information could be useful for establishment of future weed control methods in Gyeongnam province.

The occurrence of Alternaria species on cabbage in Iran

In a study on Alternaria species, associated with cabbage black spot disease in Urmia, West Azerbaijan, Iran, cabbage fields were inspected during the growing seasons of 2012–2013 and leaves with suspected symptoms of Alternaria infection were collected. A total of 135 isolates with Alternaria characteristics were obtained from 10 main growing areas in this region and studied taxonomically. On the basis of morphological characteristics of the studied isolates, 8 species viz. Alternaria arbusti, A. brassicicola, A. destruens, A. infectoria, A. perangusta, A. tenuissima, A. turkisafria and A. vaccinii were identified. Alternaria tenuissima with 53 isolates, A. brassicicola with 38 isolates and A. destruens with 29 isolates had respectively the highest frequency among the identified species and distributed all over the studied area. A. arbusti and A. perangusta each with only one isolate had the lowest frequency. Results obtained from the pathogenicity tests showed that all the tested isolates from identified species were pathogenic on cabbage leaves, although there were statistically significant differences in virulence of the tested isolates. A. brassicicola isolates had the highest virulence and A. arbusti and A. vaccinii isolates had the lowest virulence. Isolates belonging to other species had moderate virulence. Except A. brassicicola which had been previously reported from cabbage in Iran, all other seven species are reported for the first time from cabbage as the causal agents of black spot disease. Also, A. arbusti, A. perangusta and A. vaccinii are reported as new species for Iran mycoflora.

Ammonia volatilization from a Chinese cabbage field under different nitrogen treatments in the Taihu Lake Basin, China

Ammonia (NH3) volatilization is a major pathway of nitrogen (N) loss from soil-crop systems. As vegetable cultivation is one of the most important agricultural land uses worldwide, a deeper understanding of NH3 volatilization is necessary in vegetable production systems. We therefore conducted a 3-year (2010–2012) field experiment to characterize NH3 volatilization and evaluate the effect of different N fertilizer treatments on this process during the growth period of Chinese cabbage. Ammonia volatilization rate, rainfall, soil water content, pH, and soil NH4+ were measured during the growth period. The results showed that NH3 volatilization was significantly and positively correlated to topsoil pH and NH4+ concentration. Climate factors and fertilization method also significantly affected NH3 volatilization. Specifically, organic fertilizer (OF) increased NH3 volatilization by 11.77%–18.46%, compared to conventional fertilizer (CF, urea), while organic–inorganic compound fertilizer (OIF) reduced NH3 volatilization by 8.82%–12.67% compared to CF. Furthermore, slow-release fertilizers had significantly positive effects on controlling NH3 volatilization, with a 60.73%–68.80% reduction for sulfur-coated urea (SCU), a 71.85%–78.97% reduction for biological Carbon Power® urea (BCU), and a 77.66%–83.12% reduction for bulk-blend controlled-release fertilizer (BBCRF) relative to CF. This study provides much needed baseline information, which will help in fertilizer choice and management practices to reduce NH3 volatilization and encourage the development of new strategies for vegetable planting.

Detection of Bacterial and Fusarium wilt Pathogens in Cabbage by Multiplex PCR

Cabbage is one of the most important vegetable which is extensively cultivated in India and other countries. Fusarium yellows caused by Fusarium oxysporum f.sp. conglutinans is one of the most destructive diseases of cabbage and other crucifers. It causes severe loss in the yield in terms of both quantity and quality. The work on Fusarium oxysporum f.sp.conglutinans in India is very scanty. The aim of the present study was to isolate and study the morphological diversity and pathogenicity variability among F. oxysporum f.sp. conglutinans isolated from different cabbage fields. During the present work, an attempt was made to isolate, identify and characterize the Fusarium yellows of cabbage causing pathogen Fusarium oxysporum f.sp. conglutinans, a total of nine soil samples were collected from different fields out of which five were found to be positive for Fusarium oxysporum f.sp. conglutinans. The morphological, physiological characterization results of the present study including, pathogenicity reaction effectively demonstrated the confirmation of isolated pathogen as Fusarium oxysporum f.sp. conglutinans. A multiplex PCR method was developed for the easy detection of the Fusarium yellows and the black rot pathogen Xanthomonas campestris pv. campestris which in the initial stages produce symptoms which appear similar.

Assessment of N2O Emission Factor of Autumn Chinese Cabbage Fields at Three Different Geographical Location in South Korea

The level of nitrous oxide (N₂O), a long-lived greenhouse gas, in atmosphere has increased mainly due to anthropogenic sources, especially application of nitrogen fertilizers. Quantifying N₂O emission in the agricultural field is essential to develop national inventories of greenhouse gases (GHGs) emission. The objective of this study was to develop an emission factor to estimate the direct N₂O emission from an agricultural field cultivated with the Chinese cabbage during autumn season in 2010-2012. Emission factor of N₂O calculated over three years experiment using accumulated N₂O emission, nitrogen fertilization rate, and background N₂O emission was 0.0058±0.00254 kg N₂O-N kg -1 N. More extensive studies need to be conducted to develop N₂O emission factors for other upland crops in the various regions of Korea because N₂O emission is influenced by many factors including climate characteristics, soil properties, and agricultural practices as well as crop species.

Nitrogen surface runoff losses from a Chinese cabbage field under different nitrogen treatments in the Taihu Lake Basin, China

The excessive use of nitrogen (N) fertilizer for crop production can cause substantial N losses through surface runoff, generating serious nonpoint pollution. A thorough understanding of N runoff losses is necessary for optimal N management in vegetable production systems. A 3-year field experiment was conducted at a Chinese cabbage field in the Taihu Lake Basin of China to evaluate the characteristics of N runoff losses and the effect of different N fertilizer treatments on N runoff losses during the autumn and winter, 2010–2012. The results demonstrated that surface runoff was significantly and positively related to rainfall. The highest risk of N runoff loss occurred one week after fertilization, and top dressing increased this risk. NO3−-N was the main runoff component, accounting for 49.32–71.82% of the total N losses. The concentration of NO3−-N was significantly and positively related to the concentration of total N in the runoff. Significant differences in N runoff losses were observed between N fertilizer treatments. N runoff losses from conventional fertilizer were 10.43–22.68kgha−1, significantly higher than from other treatments, and the total N net runoff loss rates for conventional fertilizer treatment were 3.48–7.56%. The application of organic fertilizer reduced N runoff loss by 15.70–18.14% compared to conventional fertilizer application. Organic–inorganic compound fertilizer reduced N runoff loss by 27.37–36.27% compared with conventional fertilizer. Slow-release fertilizers had very significant positive effects in controlling N runoff loss, with a 58.29–61.01% reduction for sulfur-coated urea, a 49.33–56.05% reduction for biological carbon power urea, and a 59.79–63.59% reduction for bulk-blend controlled-release fertilizer relative to conventional fertilizer. This study provides vital baseline information for fertilizer choice and management practices, which can be used to reduce N runoff losses and encourage the development of new fertilizer strategies for vegetable planting.

경북지역 고추, 콩, 옥수수, 배추밭의 잡초종 발생 분포와 우점 양상

In this study, we surveyed the distribution pattern and dominance of weeds occurred in four summer crop fields, hot pepper, soybean, maize, and Chinese cabbage in Gyeongbuk province. The weeds were summarized as 32 family and 132 species in hot pepper field, 31 family and 116 species in soybean field, 37 family 134 species in maize field, finally 35 family and 170 species in Chinese cabbage field. Among these weeds occurred in the four summer crop fields, the compositae was commonly dominant family, it occupied 17.4% in hot pepper field, 18.1% in soybean field, 11.9% in maize field, and 16.5% in Chinese cabbage field. The major five families including compositatae, graminae, polygonaceae, convolvulaceae and cruciferae were occupied 43.2% in hot pepper field, 47.4% in soybean field, 42.5% in maize field, and 43.5% in Chinese cabbage field, respectively. Furthermore, the most dominant weed in the hot pepper, soybean, maize, and Chinese cabbage fields was Portulaca oleracea, Digitaria ciliaris, and Rorippa palustris, respectively. This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in food crop fields of Gyeongbuk province.

In vitro characterization of a (E)-β-farnesene synthase from Matricaria recutita L. and its up-regulation by methyl jasmonate

(E)-β-farnesene is a sesquiterpene semiochemical that is used extensively by both plants and animals for communication. This acyclic olefin is found in the essential oil of chamomile (Matricaria recutita) and was demonstrated that it could attract natural enemies to reduce cabbage aphids in the Chinese cabbage fields. However, little is known regarding the sequence and function of (E)-β-farnesene synthase in M. recutita. In this study, we reported a new full-length cDNA encoding (E)-β-farnesene synthase from M. recutita (Mr-βFS). The cDNA of Mr-βFS consisted of 2010bp including 1725bp of coding sequence encoding a protein of 574 amino acids with a molecular weight of 67kDa. The deduced amino acid sequence exhibits a considerably higher homology to βFS from Artemisia annua (about 92% identity) than to βFSs from other plants (about 20–40% identity). The recombinant enzyme, produced in Escherichia coli, catalyzed the formation of a single product, (E)-β-farnesene, from farnesyl diphosphate. Real-time quantitative PCR (qRT-PCR) analysis showed that Mr-βFS expression was highest in leaves and lowest in disk florets. The treatment of M. recutita with methyl jasmonate (MeJA) significantly enhanced the transcriptional level of βFS gene and the content of (E)-β-farnesene in M. recutita. The transcriptional level of βFS gene was approximately 11.5-fold higher than the control sample and the (E)-β-farnesene emission level ranged from approximately from 0.082 to 0.695μg/g after 24h induction. Our results laid a solid foundation for later improving crop aphid resistance by transgenic technology and provided an important basic data for the regulation of valuable products from M. recutita.

Estimation and mitigation of N2O emission and nitrate leaching from intensive crop cultivation in the Haean catchment, South Korea

Considering intensive agricultural management practices and environmental conditions, the LandscapeDNDC model was applied for simulation of yields, N2O emission and nitrate leaching from major upland crops and temperate deciduous forest of the Haean catchment, South Korea. Fertilization rates were high (up to 314kgNha−1year−1) and resulted in simulated direct N2O emissions from potato, radish, soybean and cabbage fields of 1.9 and 2.1kgNha−1year−1 in 2009 and 2010, respectively. Nitrate leaching was identified as the dominant pathway of N losses in the Haean catchment with mean annual rates of 112.2 and 125.4kgNha−1year−1, causing threats to water quality and leading to substantial indirect N2O emissions of 0.84 and 0.94kgNha−1year−1 in 2009 and 2010 as estimates by applying the IPCC EF5. Simulated N2O emissions from temperate deciduous forest were low (approx. 0.50kgNha−1year−1) and predicted nitrate leaching rates were even negligible (≤0.01kgNha−1year−1). On catchment scale more than 50% of the total N2O emissions and up to 75% of nitrate leaching originated from fertilized upland fields, only covering 24% of the catchment area. Taking into account area coverage of simulated upland crops and other land uses these numbers agree well with nitrate loads calculated from discharge and concentration measurements at the catchment outlet. The change of current agricultural management practices showed a high potential of reducing N2O emission and nitrate leaching while maintaining current crop yields. Reducing (39%) and splitting N fertilizer application into 3 times was most effective and lead to about 54% and 77% reducing of N2O emission and nitrate leaching from the Haean catchment, the latter potentially contributing to improved water quality in the Soyang River Dam, which is the major source of drinking water for metropolitan residents.

Indigenous generalist predators and plant residues: conservation biological control of pests in an organically managed cabbage field

Plant residues are viewed as an important source for organic matter in farmlands. We studied if wheat straw and weed residues applied to an organically managed cabbage field by favoring alternative prey may improve the suppression of lepidopteran pests by indigenous generalist predators. The trophic characteristics of predators were determined by a stable isotope approach (δ13C and δ15N). The relative contribution of alternative prey in predators species' (i.e. wolf spiders) diet was estimated using a mixed model based on their stable isotope signatures. As expected, densities of alternative prey became significantly higher in the plots with added plant residues. Consequently, population densities of predators (wolf spiders, predacious carabids and Japanese tree frogs) also became relatively higher and pest densities lower in these plots. We also note that, besides lepidopteran pests, alternative prey accounted for approximately 80% of predator diets. This finding suggests that they may play an important role in population persistence of generalist predators. The application of organic matter to the field for the enhancement of natural enemies’ impacts through increased alternative preys, which might be useful to manage lepidopteran pests in organic cultivation of cabbage.

Two year field study to evaluate the efficacy of Mamestra brassicae nucleopolyhedrovirus combined with proteins derived from Xestia c-nigrum granulovirus.

Japan has only three registered baculovirus biopesticides despite its long history of studies on insect viruses. High production cost is one of the main hindrances for practical use of baculoviruses. Enhancement of insecticidal effect is one possible way to overcome this problem, so there have been many attempts to develop additives for baculoviruses. We found that alkaline soluble proteins of capsules (GVPs) of Xestia c-nigrum granulovirus can increase infectivity of some viruses including Mamestra brassicae nucleopolyhedrovirus (MabrNPV), and previously reported that MabrNPV mixed with GVPs was highly infectious to three important noctuid pests of vegetables in the following order, Helicoverpa armigera, M. brassicae, and Autographa nigrisigna. In this study, small-plot experiments were performed to assess concentrations of MabrNPV and GVPs at three cabbage fields and a broccoli field for the control of M. brassicae. In the first experiment, addition of GVPs (10 µg/mL) to MabrNPV at 106 OBs/mL resulted in a significant increase in NPV infection (from 53% to 66%). In the second experiment, the enhancing effect of GVP on NPV infection was confirmed at 10-times lower concentrations of MabrNPV. In the third and fourth experiments, a 50% reduction in GVPs (from 10 µg/mL to 5 µg/mL) did not result in a lowering of infectivity of the formulations containing MabrNPV at 105 OBs/mL. These results indicate that GVPs are promising additives for virus insecticides.