Insecticidal activity influence of beta-cypermethrin on the pathogenicity of Beauveria bassiana against Aleurodicus disperses

The bioactivities of entomopathogen, Beauveria bassiana and a chemical beta-cypermethrin against Aleurodicus disperses were tested during these studies. The LC₅₀ values of B. bassiana were 2.74 × 10¹⁰, 1.03 × 10⁸conidia/ml after 5 and 10 days of fungal treatment. Beta-cypermethrin gave an apparent increase in adjusted larval mortality in a dose dependent manner whereas no influence of beta-cypermethrin (10 ppm) was observed on percent germination and mycelial growth of B. bassiana. Furthermore, the synergism between B. bassiana and beta-cypermethrin was also studied under laboratory and field conditions. Percent accumulated adjusted mortality of A. disperses after the application of different concentration of beta-cypermethrin and B. bassiana showed that the mortalities were directly related to the concentration of beta-cypermethrin in the mixtures and their accumulative effect was retained for an extended period.     

Bacillus thuringiensis a potential control agent for the Colorado potato beetle

In laboratory tests conducted to determine the effectiveness of the exotoxin ofBacillus thuringiensis against the Colorado potato beetle,Leptinotarsa decemlineata (Say), applications sprayed on tomato foliage at dilutions ranging from 10^?1 through 10^?4 killed 90% of the 1st and 2nd stage beetle larvae. As the dosage decreased, the time to achieve this level of mortality increased from 4 to 9 days. Adult beetles were not killed by these treatments; however they did cease feeding. In field tests, the highest dosages ofB. t. sprayed on either tomato or potato plants provided adequate or nearly complete protection when applied weekly. Young larvae that ingested sub-lethal doses developed into adults with atrophied mouthparts and antennae, transformations of the paired parts of the labial palps into an unpaired part, the appearance of a tarsal-like claw on a palp, and malformation of the cranial sclerities.     

解淀粉芽孢杆菌B9601-Y2提高玉米生长和产量的效应

采用促进植物生长的解淀粉芽孢杆菌B9601-Y2拌、浸玉米种子和浇灌土壤后均能显著提高玉米生长速度和生物量。3×101～3×105 cfu/mL浓度菌液浸泡玉米种子1 h,播种后5 d苗高比对照(清水)提高119.88%～168.85%;浸种2 h,3×104 cfu/mL和3×105 cfu/mL处理则有抑制作用。采用1.6×108、6.2×107、3.9×107 cfu/mL菌液浇灌土壤,播种后7 d苗重比对照增加20.75%、27.36%和33.96%。以3.9×107～1.6×108 cfu/mL浓度菌液拌种处理,15 d苗龄的植株重量比对照增加4.03%～29.35%,在收获期株高增加6.00%～16.29%,产量增加5.76%～11.81%。高浓度处理促生长效果不如中浓度处理。     

Biocontrol of rice blast by the phenaminomethylacetic acid producer of Bacillus methylotrophicus strain BC79

Strain BC79, isolated from primeval forest soil in Qinling, Mountains, China, was identified as Bacillus methylotrophicus based on morphological, biochemical, physiological and chemotaxonomic analyses as well as phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi in dual cultures on solid media. For exploring potential biocontrol activity, we assessed fermentation conditions for studying B. meth1ylotrophicus BC79. The active substance of BC79, phenaminomethylacetic acid, was extracted by TLC and HPLC, and identified as the strongest inhibitory substance described in B. methylotrophicus. Experiments in a greenhouse showed that application of BC79 culture filtrates 24 h before inoculation of Magnaporthe oryzae, the causal agent of rice blast, had 89.87% biocontrol efficiency. B. methylotrophicus BC79 colonized rice plant tissues and at 10 days after filtrate application, its population in leaves (1.65 × 10⁸ CFU/g) was much larger than in stems (6.78 × 10⁷ CFU/g) or roots (3.56 × 10⁷ CFU/g). Field trials indicated that BC79 culture filtrate (4000 g/667 m²) showed the highest efficiency for M. oryzae, with 84.8% biocontrol effect, followed by of 15% phenaminomethylacetic acid extract (75.5%) and 20% tricyclazole (76.1%). Seedling and post-transplant stages were the best periods to apply BC79 for control of rice blast. The B. methylotrophicus BC79 strain hence has enormous potential as an agricultural agent for biocontrol of rice blast.     

Field evaluation of Lymantria obfuscata multiple nucleopolyhedrovirus for the management of Indian gypsy moth in Jammu & Kashmir,India

The Indian gypsy moth (Lymantria obfuscata) is a pest of national significance, which attacks a wide range of forest and fruit crops in India. The outbreaks of this pest over the past few years spurred interest towards sustainable biointensive approaches for quality fruit production of apple and walnut for agricultural export in Jammu & Kashmir (J & K). The exploratory survey's were conducted for the isolation of native strains of L. obfuscata multiple nucleopolyhedrovirus (LyobMNPV) and field evaluation was conducted to determine the most promising strain as a potential biological control agent of this pest. The virus was recovered from different locations of J&K with its natural incidence varying from 0.77 to 7.43 percent. This is the first report from the Indian sub-continent and worldwide of the occurrence of NPVs in natural larval populations of L. obfuscata. The in vivo mass production was optimised by inoculating per os late 3rd instar L. obfuscata larvae with an inoculum dose of 1.44 × 10⁵ OBs/larva and followed by a 10 day incubation period. To prevent the disintegration of larval cuticle and microbial contamination, moribund larvae were harvested with an average yield of 1.42 × 10⁸ OBs/larva. The field application of LyobMNPV against the host populations on apple and willow with the pre-standardised dosage of 2.5 × 10¹² OBs/ha reduced the larval population density by 25–63%. In the year following application, the larval population density in the treated blocks was 19–28% lower as compared to controls on both apple and willow. This suggests that the virus has considerable potential as a biocontrol agent and the timely application with LyobMNPV on non-fruit trees such as willow which are the preferred hosts for egg laying may help to initiate viral epizootics to keep population outbreaks under check.     

Improved procedures for the isolation and culture of protoplasts fromSolanum etuberosum

An efficient and convenient procedure for the isolation of protoplasts fromSolanum etuberosum is described. Excised leaves of plants grownin vitro were preconditioned for 3 days in the dark at 4 C. A 16 h enzyme digestion followed with purification by flotation in Babcock bottles produced a mean yield of 12.5 × 10⁶ protoplasts/g fresh weight. Protoplast viability as judged by morphology at the time of isolation was 89%. Liquid preculture for 1 day at 1 × 10⁶ protoplasts/ml was used prior to plating at 1 × 10⁵ protoplasts/ml and gave a mean survival of protoplasts of 43% after 8 days in culture.     

Efficacy of Bacillus subtilis MBI 600 Against Sheath Blight Caused by Rhizoctonia solani and on Growth and Yield of Rice

Rice sheath blight disease(ShB),caused by Rhizoctonia solani,gives rise to significant grain yield losses.The present study evaluated the efficacy of Integral?,the commercial liquid formulation of Bacillus subtilis strain MBI 600,against rice ShB and for plant growth promotion.In greenhouse studies,four log concentrations of Integral(from 2.2×106 to 2.2×109 cfu/mL) were used as seed treatment(ST).After 25 d,seedlings were dipped(SD) into Integral prior to transplanting.At 30 d after transplanting(DAT),leaf sheaths were inoculated with immature sclerotia of the pathogen.At 45 DAT,a foliar spray(FS) with Integral was applied to some treatments.The fungicide control was 50% carbendazim at 1.0 g/L,and a nontreated control was also included.Overall,there were 10 treatments,each with five replications.ShB severity was rated at 52 DAT,and seedling height and number of tillers per plant were rated at 60 DAT.In 2009,two field trials evaluated Integral at 2.2×108 and 2.2×109 cfu/mL.Integral was applied as ST,and seedlings were produced in a nursery bed.After 32 d,seedlings were treated with Integral as SD and transplanted into 10 m2 blocks.Foliar sprays were given at 45 and 60 DAT.There were seven treatments,each with eight replications arranged as a factorial randomized complete block design.At 20 DAT,the plots were broadcast inoculated with R.solani produced on rice grains.Seedling height before transplanting,ShB severity at 90 DAT,and grain yield at harvest were recorded.Integral at 2.2×109 cfu/mL provided significant increase of seedling heights over other treatments under greenhouse conditions.The Integral treatments of ST + SD + FS at 2.2×109 cfu/mL significantly suppressed ShB over other treatments.In field studies,Integral provided significant increase of seedling height in nursery,and number of tillers per plant,compared with the control.ShB severity was significantly suppressed with higher concentrations of Integral compared to lower concentrations.Grain yield were the highest at an Integral concentration of 2.2×109 cfu/mL.Overall,Integral significantly reduced ShB severity,enhanced seedling growth,number of tillers per plant and grain yield as ST + SD + FS at the concentration of 2.2×109 cfu/mL under the conditions evaluated.     

An investigation on the bacterial flora of Agriotes lineatus (Coleoptera: Elateridae) and pathogenicity of the flora members

The wireworm Agriotes lineatus (L.) (Coleoptera: Elateridae) is a serious agricultural pest of various vegetables and fruits throughout the world. To find an effective and safe biological control agent against this pest, we investigated the bacterial flora of A. lineatus. Nineteen different bacterial strains were isolated and identified as Paenibacillus sp. (Ag1), Cellulomonas sp. (Ag2), Bacillus subtilis (Ag3), Staphylococcus sp. (Ag4), Enterococcus mundtii (Ag5), Staphylococcus sp. (Ag6), Sphingobacterium sp. (Ag7), Staphylococcus pasteuri (Ag8), Arthrobacter gandensis (Ag9), Bacillus sp. (Ag10), Chryseobacterium sp. (Ag11), Streptomyces sp. (Ag12), Oerskovia turbata (Ag13), Bacillus thuringiensis (Ag14), Pseudomonas fluorescens (Ag15), Oerskovia jenensis (Ag16), Arthrobacter gandavensis (Ag17), B. thuringiensis (Ag18), and Pseudomonas plecoglossicida (Ag19) based on conventional and molecular tests. A. gandavensis and P. plecoglossicida were isolated for the first time from any insect. The insecticidal effects of these 19 bacterial isolates and the additional 11 isolates belonging to Bacillus genus isolated from different hosts were tested on third instar larvae of A. lineatus. Ag17 (A. gandavensis), Ag18 (B. thuringiensis), and Ag19 (P. plecoglossicida) from the bacterial flora of A. lineatus, and two Bacillus isolates (Bacillus circulans Ar1 from Anoplus roboris and B. thuringiensis subsp. kurstaki BnBt from Balanicus nucum) showed 100% mortality 10 days after treatment. Our results indicate that the bacterial isolates tested in this study may be considered as a possible microbial control agent against A. lineatus.     

白僵菌与苏云金芽胞杆菌水悬浮剂研制及田间防治玉米螟研究

通过室内生物测定,研究球孢白僵菌和苏云金芽胞杆菌联合防治玉米螟的效果。研究表明,确定白僵菌与苏云金芽胞杆菌浓度分别为1.0×106孢子/mL、1.0×109孢子/mL条件下,杀虫效果达到最佳,LT90为6.64(±0.07)d,较1.0×109的Bb LT90缩短26.06%。通过助剂悬浮率、乳化效果以及助剂对微生物活性影响等确定1个白僵菌与苏云金芽孢杆菌水悬浮剂剂型配方。田间防治玉米螟结果表明,两种生防菌均在防治过程中起作用,田间玉米受害株数、活虫数均明显低于未施药对照,防治效果优于单一使用白僵菌或苏云金芽胞杆菌。     

Low susceptibility of Spodoptera cosmioides,Spodoptera eridania and Spodoptera frugiperda (Lepidoptera: Noctuidae) to genetically-modified soybean expressing Cry1Ac protein

Spodoptera cosmioides (Walker), Spodoptera eridania (Stoll) and Spodoptera frugiperda (J. E. Smith) have caused significant damage on soybean Glycine max (L.) Merrill in Brazil. Genetically-modified MON 87701 × MON 89788 soybean that expresses the Cry1Ac protein is potentially an alternative tool for the management of these species. Purified protein bioassays were done to evaluate the susceptibility of S. cosmioides, S. eridania and S. frugiperda to Cry1Ac protein. The level of efficacy of the Bt soybean plants in controlling these species was measured through laboratory and greenhouse trials under high artificial insect infestations. The biology of these insects was evaluated over their development cycles to understand their life history when fed on Bt soybean. Purified Cry1Ac protein at the maximum concentration tested (100 μg Cry1Ac mL⁻¹ diet) resulted in low mortality of S. cosmioides and S. eridania (<13%) and intermediate mortality of S. frugiperda (50%). No significant effects of the Bt soybean plants were observed in the life table parameters of S. cosmioides and S. eridania. However, S. frugiperda fed on Bt soybean plants had a prolonged larval stage (by 5 days), reduced larvae viability, increased mean generation time (by 8 days) and reduced intrinsic rate of increase. In general, the Bt soybean plants showed poor control of Spodoptera species when evaluated by leaf-disc bioassay and greenhouse trials. Consequently, other control tactics must be used in combination with MON 87701 × MON 89788 soybean in the field for the efficient management of S. cosmioides, S. eridania and S. frugiperda.     

Control of postharvest radish decay using a Cryptococcus albidus yeast coating formulation

An antagonist yeast strain, WY-1, was identified using 18S and internal transcribed spacer (ITS) 1-5.8S-ITS2 rDNA region sequences. The 18S and ITS1-5.8S-ITS2 rDNA sequences of this yeast strain were amplified and sequenced using the universal primer pairs NS1/NS8 and ITS4/ITS5. The ITS1-5.8S-ITS2 rDNA sequence and 18S neighbor-joining tree showed that WY-1 was a strain of Cryptococcus albidus. The biocontrol activity of C. albidus WY-1 on postharvest decay of radishes caused by Alternaria spp. and Fusarium spp. was investigated. In vitro, at 10⁸ CFU ml⁻¹ C. albidus WY-1 inhibited the mycelial weight increases of Alternaria spp. and Fusarium spp. by 45.3% and 59.6%, respectively. In vivo, infection incidence and lesion development of radish decay were suppressed by the application of C. albidus WY-1 at 10⁸ CFU ml⁻¹. After 6 days of incubation at 20 °C or 24 days at 4 °C, disease incidences were 2.8% and 1.4%, respectively; however, the disease incidences of control fruit were 98.6% and 87.5% under these incubation conditions, respectively. Application of C. albidus WY-1 and the chemical fungicide thiabendazole were statistically just as effective. Finally, C. albidus cell counts around inoculation sites remained high at 4 °C even 32 days after inoculation (6.7 × 10⁵ CFU per cm²).     

种植密度对全膜双垄沟播玉米子粒灌浆特征、干物质积累及产量的影响

以先玉335为试验材料,研究4个密度水平(4.5×10⁴、5.25×10⁴、6.0×10⁴、6.75×10⁴株/hm²)对旱地春玉米形态指标、灌浆特征、干物质积累、产量及其构成因素的影响。结果表明,随密度增加,株高表现为先增大后减小的趋势,处理间无显著差异,地上部分干物质积累量和叶面积指数提高,营养物质向子粒转运的效率降低。不同处理下产量受有效穗数的影响较大,随着密度增大,群体有效穗比例由77.00%降低至69.00%;灌浆速率和灌浆时间共同影响百粒重,密度较低时,子粒最大灌浆速率出现所用天数提前,有助于子粒灌浆过程提前完成;随着密度增加,穗行数和行粒数均表现为增大趋势,百粒重先增大后减小。因此,本试验中种植密度为4.5×10⁴株/hm²左右时,可以较好地协调玉米群体和个体生长关系之间的矛盾,实现子粒高产和水分高效利用的目标。     

Management of nitrogen and phosphorus rates does not suppress verticillium wilt in yukon gold

Effect of nitrogen and phosphorus fertilization rates on the incidence of Verticillium wilt caused byVerticillium albo-atrum orV. dahliae and tuber yield in potato cv Yukon Gold was evaluated in field plots. In three years of study,V. albo-atrum caused a higher incidence of wilt symptoms (74%–100%) thanV. dahliae (5%–81%) resulting in lower marketable tuber yield. In plots infested withV. albo-atrum, tuber yield ranged from 12.3-22.8 T ha1 compared to 18.1– 31.5 T ha^-1 in plots infested withV. dahliae. Application of nitrogen above (280 kg ha^-1) or below (70 kg ha^-1) the recommended rate of 140 kg ha^-1 at planting did not suppress foliar symptoms or protect against yield loss caused by eitherV. albo-atrum orV. dahliae. Similarly, phosphorus rate adjustments did not consistently affect disease incidence regardless of the pathogen. Management of nitrogen or phosphorus fertility rates at planting does not appear to be a viable approach for suppressing Verticillium wilt in the determinant, wiltsusceptible cultivar Yukon Gold.     

低温冷凉地区超高产春玉米群体生长分析研究

以“三合模式”为基础,从产量构成、光合性能、源库3方面对东北雨养玉米产区产量水平高于1.5×104kg/hm2的不同密度玉米群体进行研究。结果表明:在东北雨养地区玉米要获得高于1.5×104kg/hm2的产量,须选择耐密性品种,密度介于80000～87000株/hm2,叶片光能持续期长,吐丝后光合势大于2.87×106m2/(d·hm2),叶面积比率与叶面积维持在合理水平,生育期平均净同化率大于5.21g/(m2·d),营养生长时期相对生长率迅速,吐丝到灌浆期相对生长率稳定,吐丝后干物质积累量高于16192.48kg/hm2,转化率大于83.6%,经济系数维持在0.5左右。     

种植密度对不同熟期玉米品种子粒含水率和产量的影响

2019～2020年以陕单 650(中熟)和东单 60(晚熟)为材料,设置 4个种植密度 6.0×10⁴、 7.5×10⁴、 9.0×10⁴和10.5×10⁴株/hm²,研究密度对玉米产量及子粒含水率的影响。结果表明,增密可以提高不同熟期玉米品种的产量,陕单 650在密度为 9.0×10⁴株/hm²时最优产量为 18 083.5 kg/hm²,东单 60在密度 7.5×10⁴株/hm²时最优产量为17 472.9 kg/hm²。两个品种粒重及子粒含水率随密度的增大而减小,陕单 650达到最大灌浆速率的天数、平均灌浆速率较东单 60均早 4 d和高 0.06 g/d;陕单 650和东单 60子粒平均脱水速率为 0.98%/d和 0.93%/d,陕单 650在生理成熟 4 d后子粒含水率迅速降至 25%。当密度为 9.0×104株/hm²时,陕单 650的叶片干物质转运率明显高于东单 60。通过适度增密提高产量、缩短生育期降低子粒水分的技术途径,协同实现陕西春玉米密植高产机械子粒收获生产。     

种植密度对熟期不同夏玉米群体光合性能及产量的影响

在大田试验条件下,研究3个种植密度(67 500、82 500、97 500株/hm2)对早熟品种登海618和中晚熟品种登海605的群体光合性能及产量的影响。结果表明,随种植密度增加,单叶净光合速率下降,而群体光合速率、叶面积指数及冠层光合能力均增强,保证了群体光合产物的积累,使玉米总产量提高。两个品种均在97 500株/hm2密度下产量达到最大,且在早收获10 d的情况下登海618产量高于登海605,分别为13 840 kg/hm2和13 080 kg/hm2。随密度增大,登海605倒伏率显著提高,使其产量受到影响。     

Effects of Bacillus subtilis strain QST 713 and storage temperatures on post-harvest disease development on greenhouse tomatoes

Tomato plants in two commercial greenhouses were treated with Rhapsody (Bacillus subtilis strain QST 713, rate of 1.45%) once every 4 weeks during 2012–2013 to determine effects on post-harvest fruit infection. Populations of Bacillus and disease incidence were monitored weekly from harvested fruit over an 18-week period. Population levels of Bacillus ranged from 75 to 110 × 10⁴ colony forming units (cfu) cm⁻² of fruit surface area one week after application to 25–30 × 10⁴ cfu cm⁻² of fruit surface area 4 weeks after application. Disease incidence on harvested fruit incubated at 21 °C for 7–10 days was variable, due to variation in inoculum levels within the greenhouse as well as variable environmental conditions. Both disease incidence and severity were significantly reduced on Rhapsody-treated fruit, especially in the 1–2 week period following application. Post-harvest storage temperature (13 °C vs. 21 °C) and incubation time (12 vs. 16 days) had a significant effect on final disease severity. Rhapsody-treated fruit incubated at 13 °C had an average of 1–2% fruit infection compared to up to 20% infection on untreated fruit at 21 °C. The most frequent pathogens affecting fruit quality were Penicillium sp. and Rhizopus stolonifer. Rhapsody applications made every 4 weeks maintained sufficiently high populations of Bacillus on the fruit surface to prevent spread of these fungi onto the fruit, resulting in significant post-harvest disease control on fresh market tomatoes. When combined with storage at 13 °C for no more than 12 days, disease was reduced to negligible levels.     

灌溉量对玉米生育后期脱水阶段子粒水分的影响

以玉米品种先玉335、九圣禾2468为试验材料,测定不同灌溉量处理的玉米生理成熟至田间收获期间子粒含水率的变化。结果表明,生育期等量灌溉和分配灌溉量试验,在9.0×10~4株/hm^2、12.0×10~4株/hm^2种植密度下,灌溉量增加使子粒含水量呈增加趋势,且脱水速率减慢。灌溉量从3 600 m^3/hm^2增至7 200 m^3/hm^2,子粒含水率分别增加0.94~2.87个百分点,差异达显著水平。灌溉量与种植密度双因素辅助试验,在种植密度6.0×10~4株/hm^2至13.5×10~4株/hm^2时,灌溉量从3 000 m^3/hm^2增至6 000 m^3/hm^2,子粒含水率分别增加1.60~5.00个百分点;在灌溉量3 000 m^3/hm^2和6 000 m^3/hm^2条件下,种植密度从6.0×10~4株/hm^2增至13.5×10~4株/hm^2,子粒含水率有差异,无明显增加或降低趋势;4 500 m3/hm^2灌溉量下各种植密度处理间的子粒含水率未表现出显著差异。     

不同种植密度和栽培形式对辽单565光合性能、农艺性状及产量的影响

以矮秆耐密型玉米辽单565为试材,研究不同种植密度和栽培形式对其光合性能、农艺性状及产量的影响。结果表明,叶面积指数随着种植密度的增加总体上呈增加趋势,当种植密度超过6.75万株/hm2时,宽窄行处理叶面积指数较高。除清种处理外,光合速率随着种植密度的增加总体上呈单峰曲线变化,当种植密度超过6.00万株/hm2时,二比空和宽窄行栽培形式光合速率较高。与穗位叶和穗下叶叶向值相比,穗上叶的叶向值较高。随着种植密度的增加,穗位高逐渐增加,穗长和百粒重逐渐下降。与其他栽培形式相比,大垄双行栽培形式在不同种植密度下茎粗和穗长变化较小,且茎粗表现较好。不同生态区域测产结果表明,栽培形式间和种植密度间均存在极显著差异,栽培形式与种植密度互作极显著,在缩距增密、大垄双行和宽窄行栽培形式基础上,种植密度超过6.00万株/hm2时,辽单565易获高产。     

种植密度与化学调控对春玉米茎秆性状及抗倒伏能力的影响

以迪卡 159为供试材料,设置 6.0×10⁴(D1)、 7.0×10⁴(D2)、 8.0×10⁴(D3)和 9.0×10⁴株/hm²(D4) 4个密度水平,在 8展叶期喷施化控剂玉多十(HK)和清水为对照(CK)2个处理,研究不同种植密度与化学调控技术对植株茎秆性状的影响。结果表明,随种植密度的增大,迪卡 159的株高、穗位高显著增高,茎秆节间长变长,茎粗变小,扁率增大,茎秆强度变弱。HK处理后,株高、穗位高显著降低, 4～5节位节间长大幅度减少,茎粗增加,扁率降低,茎秆强度增强,茎秆横折强度与穿刺强度在 3个时期均随种植密度的上升呈现整体下降趋势,并于乳熟期达到最大值。HK处理后,茎秆的横折强度与穿刺强度增强,其中, 4～5节位提升幅度最大。HK处理增加了灌浆期与乳熟期第 3节位的木质素与纤维素含量, D1、 D2、 D4密度下效果显著。倒伏率随种植密度的升高呈上升趋势; HK处理可以显著降低倒伏率, 4个密度下分别比对照降低了26.15%、 47.72%、 35.17%和33.82%。