Research Overview on Occurrence and Control of Tetranychus urticae Koch in China

Tetranychus urticae Koch;Insecticide resistance;Chemical control This paper elaborates the occurrence factors and damage characteristics of Tetranychus urticae Koch in China,and emphatically summarizes three main control strategies of T.urticae,namely agricultural control,chemical control and biological control,as well as research progress in its resistance mechanisms.The problems existing in controlling T.urticae and its resistance management strategies are put forward,to provide a theoretical basis for the resistance management and comprehensive control of T.urticae.

Effects of Torreya grandis Root Rot on Seedling Growth and Screening of Its Chemical Control Agents

[Objectives]This study was conducted to prevent the occurrence of root rot disease in Torreya grandis and improve the yield and quality of T.grandis.[Methods]One-year-old and two-year-old seedlings of Torreya grandis‘Xifei’and‘Cufei’were inoculated with the root rot pathogen Fusarium fujikuroi,and the changes in photosynthesis,chlorophyll content,malondialdehyde,and defense enzyme system(superoxide dismutase,peroxidase,and catalase)activity in leaves of T.grandis seedlings were investigated using water as a control.Meanwhile,the control effects of 80%carbendazim wettable powder,64%metalaxyl·mancozeb wettable powder,430 g/L tebuconazole suspension and 30%difenoconazole·cyproconazole EC on root rot in T.grandis were investigated.[Results]After inoculation with the pathogen F.fujikuroi,the net photosynthetic rates and transpiration rates in leaves of T.grandis‘Xifei’and‘Cufei’decreased,and the contents of chlorophyll decreased,while the contents of malondialdehyde increased,and the contents of superoxide dismutase and catalase increased with time.However,peroxidase showed a high activity in T.grandis‘Cufei’only,but a trend of"increasing-decreasing-increasing"in T.grandis‘Xifei’.Among the four chemical control agents,64%metalaxyl·mancozeb wettable powder had the best control effect on root rot of T.grandis caused by the pathogenic fungus F.fujikuroi.[Conclusions]The net photosynthetic rate,transpiration rate,chlorophyll content,malondialdehyde content,superoxide dismutase activity and catalase activity could all be used as screening indicators for T.grandis varieties resistant to root rot.Meanwhile,64%metalaxyl·mancozeb wettable powder could be used as a control agent for root rot on T.grandis.

Chemical Control of Herbicide Monosulfuron Plus Propazine 44% WP against Weeds in Millet Fields and Study on Factors Influencing Yield of Millet

[Objective] The paper was to resolve the poor efficacy or phytotoxicity problems in promotion of herbicide monosulfuron plus propazine 44% WP. [Method] Using orthogonal test and Duncan＇s new multiple range statistical analysis with four factors four levels and three factors two levels, the effects of factors such as herbi- cide dose, irrigation water volume, quality of soil preparation and soil moisture content on chemical control of monosulfuron plus propazine 44% WP against weeds and millet yield were compared in the test. [Result] Seven factors all had great impact on control effect of monosulfuron plus propazine 44% WP against weeds, of which her- bicide dose, irrigation water volume, quality of soil preparation and soil moisture content were the most important factors affecting millet yield. According to millet yield and economic benefit, the optimal scheme to ensure safe, efficient and economic control of monosulfuron plus propazine 44% WP against weeds was as follows： the dose of monosulfuron plus propazine 44% WP was 1 800 g/hm2, the soil was treat- ed after sowing and before seedling emergence; the soil should be smooth and sol- id; the soil moisture should reach 15%; the fields should not be irrigated after herbi- cide application, and the damage of weeds in millet fields could be effectively con- trolled within 45 d during high efficacy duration, especially the damage of dicotyledonous weeds. [Conclusion] The study provided useful information for comprehensive technology of weeds control and ensuring high yield and good harvest of millet.

Study on the Effective Prevention and Control of Maize Rough Dwarf Disease in Different Areas with Varying Epidemic Intensity in Shandong Province

[ Objective] This study aimed to investigate the effective prevention and control of maize rough dwarf disease in different areas with varying epidemic inten-sity in Shandong Province. [Method] Control effects of single application of virus in-hibitors and composite application of virus inhibitors with seed dressing agents and pesticides on maize rough dwarf disease in different areas with varying epidemic intensity were investigated. [Result] The same treatment possessed entirely different effects in severely affected areas and slightly affected areas. To be specific, single application of virus inhibitors in slightly affected areas exhibited good control effects, with a control efficiency of 76.59% and yield increment rate of 158.21%; in severely affected areas, single application of virus inhibitors led to low control efficiency and yield increment rate. The highest control efficiency of composite application of virus inhibitors with seed dressing agents and pesticides in severely affected areas was 71.38%, and experimental plots changed from total crop failure to have certain eco-nomic output. [Conclusion] ln different areas with varying epidemic intensity of maize rough dwarf disease, different application modes should be adopted according to lo-cal conditions, thereby saving cost and improving control efficiency.

Multivariable Decoupling Predictive Control with Input Constraints and Its Application on Chemical Process

A constrained decoupling (generalized predictive control) GPC algorithm is proposed for MIMO (malti-input multi-output) system. This algorithm takes account of all constraints of inputs and their increments. By solving matrix equations, the multi-step predictive decoupling controllers are realized. This algorithm need not solve Diophantine functions, and weakens the cross-coupling of the variables. At last the simulation results demon- strate the effectiveness of this proposed strategy.

Ecological control of forest pest： a new strategy for forest pest control

In comparison with integrated pest management and chemical control, the authors put forward a new strategy of forest pest control, named ecological control of forest pest （ECFP）. This paper reviewed the development history, summarized the concept and principles of ECFP, discussed the technology and methods of ECFP, and evaluated the ECFP and its application conditions.

Effects of DPC on Agronomic Traits and Economic Characters of Machine-Harvested Cotton in the Yellow River Valley of China and Chemical Control Techniques

[Objective] The aim was to investigate the effects of DPC chemical controlling technique on agronomic traits, yield and quality of machine-harvested cotton in the Yellow River Valley of China, and clarify the reasonable control period and the application amount of DPC. [Method] The new machine-harvested cotton variety Hengmian HD008 was used as the test material, and 3 different DPC treatments were set. [Result] DPC significantly reduced plant height and branch length, reduced branch angle and leaf area, so the rational control can effectively shape the ideal plant type of machine-harvested cotton. DPC had significant effects on yield and yield components, and the proper amount of DPC could increase the number of bolls during hot days, the number bolls in autumn and the total number of bolls. It increased the boll weight and seed index, but decreased lint percentage decreased, and proper amount of DPC could increase the yield. DPC significantly increased the specific breaking strength of fibers, and proper control could improve the uniformity of fibers, but other indexes had no significant influence. [Conclusion] According to the requirements of machine harvest to the agronomic traits of cotton and the growth characteristics of cotton plant, chemical control could begin after floral bud emergence in cotton about every 10 d, and the spraying amount can be controlled according to the growth amount of the main stem. The daily growth amount of plant height should be controlled at 1.5-1.8 cm, and the plant height should be within 75-90 cm.

Nonlinear incidence rate of a pest management SI model with biological and chemical control concern

A pest management SI model with impulsive releases of infective pests and spraying pesticides is proposed and investigated. We prove that all solutions of the model are uniformly ultimately bounded. We also obtain the sufficient conditions of globally asymptotic stability periodic solution of pest-extinction and permanence of the model. The approach of combining impulsive releasing infective pests with impulsive spraying pesticides provides reliable tactical basis for the practical pest management.

CHEMICAL CONTROL OF ZETHENIA RUFESCENTARIA MOTSCH

Zethenia rufescentaria Motsch. has outbroken successively in the larch plantation of Jixi region and seriously damaged stands since 1990. Chemical control was studied for controlling the occurrence of the pest. The results showed as follows: When the third or the forth instar larvae was controlled with smoke agent of 5% Lindane, the most suitable time was July 10-13. The area controlled was 2000 hm2. The dosage was 7.5 kg/hm2 and the mortality of the pest reached 93.5%. 25%dimilin Ⅲ (flowable formulation) was used to prevent the third instar larvae. The best time was about July 5. The dosage was 150g/hm2. The mortality of the pest reached 89.85%. 3% Hexyclan dusting was also used to control adults of the pest. The best time was before the peak of their emergence (June 3). the dosage was 11.3 kg/hm2. The mortality of the pests reached 89.6%.

Chemical control of Apriona germari(Hope) larvae with zinc phosphide sticks

Larvae of Apriona germari （Hope）, found widely in China, cause serious damage to trees and are difficult to control. Since some biological control methods have not been applied effectively in the field, chemical control methods are used widely. Because of low cost, no poisonous residues and relatively safe application, zinc phosphide sticks have been tested to control the larvae as a matter of urgency. However, there were no criteria about the dosage and use. Given the characteristics of larvae tunnels on triploid Populus tomentosa trees and the one-on-one way of using poison-fumigated sticks, the larvae were treated by three treatments with zinc phosphide sticks. The treatments are as follows： inserting one stick into the first hole of the tunnel from bottom to top （T1）, inserting a stick into each of the lowest two holes （T2） and inserting one stick into the first and third hole from bottom to top separately （T3）. We cleared the frass around the holes and on the ground before inserting the sticks and blocking every hole with mud for each treatment. After the fourth investigation was carried out, the larvae of CK were still active, and had caused serious damage and emanated fresh fi＇ass from old and new holes. Some larvae treated with T1 and T2 were in an intermediate state, but all of the larvae treated with T3 died completely and their old holes had healed. The results show that inserting zinc phosphide sticks （the extent of dispersion of the sticks was 20%） is a feasible method to control A. germari （Hope） larvae in triploid P. tomentosa of pulpwood trees. Because there were no statistically significant differences （p 〉 0.05） among the three treatments, we recommend that T1 should be used for economic efficacy.

Weed Occurrence and Chemical Control Test in Public Lawn of Suzhou Urban Area of China

Weed occurrence and damage in public green lawn of Suzhou urban area was assessed using five-grade weed visual survey method. The occurrence and damage of weeds in public green lawn of Suzhou City was very common. There were totally 67 species of weeds in green lawn, with the density of 6.5 plant/m^2, the relative abundance of 7.6%, the relative coverage of 10.3%, the relative height and the occurrence frequency of 100%, and the overall damage level of weeds was above the forth level. There were 14 species of major weeds causing damage, and 15 species of weeds were found to pose regional damage. Haloxyfop-R-methyl or Ping＇an-14 could be applied to control grassy weeds in clover lawns, with the herbicidal effect above 90%. MCPA, fluroxypyr, or clopyralid could be administra- ted alone to control broadleaf weeds in Cynodon dactylon or Festuca elata lawn, with the herbicidal effect above 85%. Since the weed species in weed communities of lawn were different, the types of herbicides should be targeted, or SD additives could be added to improve the herbicidal effect.

Effects of Straw Returning and Chemical Control on Occurrence Quantity of Athetis lepigone Moschler in Summer Maize Fields

Athetis lepigone Moschler is a new kind of insect pest occurring in summer corn production areas. By investigation, it was found especially serious in straw returning fields. In this paper, its damage status was investigated in straw returning and chemical controlled fields, respectively. The results showed that the rate of damaged plants was 82% and the maximum pest number per 100 plants was 88 heads in the straw returning fields without chemical control. The application of herbicides and pesticides had no significant effects on occurrence quantity and damage rate, but the pest number per 100 plants decreased a little compared to the fields without chemical control. In the surer er maize fields without straw returning, the application of herbicides and pesticides could significantly decrease the damage of Athetis lepigone, the rate of damaged plants was 20%, and the pest number per 100 plants was 6.

Effects of chemical ecological adjustment and control experiment on phytoplankton community in the Aoshan Bay

There is a low nutrient level in the Aoshan Bay. In June 1999, the chemical adjustmentand control experiment was made in the Aoshan Bay. Following tracts investigation was carried out before the experiment and on the 1st, 2nd, 4th, 5th, 6th and 45th day/after the experiment. While the variance of amount of phytoplankton, the replacement of superior species and the species composition of phytoplankton were researched. The results show that the amount of phytoplankton in the Aoshan Bay rises gradually after the experiment. Ceratium macroceros Cleve of pyrophyta was the dominant species before the experiment, its dominant index was 37.7%. Six days after the experiment, its dominant index dropped to 17.6% . Meanwhile the dominant index of Asterionella japonics Cleve rose from 7.1% to 39.2% , it became the first dominant species. Forty-five days after the experiment, the amount of phytoplankton in the Aoshan Bay was 5.15 to 137.32 times more than that in 1997.

Biological and Chemical Control in Rot Root in Avocado by Phytophthora cinnamomi Rands

＂Avocado sadness＂ caused by the Oomycete Phytophthora cinnamomi Rands, is one of the main diseases affecting this fruit crop in Michoacan, M6xico, without having an efficient control strategy for that. In this research three Trichoderma isolates and Ridomil Gold 4E fungicide were tested in avocado trees infected with this pathogen using the growing and coloring vegetative flow growing. Results were analyzed with an experimental design completely random with four treatments and repetitions. Different responses were presented form avocado trees to each treatment. Trichoderma erinaceum Bissett, Kubicek ＆ Szackacs treatment was the best controlling disease in trees with grade II and III damage. Trichoderma aggressivum Samuels ＆ W. Gams controlled better in trees with grade III damage. At last, Trichoderma arundinaceum Zafari, Graef. and Samuels were the best controlling trees with the highest grade damage. Fungicide Ridomil Gold 4E controlled the disease in trees with the lowest grade damage （I and II）, their medias were similar to witness.

Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistance to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato

Tomato(Solanum lycopersicum)is one of the most widely grown and consumed as fresh vegetable in the world.Sclerotium rolfsii Sacc.is one of the most destructive diseases and affects more than 500 plant species.This study was conducted for“Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistant to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato”.The experiment was conducted at the Royal University of Agriculture and divided into two sections.The first section conducted under in vitro condition consists of four treatments T1 control treatment,T2 copper hydroxide,T3 azoxystrobin+difenoconazole,T4 metalaxyl+mancozeb in Nagoya Laboratory,and had been starting from 11st May to 15th May 2020.Section two was conducted in a pot in net-house which started from 1st January 2019 to 19th February 2019 and 1st January to 19th February 2020 and arranged in RCBD(Randomized Completely Block Design)with six replications and nine treatments.T0 negative control,T1 inoculate but not treatment,T2 metalaxyl+mancozeb,T3 azoxystrobin+difenoconazole,T4 copper hydroxide,T5 acibenzolar-S-methyl,T6 chicken dung+Trichoderma harzianum,T7 acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,T8 acibenzolar-S-methyl+metalaxyl+mancozeb.Data were collected on colonizing diameter in vitro.For pot experiment collected on disease incidence,incubation period Based on the result under in vitro condition metalaxyl+mancozeb highly inhibited germination of Sclerotium rolfsii when compared with another treatment.However,the application of copper hydroxide seems less effective compared with control.For in pot experiment,when treated after symptom of southern blight appeared to seem less effective on the severity of southern blight.In contrast,when applied as a protectant and curative when symptoms appeared only systemic fungicide azoxystrobin+difenoconazole significantly reduced the severity of Sclerotium rolfsii and delayed incubation period while compared with other treatments(p<0.05)and was followed by metalaxyl+mancozeb,whereas,copper hydroxide,acibenzolar-S-methyl,chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+metalaxyl+mancozeb were less effective(p>0.05).Based on the three experiments we can assume that fungicide is more effective in reducing the growth of the pathogen and delaying the incubation period of fungal colonization when compared with biological control and induced resistance.

Chemical Control of Chagas Disease Vectors

This paper presents the reasons why countries to which Chagas disease is endemic should carry out the relevant research themselves. A local technical capability for a rational improvement in the chemical control of vectors is being developed. This research includes (1) the triatomicidal activity of chemical insecticides, (2) determination of the mechanisms of action of these chemicals, (3) search for new synergists of these insecticides, (4) development of fumigation canisters which may be more widely used, and (5) development of new chemicals with a greater potential for use as triatomicides. 1989 Academic Press, Inc.

Research on Chemical Prevention and Control against Stem Base Rot of Sweet Potato

[Objective]The paper was to effectively control stem base rot of sweet potato.[Method]Chemical prevention and control test against stem base rot of sweet potato were conducted for consecutive three years from 2016 to 2018.[Result]The use of carbendazim or carbendazim+mancozeb,and carbendazim+embamycin had significant control effect on stem base rot of sweet potato.However,the applied concentration should be higher than the recommended concentration.Especially the concentration of 50%carbendazim WP should be no more than 300 times,and the prevention and control effect of 100 times dilution would be better.[Conclusion]The types and concentrations of prevention and control agents are determined in the test,which will provide certain basis for chemical prevention and control against stem base rot of sweet potato.

Evaluation of Insecticides Targeting Control of Helicoverpa armigera(Hubner)(Lepidoptera:Noctuidae)

Insecticides from different chemical groups were tested by laboratory bioassay to verify the percentage mortality of Helicoverpa armigera (Hubner 1808) (Lepidoptera: Noctuidae). The experiment was conducted in the Crop Science laboratory—Prof. CinobelinaElvas Campus—UFPI, Bom Jesus, PI, from January to June, 2013. The populations utilized came from the University’s own insect breeding laboratories. Third instar larvae of H. armigera were used to conduct the bioassay. The experimental design was fully randomized, with 13 treatments and four replications. Five larvae were used per replication, with 12 insecticides from 9 different chemical groups and a control. Each treatment consisted of three doses. The methods of application used were topical contact and ingestion in artificial diet. According to the results the percentage mortality of H. armigera larvae varied among the treatments. The results demonstrated that chlorpyrifos and spinosad were effective against third instar H. armigera larvae both on contact and by ingestion. Flubendiamide, acephate, methomyl, Bacillus thuringiensis, dimethoate, chlorantraniliprole and fipronil had good responses to control of H. armigera.

Developmental Tendency of Dry Land Farming Technologies

The developmental tendency of dry land farming technologies in the semiarid area of China were reviewed based on the overview of recent progress in dry land farming researches from China and oversea. It was emphasized that conservation tillage, limited irrigation, genetic modification and chemical control are the important aspects for the dry land farming research and development of the future. In addition, some consid-

Preparation of spherical cobalt carbonate powder with high tap density

Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25±0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.