Plant Protection
To identify the pathogen species causing a noval desease of leaf spot and stem spot of Houttuynia cordata Thunb. in Guanghan City, Sichuan Province, and provides theoretical basis for the scientific management of this disease, the leaves and stems of diseased H. cordata were collected from Guanghan City, and the pathogen was isolated and identified by tissue isolation, pathogenicity testing, morphological characterization, and molecular identification based on ITS, tef1, cal and his3 gene sequences. The results indicate that the mycelium of the pathogen is gray-white to light brown. The conidiomata, which are produced in the late growth stage, can produce two types of conidia: fusiform to oval-shaped α-type conidia and filamentous or hook-shaped β-type conidia. Multiple gene cluster analysis showed that the pathogen formed an individual branch adjacent to the Diaporthe Sojae and D. phaseolorum branches, and formed a big branch with these two branches in the phylogenetic tree, and a new species named D. houttuynia was suggested to establish to accommodate this pathogen. According to morphology and molecular identification, the pathogen causing the noval desease of leaf spot and stem spot of H. cordata in Guanghan City was identified as D. houttuynia.
In order to investigate the occurrence of root knot nematode disease in rice-vegetable rotation fields of Guangxi, and clarify the pathogen species, a sampling survey on the occurrence of rice root-knot nematode disease was carried out in 171 rice-vegetable rotation fields in 27 townships of 14 cities in Guangxi. Nematodes were isolated from samples, and the species was identified by observing the morphological characteristics of second instar larvae and perineal pattern of females, and analyzing ribosomal ITS region and 28S rDNA D2D3 region sequences. The results showed that 64 fields of them were affected with root-knot nematodes, with a detection rate of 37.4% during the rice-growing season and 25.7% during the vegetable rotation. The species of root- knot nematode on rice in Guangxi was confirmed as Meloidogyne graminicola. It indicated that the disease caused by M. graminicola had occurred widely in rice-vegetable rotation fields in Guangxi, and more attention should be paid.
In order to master the quality and safety of edible fungi, the levels of 62 kinds of pesticide residues in edible fungi sold in Beijing from 2021 to 2022 were screened, the pesticide residues of insecticides and fungicides in 6 common edible fungi were evaluated by food safety index method, and the risk of chronic and acute dietary intake of 19 pesticides were also evaluated. The results showed that the IFS values of 15 insecticides and 4 fungicides detected in edible fungi and the average food safety index values of 6 edible fungi were all less than 100. The pesticide residues detected had little influence on the edible fungi, and the six edible fungi were in a good state of safety, the risk of chronic dietary intake and the risk of acute dietary intake of 19 detected pesticide residues in edible fungi were both lower than 100%, and the risk of both chronic and acute dietary intake were lower. However, the risk values of dietary intakes of two pesticides, cyromazine and emamectin benzoate, were relatively high among the 19 pesticides detected. Therefore, it is necessary to strengthen the supervision of the use of cyromazine and emamectin benzoate in edible fungi to ensure the quality and safety of edible fungi products.
This study aims to clarify the effect of pesticide synergists (main ingredients are compound modified vegetable oil, complex sugar alcohols, non-ionic surfactant) on the physical properties of beta-cypermethrin, emamectin benzoate, nicotine·matrine, imidacloprid and chlorobenzuron, in order to explore their synergistic mechanism. The effects of pesticide synergists on the surface tension, contact angle, expanded diameter and maximum retention of the above 5 insecticides were determined. The results showed that the combination of pesticide synergists and 5 insecticides showed different improvements in physical properties. The results showed that pesticide synergists had a basic condition for enhancing the physical properties of the 5 insecticides, and the synergistic effect of their insecticidal effect needed to be verified by further bioassay.
The storage environment of grain affects the growth, development, reproduction, survival rate and population dynamics of stored grain pests, and the main influencing factors are temperature, humidity, food, gas and so on. In order to clarify the effects of different environmental factors on the development of grain storage pests, the status quo, and latest progress of research about the effects of different storage environments on grain storage pests in recent years were reviewed. The environmental requirements of grain storage pests vary from species to species, and their growth, development, reproductive potential, vitality and seasonal behavioral activities will change along with the environment change. In recent years, the studies on using environmental factors to control the damage of grain storage pests have been carried out extensively, and most of them focus on the control of grain storage pests through temperature, humidity and gas regulation, to achieve the purpose of green grain storage. Based on the analysis and summary, the development prospect of using environmental factors to control pests in stored grain is prospected, which provides a theoretical basis for the selection and implementation of pest control methods in the future, and provides a reference for the further development of technical equipment.
In order to explore the combined transformation ability of saprophytic edible fungus-Pleurotus pulmonarius and saprophytic insect- Protaetia brevitarsis larvae (PBL) to 11 kinds of forest and fruit tree branch waste, P. pulmonarius PL2 strain was used to biotransform different forest and fruit tree branches, and the mycelial growth rate, fruiting body yield, fruiting body polysaccharide content and antioxidant activity of fruiting body extract were determined. After that, the spent substrate of P. pulmonarius based on 11 kinds of wood branches was biotransformed by PBL, and the Hassan method was used to comprehensively evaluate the combined transformation effect of P. pulmonarius and PBL on 11 kinds of wood branches. The results showed that there were significant differences in the mycelial growth rate, fruiting body yield, fruiting body polysaccharide content and fruiting body antioxidant activity of P. pulmonarius strains among different types of branches. The mycelial growth rate was the fastest in beech wood (10.05 mm/d), the biological efficiency was the highest in honeysuckle branches (68.95%), the polysaccharide content was the highest in peach wood (9.52%), and the comprehensive antioxidant activity was the strongest in poplar wood (OD 0.6409). Further studies showed that there were significant differences in the combined transformation effect of P. pulmonarius and PBL on 11 kinds of branches. Among them, the combined transformation effect on honeysuckle branches was the best. 1 kg honeysuckle branches could produce 846.19 g of P. pulmonarius fruiting bodies. The weight gain of PBL was 45.97 g, and the amount of larvae frass production was 499.54 g. The results of this study showed that the combined conversion effect of P. pulmonarius and PBL on forest fruit tree branch waste was significant and had certain application value, which could provide theoretical basis for the ecological high-value utilization of forest fruit tree branch waste resources.
In order to understand the aphid resistance of rapeseed and screen aphid resistant germplasm resources to provide parents for rapeseed breeding of aphid resistance, 18 rapeseed cultivars were identified by aphid index under the condition of natural aphid sensitivity in Luoping and Luxi of Yunnan, and the occurrence rule of aphid and its effect on yield were analyzed. The results showed that the peak period of aphids occurred between flowering and maturity, and the mild and dry climate was conducive to the growth and reproduction of aphids. The peak period in Luxi was earlier than Luoping. Correlation analysis showed that the aphid index was negatively correlated with rape yield and its components, and was significantly correlated with 1000-grain weight and yield per plant. The occurrence of aphid damage would cause 4.97%-79.69% yield loss of rapeseed. 5 aphid resistant cultivars and 13 aphid sensitive cultivars were selected from 18 cultivars. ‘Yunyouza 28’ and ‘Yunyouza 18’ showed high resistance, which could be used as basic materials for rapeseed aphid resistance breeding.
To clarify whether Spodoptera frugiperda poses a threat to fruit and vegetable production in China, a comparative analysis of the feeding selectivity of 3rd-5th instar larvae of S. frugiperda on maize, sweet potato, tomato, and dongzao jujube leaves was conducted by leaf disc method. The feeding preferences of primary larvae initially domesticated on sweet potato and tomato leaves until they developed to the 3rd-5th instar larvae stages were examined. We assessed their selectivity for the initial food used for domestication and three other foods, compared feeding selectivity between various plant parts. The feeding preferences of S. frugiperda across all instar stages were as follows: maize (43.23%-61.82%)> sweet potato (20.37%-25.62%)> tomato (10.91%-24.3%)> dongzao jujube (5.45%-9.26%). Notably, after being domesticated on sweet potato and tomato leaves to 5th instar larvae, S. frugiperda exhibited heightened selectivity for the food they were initially domesticated on compared to maize. In contrast, although 3rd and 4th instar larvae retained a strong preference for maize leaves, they also demonstrated a substantial increase in selection rates for the food initially used for domestication. This increase ranged from 16.42-24.11 percentage points for sweet potato and 18.07-20.89 percentage points for tomato, compared to uncultivated larvae. Furthermore, the feeding selectivity analysis for different plant parts revealed that younger larvae displayed a preference for new leaves and corn whiskers of maize, whereas older larvae exhibited a preference for old leaves and male panicles. Concerning plant parts, younger larvae favoured plant stalks, whereas older larvae showed a preference for plant leaves. Our findings indicate that although S. frugiperda larvae exhibit lower feeding selectivity for sweet potato, tomato and dongzao jujube compared to maize, they still pose a potential threat to the production of these crops after domestication or under environmental stress. Notably, distinct variations in feeding choices for different parts of the plant were observed among younger and older larvae.
The objectives of this study were to clarify the multi locus sequence typing (MLST) of tobacco wildfire pathogen, and provide strong technical support for formulating effective control measures and breeding varieties, and a new perspective for biological characteristics study of the pathogen. Wildfire disease samples were collected from five tobacco production areas in Hunan, Chongqing and other provinces (Municipalities). And then tissue isolation and identification were carried out. MLST typing was applied to screen housekeeping gene, and the genetic diversity of the tested strains was analyzed. The results showed that 144 strains of tobacco wildfire pathogen were isolated from five tobacco producing provinces (Municipalities). Three housekeeping gene, Pgi, Pfk, and Gap were screened, and a total of 92 ST genotypes were obtained. Using the Pgi gene as the standard, the tested strains could be divided into 5 subgroups, 4 single groups, with a large number of subgroup 1 and subgroup 2 strains. The subgroup 1 strains came from 5 tobacco producing provinces (Municipalities), and ST43 of this subgroup belonged to the main population in China. It indicated that the genetic polymorphism of tobacco wildfire pathogens in China was rich, and there was no correlation between tobacco varieties and pathogen groups.
This study focuses on discovering the antimicrobial fungal resources from forest litter fungi, screening out and identifying the fungal strains with antimicrobial activities, and isolating and purifying their antimicrobial compounds. The forest litter from the Greater Hinggan Mountains was selected as test materials, then the fungi were isolated by particle separation method, the taxonomic data were measured by gene sequence comparison, the antibacterial activity was measured by well diffusion method, the monomeric compounds were isolated by column chromatography, and the chemical structure was determined by spectral analysis. Fungal strain SGSF801 was isolated and identified as a new strain of Neocucurbitaria salicis-albae by multiple sequence analysis. The results of the antimicrobial assay showed that the rice fermentation products had strong antimicrobial activities against plant pathogens Ralstonia solanacearum, Pseudomonas syringae and Rhizoctonia solani. The product of fungal rice fermentation was isolated and purified to obtain a monomeric compound, which was identified as Cercosporamide by 1H-NMR and 13C-NMR, and its molecular formula was C16H13NO7. Its MIC values were 31.25-62.5 μg/mL for Ralstonia solanacearum and 125-250 μg/mL for Pseudomonas syringae. In this study, Cercosporamide was isolated from fungal genus Neocucurbitaria for the first time, and it was found to have antibacterial activities against plant pathogens, which provided a basis for further utilization of litter fungi resources.
The cold acclimation can improve the cold tolerance of insect significantly. This article reviewed the methods of insect cold acclimation and the biological indicators for cold tolerance, the biotic factors (insect development stage, gender and diapause) and abiotic factors (temperature, photoperiod, humidity, etc.) that affect the cold acclimation of insect were analyzed. Then, the impact of cold acclimation on insect in terms of growth and development, reproductive capacity and offspring was clarified. Furthermore, the mechanism of improving insect cold tolerance through cold acclimation was explored from the perspectives of cold resistance related proteins and metabolic regulation. It is expected to provide reference for the deep study of cold acclimation and cold storage techniques of insects, in order to promote the utilization of natural enemies and pest control.
To explore the effect of 0.02% chlorin iron SP on rice growth and yield after seed soaking and its dosage, the 'Nanjing 9108' was used as experimental variety. Rice seeds were soaked in 0.02% chlorin iron SP at different concentrations. 0.0016%, 28(s)-homobrassinolide AS and 0.136% gibberellic acid·indoleacetic acid·brassinolide SP were used as control agents, and the seeds with water immersion as blank control. The rice growth status was investigated at seedling stage, tillering stage and maturity stage, respectively, and the yields were measured at harvest stage. The results showed as follows: seed soaking with 0.02% chlorin iron did not affect the germination of rice, but the emergence rate of rice decreased with the increase of chlorin iron concentration. Seed soaking with 0.02% chlorin iron increased the fresh weight, root number and tillering percentage of rice seedling. When 0.02% chlorin iron was diluted 15000-10000 times, it could increase the panicle length, the number of solid grains and improve the rice yield. Therefore, seed soaking with 0.02% chlorin iron 15000-10000 times solution can promote rice growth, improve rice yield. The demonstration application can be expanded in rice production.
To study the suitable growth areas and distribution influencing factors of Solidago canadensis L. in China for effective prevention and control, the Maximum Entropy model (Maxent) and ArcGIS software were used to predict the potential habitat of Solidago canadensis L. in China under current and future (2041—2060 and 2061—2080) climate models. The results showed that the predicted AUC value of the current fitness zone was 0.933 and the model prediction results were ideal; the distribution of the fitness zone was mainly influenced by the maximum temperature and precipitation; the potential fitness zone was mainly distributed in east and central China, mainly in the whole area of Shanghai, south-central Jiangsu Province, central Anhui Province, northern Jiangxi Province, eastern Hunan Province, eastern Hubei Province, and some parts of Zhejiang Province and the area along the coastline. Over time, from 2041 to 2060, the area of the middle and high fitness zones will increase by 1060400 km2 and the low fitness zone will increase by 1106200 km2 compared with the present; from 2061 to 2080, the area of the high and middle fitness zones will increase by 1109900 km2 and the low fitness zone will increase by 1115500 km2 compared with the present. Overall, under future climate change, the habitat zone of Solidago canadensis L. shows a trend of continuous expansion, and it is suggested that the relevant authorities should develop a responsive hierarchical management strategy based on the changing trend of its potential habitat zone to prevent further spread.
Xiangyang district is an important granary in Hubei Province, rice and wheat rotation is the main cultivation mode in the area. Grain drop and spike rot had appeared in rice production after using rice seeds successively reserved by farmers themselves. In order to explore the cause of poor growth of rice, samples on the spot for investigation were taken and analysis of these phenomena was carried out. Through the method of morphological characteristics observation and molecular biology identification, using the rice ‘Huanghuazhan’ purchased from the market as control, 41 pairs of rice molecular specific markers were detected, the virulence of chemical agents to the isolated pathogens was determined by the growth rate method. Four species of pathogens were isolated from withered rod and rotten ears including Nigrospora oryzae, Fusarium proliferatum, Fusarium equiseti, Fusarium graminearum; the seeds from farmers which were successively reserved for 6 years had no heteromorphosis, but rice grains harvested in the no-tillage rice field had 12 fingerprints different from the contrast. It indicated that the seeds of ‘Huanghuazhan’ preserved by farmers for 6 years had variation in field growth; Zoloether·propineb 70% WG and Kresoxim-methyl·epoxiconazole 23% SC could inhibit the growth of all pathomycetes. Continuous seed retention for many years will cause the vitality of rice seeds to decay, resulting in weak growth of rice in the field, vulnerable to disease invasion, and abnormal growth. Correctly using seeds, scientific management and the control of suitable agrochemicals are important measures to ensure the safe production of rice.
The pathogen and symptoms of sesame stem spot blight were described, and the epidemic regularity of sesame stem spot blight was introduced from the aspects of occurrence condition, transmission route, epidemic time and the relationship between climatic conditions and the disease. The agricultural control measures of sesame stem spot blight were introduced from the aspects of selecting resistant varieties, strengthening field management and rational crop rotation. The main fungicide control measures were introduced from seed treatment, soil disinfection, fungicide inhibition and pesticide control. It is suggested that the comprehensive prevention and control model of sesame stem spot blight should be based on the selection of agricultural control measures, i.e. disease-resistant varieties, scientific management and rational crop rotation, and opportunely take chemical control measures, i.e. soil disinfection, seed treatment and fungicide spraying, which can not only control the development of the disease but also meet the demand of people for green food.
In order to find out whether applying insecticides to control Solenopsis invicta in winter can achieve good control effect, this experiment compared the control effects of 0.6% cypermethrin powder and 0.08% indocarb baits in winter and summer. The results showed that the time after treatment, the difference of seasons and the kinds of agents had significant effects on the control effect of the nests of S. invicta. The control effect of 0.6% cypermethrin on the nests of S. invicta was significantly better than 0.08% indocarb in the range of 7-30 d after treatment in winter, and the effect of 0.08% indocarb on the nest of S. invicta was higher than 0.6% cypermethrin in the range of 15-45 d in summer. The effect of 0.08% indocarb baits on the nests of S. invicta in winter increased with the increase of time after treatment, and the highest effect (82.03%) was found at 45 d after treatment. The effect of 0.08% indocarb baits on S. invicta in summer was 92.49% at 15 d after treatment, which had no significant difference compared with 30 d and 45 d. The control effect of 0.6% cypermethrin on the nest of S. invicta decreased with the increase of time after treatment, but the decrease rate was slower in winter than in summer. The control effect of the two agents on the workers of S. invicta decreased with the increase of time after treatment. The control effect of 0.08% indocarb baits on the workers was significantly higher in winter than in summer except 7 d after treatment. The control effect of 0.6% cypermethrin powder on worker ants had no significantly difference within 7 d to 30 d. But at 45 d, it was significantly higher in winter (97.86%) than in summer (80.57%). In conclusion, when the weather in Hainan is fine in winter and the temperature is between 13-21℃, 0.08% Indocarb baits or 0.6% cypermethrin powder can be used to control S. invicta. The evaluation of the control effect is postponed to 30-45 d after treatment.
Fall armyworm (Spodoptera frugiperda) has posed a great threat to food production security in China since its invasion. It is of great significance for food production security to understand local population dynamics of fall armyworm and take effective prevention and control measures. In this study, the dynamics of fall armyworm adults in Zhaotong, Yunnan Province had been monitored throughout the year in 2021, and a control demonstration area was established to conduct a comparative study on prevention and control schemes. The results showed as follows: (1) The adult fall armyworm began to appear on March 1st in Zhaotong; The occurrence time sequence developed from southwest to northeast. (2) The occurrence of adult fall armyworm was mainly concentrated in Qiaojia County, Ludian County, Yongshan County, Yiliang County, Zhaoyang District and Daguan County. (3) The largest population period was observed in Qiaojia County and Yongshan County in the southwest of Zhaotong from April to June, and a large number of fall armyworm migrated into Ludian County, Yiliang County and Zhaoyang District in August. (4) The physical inducement of fall armyworm by sexual attraction, searchlight trap and mixed measurement of sexual attraction + light trap could significantly reduce the harm of fall armyworm and diminish the loss of maize yield. The mixed measurement had the most significant controlling effects.
Based on the data of the occurrence, the beginning and the occurrence degree of the central diseased plants of sclerotinia sclerotiorum in the sunflower from 2000 to 2021, as well as the meteorological data of the same period, the correlation between the occurrence period and degree of sclerotinia sclerotiorum on sunflower and meteorological conditions was analyzed, and the corresponding forecasting equations were established. The results showed that temperature and humidity were the key factors affecting the occurrence of sclerotinia sclerotiorum. Precipitation, mean wind speed and sunshine hours also had important effects on the occurrence time and degree of Sclerotinia sclerotiorum. Through stepwise regression, three prediction models were established, all of which passed the significance test of 0.01 level. The fitting effect of historical data is good, the trial report effect is good, and it can be put into actual operation.
The aim is to clarify the biocontrol application effect of Bacillus altitudinis, and lay a foundation for the development and application. Two B. altitudinis strains of JYW21 and JYW26 with good controlling effects against rice blast were preliminarily screened through enzyme and antagonistic activity to Magnaporthe oryzae. In this experiment, their biocontrol effects against rice blast were verified in different conditions (in leaf blades, greenhouse and field tests). At the same time, the growth promotion effect of rice was determined by seed germination, potting and field tests. The control effects of B. altitudinis were at least 96% in leaf blades and 79% in greenhouse respectively, and the control effects were 55% against leaf blast and 70% against panicle blast in field experiments. At the same time, it had a higher biocontrol effect on rice sheath blight and rice smut disease. The experimental results also showed that B. altitudinisJYW21 and JYW26 played a good role in rice seeds germination, plant growth, which could increase the germination rate of rice by 6.27% and 6.81%, seedling height by 12.91% and 14.91%, seedling fresh weight by 21.43% and 28.57%, plant height by 24.67%and 18.67%, fresh weight by 64.04% and 61.79%, root length by 30.96% and 27.94%, and root weight by 24.71% and 25.88% in greenhouse, respectively. Under field conditions, B. altitudiniss JYW21 and JYW26 increased rice tillering number by 20.59% and 15.27%, panicle weight by 19.55% and 3.53%, thousand seed weight by 4.77% and 1.25%, respectively. These results showed that the two strains of B. altitudinis could not only be used to control rice blast and other fungal diseases, but also could promote the growth and production of rice. It was also found that the two strains of B. altitudinis could increase the content of chlorophyll in rice leaves, which might be one of the reasons for promoting the growth of rice.
A serious radish rot was found in the field of Tianjin. 5 bacterial isolates were isolated from diseased radish tissues. In order to provide reference for the diagnosis and prevention of this disease, pathogen identification was carried out using morphology, pathogenicity test and moleculer identification, and the toxicities of 20 kinds of bactericides were tested by inhibition zone method. The results showed that the pathogen was identified as Xanthomonas campestris pv. campestris. Antibacterial activity differed among the different agents. Among 20 kinds of the tested agents, 13 agents had antibacerial effects on Xanthomonas campestris pv. campestris, of which 0.3% tetramycin aqueous solutions and 80% ethylicin emulsifiable concentrate were more effective than 98% streptomycin sulphate TC. 7 agents, including 27.12% copper dihydroxosulphate suspension concentrate, had no inhibitory action.
Plant Protection
