Prevention and Control of Gentiana macrophylla Pall Root Rot Disease

The root rot is a major disease affecting yield of Gentiana macrophyl a pal , reducing yield or even causing total crop failure. This research introduced the occurrence characteristics and various control techniques of root rot of Gentiana macrophyl a pal , in order to provide references for farmers.

The Therapeutic Effect of Onion on the Pathogenic Bacteria of Gill Rot Disease in Grass Carp

[Objective] The curative effect of onion on bacterial rotted gill disease in grass carp was researched [Method] The combination method of taking medicine through oral and spraying was used to cure sick grass carp for 1 period of treatment in room under artificial conditions. [Result] Different concentrations of onion generated different cure rates. When the combination was adding 1.0% - 2.0% medicine into feed and spraying 2.0 g,/m3 - 5.0 g,/m3, the curative result was the best with cure rate was 70% -90% [ Conclusion] The onion was effective on curing bacterial rotted gill disease in grass carp and could be taken as curative medicine.

First Report of Fusarium striatum Causing Root Rot Disease of Panax notoginseng in Yunnan,China

Panax notoginseng is a traditional Chinese medicinal plant.Root rot of P.notoginseng is one of the most serious diseases affecting P.notoginseng growth and causes wilted leaves,fewer lateral roots and rotten roots.Root rot is a soil-borne disease,and mainly occurs from June to August in Yunnan Province when the temperatures are high and the air is humid.In this study,the endophytic fungal genus Fusarium isolate E-2018.1.22-#3.2 was obtained from a P.notoginseng embryo.Fusarium isolate E-2018.1.22-#3.2 was identified as Fusarium striatum based on morphological characteristics and molecular analysis.The fungus was found to have conidiophores and macroconidia,and its ITS,LSU and TEF-1αgenes shared 100%,99.2%and 99%identities with the homologous genes of Fusarium striatum,respectively.Isolate F.striatum E-2018.1.22-#3.2 can cause root rot symptoms,including black,soft roots,fewer lateral roots and leaf wilt,in 93%of the experimental P.notoginseng plants,and could be re-isolated,fulfilling Koch’s postulates.When the P.notoginseng plants were treated with the fungicide pyraclostrobin,isolate F.striatum E-2018.1.22-#3.2 was unable to cause root rot.We have therefore demonstrated that F.striatum E-2018.1.22-#3.2 is able to cause root rot disease in P.notoginseng.This is the first report of root rot disease caused by F.striatum on P.notoginseng in China.

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.

Formulation of Biofungicides from Cymbopogon citratus and Tithonia diversifolia: Evaluating Its Antimicrobial Activities against Pythium myriotylum, the Causal Agent of Root Rot of Xanthosoma sagittifolium (L.) Schott

Three fungicide formulations, namely M1, M2 and M3, were prepared from sodium bicarbonate, citronella essential oil and sunflower slurry. The stability of M1, M2 and M3 formulations was determined based on pH, temperature, order of incorporation of the inputs and storage time. The most stable formulations were used for antagonistic tests on Pythium myriotylum. The Minimum Inhibitory Concentration (MIC) was used for the greenhouse tests and the mode of action was determined in vitro. The study showed that the order of incorporation of the inputs “Essential Oil-Tween 80-Bicarbonate-Slurry” (EO-T80-B-S) promotes stability. M1 and M2 are stable at 4°C, 25°C, 37°C and 40°C temperatures and have a pH of 7 and 8 respectively. The Minimum Inhibitory Concentration of M1 and M2 is 1% on P. myriotylum. M1 and M2 act on Pythium by membrane lysis, inhibiting proton pumps and inhibiting protein synthesis. The formulations M1 and M2 reduce the incidence of root rot disease in cocoyam plants growth in the greenhouse. M1 and M2 are potential candidates for improvement of cocoyam seedlings production in Cameroon.

Pyramiding the disease resistant genes to southern rust and stalk rot in maize(Zea mays L.) with marker-assisted selection

Southern corn rust(SCR) caused by Puccinia polysora Underw and maize stalk rot caused by Pythium inflatum Matthews(MSR-2) are two destructive diseases of maize(Zea mays L.) in China.Our previous studies indicated that maize inbred line Qi319 is highly resistant to SCR but susceptible to MSR-2,while inbred line 1145 is highly resistant to MSR-2 but susceptible to SCR.The SCR resistant gene(RppQ) in Qi319 and MSR-2 resistant gene(Rpi1) in 1145 have been mapped on chromosome 10 and 4 respectively.In this research,through marker-assisted selection(MAS) with the molecular markers,bnlg1937 tightly linked to Rpi1 and phi041 tightly linked to RppQ,pyramid breeding of the two kinds of disease resistant genes were carried out from the year of 2003 to 2007.Two homozygotic inbred lines of F5 generation,DR94-1-1-1 and DR36-1-1-1 were identified.MAS result suggested DR94-1-1-1 and DR36-1-1-1 contained the two resistance genes RppQ and Rpi1.Field inoculation tests confirmed their high resistance to the two diseases.In addition,field investigation indicated that the two selected inbred lines,particularly DR94-1-1-1,had excellent agronomic traits such as plant height,ear height and yield-relating traits including ear length,ear diameter,ear weight,kernels per ear,kernels per row and kernel weight per ear.The two selected inbred lines DR94-1-1-1 and DR36-1-1-1 can either be directly developed into commercial variety or used as immediate donors of SCR and MSR resistance breeding programs in maize.

Biological Control of Erwinia carotovora ssp. carotovora by Streptomyces Species

Ten isolates of Erwinia carotovora ssp. carotovora (Ecc) were isolated from infected potato tubers of Picasso, Sante, and Nevskiy varieties collected from different regions in Kyrgyzstan. Isolates were identified as Erwinia carotovora ssp. carotovora (Ecc) by standard bacteriological techniques and pathogenicity tests on tubers and also by PCR analyses. Tests on the pathogenicity of E. carotovora ssp. carotovora (Ecc) strains to host plants by artificial inoculation have shown a high sensibility of the Picasso variety. As a result, five isolates were chosen, three isolates (EcPo1, EcPo2, and Eco3) were highly pathogenic, while two isolates (Eco4 and Eco5) were weakly pathogenic. The antagonistic bacteria, Streptomyces diastatochromogenes strain sk-6, and Streptomyces graminearuss strain sk-2, have a highly significant effect on soft rot bacteria isolates (Ecc), more than the other tested antagonistic organisms in vitro screening biotests. The Streptomyces diastatochromogenes sk-6 was selected for the control assay of storage potatoes against the most common soft rot bacterial strain in Kyrgyzstan, Erwinia carotovora sp. carotovora EcPo2. The pretreatment of potato tubers with antagonistic bacteria successfully prevented the initial infection multiplication of soft rot bacteria and reduced soft rot disease of potatoes in storage. These results justify selection of the dose 106 cells/ml of bacteria Streptomyces diastatochromogenes sk-6 for use in powdering the infected or non-infected potato tubers to suppress the development soft rot during storage. Streptomyces diastatochromogenes sk-6 as a biological disinfectant could destroy surface and internal infections, protect the tubers from the growth of phytopathogenic bacteria in the early period of their reproduction, and improve the overwintering of winter crops.

Monitoring the Turmeric Finger Disease and Growth Characteristics Using Sensor Based Embedded System —A Novel Method

In this cyber era, novelty plays a prime role in the field of agriculture that majorly depends on computer-based measurements and control. Herein before, it was totally controlled and performed by the agriculturists. One of the technological innovative methods to measure and monitor the turmeric finger growth characteristics is the embedded system that is based on sensor array module such as flex sensor, temperature sensor and pH sensor. The experimental work has been designed and tested with five set of nodes and the growth of turmeric finger is tenuously monitored by measuring the change in flex resistance. Out of five nodes, two nodes were diseased. Deliberately, one node was left as such and the other node was treated with natural pesticides (pseudomonas and viride) to restrict the rhizome rot disease attack. After cultivation, it was found that the rhizome rot disease attack on the node which was treated with pesticides was comparatively lesser than the other node. The five different nodes have been used in the experimental work with an average flex sensor resistance of 3.962 cm/kΩ. In a nutshell, this proposed method manifests the farmers to detect the rhizome rot disease at its earlier stage and to prevent it as well by screening the growth of the turmeric fingers when it is under the soil.

Pathogenicity of Klebsiella pneumonia(KpC4)infecting maize and mice

Recently, a new bacterial top rot disease of maize has frequently appeared in many areas of Yunnan Province, China. The pathogen of the disease was identified as Klebsiella pneumoniae （KpC4）, which is well known to cause pulmonary and urinary diseases in humans and animals and occasionally exists as a harmless endophyte in plants. To evaluate the viru- lence of the maize pathogen to maize and mice, we inoculated maize and mice with routine inoculation and intraperitoneal injection respectively according to Koch＇s postulates. The results showed that KpC4 and the clinical strain K. pneumoniae 138 （Kp138） were all highly pathogenic to maize and mice and the strain re-isolated from diseased mice also caused typical top rot symptoms on maize by artificial inoculation. It is highlighting that a seemingly dedicated human/animal pathogen could cause plant disease. This is the first report of K. pneumoniae, an opportunistic pathogen of human/animal, could infect maize and mice. The findings serve as an alert to plant, medical and veterinarian scientists regarding a potentially dangerous bacterial pathogen infecting both plants and animals/humans. The maize plants in the field could serve as a reservoir for K. pneumoniae which might infect animals and probably humans when conditions are favorable. The new findings not only are significant in the developing control strategy for the new disease in Yunnan, but also serve as a starting point for further studies on the mechanism of pathogenesis and epidemiology of K. pneumoniae.

紫花野菊软腐病的病原鉴定

紫花野菊(Chrysanthemum zawadskii Herbich),又称山菊、西伯利亚菊,是浙江省淳安县高山特色茶用菊花,饮用历史悠久。该菊味微苦,性温和,有清热解毒和消炎降火的功效。2020年5月,淳安县多个苗圃发现一种紫花野菊茎叶部病害,发于幼苗茎基部,或植株的中上部茎,初期表现为病部产生湿润状暗绿色斑点,遇雨水病斑呈水渍状迅速扩展,茎表皮组织发黑腐烂,无臭味,病原细菌沿导管向叶柄和叶脉发展,叶柄及叶脉发黑,叶片瘫软。

Synthesis of selenium-doped carbon from glucose:An efficient antibacterial material against Xcc

Se/C as a novel carbon-based biomaterial was prepared by using cheap and abundant glucose as the carbon source.It was highly active and could well restrain Xanthomonas campestris pv.campestris(EC50=4.7403 μg/mL),a very harmful germ causing the devastating cabbage black rot disease and resulting in huge economic losses.As a type of carbon material insoluble in wate r,Se/C is bio-compatible and can adhere onto the leaves of the plants to allow a slow and sustained release of its efficacy,affording an efficient method for the cabbage black rot disease prevention and cure.This work as the first report on the bioactivity studies of Se/C significantly expands the application scopes of the selenium-containing materials and may draw continuous attentions from a broad field.