Peach Aphid Myzus Persicae Research Articles

Molecular mechanisms for selective action of afidopyropen to Myzus persicae and Coccinella septempunctata.

Afidopyropen is a novel insecticide with high selectivity between sucking insects such as the peach aphids Myzus persicae and natural enemies like the seven-spotted lady beetle Coccinella septempunctata. However, the mechanisms of selective action for afidopyropen remain unknown. The LC50 values of afidopyropen to the 1st-4th instar larvae and adult C. septempunctata were 372- to more than 7267-fold higher than that to adult M. persicae. Though the activity of cytochrome P450s in M. persicae was 6.1- to 7.5-fold higher than that in C. septempunctata, the latter has much higher activities of carboxylesterase (CarEs) and glutathione S-transferases (GSTs), and the crude enzyme of C. septempunctata and M. persicae showed similar metabolism efficiency to afidopyropen. Molecular docking results demonstrated that afdopyropen showed higher binding affinity to the vanilloid-type transient receptor potential (TRPV) channel of M. persicae (-9.1 kcal/mol) than to that of C. septempunctata (-8.2 kcal/mol). And the EC50 value of afdopyropen to the TRPV channel of C. septempunctata (41 360 nM) was 19 885-fold higher than that in M. persicae (2.08 nM). Our results demonstrated that the significantly different sensitivity of M. persicae and C. septempunctata TRPV channel to afidopyropen play a key role in the high selectivity of afidopyropen. These findings provide new insights into the selective mechanisms of afidopyropen against insect pests and natural enemies as well as the theory support for coordinated application of chemical control and biological control. © 2024 Society of Chemical Industry.

Effect of Sulfur Dioxide as a Component of the Volatile Organic Compounds of Fungi of the Genus <i>Lecanicillium</i> on the Phytophagous Western Flower Thrips and Peach Aphid

Earlier, using the MS7-200 quadrupole mass spectrometer developed by the IAP RAS, sulfur dioxide was detected as part of volatile organic compounds (VoCs) released into the air by entomopathogenic fungi (EPF) of the genus Lecanicillium. In this work, we evaluated the effect of this compound on such dangerous phytophages as the Western flower thrips Frankliniella occidentalis and the peach aphid Myzus persicae in low doses corresponding to the content of sulfur dioxide in the composition of VOCs over the growing mycelium of fungi. It was found that sulfur dioxide did not have a negative effect on female thrips F. occidentalis and their fertility when sulfur dioxide is injected into vials at concentrations of 9 and 17 ppm and kept for 2 hours. At a dose of 33 ppm, sulfur dioxide caused a 10% mortality of female thrips after 2 hours and 15.4% after 1 day, while a 36% decrease in female fertility was observed. Sulfur dioxide at concentrations of 17-33 ppm was nontoxic for peach aphid females after 2 hours. Aphid mortality at the level of 26% was noted after 2 days at a sulfur dioxide concentration of 33 ppm, while fertility decreased by 22%. At a dose of 23 ppm, sulfur dioxide reduced the fertility of aphids most significantly - by 30%. The data obtained indicate the influence of sulfur dioxide contained in the composition of fungal VOCs on the behavioral reactions of phytophages.

Virus Yellows in sugar beet – possibilities to achieve virus resistance

Virus yellows in sugar beet is caused by different virus species. Monitoring has shown that Beet yellows virus (BYV), Beet mild yellowing virus (BMYV), Beet chlorosis virus (BChV) are common and widespread, while Beet mosaic virus (BtMV) is less prevalent. The green peach aphid (Myzus persicae) is considered the main vector of these viruses. Sugar beet varieties with resistance or tolerance traits are currently not available to practical growers, therefore it is imperative to support breeding efforts with improved strategies to achieve virus resistance. For this purpose, a field test was established in which yield differences between susceptible and tolerant varieties can be generated by a 3% inoculation with BMYV-carrying aphids. A greenhouse bioassay has also been developed to distinguish susceptible and tolerant genotypes following BYV infection. Both assays pave the way for future use of natural resources such as wild forms and other breeding material to screen for virus resistance. In addition, molecular biology approaches are used to identify plant susceptibility factors of the plant-virus interaction, which will be knocked out via modern precision breeding methods to generate recessive virus resistance. Consequently, genotypes with naturally occurring mutations in the appropriate factors can be used for crossbreeding processes into elite breeding material.

Botanical formulations for the ecological management of Myzus persicae (Sulzer) and Aphis gossypii (Clover) (Hemiptera: Aphididae) and their side effects on parasitoids

The peach aphid Myzus persicae (Sulzer) and cotton aphid Aphis gossypii (Clover) (Hemiptera: Aphididae) are considered to be key pests affecting greenhouse pepper crops in Argentina as a result of their frequent occurrence and the seriousness of the damage caused by their feeding behavior and the transmission of virus. The goal of this research was to determine the efficiency of botanical products to control aphids and their side effects on parasitoids in this crop. Thus, three biorational pest control formulations derived from essential oils (EO) and plant extracts (Es) were tested, namely (i) neem EO, cinnamon EO, clove EO, oregano EO and American marigold EO (formulation 1); (ii) garlic EO and cinnamon EO (formulation 2); (iii) garlic E and rue E (formulation 3); and a soy lecithin adjuvant (lecithin), and finally, a control (water spray method). For this research, a completely randomized design was replicated 3 times. These treatments were applied directly to the foliage by means of a backpack sprayer on a weekly basis until the end of this trial. Subsequently, the total number of healthy aphids and parasitized aphids (mummies) on every leaf was recorded in the field and the laboratory through repeated measures Analysis of Variance (ANOVA) and LSD Fisher method. The results showed that formulation 1 and formulation 3 recorded a lower number of aphids and mummies compared to the other treatments. This evidence would demonstrate that these formulations repel aphids and parasitoids without the lethal effects caused by the use of broad spectrum insecticides.

Effects of liquid vermicompost and synthetic NPK fertilizer sources on Myzus persicae Sulzer (Aphididae: Hemiptera) fed on tobacco

Green peach aphid (Myzus persicae Sulzer (Aphididae: Hemiptera)) is a polyphagous pest that causes economic losses in the tobacco. In addition to general aphid damage, it is a vector for important viral diseases in tobacco. Fertilization methods, which are used to increased soil fertility, in the plant growing phase, contribute significantly to the optimal physical, chemical and biological properties of the soil, which allows the plants grown in that soil to be more resistant to diseases and pests. Therefore, in this study, the effects of liquid vermicompost and synthetic fertilizer applications on the development and biological parameters of green peach aphids were investigated in comparison with the control. The experiments were carried out under controlled climate chambers. Life table parameters were obtained using the data obtained for the development and reproduction of the aphids. In the study, while there was no statistically significant difference between population parameters, both treatments were found to suppress the pest populations compared to the control application. This application can be used as an ecological control method for the pest.

Involvement of clathrin-dependent endocytosis in cellular dsRNA uptake in aphids

RNAi is an essential technology for studying gene function in eukaryotes, and is also considered to be a potential strategy for pest control. However, the mechanism behind the cellular uptake of dsRNA in aphids, a group of important agricultural sucking pests, remains unknown. Here, using the pea aphid Acyrthosiphon pisum as model for aphids, we identified two core genes of clathrin-dependent endocytosis (CDE), Apchc and Apvha16. We confirmed that expression of Apchc, Apvha16 and RNAi core component genes (ApAgo2, ApDcr2 and ApR2d2) were simultaneously induced at 12 h after feeding dsRNA. By using an RNAi-of-RNAi approach, we demonstrated that suppression of Apchc and Apvha16 transcripts by RNAi significantly impaired RNAi efficiency of selected reporter genes (RGs), including ApGNBP1, Apmts and Aphb, suggesting the involvement of CDE in cellular dsRNA uptake in aphids. Further confirmation was also provided using two inhibitors, chlorpromazine (CPZ) and bafilomycin A1 (BafA1). Administration of CPZ and of BafA1 both led to an impaired silencing efficiency of the RGs in the pea aphid. Finally, these RNAi-of-RNAi results were reconfirmed in the peach aphid Myzus persicae. Taking these findings together, we conclude that CDE is involved in cellular dsRNA uptake in aphids.

Direct and Indirect Effect of Myzus Persicae Infestation on Buildup of Whitefly (Bemisia tabaci) in Tomato Crop under Laboratory Conditions

The tomato crop is affected by a number of pests in the world as well as in China and Pakistan. The whitefly (Bemisia tabaci) is considered a very serious and damaging pest of tomato crop along with many other vegetables and field crops. Population buildup of whitefly is affected by many factors, including biotic and a biotic. One of the factors affecting the whitefly population in the tomato crop is green peach aphid (Myzus persicae) infestation before the whitefly attack. This project designed to note the direct and indirect effect of Myzus persicae infestation on the population setup of whitefly in tomato crops. The results revealed that whitefly prefers tomato plants without having aphids on them (choice) and can be settled on the tomato plants also when there are aphids present (no choice). The period after aphid infestation have a negative effect on the whitefly population, and the density of aphids/leaf has also influenced the whitefly population.

Nicotinamide Inhibits Aphid Fecundity and Impacts Survival

Nicotinamide (NAM) alters behavior in C. elegans and Drosophila, serving as an agonist of TRPV channels affecting sensory neurons and mimicking the mode of action of insecticides used to control phloem-feeding insects. The impact of NAM on green peach aphid (Myzus persicae) behaviors was assessed in artificial diet assays and foliar applications to Arabidopsis plants. Aphids feeding on artificial diets supplemented with NAM impaired stylet movement causing feeding interruptions and ultimately starvation and death. Aphid feeding behaviors were negatively impacted on NAM sprayed plants at concentrations as low as 2.5 mM leading to increased mortality. In choice assays with NAM sprayed leaves aphids showed clear preference for untreated control leaves. NAM is an intermediate in the NAD salvage pathway that should accumulate in nicotinamidase (nic) mutants. LC-MS analysis showed NAM accumulates 60-fold in nic-1-1 Arabidopsis mutants as compared with Col-0. Aphid reproductive potential was significantly decreased on nic-1-1 mutant plants, resulting in a smaller colony size and arrested population development. The results support the hypothesis that dietary NAM causes behavioral changes in aphids, including altered feeding, reduced reproduction, and increased mortality. NAM is thought to bind to TRPV channels causing overstimulation of sensory neurons in the aphid feeding apparatus.

Dynamic transcriptomes of resistant and susceptible peach lines after infestation by green peach aphids (Myzus persicae S\xfclzer) reveal defence responses controlled by the Rm3 locus

BackgroundThe green peach aphid (GPA), Myzus persicae (Sülzer), is a widespread phloem-feeding insect that significantly influences the yield and visual quality of peach [Prunus persica (L.) Batsch]. Single dominant gene (Rm3)-based resistance provides effective management of this invasive pest, although little is known about the molecular responses of plants to GPA feeding.ResultsTo illustrate the molecular mechanisms of monogenic resistance in peach to young tissue-infecting GPAs, aphid-resistant/aphid-susceptible peach lines from a segregating population with Rm3/rm3 and rm3/rm3 genotypes were infested with GPAs for 3 to 72 h. Transcriptome analysis of the infested tissues identified 3854 differentially expressed genes (DEGs). Although the majority of the DEGs in the resistant line also responded to aphid attack in the susceptible line, the overall magnitude of change was greater in the resistant line than in the susceptible line. The enriched gene ontology of the 3854 DEGs involved in plant defence responses included redox situation, calcium-mediated signalling, transcription factor (e.g., WRKY, MYB, and ERF), MAPK signalling cascade, phytohormone signalling, pathogenesis-related protein, and secondary metabolite terms. Of the 53 genes annotated in a 460 kb interval of the rm3 locus, seven genes were differentially expressed between the aphid-resistant and aphid-susceptible peach lines following aphid infestation.ConclusionsTogether, these results suggest that the Rm3-dependent resistance relies mainly on the inducible expression of defence-related pathways and signalling elements within hours after the initiation of aphid feeding and that the production of specific secondary metabolites from phenylpropanoid/flavonoid pathways can have major effects on peach-aphid interactions.

Volatile β-Ocimene Can Regulate Developmental Performance of Peach Aphid Myzus persicae Through Activation of Defense Responses in Chinese Cabbage Brassica pekinensis.

In nature, plants have evolved sophisticated defense mechanisms against the attack of pathogens and insect herbivores. Plant volatile-mediated plant-to-plant communication has been assessed in multitrophic systems in different plant species and different pest species. β-ocimene is recognized as an herbivore-induced plant volatile that play an important role in the chemical communication between plants and pests. However, it is still unclear whether β-ocimene can active the defense mechanism of Chinese cabbage Brassica pekinensis against the peach aphid Myzus persicae. In this study, we found that treatment of Chinese cabbage with β-ocimene inhibited the growth of M. persicae in terms of weight gain and reproduction. Moreover, β-ocimene treatment negatively influenced the feeding behavior of M. persicae by shortening the total feeding period and phloem ingestion and increasing the frequency of stylet puncture. When given a choice, winged aphids preferred to settle on healthy Chinese cabbage compared with β-ocimene-treated plants. In addition, performance of the parasitoid Aphidius gifuensis in terms of Y-tube olfaction and landings was better on β-ocimene-treated Chinese cabbage than on healthy plants. Furthermore, β-ocimene significantly increased the expression levels of salicylic acid and jasmonic acid marker genes and the accumulation of glucosinolates. Surprisingly, the transcriptional levels of detoxifying enzymes (CYP6CY3, CYP4, and GST) in aphids reared on β-ocimene-treated Chinese cabbage were significantly higher than those of aphids reared on healthy plants. In summary, our results indicated that β-ocimene can activate the defense response of Chinese cabbage against M. persicae, and that M. persicae can also adjust its detoxifying enzymes machinery to counter the host plant defense reaction.

Effect of different headspace concentrations of bornyl acetate on fecundity of green peach aphid and balsam woolly adelgid

ABSTRACTBalsam woolly adelgid (Adelges piceae) (Hemiptera: Adelgidae) (BWA) is an exotic pest introduced from Europe to North America in the early 1900s. Subsequent introductions and spread have enabled this pest to infest native Fraser fir stands in the Southern Appalachians and become a troublesome pest for the region’s Christmas tree industry. Means to study its fecundity and control it are consequently of high importance. Headspace solid phase micro-extraction coupled with gas chromatography and mass spectrometry were used to compare chemical differences in stem tissue between a resistant species, Veitch fir (Abies veitchii) and the susceptible Fraser fir (Abies fraseri). Comparisons demonstrated that bornyl acetate (BA), a terpenoid, was qualitatively more abundant in resistant Veitch fir than Fraser fir. Varying headspace concentrations of BA were tested to ascertain any biological impacts on egg eclosion of BWA, as well as fecundity of green peach aphid (Myzus persicae) (GPA), an insect serving as a proxy. Varying concentrations of BA and a known number of adelgid eggs did not indicate any impact of concentration on egg eclosion success. However, defoliated Veitch fir branches in treatment jars produced a significant negative impact on BWA eclosion success. Implications of these findings are discussed.

Using bioassays with the green peach aphid (Myzus persicae) to determine residual activity of two systemically soil-applied neonicotinoid insecticides in field-grown tobacco

ABSTRACTDuration of systemic pesticide activity under field conditions has wide implications for pest management. Our aim was to determine the duration of activity of systemic insecticides commonly used in cultivated tobacco (Nicotiana tabacum) by measuring the levels of insect infestations on field plots and effects on reproduction and survival of the green peach aphid (Myzus persicae) in controlled bioassays using field grown leaves. Plants were treated with different concentrations of two systemic neonicotinoid pesticides, imidacloprid and thiamethoxam, and grown in small field plots. Our results show that these materials are effective under field conditions against aphids for at least 13 weeks after transplant. Pesticides also affected aphid reproduction and nymph survival in bioassays, although some aphids survived on pesticide-treated leaves. We also observed that leaf age affected aphid survival. We showed that neonicotinoids were very effective against M. persicae, aphids are a useful organism to assess pesticide efficacy early in the growing season, but plant characteristics are more important than pesticide concentration in the second half of the growing season.

Arabidopsis thaliana growth more than defense affects Myzus persicae populations

Aphids and other herbivorous insects are able to travel between plants in their environment. While plants cannot directly choose their consumers, they may stop or mitigate the harmful effects of herbivory using secondary metabolites. A salicylic acid (SA) pathway facilitates defense from biotrophic fungi and some necrotrophic pathogens, while a jasmonic acid (JA) pathway is associated with defense from other necrotrophic pathogens and chewing insects. We investigated the effect of deficiency in SA or JA in Arabidopsis thaliana on plant growth and on herbivory by green peach aphids (Myzus persicae). Three ascensions of A. thaliana were placed in two blocks with three aphids on each individual. The genotypes consisted of a SA-deficient ascension (Sid2), a JA-deficient ascension (Lox2), and a wild type (Col). Wild-type A. thaliana showed significantly greater growth relative to the other ascensions, suggesting better performance, as well as dramatically higher aphid count. Aphid count showed a significant positive correlation with plant growth, suggesting that M. persicae is attracted to signs of growth in A. thaliana, or reproduces more on growing plants. It appears that wild-type plants showed greater growth throughout the experiment, and were thus targeted by the highly responsive M. persicae. This behaviour may be exploited for agricultural purposes; herbivorous insects may be diverted to fast-growing trap crops lacking agricultural value in order to protect primary crops. Faculty Sponsor: Dr. Chad Harvey

Preventative Insecticidal Control of Green Peach Aphids, 2014: Table 1

The study was conducted in a greenhouse at the AgriLife Research and Extension Center in Overton, TX. The objective of the trial was to assess the efficacy of different rates of Mainspring™ Cyantraniliprole (MoA 28), as a preventative treatment for green peach aphid ( Myzus persicae Sulzer) control on pansies ( Viola tricolor ), compared to that of Endeavor, a known effective product. Treatments were assigned to individual plans in 4-inch pots (experimental units) in a CRD with six replicates. Plants were kept in individual mesh cages (item …

Enhanced aphid detoxification when confronted by a host with elevated ROS production

Reactive oxygen species (ROS) plays an important role in plant defense responses against bacteria, fungi and insect pests. Most recently, we have demonstrated that loss of Arabidopsis thaliana BOTRYTIS-INDUCED KINASE1 (BIK1) function releases its suppression of aphid-induced H2O2 production and cell death, rendering the bik1 mutant more resistant to green peach aphid (Myzus persicae) than wild-type plants. However, little is known regarding how ROS-related gene expression is correlated with bik1-mediated resistance to aphids, or whether these aphids biochemically respond to the oxidative stress. Here, we show that the bik1 mutant exhibited elevated basal expression of ROS-generating and -responsive genes, but not ROS-metabolizing genes. Conversely, we detected enhanced detoxification enzymatic activities in aphids reared on bik1 plants compared to those on wild-type plants, suggesting that aphids counter the oxidative stress associated with bik1 through elevated metabolic resistance.

Chemical Composition of Essential Oil from Eucalyptus citriodora Leaves and Insecticidal Activity Against Myzus persicae and Frankliniella schultzei

Essential oils, volatile compounds obtained from plants, provide an alternative approach for controlling agricultural pests due to problems with conventional chemical products, such as insect resistance, environmental issues and human health concerns. This work aimed to extract essential oil from Eucalyptus citriodora to assess its chemical composition and insecticidal activity against the green peach aphid (Myzus persicae) and thrips (Frankliniella schultzei). The essential oil was obtained by hydrodistillation using the Clevenger apparatus and analyzed by gas chromatography with a flame ionization detector and mass spectrometry (GC-FID and GC-MS). A Potter tower was used to spray the insects with the essential oil solutions. The major components found in E. citriodora essential oil were citronellal (29.31 %), geraniol (27.63 %), β-citronellol (14.88 %) and δ-cadinene (6.32 %). Mortality of M. persicae and F. schultzei nymphs were 85.5 % and 34.8 %, respectively, using essential oil at 1 % (w v−1). Estimated values of LC50 (0.40 % w v−1) and LC90 (1.15% w v−1) for M. persicae evidences the potential use of E. citriodora essential oil in controlling this pest.

Transgenic tetraploid Isatis indigotica expressing Bt Cry1Ac and Pinellia ternata agglutinin showed enhanced resistance to moths and aphids

Co-expression of multiple genes encoding different kinds of insect resistant proteins has been developed to confer a broader spectrum of pest control. Tetraploid Isatis indigotica Fort was transformed with a plasmid, p3300BP, containing Bacillus thuringiensis Cry1Ac gene (Bt) and Pinellia ternata agglutinin gene (Pta) and the selectable marker herbicide resistance gene (Bar) driven by the CaMV35S promoter via Agrobacterium tumefaciens-mediated transformation. The integration and expression of introduced genes in regenerated transgenic plants were confirmed by PCR and Western blot assays. Insect bioassay test demonstrated transgenic lines had significant inhibition to diamondback moths (Plutella xylostella L.) and peach potato aphids (Myzus persicae Sulzer) simultaneously. Our study reported here would be a great motivation for field culture of tetraploid I. indigotica, also providing an efficient molecular breeding strategy to provide insect tolerant plants.

COMPARISON OF APPLICATION METHODS FOR TOBACCO BUDWORM CONTROL, 2010

Anthranilic diamide insecticides, two of which have recently been registered for use in tobacco, may be more persistent in plant tissue and move within leaf tissue to a great extent than other registered chemistries. These characteristics may allow anthranilic diamaide insecticides to be applied using different methods than standard materials used against TBW. Standard insecticide application methods for TBW control recommend a volume of 30 gpa water applied with 60 psi pressure using solid or hollow cone nozzles. Using one of the registered anthranilic diamaide insecticides registered in tobacco (Belt, Bayer CropScience) applied at a rate of 3.0 fl oz/acre, we compared 4 application volumes (5, 10, 20, and 50 gpa water) applied at 2 pressures (30 and 60 psi) to determine if applications at lower volumes and pressures were as effective as those at higher volumes with greater pressure. Greenhouse grown tobacco plants were transplanted on 4 May. Plants were treated with 0.8 fl oz/1000 plants Admire Pro 5 d prior to transplant to control early season tobacco flea beetle (Epitrix hirtipennis) and green peach aphid (Myzus persicae) populations. Four row plots, 50 ft in length, were established immediately after transplant. Plots were 0.018 acres each. Each treatment was replicated 4 times, and plots were arranged in an RCBD, blocked by replicate. Six wk after transplant, 10 plants each in rows 2 and 3 of each plot were infested with laboratory reared 2 instar TBW larvae, purchased as eggs from Chesapeake PERL (Savage, MD). Treatments were applied the d after larval infestation. Larval survival and leaf area consumed were rated 3, 7, and 14 d after foliar treatments were applied. Treatments were applied using a single nozzle boom fitted with a TG3 solid cone tip and powered by a CO2 pressurized backpack sprayer. Data were analyzed via Proc Mixed (SAS v. 9.1.3; Cary, NC) with replicate as a random variable. Each date was analyzed separately, not as a repeated measure.

Population development of the green peach aphid and beneficial insects in potato fields in British Columbia

AbstractUsing 4 years of potato monitoring data containing insect counts, population development of the green peach aphid (Myzus persicae (Sulzer)) (Hemiptera: Aphididae), ladybird beetles (Harmonia axyridis (Pallas) and Coccinella septempunctata L.) (Coleoptera: Coccinellidae), and hymenopterous aphid parasitoids is described and used to consider revisions to current sampling plans. Depending on the year, field monitoring for aphids commenced between early May and early June. Aphid populations typically increased after 1 July and fluctuated until the end of the monitoring period (September). Winged M. persicae began to appear in sweep-net samples in late May, well in advance of the detection of aphids in visual samples. Aphid counts from field edge and interior sample sites were correlated and edge population levels were slightly and significantly greater than interior levels over the period 10 June – 14 July in 2 of the 4 years analyzed, suggesting a mild but inconsistent edge effect approaching mid season. Using an action threshold of 1 aphid/leaf to restrict the aphid-mediated spread of potato leaf roll virus (PLRV), the earliest whole-field action threshold was exceeded during 18–24 June in 1997. Using an action threshold of 10 aphids/leaf to address aphid-induced yield loss in fields not at risk to PLRV, the earliest whole-field action threshold was exceeded during 16–22 July in 1997. Therefore, monitoring for aphids can begin much later than the time it is currently commenced. A case is presented for monitoring only the edges of potato fields for an action threshold of 10 aphids/leaf, as interior samples rarely exceeded this action threshold when edge samples were below. This would further reduce the effort in sampling potato fields for aphids. Population development of ladybird beetle adults and larvae showed peaks occurring at different times during the growing season, depending on the year. Parasitism of aphids by hymenopterans occurred at low to moderate levels throughout the growing season (13% of total aphids in visual samples, on average), with peak parasitism appearing toward the end of the growing season in each year.

Diseases, pests, and abiotic disorders of greenhouse-grown water spinach (Ipomoea aquatica) in Ontario and California

Water spinach, a specialty vegetable and a member of the sweet potato family, is cultivated for Asian markets in California (United States) and Ontario (Canada). Foliar diseases of this vegetable observed in commercial greenhouses of Ontario in 1993 and 1994, as well as in greenhouses of California in 1998, were attributed respectively to Phyllosticta ipomoeae, Cercospora ipomoeae, and Pseudomonas syringae pv. syringae in the present study. In Ontario, C. ipomoeae infected less than 1% of plants, with less than 25% of the foliage affected, while Phyllosticta ipomoeae occurred on 100% of plants in some greenhouses, with leaf spotting affecting up to 25% of the foliage. In California, Pseudomonas syringae pv. syringae occurred on less than 25% of plants with up to 25% of the foliage affected. In Ontario, no virus was detected in eight suspect foliage samples while damage from vectors of plant viruses such as the green peach aphid (Myzus persicae) was minor and from Western flower thrips (Frankliniella occidentalis) was moderate. Edema affected water spinach at four sites in Ontario in 1994, with both the incidence and severity exceeding 75% at one site. For fungal and bacterial pathogens, Koch's postulates were fulfilled by inoculation and reisolation. Morphological characteristics of isolates in vitro and in vivo were used to identify the fungal pathogens, and LOPAT tests and fatty acid analyses were applied to identify the bacterial pathogen. Symptoms and etiology are discussed. This is the first report of these diseases, pests, and abiotic disorders on water spinach in Ontario and California.