The efficiency of two Trichogramma species as biocontrol agents against the European corn borer (ECB) Ostrinia nubilalis (Lepidoptera: Crambidae) was investigated under field conditions. Five inundative releases of Trichogramma ostriniae and T. brassicae (Hymenoptera: Trichogrammatidae) were done in sweet corn plots. Ostrinia nubilalis sentinel egg masses were placed on corn plants in order to compare the efficiency of the two Trichogramma species. The parasitism rate of O. nubilalis egg masses by T. ostriniae was 13% higher than egg masses parasitized by T. brassicae. Likewise, the percentage of eggs parasitized per mass by T. ostriniae was significantly higher following two of the five releases. Attacked egg masses showed an average of 29% of eggs parasitized by T. ostriniae, versus 14% of eggs parasitized by T. brassicae. The rate of parasitoid emergence from sentinel egg masses was also significantly higher for T. ostriniae than for T. brassicae. Damages to plants due to ECB did not differ significantly in presence of the two parasitoid species. However, plants in plots receiving parasitoids showed less damage than plants in control plots. Overall, T. ostriniae was clearly more efficient than T. brassicae to parasitized egg masses of O. nubilalis in sweet corn.
Ten products, commercially available as biostimulants or reported for their biostimulating properties, were tested under conventional and organic growing systems for their effects on mustard microgreens (Brassica juncea) grown in presence of abiotic (salt) or biotic (Pythium ultimum) stress. Drench application of wollastonite (calcium silicate) significantly improved the germination rate of mustard seeds sown in a substrate inoculated with P. ultimum in conventional growing system exclusively. In both growing systems, no significant effect of biostimulants was observed on the dry biomass or the proportion of healthy microgreens grown in presence of P. ultimum. None of the biostimulants significantly increased the germination rate of seeds exposed to a salinity stress in both growing systems while humic acid, triacontanol, chitosan, and Bacillus subtilis PTB185 significantly decreased the germination rate of seeds exposed to 40, 80 or 120 mM NaCl L-1 under conventional or organic management. Seed treatment with Trichoderma harzianum T-22 and humic acid resulted in microgreens with a significantly higher dry biomass when subjected to 40 and 80 mM NaCl L-1 under conventional and organic management, respectively. The study showed that the effects of the biostimulants vary from beneficial to detrimental and that plant response to biostimulants is influenced by the cultivation conditions.
Organic soils are an important resource for vegetable crops. However, these crops are very demanding in terms of pest control, fertilization and tillage. Combined with organic soil subsidence, current practices threaten the sustainability of this resource. In this study, we test the potential of Sunn hemp ( Crotalaria juncea) ) as a green manure to control populations of plant-parasitic nematodes and as a carbon input to the soil. Incorporating Sunn hemp resulted in a tenfold reduction in populations of the northern root-knot nematode ( Meloidogyne hapla) ) and a significant increase in carrot yields the following year. However, no significant effect was observed on the root-lesion nematode, Pratylenchus penetrans. .
Cyclamen mite (Phytonemus pallidus Banks) can be eliminated from strawberry (Fragaria x ananassa Duchesne) planting material when transplants are subjected to a controlled atmosphere temperature treatment (CATT) at 35 degrees C, 50% CO2 and 10% O-2 under high relative humidity for 48 h. In our previous research, CATT reduced cyclamen mite numbers by 99.9%, but its effects on plant vigour were not assessed. The objective of this study was to assess the survival, yield and growth of different strawberry cultivars ('Albion', 'Murano', 'Seascape') and plant types (bareroot plants, trayplants) that received CATT before planting compared to untreated control plants. CATT slightly increased the risks of plant mortality, and plant losses were greater for trayplants than for bareroot plants. CATT resulted in increased runner production for 'Albion' transplants but caused no effects on other cultivars. Fruit yields were either unaffected or decreased by CATT, suggesting stimulation of vegetative rather than reproductive growth. Based on these results, disinfection of strawberry transplants using CATT would be more suitable for plants destined for propagation rather than for fruit production. Our research highlights the need to develop a universal and easily adoptable treatment effective against multiple pests and pathogens to produce clean strawberry transplants.
Tetranychus urticae Koch (two-spotted spider mite) is an agricultural pest with a host range of over 1100 species of plants. Tetranychus urticae has rapidly developed resistance to a variety of synthetic chemical pesticides due to its high fecundity and short generation time. Plant essential oils have been recognized as a novel natural source of pest control that have a reduced impact to the environment and human health compared to synthetic pesticide application, and which may provide a viable alternative for managing T. urticae. The present study assessed the potential of a plantderived product (product 102) as an acaricide, through topical and residual bioassays on a variety of plant species (Brassica oleracea L.), cucumber (Cucumis sativus L.), hops (Humulus lupulus L.) and hemp (Cannabis sativa L.). The results of our study indicate that C. sativa is not a suitable plant to host T. urticae. Product 102 was determined to be effective at preventing the growth of two known fungal species of economic concern (Cladosporium herbarum Persoon and Botrytis cinerea Persoon). By conducting acute contact toxicity tests, we also determined that product 102 is significantly less toxic to Bombus impatiens Cresson compared to the commonly used synthetic insecticide imidacloprid.
Les sols organiques sont une ressource importante pour les cultures maraîchères. Par contre, ces cultures sont très exigeantes en termes de contrôle phytosanitaire, de fertilisation et de travail du sol. Combinées à la problématique d’affaissement des sols organiques, les pratiques actuelles menacent la pérennité de cette ressource. Dans cette étude, nous testons le potentiel de la crotalaire (Crotalaria juncea) comme engrais vert afin de contrôler les nématodes phytoparasites et comme apport de carbone. L’enfouissement de la crotalaire a permis de réduire de dix fois les populations du nématode cécidogène du Nord (Meloidogyne hapla) et d’augmenter significativement les rendements de carottes l’année subséquente. Aucun effet significatif n’a cependant été observé sur le nématode des lésions, Pratylenchus penetrans.
Plants develop defence mechanisms in response to abiotic and biotic stresses that can have both negative and positive effects. Tomatoes grown in the field are normally exposed to abiotic stresses such as high temperatures and water shortages, as well as biotic stresses such as tomato yellow leaf curl virus (TYLCV), which greatly reduces productivity in this crop. In this study, two TYLCV Korean isolates were used as molecular and physiological tools to identify interactions between TYLCV infection and drought tolerance in tomato. The tomatoes were inoculated by TYLCV-infectious clones and exposed to drought stress, which led to wilted leaves on plants in the mock group, while those on TYLCV-inoculated plants showed no significant drought symptoms. Moreover, the average relative water content (RWC) was higher in TYLCV-infected plants than in the mock group, and genes associated to drought tolerance were pre-activated in well-watered tomato plants. These results confirm that TYLCV infection enhance drought tolerance in tomato plants and pre-inoculation with symptomless TYLCV isolates can be applied to tomato plants before being cultivated in water-deficit regions.
Oak wilt, which develops in the outer sapwood, is the most destructive disease of oaks in the United States. Species of red oaks are more susceptible to this disease than white oak species and are more likely to facilitate the spread of the pathogen Bretziella fagacearum. To prevent its establishment in new areas, phytosanitary certificates are mandatory for commercial trade, as is the inspection of logs to confirm identification. A literature survey and the results of our assays with seven oak species confirm that it is easy to identify wood of the red and white oak groups using anatomical features. Specifically, earlywood vessels are generally open in red oaks, while they appear occluded with tyloses in white oaks. Such plugs are the consequence of air embolism (cavitation) and not the cause of the wilting process. Although these wide vessels are efficient for water transport, they are vulnerable to cavitation that appears to favour the growth of the oak wilt pathogen. Compartmentalization of infected wood succeeds in restraining cavitation and pathogen spread, allowing some trees to recover from oak wilt.
Metabolomics is one of the most eminent and newly emerging omic sciences. It is a powerful tool to study metabolic changes that occur in an organism. Plants produce a wide range of metabolites and the study of these metabolites can answer a number of questions that arise in the minds of researchers. Change in the metabolites is the most important feature in a genetically modified plant or plant interactions with pests, pathogens and the environment. Plant pathogen interactions are amongst the most biochemically complex mechanisms and pose a great challenge in front of plant pathologists; metabolomics not only play a great role in deciphering these complex interactions but also the study of certain defence-related metabolic changes can be utilized in a number of ways to protect the plant from the harmful pathogens. The science of metabolomics utilizes a number of techniques to study the wide variety of metabolites. This review will give a brief about the various techniques used in metabolomics and how some of these techniques have been successfully utilized in the field of plant pathology.
Plant-parasitic nematode populations were analyzed from composite soil samples collected from 62 vineyard blocks throughout Nova Scotia in 2018 and 2019. Nematode groups of potential concern that were found included ring nematodes (family Criconematidae), dagger nematodes (Xiphinema spp.), and root-knot nematodes (Meloidogyne spp.). Ring nematodes were overall the most widespread and abundant group of plant-parasitic nematodes, recovered from 79% of blocks with an overall average population density of 114 nematodes per 100 cm3 soil. Ring nematodes tended to be more abundant in older blocks. DNA sequence analyses of a subset of the ring nematode populations confirmed the presence of Mesocriconema xenoplax, which is the species known to be damaging to and most widely associated with grapevine globally. The analyses indicated that Criconema permistum was also present, notably in samples with the greatest ring nematode population densities. The results indicate that ring nematodes could be affecting the health of Nova Scotia vineyards, particularly in the future as populations continue to develop in relatively young vineyards and as older blocks are replanted. Additional research is needed to delineate the distribution of M. xenoplax vis-a-vis other species and to experimentally assess the host-parasite relationship between C. permistum and grapevine.
Chemical composition, antioxidant, and allelopathic activities of extract from leaves and cones of Tunisian Cupressus arizonica were evaluated. The values of essential oils (EO) yields were 0.18% for leaves and 1.07% for cones. Following GC/MS analysis of C. arizonica leaves and cones, the major compounds identified in leaves EO were umbellulone (19.4%) and alpha-pinene (10.75%) while the EO of the cones was characterized by its richness with alpha-pinene (81.3%). In comparison with different extracts, the highest total antioxidant capacity was registered with ethanolic extracts of leaves followed by that of cones. However, the antioxidant activity was stronger with ethanolic extract of leaves than that of cones using both DPPH or ABTS in free radical scavenging activity assays. Results of allelopathic activity showed that the germination reduction depends on the nature of extract and their concentration level. All extracts of C. arizonica decreased the germination of Sinapis arvensis compared to the control. The EO from leaves and cones had the greatest reduction on germination and the strongest growth inhibition followed by the ethanolic extract then the aqueous extract. Results of this study can lead to identification of new phytotoxic compounds in extracts of C. arizonica useful in controlling weeds.
In North America, the potential of the American hoverfly Eupeodes americanus (Wiedemann, 1830) (Diptera: Syrphidae) as a biocontrol agent has been demonstrated, particularly against the foxglove aphid Aulacorthum solani Kaltenbach, 1843 (Hemiptera: Aphididae). Since no information is available to distinguish the larval instars of this species, the present study used the semi-continuous observation (time-lapse photography and stereo microscope) of the three larval stages to build a table of morphological traits and a dichotomic key for discriminating the larval instars by observation under stereo microscope. Discriminating traits are black hairs at first instar and fused posterior breathing tubes at third instar.
The objectives of this study were to determine the qualitative production of extracellular enzymes produced by ten endophytic fungi and to investigate their antifungal potential against some phytopathogenic fungi namely, Alternaria alternata, Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani. In addition, the endophytic fungal isolates were screened for enzyme production by plate assay method. All endophytic fungi were able to produce proteases and cellulases with different levels except Alternaria alternata. Meanwhile, Fusarium, Alternaria, Nigrospora and Phoma species produced amylase. None of the tested endophytic fungi showed laccase production. Endophytic fungi filtrates revealed variable antifungal activities against the tested phytopathogenic fungi with Curvularia lunata filtrate being the most effective. This filtrate induced 48% and 80% growth inhibition of B. cinerea and R. solani, respectively. The phytochemical analysis of the endophytic fungi crude extract disclosed the presence of alkaloids and terpenoids. Morphological observations by optical microscope showed uncommon hyphal deformation and enlargement of cytoplasmic vacuoles of R. solani when treated with C. lunata filtrate. Furthermore, C. lunata (hyphal suspension and filtrate) was examined to control root rot caused by R. solani on faba bean plants in vivo. Both antagonistic treatments significantly reduced root rot severity.
The development of molecular tools for agricultural analysis promoted property crop production improvement to rising food security from stress caused by organic phenomenon factors, as well as the insect pest attack. Crop productivity has inflated quintuple over the past few decades due to high-yielding varieties, irrigation, fertilizers, and pesticides. However, the planet population is anticipated to grow staggeringly over subsequent four decades, from nine to ten billion individuals. It’s so imperative to extend the assembly of food grains to feed the population. As way as ancient agriculture technology is bothered, it still incorporates a good distance to travel. The molecular tools wont to shield crops from organic phenomenon stress during this instance like plant alpha-amylase inhibitors, vacuolar ATPase, hemoprotein P450 monooxygenase, enzyme modulating oostatic issue (TMOF), enzyme inhibitors (PIs), with the exception of sterol enzyme (CHOx), lipoxygenases (enzyme), and technology, etc. despite not being wholesome. Additionally to delivery ecologically property farming practices into our daily lives, bionanotechnology will give opportunities for developing nations and developed nations shortly. It should have an enormous impact on farming systems while not the employment of pesticides. There area unit considerations concerning the food safety risks related to transgenic plants since the unfold of antibiotic resistance, the changes within the nutrient composition of plants, and also the production of noxious proteins and allergens can not be answered currently. Besides victimization high-yielding varieties, irrigation, and fertilizers, it’s a potent role in minimizing the economic losses caused by insects. Within the current context of insect pest management, it’s imperative to develop bionanotechnology-based tools for pest management. However, their economical use necessity takes for reckoning the numerous ecological role useful insect play for the longer-term development of agriculture.
The silverleaf whitefly (SLW), Bemisia tabaci, is an exotic pest that causes sporadic crop damage in Canadian greenhouses, mainly on tomatoes. Its plant feeding is responsible for both direct damage as well as the transmission of plant viruses. Interestingly, omnivorous predators, which are used as biological control agents for multiple whitefly species, can establish on greenhouse crops even before the pest has established, using alternative food resources and host plants to support the predator. However, the efficiency of such indigenous omnivorous biological agents in the suppression of high density and intense SLW infestations remains unknown. This research aimed to assess the potential of two indigenous omnivorous biological agents, Dicyphus hesperus and Orius insidiosus to control SLW infestations and their effects on tomato plant health and yield at both early stages of the crop cycle, and at high pest densities. This study showed that populations of B. tabaci are able to grow rapidly. However, neither of the introduced densities of B. tabaci nor the infestation time had a significant effect on the incidence of tomato irregular ripening disorder (TIR) and yield. Our results also show that the introduction of three or five D. hesperus adults per cage reduces the number of B. tabaci larvae and pseudo-nymphs, while O. insidiosus did not significantly reduce SLW populations. Our results suggest that D. hesperus could control high levels of SWL and at an early stage in the cropping cycle.
Buckeye rot disease of tomato caused by Phytophthora nicotianae var. parasitica is the most destructive disease for reducing tomato yields especially in those regions where fruiting coincides with rainy season. In the present study, the pathogen was characterized by sequencing the DNA region coding for internal transcribed spacer (ITS) region and sequence was deposited in NCBI with accession no. MF398189. The phylogenetic analysis using the Maximum Composite Likelihood (MCL) approach revealed that the isolated pathogen clustered together with P. nicotianae with high bootstrap value of 99%. Incubation period of 120 h was observed in pin-prick method of pathogen inoculation compared to 168 h in surface inoculation method. Further, the disease resistance induced by nine different elicitors of induced resistance against buckeye rot disease of tomato were studied under field conditions for two consecutive years 2016 and 2017. Minimum disease incidence of 9.57% and 7.93% was observed with foliar spray of 8-aminobutyric acid (2 mM) for 2016 and 2017, respectively. It was followed by potassium chloride (100 mM) with disease incidence of 11.32% and 8.85% for year 2016 and 2017, respectively. Maximum fruit yield of 7.02 kg and 8.12 kg was found in treatment with 8-aminobutyric acid as compared to 2.61 kg and 2.55 kg in control for year 2016 and 2017, respectively.
The codling moth granulovirus (CpGV) and the egg parasitoids of the genus Trichogramma spp. are known as biocontrol agents of codling moth but interactions between them are unknown. The aim of this study was to assess the compatibility and the complementarity of Trichogramma minutum and CpGV. Bioassays were conducted in the laboratory the first year, as well as in an orchard over two years with the two biocontrol agents used alone or in combination. Parasitism of codling moth decreased in glass tube bioassays when CpGV was applied on eggs prior to parasitism, suggesting that female parasitoids discriminated between eggs covered or not with the virus. In contrast, egg discrimination was not observed in the orchard, since the presence of CpGV on codling moth eggs did not affect T. minutum parasitism. Both biocontrol agents together caused 77 and 79% mortality to codling moth in the orchard in the first and the second year of the study, respectively. Our results in the orchard showed that the combined use of CpGV and T. minutum to control the codling moth is compatible. Therefore, the utilization of both biocontrol agents is a promising alternative to control this pest in apple orchards.
