Journal of Plant Diseases and Protection最新文献

Whitefly, Bemisia tabaci (Gennadius), and leafhopper, Amrasca biguttulla biguttulla, Ishida, are the major biotic constraints in cultivation of okra, causing considerable economic damage. The present study aims to evaluate the laboratory and field efficacy of butenolide insecticide, flupyradifurone 200 SL against these key sucking pests, its phytotoxicity, safety to natural enemies as well as pollinators and cost-efficiency in okra. Dose probit mortality assays indicated flupyradifurone to be the most toxic and thiamethoxam least toxic to leafhopper and whitefly. Based on the LC₅₀ values for whitefly and leafhopper, flupyradifurone exhibited 11.07 and 2.98-fold difference, respectively, when compared to thiamethoxam. Laboratory bioassays confirmed that the maximum dose of flupyradifurone (250 g a.i. ha⁻¹) had a high level of toxicity to whitefly adults and leafhopper nymphs. Of the three field rates (150, 200, 250 g a.i. ha⁻¹) of flupyradifurone evaluated under open field conditions, application at 250 g a.i. ha⁻¹ was most effective for the control of whitefly and leafhopper population with a high marketable fruit yield in okra. Flupyradifurone reduced the population of whitefly by 71.80 & 76.68 per cent and leafhopper by 82.19 and 80.21 per cent during first and second season, respectively, as compared to untreated control. Furthermore, it was superior and more economical, giving the highest benefit: cost ratio (2.77) than other test insecticides included for comparison. Flupyradifurone application showed no phytotoxic symptoms on the okra crop. Additionally, it was found to be safer to natural enemies i.e. spiders and rove beetles that are prevalent in the okra ecosystem. The Kaplan–Meier survival analysis showed that flupyradifurone was apparently less toxic to honey bees in short-term and long-term exposure assays. These findings will aid in utilizing the flupyradifurone in insecticide window spray schedules and IPM programs for the management of sucking pests in okra.

Insufficient analysis of carriers and their interaction with biocontrol agents can lead to ineffective formulations. Therefore, it is important to thoroughly study the compatibility and interactions between carriers and biocontrol agents for high-quality biological formulations. The present study aimed to evaluate the effect of four different formulation compositions containing gum katira biogel, vermiculite, and diatomaceous earth on the survival and infectivity of infective juveniles (IJs) of two entomopathogenic nematodes (EPNs) species namely, Steinernema abbasi and Heterorhabditis indica at 25 and 35 °C. The physicochemical analysis of the prepared formulations revealed their slightly acidic nature with pH ranging from 5.65 to 6.10. Rheological studies validated the solid-like behavior of the developed formulations. The highest survival of S. abbasi IJs was observed in the case of gum katira biogel-vermiculite blended composition at both 25 °C (94.2%) and 35 °C (88.4%) after 90 days of storage. Interestingly, gum katira biogel alone sustained maximum survival percentage (63.5%) of H. indica as compared to control (41.5%) after 90 days at 25 °C. The formulation compositions failed to retain alive H. indica IJs at 35 °C even after seven days of storage. Moreover, the gum katira singly or in combination with vermiculite resulted in superior infectivity against Galleria mellonella (4th instar larvae) as compared to the other treatments in case of both the nematode species. The presence of diatomaceous earth in all the compositions irrespective of moisture and EPN species showed a negative impact on the survival and infectivity of IJs after 90 days of storage. Gum katira biogel alone or in combination with vermiculite was favorable to sustaining the survivability and infectivity of test EPN IJs at ambient storage temperatures. These formulants can further be used to develop biocontrol EPN formulations for organic farming and integrated pest management programs.

Abstract

In an integrated nematode management system, the best results are generally obtained by rotating crops with resistant plants, antagonists, or poor host of parasites. Some reports indicate that Stylosanthes spp. have the potential to control nematodes. Thus, this study aimed to assess the reaction of Stylosanthes spp. ‘Campo Grande’ to Pratylenchus brachyurus and Meloidogyne javanica penetration and reproduction at different inoculum levels and examine the histopathology and histochemistry of parasitized plants. Stylosanthes did not prevent P. brachyurus penetration in roots. However, the number of penetrated nematodes was lower than that in soybean from 17 days after inoculation onwards. The numbers of second-stage and third-/fourth-stage juveniles of M. javanica in Stylosanthes roots were close to zero, and no females were observed. Assays conducted using increasing levels of inoculum (P. brachyurus or M. javanica) showed that Stylosanthes was resistant to the parasites, with a maximum reproduction factor of 0.59 for P. brachyurus and 0.07 for M. javanica. Histopathological analysis showed the presence of P. brachyurus in Stylosanthes, but without rupture of plant cells. M. javanica individuals were not observed. Histochemistry revealed the presence of phenolic compounds in the epidermis of Stylosanthes and proteins in plant cells. These results show that Stylosanthes spp. ‘Campo Grande’ can be used in crop rotation programs in fields with mixed infestation of P. brachyurus and M. javanica.

Kiwifruit, which is known for its unique flavour and high value, is extensively cultivated in the world, especially in China. In 2022, a unique case of leaf spot disease was discovered in Xifeng, Guizhou Province, China, with symptoms deviating from those reported in previous studies. We isolated the pathogenic fungal strain YYK-A and YYK-F using the tissue isolation method and verified them using Koch’s postulates. The colony appeared white during early growth and gradually turned black at later stages. The conidia exhibited 3–8 transverse septa, 0–2 longitudinal septa and measured 10.0–53.0 × 5.0–13 µm in size. The strain was identified as Alternaria longipes, which was supported by phylogenetic analyses based on multigene sequences. The inhibitory activity of five fungicidal active substances against A. longipes was investigated using the mycelium growth method to formulate an effective disease management strategy. Honokiol displayed the highest inhibitory activity against A. longipes with an EC₅₀ of 9.57 mg L⁻¹. To our knowledge, this is the first report of A. longipes causing kiwifruit leaf spot in China.

The Western flower thrips (WFT), Frankliniella occidentaliss (Pergande) (Thysanoptera: Thripidae), is the main pest of many vegetables and ornamental plants in greenhouses in Antalya province (southwestern part of Turkey). The objectives of this study were: (i) to isolate indigenous Entomopathogenic fungi (EPFs) from naturally infected individuals of WFT in the coastal area of Antalya, where greenhouse cultivation is intensively done, (ii) to identify EPF isolates using DNA sequencing, and (iii) to assess the effectiveness of the isolates against various developmental stages [larvae (1st and 2nd instars), pupa and adult (only females)] of WFT under laboratory conditions. In pathogenicity assays, all isolates were tested at three different conidial concentrations (1 × 10⁵, 1 × 10⁶ and 1 × 10⁷ conidia/ml), using the spray method. Two Beauveria bassiana (Balsamo) Vuillemin (Deuteromycota: Hyphomycetes) isolates (M48 and M49) and Isaria fumosorosea Wise formerly [formerly known as Paecilomyces fumosoroseus (Wise) (Ascomycota: Hypocreales)] isolate (M50) were the most pathogenic, causing 100% mortality of WFT larvae within 7–10 days at the highest concentration (1 × 10⁷ conidia/ml). These three isolates also caused a mortality of more than 85% in the pupae of WFT. The Lecanicillium psalliotae (Treschew) Zare & W. Gams (Ascomycota: Hypocreales) isolate (DOA3) was the most virulent against adult females of WFT, causing 100% morality at the highest concentration 10 days after treatment. The current study’s findings suggested that certain EPF extracted from WFT cadavers may provide an important foundation for the creation of bioproducts, as well as a possible alternative technique for regulating WFT.

Avocado (Persea americana) crop suffers important economic losses due to fungal diseases. Enterolobium cyclocarpum and Amphipterygium adstringens are saponins-producing species and their crude extracts have shown antimicrobial activity. The aim of this work was to evaluate in vitro antifungal activity of aqueous extracts from E. cyclocarpum (leaves and bark), A. adstringens (branches), and their saponins-rich fractions against Colletotrichum gloeosporioides, an avocado pathogen. The fungus was isolated from avocado fruits from Uruapan Michoacan (Mexico) and its molecular identification was performed by sequencing. Saponins-rich fractions (SRF) were obtained by partitioning infusions with n-butanol followed by precipitation with acetone. Antifungal activity of infusions and SRF was evaluated by the agar diffusion method and the strongest growth inhibition of C. gloeosporioides (33%) was achieved with the SRF of E. cyclocarpum bark. Erythrocyte hemolysis was observed with the three infusions and the sarsasapogenin was putatively identified in the product of Amphipterygium branch aqueous extract (ARA) acid hydrolysis by gas chromatography-flame ionization detector (GC-FID). These results highlight the antifungal potential of saponins from this medicinal plant against avocado pathogenic fungi.

The root-knot nematode Meloidogyne paranaensis is one of the main problems for coffee production in Latin American countries. In Mexico, this nematode is found damaging shaded coffee plantations, with a wide variety of associated vegetation. The plant species present in these agroecosystems could serve as nematode alternative hosts, helping to maintain and disperse the population of M. paranaensis even when control measures are carried out for coffee trees. The aim of this work was to evaluate the ability of M. paranaensis to reproduce in 13 plant species commonly associated with shade-grown coffee plantations. The plants were inoculated with eggs and J2 of M. paranaensis, 10 months later, the host susceptibility index and the resistance level were calculated based on the nematode population density. Meloidogyne paranaensis reproduced in 11 of the evaluated plants which presented different resistance levels. Citrus aurantium, Citrus reticulata, Inga jinicuil, Inga vera and Musa AA, were highly susceptible compared to Coffea arabica and Coffea canephora. On the other hand, Macadamia integrifolia and Psidium guajava are considered resistant to moderately resistant with a reproduction rate less than one and a susceptibility index less than 10 with respect to C. arabica and less than 25 with respect to C. canephora. Persea schiedeana and Syzygium jambos did not allow M. paranaensis reproduction, so they are considered highly resistant. The results of this study provide important information for the M. paranaensis management in infested shade-grown coffee plantations. It is necessary to evaluate other woody and herbaceous plant species to improve control measures for this nematode.

The control of fall armyworm (FAW), Spodoptera frugiperda, has been a significant concern to corn and rice agroecosystems in the Philippines. As one of the strategies for FAW management, recent studies have focused on developing entomopathogen-based control tactics, of which utilization of entomopathogenic nematodes is considered as a promising option. This paper evaluated the efficacy of the Philippine isolates of Heterorhabditis indica (HiBSDS, HiMAP, HiPBCB) and Steinernema abbasi (SaMBLB) against the two strains of S. frugiperda. Results showed that all isolates are virulent to both strains 24–48 h post-infection (hpi). However, to achieve similar FAW mortality, H. indica was found to require less IJ measured through penetration percentage as compared with S. abbasi. Lower LC₅₀ and LT₅₀ values were also observed for H. indica isolates than SaMBLB. Among the H. indica isolates, no intraspecific variability in terms of virulence was observed. More apparent is the interspecific variability between S. abbasi and H. indica, as the latter demonstrated higher virulence activity. The FAW strains also showed similar level of sensitivity relative to each of the EPN treatments. Although this warrants further greenhouse and field efficacy study, the findings demonstrated the biocontrol potential of these local EPN isolates against FAW which can also be incorporated in integrated pest management of this insect pest in the Philippines.

Global agriculture is heavily dependent on sustainable plant protection. Worldwide, the concept of integrated pest management (IPM) is being followed. IPM utilizes a range of strategies, with chemical synthetic pesticides being employed only as a last resort. However, in agricultural practice, farmers continue to rely primarily on this option. To further reduce this dependence, new strategies are being sought to strengthen the use of biological control within the IPM approach including the identification of novel non-synthetic natural compounds. Here, we discuss and report on the state of the art in biological control research in areas such as biocontrol agents and application of ecological principles. These practices can help to establish sustainable plant protection systems, with the greatest impact achieved when they are used in appropriate combinations. We highlight the conditions that currently prevent or hinder the increased use of biocontrol measures. On the background of agroecological experiences, we discuss why additional advancements in plant protection practices are imperative to more effectively break the life cycles of pests, diseases and weeds. We emphasize the significance of a judicious application of chemical control technologies, adapted to local conditions. Additionally, we highlight the key role and expertise of operators in implementing these practices and their knowledge thereof.

Abstract

Plant leaf disease identification and classification are the most essential and demanding tasks in the agriculture field. In traditional researches, various automated detection technologies have been developed with the goal of more accurately identifying plant leaf disease. Nevertheless, it faces some problems related to complex mathematical modeling, increased time consumption, processing overhead, and mis-prediction results. Therefore, a novel probabilistic intermittent neural network and artificial jelly fish optimization-based plant leaf disease detection system is proposed in this paper. The proposed work aims to “make a new detection scheme to identify correctly plant leaf disease from the given dataset.” Here, the probabilistic intermittent neural network (PINN) classification technique is used to predict label as normal or affected by disease. If it is disease affected, the residual multi-scale Unet segmentation (RMUNet) segmentation technique is applied to segment the disease affected region. Finally, the simulation outcomes confirm the efficiency of the proposed leaf disease identification system under some variables.