查看更多>>摘要：? 2021 Elsevier LtdFusarium spp. complex, (Fusarium verticillioides, F. subglutinans, F. moniliforme, F. graminearum) causing post flowering stalk rot (PFSR), has been reported as a serious disease in southern Rajasthan, and eastern Gujarat in winter maize. In the present study, emphasis has been laid on the efficacy of twenty seven Trichoderma strains against F. verticillioides which is a major causal organism. Efficacy evaluation of Trichoderma strains was based on the radial growth of the pathogen in the presence of biological control agent (BCA). Based on per cent inhibition three potential native strains of Trichoderma spp (Trichoderma harzianum BThr29, T. asperellum BTas25, and T. erinaceum BTer43) were selected for biological control of PFSR in the field. T. harzianum BThr29, T. asperellum BTas25, and T. erinaceum BTer43 showed per cent inhibition of F. verticillioides by 87.8, 83.9, and 81.1 percent respectively. Maize plants were artificially inoculated with F. verticillioides, and three potential Trichoderma strains were delivered as soil application (Trichoderma enriched FYM 10 tones ha?1), seed treatment (10 g/kg seeds), and drenching (10 g/liter water). Split stem observation at the harvest of crop showed a restricted lesion of T. harzianum BThr29 treated plant at par with fungicidal application with an average mean rating scale of 1–1.3, which showed less than 50% discoloration in inoculated internode. In control, the mean disease rating scale was 3–3.4 which showed 51–75% of the inoculated internode is discolored. Application of Trichoderma strains improved crop stand by reducing lodging from 42.1 to 71.1% in inoculated maize plants, and reduced PFSR disease severity from 17.58 to 62.37%, Fungicidal application reduced lodging of maize plant from 57.91 to 77.78% and PFSR disease by 58.24–64.35% as compared to untreated control. The results obtained suggested that Trichoderma harzianum BThr29 has the potential to be used as a non-chemical alternative for PFSR disease management in maize crops.
查看更多>>摘要：? 2021 Elsevier LtdThe sugarcane borer, Diatraea saccharalis (Lepidoptera: Crambidae), is the primary pest of sugarcane, Saccharum spp., in much of North and South America. Control of D. saccharalis can be obtained through judicious application of insecticides, but more research is needed to optimize chemical control strategies. A series of field trials evaluated the duration of protection and influence of application water volume on D. saccharalis control in Louisiana sugarcane from 2018 to 2020. Results across trials demonstrated superior control was achieved with chlorantraniliprole over novaluron and tebufenozide. Analysis of insecticide concentrations present in leaf sheath tissue of the target internode suggests chlorantraniliprole and novaluron are achieving systemic activity, but not tebufenozide. Chlorantraniliprole concentrations remained above lethal levels for more than 8 wk after application. The percentage of bored internodes was 1.3- and 1.9-fold greater following applications with a water volume of 18.7 L/ha relative to those made with 46.7 and 186.8 L/ha, respectively, across insecticides. Collectively, results suggest chlorantraniliprole applied early in the season with sufficient water volume can provide nearly season-long protection of sugarcane against D. saccharalis injury.
查看更多>>摘要：? 2021 Elsevier LtdSmallholder farmers in sub-Saharan Africa (SSA) face several challenges that include pests and diseases. Plant-parasitic nematodes (PPN) reduce crop yields and affect their quality. They are an emerging threat to smallholder agriculture with several species attacking economically important crops. In SSA, most PPN control strategies are therapeutic and therefore unsustainable. Cost-effective nematode management strategies that promote soil health and enhance soil suppressiveness against PPN are therefore needed. These strategies can fit into most smallholder cropping systems and in addition to controlling PPN, they also promote soil and plant health and tolerance to other diseases. Most smallholders in SSA still use traditional farming methods although some countries have adopted conservation agriculture (CA) and integrated soil fertility management (ISFM). This review analyzes the potential impact of CA and ISFM on PPN communities and it also provides a concise summary of low-cost PPN control strategies and their efficiency against specific nematode species. Variations in their efficacy is also discussed. The strategies are proposed for adoption across SSA based on site-specific conditions.
查看更多>>摘要：? 2021 Elsevier LtdAnthracnose caused by Colletotrichum spp. is an important disease of pepper (Capsicum annuum), affecting fruits and the overall yield worldwide. The disease was recently observed for the first time in Israel in the summer of 2020. In this study, morphology, phylogenetic analysis using glutamine synthase (gs) and the intergenic region between apn2 and Mat1-2 genes (ApMat) sequences, and pathogenicity assays were conducted to characterize and identify the Colletotrichum isolates retrieved from symptomatic pepper fruits. This is the first report of Colletotrichum aenigma and C. perseae as pathogens of pepper anthracnose in Israel.
查看更多>>摘要：? 2021 Elsevier LtdBacterial soft rot is a destructive disease affecting calla lily production, and it is mainly caused by Pectobacterium carotovorum (Pc). In 2019, this destructive disease was observed in the Shandong and Jiangsu Provinces of China and resulted in serious economic losses for commercial greenhouse producers of ornamental plants. The disease symptoms on leaves and stems were yellow and dark brown patches, and then water-soaked lesions that turned to wet rot occurred on the stems. In total, we obtained twenty-eight calla lily soft rot samples collected from Shandong and Jiangsu. Fifteen colonies on LB medium were milky white, nearly round, with a smooth surface and neat edges. The soft rot symptoms in calla lily caused by artificial inoculation were the same as the natural symptoms in the field. Based on the phenotypic properties determined by morphological, biochemical and physiological analyses, 16S ribosomal DNA gene sequence analysis, and multilocus sequence analysis, the pathogen was identified as P. aroidearum. In addition, all P. aroidearum strains exhibited high virulence and a wide host range on monocotyledonous and dicotyledonous plants. This study is the first official report of P. aroidearum causing calla lily soft rot in China, and the results contribute to a better understanding of the disease.
查看更多>>摘要：? 2021 The AuthorsFollowing the discovery of Asian citrus psyllid (ACP) in 1998 and Huanglongbing (HLB) in 2005, this destructive disease associated with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) now affects most mature citrus trees in Florida. Despite the endemic presence of ACP and HLB, Florida citrus growers continue to plant new trees. The young trees are more vulnerable to both ACP infestation and CLas infection; therefore, protection from the vector psyllid by exclusion or other control methods is of paramount importance. Individual protective covers (IPCs), bags made from fine mesh netting, are a vector exclusion tool, which could prevent psyllids from transmitting CLas to young trees during the early years of growth. The use of IPCs is an environmentally friendly pest management strategy, contrary to the frequent use of insecticides to control ACPs. In this study, we investigated the efficacy of IPCs to protect trees from ACP and CLas infection in a citrus grove in southwest Florida during the first two years after planting. IPCs were compared against insecticide applications to control ACPs and tree health and growth were assessed. We found that IPCs effectively excluded psyllids, prevented CLas infection, altered microclimatic conditions in the tree canopy, and positively influenced most of the horticultural traits measured. However, IPCs promoted the incidence of other “diseases” such as greasy spot and sooty mold and of scale insects but reduced occurrence of citrus canker and citrus leaf miner. This suggests that use of IPCs may be an effective approach to protect young trees from ACP and HLB, but integrated pest management approaches will be needed for other pests during IPC use and after removal to maintain overall health of citrus trees.
查看更多>>摘要：? 2021 The AuthorsMulti-cropping of vegetables on the same plastic mulch builds up the population of root-knot nematodes (RKN; Meloidogyne spp.), which can severely reduce crop growth and yield. Vegetable growers in the southeastern US usually fumigate soil while laying the plastic mulch in the spring. They then apply non-fumigant nematicides via drip irrigation systems for subsequent crops grown on the mulch. With the advent of new and emerging nematicides, this research was aimed to investigate the best chemical control practice for M. incognita in a pepper and squash plasticulture system. Field trials were conducted in the spring (pepper) and summer (squash) of 2019 and 2020. The spring treatments were soil fumigants of 1,3-dichloropropene, allyl isothiocyanate, and 1,3-dichloropropene plus chloropicrin (Pic60), a RKN-resistant cultivar (Carolina Wonder), and an untreated check. Summer treatments were the non-fumigant nematicides fluopyram, fluensulfone, fluazaindolizine, oxamyl, and Burkholderia spp. strain A396. All spring treatments, except allyl isothiocyanate, reduced (P < 0.05) root galling compared to the untreated check at pepper harvest. At the end of the season, the population density of M. incognita in the soil was only lower (P < 0.05) for the RKN-resistant cultivar treatment than that of the untreated check. Though the RKN-resistant cultivar treatment had the lowest (P < 0.05) soil RKN population and significantly reduced root galling, it had the lowest pepper fruit yield. In contrast, pepper associated with Pic60 treatment had the highest fruit yield. For the summer trial, squash plots treated with fluensulfone had the lowest root gall index and oxamyl had the highest (P < 0.05); however, no difference was observed between fluensulfone and oxamyl with other treatments. In 2019, plots treated with Burkholderia spp. and fluensulfone had higher fruit yield (P < 0.05) than fluazaindolizine; however, squash yield was similar among the treatments in 2020. This study suggests that Pic60 (a mix of nematicide and fungicide active ingredients) is likely an ideal fumigant to apply when laying the plastic mulch because of its broad-spectrum effect, and any of the non-fumigant nematicides may be used in RKN control on squash.
查看更多>>摘要：? 2021 The AuthorsThe alfalfa weevil Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) is a major pest of alfalfa worldwide. In Spain, insecticide sprayings are mainly used for control with low efficacy. As a potential more sustainable control method, we determined the effectiveness of an alfalfa winter cutting for reducing pest populations in the spring and its interaction with parasitism rate due to Bathyplectes spp. (Hymenoptera: Ichneumonidae). Forty-two commercial fields were split in two parts and one was mowed during winter. Larval abundance in each part of the field was sampled by sweep netting in 2019 and 2020 before the first alfalfa spring cutting, when damage is caused. The rates of parasitism due to Bathyplectes anura (Thomson) and Bathyplectes curculionis (Thomson) were estimated by rearing larvae in the laboratory. Winter cutting significantly reduced the spring larval weevil populations and favored the rate of larval parasitism. Our results suggest that winter cutting can be a useful cultural method for alfalfa weevil control that has potential to be a component of an integrated pest management program.
查看更多>>摘要：? 2021Kiwiberry (Actinidia arguta), originating from northeast Asia, is a new fruit product. Since 2018, fruits of kiwiberry showing brown spots were observed in orchards of Zhejiang Province, China. Disease symptoms started from the initial stage of fruit development. The brown spots on young fruits extended as the fruits developed. The fungus strain isolated from the affected fruits was preliminarily identified as Alternaria species according to morphological characteristics. Further molecular identification based on a multi-locus phylogenetic analysis comprised of partial sequences of internal transcribed spacer (ITS) rDNA region, endopolygalacturonase (endoPG) gene, major allergen (Alta1) gene, and 28S ribosomal RNA (LSU) gene verified that the fungus is Alternaria alternata. The pathogenicity of the isolated fungus was confirmed by artificial inoculation. The present identification constitutes the first report of A. alternata as the causal agent of brown spot on kiwiberry in China.
查看更多>>摘要：? 2021Early blight, caused by Alternaria solani, and brown leaf spot, caused by a number of small-spored Alternaria spp. including Alternaria alternata sensu stricto, Alternaria arborescens, and Alternaria tenuissima, are observed annually in all midwestern potato production areas. However, Alternaria spp. have developed reduced sensitivity and/or resistance to many single-site mode of action fungicides such as quinone outside inhibitor (QoI; FRAC group 11), succinate dehydrogenase inhibitor (SDHI; FRAC group 7), and anilinopyrimidine (AP; FRAC group 9). Mean in vitro sensitivity EC50 values (effective concentration where fungal growth is inhibited by 50%) of A. alternata (n = 16), A. arborescens (n = 3), A. tenuissima (n = 5), and A. solani (n = 58) in response to the AP fungicides pyrimethanil and cyprodinil and the phenylpyrrole (PP) fungicide fludioxonil were determined via mycelial growth assays. Significant fungicide by isolate interactions were observed for all Alternaria spp. evaluated in vitro, indicating reduced-sensitivity of some isolates to individual fungicides. EC50 values for three non-baseline A. solani isolates collected in 2010, 2011 and 2013 were within the baseline for all three fungicides. A significant correlation was observed between pyrimethanil and cyprodinil EC50 values among A. alternata isolates, but no relationship was observed with the other fungicides or in A. solani. In greenhouse evaluations, a significant loss of disease control was observed for some non-baseline A. solani isolates, and this was more pronounced in the AP fungicides, pyrimethanil and cyprodinil. No significant correlation was observed between in vitro EC50 value and area under the dose response curve based on greenhouse assays, likely due to the limited number of isolates evaluated. Further research is needed to determine if these reductions affect control of early blight and brown leaf spot in potato under field conditions. Results from this study indicate that fludioxonil and cyprodinil are potentially good additions into fungicide rotation programs or as co-pack chemistries for control of leaf spot diseases and fungicide resistance management.
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