BIOLOGICAL NEMATICIDES ASSOCIATED WITH POULTRY LITTER IN THE CONTROL OF NEMATODES IN SOYBEAN AND SECOND CORN CROP

ABSTRACT Alternative management measures have been used to reduce nematode population levels in affected areas. In this perspective, the objective was to evaluate the efficiency of nematicides based on fungus and bacterium, associated with poultry litter applied via ground in the management of Pratylenchus brachyurus and Heterodera glycines in soybean and corn crops in succession. The experiment was conducted in the 2018/19 growing season in the municipality of Ipameri– GO (-17°34’55.58”S−48°12’02.35”O) in naturally infested field, arranged in a randomized block design, with 10 treatments and 4 replicates, being: T1- Witness/ control, T2- Poultry litter, T3- P. lilacinum + T. harzianum, T4- B. subtilis + B. licheniformis, T5- P. chlamydosporia, T6- Abamectina, T7- P. lilacinum + T. harzianum + Poultry litter, T8- B. subtilis + B. licheniformis + Poultry litter, T9- P. chlamydosporia + Poultry litter, T10- Abamectina + Poultry litter. The poultry litter was added in the soil 10 days before planting. The plots were composed of 6 lines of 6 m, with a spacing of 0.5 m. In the soybean crop at 45 and 90 days after sowing (DAS), the fresh weight of the roots (MFR), nematological variables and productivity were evaluated. In corn, only nematological variables were evaluated at 60 DAS. The treatments using P. lilacinum + T. harzianum and B. subtillis + B. licheniformes increased the MFR and reduced the number of P. brachyurus and H. glycines at the root. P. chlamydosporia associated with poultry litter increased in productivity in soybean plants.

Response of onion (Allium cepa L.) to plant population and weed control methods in a chicken weed (Portulaca quadrifida L.) infested field In Sudan Savanna, Nigeria

Chicken weed is a significant weed in India and it occurs under onion cultivated field at Birnin Kebbi in the Sudan Savannah, Nigeria. On-farm experiment was conducted at Birnin Kebbi during the 2017/2018 and 2018/2019 dry season to evaluate the effect of plant population and weed control methods on the management of chicken weed (Portulaca quadrifida) alongside other weeds in onion field. The experiment consisted of three plant populations (500,000, 333,333 and 250,000 plants per hectare) and twelve weed control methods (Pendimethalin at 1.0 kg a.i. ha-1, + 1Hw; pendimethalin at 1.5 kg a.i. ha-1 + fluazifop-p-butyl at 2.0 kg a.i. ha-1; pendimethalin at 2.0 kg a.i. ha-1; butachlor at 2.0 kg a.i. ha-1 + 1Hw; butachlor at 2.8 kg a.i. ha-1 + oxyfluorfen at 1.0 kg a.i. ha-1; butachlor at 3.6 kg a.i. ha-1; fluazifop-p-butyl at 2.0 kg a.i. ha-1; oxyfluorfen at 1.0 kg a.i. ha-1 + 1Hw; hoe weeding at 3 (WAT); hoe weeding at 3 and 6 WAT; weed free and weedy check). The experiment was laid out in a randomized complete Block design replicated three times. Results showed that weed, growth and yield parameters were not significantly affected by plant population. Pendimethalin at 1.5 kg a.i. ha-1 + fluazifop-p-butyl at 2.0 kg a.i. ha-1 and weed free plots consistently recorded the lowest weed cover and highest weed control efficiency. Butachlor at 2.0 kg a.i. ha-1 + 1 Hw recorded the lowest crop injury score. Increase in plant height was observed when pendimethalin at 1.0 and 1.5 kg a.i. ha-1 + 1 Hw and fluazifop-p-butyl at 2.0 kg a.i. ha-1 respectively was applied, while application of pendimethalin at 2.0 kg a.i. ha-1 and butachlor at 2.0 kg a.i. ha-1 + 1 Hw recorded highest number of leaves and leaf area. Cured bulb and marketable bulb yield were greater with the use of pendimethalin and butachlor at 1.0 and 1.5 kg a.i. ha-1 + 1 Hw and the pooled data respectively. Application of pendimethalin and butachlor at the rate of 1.0 and 2.0 kg a.i. ha-1 followed by 1 Hw at 6 WAT respectively was therefore recommended for the control of chicken weed alongside other weed species in the ecology

Herbal Plants as Alternatives for the Management of the Red Imported Fire Ant, Solenopsis Invicta (Hymenoptera: Formicidae)

The red imported fire ant (RIFA) is one of the most detrimental invasive species, threatening native ecosystems, human health, and economic activities worldwide. In the quarantine zone of Taiwan, RIFA re-infestation frequently occurs despite the intensive application of synthetic pesticides, making its control costly and ineffective. Thus, there is an urgent need to identify effective, eco-friendly, and sustainable alternatives for controlling RIFA populations. In this study, we examined the efficacy and feasibility of planting herbal species for RIFA control. Five herbal species, Tagetes lemmonii, Armoracia rusticana, Cymbopogon citratus, Cymbopogon nardus, and Chrysopogon zizanioides, were planted in a RIFA-infested field with local weeds as controls. Bait and pitfall traps and RIFA intruded plants were used to compare the ant activity in the control fields and those containing herbal plants. The RIFA repellent activity of the five herbal plants and their basal soil was further evaluated through digging bioassays. Generally, the field surveys showed more ants and intruded plants in the control than in the herbal groups; however, the significance varied based on the trap type and plant species. The bioassays demonstrated the significant repellency of the aboveground parts of T. lemmonii, C. nardus, and C. citratus, and the belowground parts of T. lemmonii, C. citratus, and V. zizanioides against RIFA. The basal soil of T. lemmonii, C. citratus, and C. nardus also exhibited deterrent activity toward RIFA. Our results demonstrated that herbal plants are eco-friendly, sustainable alternatives for controlling and preventing RIFA infestation in severe infested and non-infested areas.

Developing a Real-time PCR Assay for Direct Identification and Quantification of Soybean Cyst Nematode, Heterodera glycines, in Soil and Its Discrimination from Sugar Beet Cyst Nematode, Heterodera schachtii

The soybean cyst nematode (SCN) Heterodera glycines continues to be a major threat to soybean production worldwide. Morphological discrimination between SCN and other nematodes of the H. schachtii sensu stricto group is not only difficult and time-consuming, but also requires high expertise in nematode taxonomy. Molecular assays were developed to differentiate SCN from sugar beet cyst nematode (SBCN) and other nematodes; and to quantify SCN directly from DNA extracts of field soils. SCN and SBCN-specific quantitative real-time PCR (qPCR) primers were designed from a nematode-secreted CLAVATA gene and used for these assays. The primers were evaluated based on specificity, efficiency, and target specificity to SCN or SBCN using DNA from 20 isolates of SCN and 32 isolates of other plant-parasitic nematodes. A standard curve relating threshold cycle and log values of nematode numbers was generated from artificially infested soils and was used to quantify SCN in naturally infested field soils. There was a high correlation between the SCN numbers estimated from naturally infested field soils by conventional methods, and the numbers quantified using the SYBR Green I-based qPCR assay. The qPCR assay is highly specific and sensitive and provides improved SCN detection sensitivity down to 1 SCN egg in 20 g of soil (10 eggs/200 g soil). This assay is useful for efficient detection and quantification of SCN directly from field soil. Species-specific conventional PCR assays were also developed each for SCN and SBCN, alongside a qPCR assay that simultaneously discriminates SCN from SBCN. These assays require no expertise in nematode taxonomy and morphology, and may serve as useful diagnostic tools in research, diagnostic labs, and extension services for SCN management. Sensitive and accurate detection and quantification of SCN are essential for recommending effective management measures against SCN. We also investigated the impact of soil texture and nematode life stage on molecular quantification of SCN.

Resistance to Charcoal Rot Identified Within Soybean Cyst Nematode Resistant Accessions

Two infectious root diseases that cause significant yield losses worldwide in soybean [Glycine max (L.) Merr.] are charcoal rot caused by Macrophomina phaseolina (Tassi) Goid. and the soybean cyst nematode, caused by Heterodera glycines Ichinohe. The objective of this research was to evaluate resistance to charcoal rot in a set of 120 soybean accessions reported to have resistance to one or more races of soybean cyst nematode so that lines with combined resistance could be identified. These accessions were screened in infested field in 2006 and 2007. Charcoal rot severity ranged from 1 to 5, where 1 is resistant and 5 susceptible. The result showed that out of the 120 soybean accessions tested for charcoal rot resistance 12 were identified to have moderate levels of resistance, 51 had moderate susceptibility, and 60 were susceptible. Furthermore, the accessions with moderate resistance to charcoal rot had resistance for one to two races of soybean cyst nematode. Within the lines identified with moderate resistance to charcoal rot, nine had a yellow seed coat, a desirable agronomic trait. These lines can be used as parents in soybean breeding programs for developing soybean cultivars with combined resistance to both charcoal rot and soybean cyst nematode.

CRISPR-Based Isothermal Next-Generation Diagnostic Method for Virus Detection in Sugarbeet

Rhizomania is a disease of sugarbeet caused by beet necrotic yellow vein virus (BNYVV) that significantly affects sugarbeet yield globally. Accurate and sensitive detection methods for BNYVV in plants and field soil are necessary for growers to make informed decisions on variety selection to manage this disease. A recently developed CRISPR-Cas-based detection method has proven highly sensitive and accurate in human virus diagnostics. Here, we report the development of a CRISPR-Cas12a-based method for detecting BNYVV in the roots of sugarbeet. A critical aspect of this technique is the identification of conditions for isothermal amplification of viral fragments. Toward this end, we have developed a reverse transcription (RT) recombinase polymerase amplification (RPA) for detecting BNYVV in sugarbeet roots. The RT-RPA product was visualized, and its sequence was confirmed. Subsequently, we designed and validated the cutting efficiency of guide RNA targeting BNYVV via in vitro activity assay in the presence of Cas12a. The sensitivity of CRISPR-Cas12a trans reporter-based detection for BNYVV was determined using a serially diluted synthetic BNYVV target sequence. Further, we have validated the developed CRISPR-Cas12a assay for detecting BNYVV in the root-tissue of sugarbeet bait plants reared in BNYVV-infested field soil. The results revealed that BNYVV detection is highly sensitive and specific to the infected roots relative to healthy control roots as measured quantitatively through the reporter signal. To our knowledge, this is the first report establishing isothermal RT-RPA- and CRISPR-based methods for virus diagnostic approaches for detecting BNYVV from rhizomania diseased sugarbeet roots.

Virulence of five Phytophthora species causing rhododendron root rot in Oregon.

Phytophthora root rot is a destructive disease of rhododendron, causing substantial losses of this nursery crop in infested field and container production areas. Historically, Phytophthora cinnamomi was considered the main causal agent of the disease. However, a recent survey of soilborne Phytophthora species from symptomatic rhododendrons in Oregon revealed that P. plurivora is more common than P. cinnamomi and that several other Phytophthora species may also be involved. We investigated the ability of the five most abundant species from the survey to cause root rot: P. plurivora, P. cinnamomi, P. pini, P. pseudocryptogea, and P. cambivora. Three to four isolates were selected for each species from across six Oregon nurseries. Media of containerized Rhododendron catawbiense ‘Boursault’ was infested with single isolates in a randomized complete block design in a greenhouse. Phytophthora cinnamomi, P. pini, and P. plurivora rapidly caused ≥ 90% incidence of severe root rot while P. pseudocryptogea caused more moderate disease with 46% incidence of severe root rot. Phytophthora cambivora failed to produce enough inoculum and was used at a lower inoculum density than the other four species, but occasionally caused severe root rot (5% incidence). No differences in virulence were observed among isolates of same species, except for one isolate of P. plurivora that caused less disease than other P. plurivora isolates. This study demonstrates that all five Phytophthora species, which were representative of 94% of the survey isolates, are capable of causing severe root rot and plant death, but that not all species are equally virulent.

Impact of mulch-based cropping systems using green mulch and residues on the performance of advanced mutant lines of maize (Zea mays (L.)) under infested field with the parasitic weed Striga asiatica (L.) Kuntze in Madagascar.

In Madagascar, cereal yields remain insufficient due to various biotic and abiotic constraints, including Striga asiatica, a parasitic weed that has contributed to decreased maize yield up to 100%. This work aims to assess the impact of the practice of two cropping systems on the maize crop infested by S. asiatica. PLATA maize seed of the putative tolerant mutant line from the M5 generation after gamma irradiation at 100, 200 and 300 Gy and of the sensitive parent variety were grown in fields naturally infested or artificially inoculated with one pinch of around 3000 ready-to-germinate seeds of S. asiatica. The cropping system (SCV) is a community of plants that is managed by a farm unit to achieve various human goals. The residue of Stylosanthes sp. legumes was used as mulch SCVm and the legume cowpea was planted with the host plant for the intercropping system SCVv. Results have shown that the use of mulch, either residue SCVm or green mulch SCVv, minimizes S. asiatica infestation on maize plants. The SCV reduces significantly the number of emerging Striga plants with an emergence of 1.33 ± 0.36 for SCVm, 4.33 ± 0.27 for SCVv and 15.00 ± 1.08 for the control. Moreover, M5 lines have shown significant differences in plant survival rate of 50.57 ± 1.25% to 80.00 ± 0.91%, versus 13.50 ± 0.47% for the parent variety. Yields of the parent and M5 lines on SCVm are, respectively, 3.46 ± 0.02 t/ha and 4.64 ± 0.01 t/ha, and 2.30 ± 0.04 t/ha and 3.61 ± 0.05 t/ha for SCVv, while that of the control plot remains low, varying from 0.50 ± 0.04 t/ha to 2.29 ± 0.01 t/ha. Cover increases soil humidity and delays the development of S. asiatica and infection of the host plant, thus improving host plant yield. These results demonstrate the benefit of the integrated approach of mutation breeding and cultural practice to ensure more durable crop production under heavy Striga infestation.