Investigating Field Efficacy and Safety of Conjunctival Brucella abortus S19 Vaccine in Cattle

Background: Vaccination is the most fundamental strategy in the control and eradication of brucellosis. Several vaccination programs with different vaccines have been carried out in many countries in which brucellosis continues to be a problem in livestock. One of the recommended vaccines against brucellosis in cattle is the live Brucella abortus S19 vaccine. The aim of this study is to evaluate the results of field safety and efficacy trials for the conjunctival Brucella abortus S19 vaccine prior to the mass vaccination program. Methods: In this study, 81 female cattle were vaccinated with a reduced dose of Brucella abortus S19 vaccine with the conjunctival route. The immune response after vaccination was investigated by suggested serological tests; namely, Rose Bengal Plate Test, Serum Agglutination Test and Complement Fixation Test. Result: No adverse effect was observed within the scope of safety. Isolation of vaccine strain was observed only in a milk sample of lactating animals. Excluding the diagnosis criteria of the serological tests, humoral immune response was observed in most of the animals by all the serological tests one month after vaccination. Antibody levels lasted approximately 4 months after vaccination. In conclusion, the results of this study demonstrated that besides vaccine-induced antibodies, the vaccine including changes in dose and administration way in this study did not cause any significant risks for the target animals.

Maize Growth Responses to a Humic Product in Iowa Production Fields: An Extensive Approach

Field evaluations of commercial humic products have seldom involved replication across location or year. To evaluate the consistency of humic product efficacy in field conditions, we determined the effects of a humic product on maize (Zea mays L.) growth in high-yielding Midwestern (US) fields through the following two extensive approaches: (i) replicated strip plots in five site—year combinations from 2010 to 2013; and (ii) demonstration strips in 30–35 production fields annually from 2009 to 2011 that covered major areas of Iowa. Mechanized combine measurements of grain yield showed increases of 0.2–0.4 Mg ha–1 (1–4%) with humic product application for all five site—year combinations of the replicated strip plots. Six of 10 humic treatments within the fields responded positively (P < 0.07), and the positive responses of two more treatments approached significance at the benchmark of P = 0.10. In the demonstration strips, maize grain weight in hand-collected samples increased significantly (P < 0.004) with humic product application in each of the three growing seasons, and across all the three seasons by 6.5% (P < 0.001). Grain weight increased numerically for 76 of the 98 demonstration strips. Yield component analysis for both the replicated strip plots and the demonstration strips attributed the yield boosts largely to increased ear length, especially of the shorter ears. Humic product application caused significantly (P < 0.10) greater total leaf area in all eight field treatments at three site—year combinations. Humic product application did not consistently affect nutrient concentrations of the grain or stover or any measured soil property. These results represent among the widest geographic evaluations published on field efficacy of a humic product. They demonstrate the capability of a humic product to improve maize growth in high-yielding conditions.

Effectiveness of Cordyceps sp. and Beauveria Bassiana Against Large Cabbage-heart Caterpillar, Crocidolomia Pavonana Fabricius (Lepidoptera: Crambidae)

Crocidolomia pavonana Fabr. (Lepidoptera: Crambidae) is a major pest on various cabbage crops in Indonesia. Various insecticides have been used to control this insect pest including several entomopathogenic fungi, and this cabbage caterpillar has become resistant to various insecticides. In order to develop insecticides from entomopathogenic fungi, species or varieties from natural area such as forest are needed. A bioassays of Cordyceps sp. and Beauveria bassiana has been carried out in the laboratory. Inoculum of Cordyceps sp. obtained from the Dipterocarpaceae forest in South Kalimantan, Indonesia recovered from dead ants by the mycelium of Cordyceps sp. Four concentration of Cordyceps sp. and Beauveria bassiana inoculum and tween80 as a control were tested against 3rd instar larvae of C. pavonana with five replications. Field efficacy trial was carried out in a screen house (8 x 12 M2) using Chinese cabbage plants (Brassica juncea) aged 28 days after sowing, with a spacing of 0.4 M between rows. Three formulation of Cordyceps sp. and tween80 as a control were used with 6 replications. The result of the bioassays in the laboratory showed that Cordyceps sp. with concentration of 1 x 107 conidia mL-1 was able to give 100% mortality od C. pavonana larvae, while B. bassiana with the same concentration caused morality of C. pavonana larvae of 98.33%, although statistically not significantly different. The results of probit analysis also showed that LC90 Cordyceps sp. against cabbage caterpillar larvae was 1.57 x 106 conidia mL-1, while B. bassiana required a concentration of 2.6 x 106 conidia mL-1 to reach the LC90 value. The results of filed trial showed that the formulation of Cordyceps sp. 1 x 107 conidia mL-1 using palm oil cooking oil was able to give an average mortality of 86.7%, and significantly higher (P<0.05) than the other treatment. The results of this study indicate that the inoculum of Cordyceps sp. from Dipterocarpaceae forest is very promising to be developed as an insecticide to control C. pavonana in cabbage

Meta-analysis of the field efficacy of seed- and soil-applied nematicides on Meloidogyne incognita and Rotylenchulus reniformis across the U. S. Cotton Belt

Meta-analysis was used to compare yield protection and nematode suppression provided by two, seed- and two, soil-applied nematicides against Meloidogyne incognita and Rotylenchulus reniformis on cotton across three years and several trial locations in the United States Cotton Belt. Nematicides consisted of thiodicarb- and fluopyram-treated seed, aldicarb and fluopyram applied in-furrow and combinations of the seed treatments and soil-applied fluopyram. The nematicides had no effect on nematode reproduction or root infection but had a significant impact on seed cotton yield response (¯D) with an average increase of 176 and 197 kg/ha relative to the nontreated control in M. incognita and R. reniformis infested fields, respectively. However, because of significant variation in yield protection and nematode suppression by nematicides, five or six moderator variables [cultivar resistance (M. incognita only), nematode infestation level, nematicide treatment, application method, trial location, and growing season] were used depending on nematode species. In M. incognita infested fields, greater yield protection was observed with nematicides applied in-furrow and seed-applied + in-furrow than solo seed-applied nematicide applications. Most notably of these in-furrow nematicides were aldicarb and fluopyram (>131 g/ha) with or without a seed-applied nematicide compared to thiodicarb. In R. reniformis infested fields, moderator variables provided no further explanation of the variation in yield response by nematicides. Furthermore, moderator variables provided little explanation of the variation in nematode suppression by nematicides in M. incognita and R. reniformis infested fields. The limited explanation by the moderator variables on the field efficacy of nematicides in M. incognita and R. reniformis infested fields demonstrates the difficulty of managing these pathogens with nonfumigant nematicides across the U. S. Cotton Belt.

Entomopathogenic Nematodes for the Management of Plum Curculio in Highbush Blueberry

Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae) is a key pest of stone and pome fruits in the United States. Application of certain entomopathogenic nematode (EPN) species has shown efficacy in some crops when targeting the larval stage of C. nenuphar in soil. To date, however, no EPNs have been tested for the control of this pest in highbush blueberries. In 2020, laboratory and field studies were conducted to: (1) determine the persistence of Steinernema riobrave, S. carpocapsae, S. feltiae, and Heterorhabditis bacteriophora in acidic blueberry soil; (2) compare the virulence of these EPNs to C. nenuphar larvae and pupae; and (3) compare the efficacy of these EPN species to control this pest in blueberry fields. The greatest persistence in blueberry soil was exhibited by S. riobrave followed by S. carpocapsae. Superior virulence was observed in S. riobrave against C. nenuphar larvae and pupae. Promising levels of virulence were also observed in S. carpocapsae and S. feltiae against the larvae, but S. scarabaei had low virulence. In the field, S. riobrave provided significantly higher levels of C. nenuphar suppression (90%) than the other EPNs. The field efficacy of S. riobrave against C. nenuphar at low and high rates was confirmed in 2021. Steinernema riobrave has the potential to become an important component in the management of C. nenuphar in highbush blueberry.

Barrier Longevity of NaCl-Laden Soil against Subterranean Termites in an Earth Embankment

Subterranean termite-induced damage to earth embankments in agricultural systems occurs globally. NaCl-laden soil barriers (NLSBs) are an environmentally sustainable termite control method, and have exhibited good potential in preventing termite-related tunneling damage in Zhejiang Province, China. The persistence of the NaCl concentration in NLSBs is a key characteristic for the long-term prevention of subterranean termite infestations. This study is a scientific attempt to estimate the field efficacy and barrier longevity of NLSBs in reservoir embankments based on the Richards equation and the convection–dispersion equation using HYDRUS (2D/3D). The observed and simulated NaCl concentrations at the end of a 1915-day simulation were compared. The results indicated that the proposed model performed well and can effectively characterize the water flow and salt transport in NLSBs. The salt desalination rate of the NLSB in the upstream slope was higher than that in the downstream slope, both of which were significantly higher than that at the embankment axis. Regardless of the type of embankment (homogeneous or core-wall), the barrier longevity of NaCl-laden soil against subterranean termites can reach 50 years with an optimized NaCl/soil ratio in different parts of the embankment.

Durability of efficacy of microbial bioprotectants against plant diseases

Plant pathogens can develop resistance to conventional plant protection products but their ability to overcome the effect of microbial bioprotectants is still poorly known. However, various studies show that susceptibility of plant pathogens to microbial bioprotectants can be highly variable. This may contribute to the inconsistent efficacy of microbial bioprotectants sometimes observed in the field. An important question is whether the widespread use of microbial bioprotectants in the field could conduct to the selection of even more resistant phenotypes of plant pathogens. This chapter highlights current knowledge concerning erosion of microbial bioprotectants against plant pathogens and its possible consequences for field efficacy.

Potential Role of Rice Plant Growth Promoting Phylloplane and Rhizospheric Bacteria in Controlling Xanthomonas oryzae pv. oryzae

Rice is an important cereal worldwide and it occupies the top position among the cereals in Bangladesh. Rice plant suffers from around 32 diseases of which ten are major in Bangladesh at present. Among the diseases, Bacterial Blight (BB) caused by X. oryzae pv. oryzae (Xoo) considered as a most destructive disease occurs in both rainfed and irrigated seasons of Bangladesh. BB causes considerable yield loss varies from 30 to 50% depending on the outbreak. It is also an important disease in most of the South and Southeast Asian countries. To develop environment-friendly sustainable management approach against BB of rice, in total sixty three plant growth promoting bacteria were identified from rice phylloplane and rhizosphere that are antagonistic to X. oryzae pv. oryzae during boro and aman seasons 2018 and 2019.These bacterial species inhibited the growth of X. oryzae pv. oryzae in vitro by 20.83 to 76.19%. These bacterial isolates were identified by sequencing of PCR products of 16SrDNA belonging to the genera mostly Pseudomonas, Bacillus and Serratia. Out of these bacterial species, 48 bacterial species were found as positive for IAA production, all 63 bacterial species were found positive for siderophore production and 48 were found capable to solubilize insoluble phosphate. Based on growth inhibition of X. oryzae pv. oryzae in in vitro, thirty two bacterial species were selected for plant growth promotion assessment and evaluation of net house and field efficacy in controlling BB of rice. These bacterial species were formulated using talcum powder which was viable for at least three months post formulation. Assessment of plant growth promoting determinants revealed that all 32 bacterial species identified in this study enhance the growth of rice plants as measured by root and shoot length and and reduced the BB severity in susceptible rice cultivar significantly as compared with untreated control.