Plant Growth-Promoting Rhizobacteria Allow Reduced Application Rates of Chemical Fertilizers

The search for microorganisms that improve soil fertility and enhance plant nutrition has continued to attract attention due to the increasing cost of fertilizers and some of their negative environmental impacts. The objectives of this greenhouse study with tomato were to determine (1) if reduced rates of inorganic fertilizer coupled with microbial inoculants will produce plant growth, yield, and nutrient uptake levels equivalent to those with full rates of the fertilizer and (2) the minimum level to which fertilizer could be reduced when inoculants were used. The microbial inoculants used in the study were a mixture of plant growth-promoting rhizobacteria (PGPR) strains Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4, a formulated PGPR product, and the arbuscular mycorrhiza fungus (AMF), Glomus intraradices. Results showed that supplementing 75% of the recommended fertilizer rate with inoculants produced plant growth, yield, and nutrient (nitrogen and phosphorus) uptake that were statistically equivalent to the full fertilizer rate without inoculants. When inoculants were used with rates of fertilizer below 75% of the recommended rate, the beneficial effects were usually not consistent; however, inoculation with the mixture of PGPR and AMF at 70% fertility consistently produced the same yield as the full fertility rate without inoculants. Without inoculants, use of fertilizer rates lower than the recommended resulted in significantly less plant growth, yield, and nutrient uptake or inconsistent impacts. The results suggest that PGPR-based inoculants can be used and should be further evaluated as components of integrated nutrient management strategies

Comparison of Plant Growth-Promotion with \u3ci\u3ePseudomonas aeruginosa\u3c/i\u3e and \u3ci\u3eBacillus subtilis\u3c/i\u3e in Three Vegetables

Our objective was to compare some plant growth-promoting rhizobacteria (PGPR) properties of Bacillus subtilis and Pseudomonas aeruginosa as representatives of their two genera. Solanum lycopersicum L. (tomato), Abelmoschus esculentus (okra), and Amaranthus sp. (African spinach) were inoculated with the bacterial cultures. At 60 days after planting, dry biomass for plants treated with B. subtilis and P. aeruginosa increased 31% for tomato, 36% and 29% for okra, and 83% and 40% for African spinach respectively over the non-bacterized control. Considering all the parameters tested, there were similarities but no significant difference at P \u3c 0.05 between the overall performances of the two organisms

Increased Plant Uptake of Nitrogen from \u3csup\u3e15\u3c/sup\u3eN-depleted Fertilizer Using Plant Growth-Promoting Rhizobacteria

Harmful environmental effects resulting from fertilizer use have spurred research into integrated nutrient management strategies which can include the use of specific microorganisms to enhance nutrient use efficiency by plants. Some strains of plant growth-promoting rhizobacteria (PGPR) have been reported to enhance nutrient uptake by plants, but no studies with PGPR have used 15N isotope techniques to prove that the increased N in plant tissues came from the N applied as fertilizer. The current study was conducted to demonstrate that a model PGPR system can enhance plant uptake of fertilizer N applied to the soil using different rates of 15N-depleted ammonium sulfate. The experiments were conducted in the greenhouse with tomato using a mixture of PGPR strains Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4. Results showed that PGPR together with reduced amounts of fertilizer promoted tomato growth compared to fertilizer without PGPR. In addition, atom% 15N per gram of plant tissue decreased as the amount of fertilizer increased, and PGPR inoculation resulted in a further decrease of the atom% 15N values. The atom% 15N abundance in plants that received 80% fertilizer plus PGPR was 0.1146, which was significantly lower than 0.1441 for plants that received 80% fertilizer without PGPR and statistically equivalent to 0.1184 for plants that received 100% fertilizer without PGPR. The results demonstrate that increased plant uptake of N applied in fertilizer could be achieved with PGPR as indicated by the differences in 15N uptake. Strains of PGPR that lead to increased nutrient uptake by plants should be evaluated further as components in integrated nutrient management systems

Microbial Content of Abattoir Wastewater and Its Contaminated Soil in Lagos, Nigeria

Microbial content of wastewater in two abattoirs and the impact on microbial population of receiving soil was studied in Agege and Ojo Local Government Areas in Lagos State, Nigeria. Wastewater samples were collected from each of the abattoirs over three months period and examined for microbial content. Soil samples contaminated with the wastewaters were also collected and analyzed for microbial content as compared to soil without wastewater contamination in the neighborhood (control). Some physico-chemical parameters of the samples such as total dissolved solid, chemical oxygen demand, etc., were examined. The wastewater samples from both abattoirs were highly contaminated; Agege abattoir showed mean bacterial count of 3.32 × 107 cfu/ml and Odo abattoir showed mean count of 2.7 × 107 cfu/ml. The mean fungal populations were 1.6 × 105 and 1.2 × 105 cfu/ml for Agege and Odo abattoirs respectively. In the contaminated soil sample, mean bacterial count was 3.36 × 107 cfu/ml compared to the 1.74 × 106 cfu/ml of the control sample. High microbial load in abattoir wastewater with negative effects on microbial population in soil, in this study, further confirmed the need to treat wastewater rather than discharging it to the environment

What’s New in Plant Pathology

Extension Plant Pathology Team Update Changes to the Plant Disease Management Section of the 2015 Weed Guide During the past year, several new products have become available for disease management. These products and additional products have been added to the Plant Disease Management Section of the 2015 Weed Guide. Products added to the Weed Guide have been summarized in Tables 1-3. Table 1. Foliar Products Table 2. Seed Treatment Products Table 3. Seed Treatment Nematicide

Corn Disease Profiles: Diseases Favored by Dry Conditions

Extension Circular 1910 (EC1910) Extreme weather events are predicted to become increasingly common and could bring periods of drought as well as intense rainfall events. Wet conditions are favorable for many plant pathogens and the development of diseases, but some diseases may also develop during or following dry weather. The timing during the season when dry conditions occur, as well as other factors, such as temperature, impact which diseases develop and when. The list summarizes some of the most common corn diseases that can develop during dry conditions: Seedling Root Rot Diseases, Nematodes, Common Smut, Rust Diseases Charcoal Rot, Stalk and Crown Rot Diseases, and Aspergillus Ear Rot. (Illustrated with photographs.

Corn Disease Profiles: Diseases Favored by Wet Conditions

Extension Circular 1909 (EC1909) Extreme weather events are predicted to become increasingly common and could bring periods of more intense rainfall. Wet conditions are favorable for many plant pathogens and the development of diseases. Seasonal timing when these conditions occur, as well as other factors such as temperature, impact which diseases develop and when. Listed, described, and illustrated are some common corn diseases favored by wet conditions: Pythium Root Rot, Eyespot, Northern Corn Leaf Blight, Gray Leaf Spot, Physoderma Brown Spot, Rust Diseases (Puccinia spp.), Stalk and Crown Rot Diseases (such as those caused by Fusarium and Diplodia spp.), and Ear Rot Diseases (such as those caused by Fusarium, Gibberella, and Diplodia spp.)

Corn Disease Profiles: Diseases Favored by Wet Conditions

Extension Circular 1909 (EC1909) Extreme weather events are predicted to become increasingly common and could bring periods of more intense rainfall. Wet conditions are favorable for many plant pathogens and the development of diseases. Seasonal timing when these conditions occur, as well as other factors such as temperature, impact which diseases develop and when. Listed, described, and illustrated are some common corn diseases favored by wet conditions: Pythium Root Rot, Eyespot, Northern Corn Leaf Blight, Gray Leaf Spot, Physoderma Brown Spot, Rust Diseases (Puccinia spp.), Stalk and Crown Rot Diseases (such as those caused by Fusarium and Diplodia spp.), and Ear Rot Diseases (such as those caused by Fusarium, Gibberella, and Diplodia spp.)

What\u27s New in Plant Pathology

Changes to the Disease Management Section of the 2016 Guide for Weed, Disease, and Insect Management in Nebraska Biological control Products Trivapro Fungicide Priaxor D. Fungicide Table 1. Foliar products for disease control that were updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska. Table 2. Seed treatment products for disease control that were updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska. Table 3. Seed treatment nematicide product that was updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska

Weather Variability and Disease Management Strategies

This year’s title of “weather variability and disease management strategies” was chosen because we need to remember how weather conditions this year have impacted crop productivity and disease development. This will enable us to look forward and develop better management decisions for future growing seasons. Agricultural production is dependent on many climatic factors such as rain, humidity, temperature, and sunlight. These climate conditions have direct effects on yield as well as other indirect effects. One specific indirect effect of extreme weather events is increased pressure from pathogens and pests. Plant pathogens are commonly favored by very specific, and sometimes extreme, weather conditions. Pathogens take advantage of these conditions to infect, reproduce, and cause disease in crops that can lead to economic losses, ultimately in the loss of yield quality or quantity. Scientific projections indicate that climate change will continue to have major impacts on crops across the country and the world. It is therefore not surprising that this year the United Nations Summit in New York on September 23 focused on climate change in agriculture with discussions on Global Alliance for Climate-Smart Agriculture. Nebraska is known for its leadership in agricultural production and one germane concern is how we will be able to utilize the available climate data in a timely fashion to our advantage in protecting our crops from the negative impacts of climate change and pathogens. We need to act in a way that can leverage climate change to our advantage, where possible. It is important to monitor soil moisture and irrigation. Late planting and dryer than normal conditions in 2014 resulted in irrigation late into the season in some locations, which will unfortunately result in reduced profits for such farms. Temperature is also an important factor. When conditions are warmer, crops tend to grow faster and the time for seed maturity reduces. However, warmer conditions have the potential to reduce yield and, in addition, can promote certain diseases. The dry and hot weather conditions of 2014, for example, supported charcoal rot infections that were seen in both corn and soybean in many locations this year. Weed control and timely applications of herbicide will be crucial preparation steps in mitigating the impacts of climate change in 2015. Weeds not only act as alternate hosts for many pathogens but also deplete soil moisture. Below we present information on the influence of weather variability on development of diseases in Nebraska field crops. In 2015, crop production practices should be well planned to be climate-ready and climate-compliant