Evaluating \u3ci\u3ePseudomonas aeruginosa\u3c/i\u3e as Plant Growth–Promoting Rhizobacteria in West Africa

Some parameters of growth were examined in three test crops as indices of plant growth–promoting rhizobacteria (PGPR) ability of Pseudomonas aeruginosa. Crops include Abelmoschus esculentus L. (okra), Lycopersicon esculentum L. (tomato), and Amaranthus sp. (African spinach). This study aimed to examine the effectiveness of PGPR in West Africa and determine whether the inoculation method has an impact on PGPR’s effectiveness. Bacterium was isolated from topsoil in the Botanical Garden, University of Lagos, Nigeria. Inoculation with bacteria was done by soaking seeds in 106 cfu/ml of bacterial suspension, and coating was done using 10% starch (w/v) as seed adhesive with 106 cfu/ml of bacterial suspension. The third treatment involved soaking seeds in distilled water and later applying NPK 15:15:15 fertilizer. Control seeds were soaked in distilled water. Two methods of bacterial inoculation (soaking and coating) produced statistically similar results to plants grown with fertilizer but performed better than the control, suggesting a high potential of P. aeruginosa as PGPR

Plant-Microbes Interactions in Enhanced Fertilizer-Use Efficiency

The continued use of chemical fertilizers and manures for enhanced soil fertility and crop productivity often results in unexpected harmful environmental effects, including leaching of nitrate into groundwater, surface runoff of phosphorus and nitrogen runoff, and eutrophication of aquatic ecosystems. Integrated nutrient management systems are needed to maintain agricultural productivity and protect the environment. Microbial inoculants are promising components of such management systems. This review is a critical summary of the efforts in using microbial inoculants, including plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi for increasing the use efficiency of fertilizers. Studies with microbial inoculants and nutrients have demonstrated that some inoculants can improve plant uptake of nutrients and thereby increase the use efficiency of applied chemical fertilizers and manures. These proofs of concept studies will serve as the basis for vigorous future research into integrated nutrient management in agriculture

\u3ci\u3eNeofusicoccum luteum\u3c/i\u3e as a Pathogen on Tejocote (\u3ci\u3eCrataegus mexicana\u3c/i\u3e)

Tejocote (Crataegus mexicana), a small pome crab-apple-like fruit, is becoming economically important in California with increasing production, so consideration of diseases that hinder the yield is important. Diseased trees of tejocote were observed in four orchards of Riverside and San Diego Counties of California. Ten symptomatic/asymptomatic samples were studied from each of the orchards. Five most frequently isolated fungi were identified on the basis of morphological characters and sequence data of the internal transcribed spacer ITS1-5.8SITS2 and partial β-tubulin gene. Three isolates were identified as Neofusicoccum luteum and two as Phomopsis sp. Pathogenicity tests were conducted by inoculating detached shoots of healthy tejocote trees. Significant lesions were observed on all shoots inoculated with the three N. luteum isolates (designated UCR1190, UCR1191, and UCR1192), but not on the shoots inoculated with other isolates or the non-inoculated controls. Results indicated that all three N. luteum isolates are aggressive pathogens on tejocote. This pathosystem should be further studied with a goal of designing appropriate disease management strategies

Identification of \u3ci\u3eErwinia rhapontici\u3c/i\u3e as the Causal Agent of Crown and Shoot Rot and Pink Seed of Pea in Nebraska

Over the last five years, the production of dry yellow peas (Pisum sativum L.) has been increasing in Nebraska and other areas of the Central High Plains, according to a USDA report (Jasa 2013). Dry pea is a short-season crop with a low water requirement, making it a good rotational crop for the high plains. We have noted bacterial pathogens, potentially a disease complex, that may negatively impact the production of pea in this region, and one of the emerging pathogens is Erwinia rhapontici. This pathogen is a gram-negative bacterium that has been reported from soil, seed, and different plant tissues, causing pink seed, crown rot, shoot and stem rot, blossom rot, or soft rot on more than 20 plant hosts, including pea (Huang et al. 2003). The disease was first reported on pea in the United States from Montana in 2002 and was later found in North Dakota in 2006 (Wise et al. 2008). Erwinia rhapontici belongs to the carotovora subgroup of Erwinia. Unlike many members of the soft rot carotovora subgroup that produces pectolytic enzyme, E. rhapontici does not degrade pectate. The organism is capable of fermenting glucose, fructose, maltose, and sucrose. Also, it produces a diffusible pink pigment on sucrose-peptone agar but not on potato dextrose agar nor nutrient agar. However, it has been shown that some strains may not produce pink pigments regardless of the type of media used (Huang et al. 2003). Proferrosamine A has been identified in the pink pigment produced, it is associated with iron deficiency in plants, and was suspected by Huang et al. (2003) as partly a pathogenicity determinant and virulence factor of E. rhapontici

Origin of agricultural plant pathogens: Diversity and pathogenicity of \u3ci\u3eRhizoctonia\u3c/i\u3e fungi associated with native prairie grasses in the Sandhills of Nebraska

The Sandhills of Nebraska is a complex ecosystem, covering 50,000 km2 in central and western Nebraska and predominantly of virgin grassland. Grasslands are the most widespread vegetation in the U.S. and once dominated regions are currently cultivated croplands, so it stands to reason that some of the current plant pathogens of cultivated crops originated from grasslands, particularly soilborne plant pathogens. The anamorphic genus Rhizoctonia includes genetically diverse organisms that are known to be necrotrophic fungal pathogens, saprophytes, mycorrhiza of orchids, and biocontrol agents. This study aimed to evaluate the diversity of Rhizoctonia spp. on four native grasses in the Sandhills of Nebraska and determine pathogenicity to native grasses and soybean. In 2016 and 2017, a total of 84 samples were collected from 11 sites in the Sandhills, located in eight counties of Nebraska. The samples included soil and symptomatic roots from the four dominant native grasses: sand bluestem, little bluestem, prairie sandreed, and needle-and-thread. Obtained were 17 Rhizoctonia-like isolates identified, including five isolates of binucleate Rhizoctonia AG-F; two isolates each from binucleate Rhizoctonia AG-B, AG-C, and AG-K, Rhizoctonia solani AGs: AG-3, and AG-4; one isolate of binucleate Rhizoctonia AG-L, and one isolate of R. zeae. Disease severity was assessed for representative isolates of each AG in a greenhouse assay using sand bluestem, needle-and-thread, and soybean; prairie sandreed and little bluestem were unable to germinate under artificial conditions. On native grasses, all but two isolates were either mildly aggressive (causing 5–21% disease severity) or aggressive (21–35% disease severity). Among those, three isolates were cross-pathogenic on soybean, with R. solani AG-4 shown to be highly aggressive (86% disease severity). Thus, it is presumed that Rhizoctonia spp. are native to the sandhills grasslands and an emerging pathogen of crops cultivated may have survived in the soil and originate from grasslands

Neofusicoccum luteum as a pathogen on Tejocote (Crataegus mexicana)

Tejocote (Crataegus mexicana), a small pome crab-apple-like fruit, is becoming economically important in California with increasing production, so consideration of diseases that hinder the yield is important. Diseased trees of tejocote were observed in four orchards of Riverside and San Diego Counties of California. Ten symptomatic/asymptomatic samples were studied from each of the orchards. Five most frequently isolated fungi were identified on the basis of morphological characters and sequence data of the internal transcribed spacer ITS1-5.8S-ITS2 and partial β-tubulin gene. Three isolates were identified as Neofusicoccum luteum and two as Phomopsis sp. Pathogenicity tests were conducted by inoculating detached shoots of healthy tejocote trees. Significant lesions were observed on all shoots inoculated with the three N. luteum isolates (designated UCR1190, UCR1191, and UCR1192), but not on the shoots inoculated with other isolates or the non-inoculated controls. Results indicated that all three N. luteum isolates are aggressive pathogens on tejocote. This pathosystem should be further studied with a goal of designing appropriate disease management strategies

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

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.)