Peanut (Arachis hypogaea L.) is cultivated in tropical and subtropical regions of the world as an important source of oil and protein. Until now, bacterial wilt, caused by Ralstonia solanacearum, was the only known bacterial disease of peanut. In 2020, widespread incidence of poor stand establishment was observed in multiple production fields planted to the Spanish-type peanut varieties in the Texas Panhandle. The observed symptoms included seed rot, pre- and postemergence damping-off, poor seedling vigor, poorly developed root systems with little or no nodule formation, and death. Subsequent diagnosis of symptomatic seedlings recovered two bacterial species identified by BLAST using 676- and 661-bp 16S rRNA fragments as a Ralstonia sp. and a Pantoea sp., respectively. To investigate a possible causative role of these bacteria in the observed peanut disease, the pathogenicity of the two isolates was evaluated under greenhouse conditions relying on Koch’s postulates. Cell suspensions of the two bacteria, separately and in combination, were used to inoculate seeds of a Valencia-type peanut variety with no history of the disease and found to be pathogenic on the resultant seedling plants. Symptoms that developed on the inoculated plants were similar to the symptoms initially observed in the field, including seed rot, pre- and postemergence damping-off, poor seedling vigor, and root establishment. The two bacteria were also successfully recovered from inoculated and symptomatic plants, thus satisfying Koch’s postulates. Given the early onset of symptom development on affected seeds and seedlings, a seedborne origin of the disease, described here as early-decline bacterial disease of peanut, was investigated in the same batches of peanut seeds that were planted, as well as seeds later harvested in some of the affected fields. Identical bacterial species, on the basis of 16S rRNA identity, were recovered from all of the seeds evaluated indicating that the bacteria are both seedborne and seed-transmissible. Multilocus sequence analysis involving six genes (dnaK, fumC, gyrB, murG, trpB, and tuf) showed that these new strains are most closely related to R. pickettii and Pantoea dispersa, but also phylogenetically distinct. The two bacteria were designated Ralstonia sp. strain B265 and Pantoea sp. strain B270. Losses from the disease in affected fields in 2020 averaged 50% (US$1.12 million) from a total of nine production fields. Findings from this study provide evidence for two new bacterial pathogens of peanuts capable of infecting Spanish and Valencia peanut varieties.

Wheat ( Triticum aestivum L.) yield and economic losses caused by pathogens were estimated annually by plant pathologists from 29 U.S. states and Ontario, Canada, from 2018 through 2021. During this 4-year period, plant pathogens caused an estimated reduction of 560 million bushels, with an estimated loss value of US$2.9 billion. Annual losses ranged from 111 million bushels in 2018 to 188 million bushels in 2019. Based on the number of acres planted, the average per-acre loss caused by plant pathogens was US$18.10 across all years and state/province recording estimates. Fusarium head blight (caused by multiple species of Fusarium) was responsible for the greatest overall estimated reduction in yield, followed by stripe rust (caused by Puccinia striiformis) and leaf rust (caused by P. triticina). Although important disease management costs, such as pesticide application, were not considered, the results show the importance of continued plant disease education and research. Quantifying estimated losses associated with plant pathogens impacting wheat remains an important endeavor. Estimates provided by this group of experts are expected to be used as a guide to influence funding for plant disease research by directing Extension and research through both applied and basic efforts. Moreover, the continued effort to quantify plant diseases and their influence on yield losses, as well as the economics of managing plant diseases, will help inform the industries that influence plant disease management and shape on-farm disease management efforts.

The genus Pantoea has historically been associated with two diseases of corn, Stewart's wilt caused by P. stewartii and necrotic or white leaf spots or streaks and stalk rot caused by P. ananatis. In 2020 and 2021, a sudden and unusual decline of corn stands was observed in corn fields in two counties in the Texas High Plains region. Symptoms observed included initial light green, elongated, slightly translucent, and nonchlorotic streaked lesions with nonwavy margins that developed on leaf blades during corn vegetative growth stages, with lesions becoming necrotic at the onset of crop reproduction. Additionally, stunting of affected plants, poor ear development, and stalk rot were associated with affected stands. Diagnosis of symptomatic tissues consistently recovered bacteria. BLAST searches of the partial 16S rRNA sequences of the bacterial isolates identified them as belonging to the genus Pantoea. Investigations of the pathogenicity of two bacterial isolates, B566 and B623, under greenhouse conditions relying on Koch's postulates resulted in the development of symptoms identical to those observed on symptomatic field corn plants. The two bacteria were also successfully recovered from symptomatic leaf and stem tissues, thus satisfying Koch's postulates. Sequence analysis showed that these isolates are closely related to P. ananatis but also phylogenetically distinct. The findings from this study provide evidence for a new disease of corn caused by two Pantoea species that can result in stand decline of infected corn plants.

Wheat curl mites (WCM; Aceria tosichella) are an important global pest of cultivated wheat. Their feeding activities on epidermal cells of wheat leaves result in characteristic leaf curl symptoms t...

Foliar symptoms resembling those associated with late-season decline (LSD) disease of corn, caused by the bacteria Pantoea ananatis, were observed in commercial fields of sorghum plants in 2023 in the Texas panhandle. Diagnosis of symptomatic tissues consistently recovered bacterial isolates that were subsequently identified, based on partial sequences of their respective 16S rRNA gene, as P. ananatis. The pathogenicity of a representative isolate on sorghum was investigated using the method of Koch's postulates and resulted in the successful reproduction of LSD-like foliar symptoms identical to those described for corn, as well as those observed in affected sorghum fields.