Molecular and morphological characterization of a first report of Cactodera torreyanae Cid del Prado Vera & Subbotin, 2014 (Nematoda: Heteroderidae) from Minnesota, the United States of America.

Cactodera torreyanae Cid del Prado Vera & Subbotin, 2014 cysts were discovered during a Pale Potato Cyst Nematode (PCN) survey conducted by Minnesota Department of Agriculture as part of the Animal and Plant Health Inspection Service (APHIS) efforts to survey states for the presence of PCN. The soil samples were collected from a potato field, located in Karlstad, Kittson County, Minnesota, USA. Two out of 175 vials submitted for identification to the Mycology and Nematology Genetic Diversity and Biology Laboratory (MNGDBL) contained few cysts and juveniles of C. torreyanae. Cysts were dark brown in color, lemon-shaped to elongated with distinct vulval cone. Vulva with denticles present around fenestra, cyst length to width ratio between 1.6 and 2.3 and anus distinct. The juveniles had rounded stylet knobs, some sloping slightly posteriorly. The molecular analysis included sequence and phylogenetic analysis of ITS rRNA, D2-D3 expansion segments of 28S rRNA and COI of mtDNA genes. The nematode species was identified by both morphological and molecular means as Cactodera torreyanae. To the best of our knowledge this represents the first report of Cactodera torreyanae from the United States and first report of this cyst nematode species from potato fields. Definite host plant for this nematode remains unknown.

First report of Cactodera milleri Graney and Bird, 1990 from Colorado and Minnesota.

In 2019, Cactodera milleri cysts were discovered from soil samples collected from a Chenopodium quinoa field, located in Mosca, Alamosa county, Colorado, USA. Approximately 200 lemon shaped cysts and several hundred juveniles were recovered from the affected quinoa plants. The same species was also identified from several counties in Minnesota from samples submitted over the years by the Minnesota Department of Agriculture as part of the Animal and Plant Health Inspection Service (APHIS) efforts to survey states for the presence of Pale Potato Cyst Nematode. The cysts and juveniles (J2) were recovered from soil samples through sieving and Baermann funnel extraction. The nematode species was identified by both morphological and molecular means as Cactodera milleri (Graney and Bird, 1990). To our knowledge this represents the first report of Cactodera milleri from Colorado and Minnesota.

Characterization of the Response of Ornamental Graminoids to Attempted Infection by Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum causes Sclerotinia stem rot (SSR) (also called white mold), resulting in stem rot and death of many common herbaceous ornamental plant species. Resistant plants would be useful to manage SSR; however, the host range of S. sclerotiorum is unclear. The goal of this study was to determine how the ornamental graminoids Pennisetum glaucum, Setaria italica, Juncus inflexus, Carex flagellifera, Isolepis cernua, and Acorus gramineus respond to inoculation with S. sclerotiorum. Plants were inoculated in the field and in controlled environments at 13, 16, 19, or 22°C with or without wounding, and evaluated for SSR. Inoculated detached leaves were stained to examine infection and oxalate oxidase production. A. gramineus developed SSR in field and controlled environments. Sclerotinia stem rot was not observed on P. glaucum in field environments. The disease developed on P. glaucum and S. italica in controlled environments, and severity increased with decreasing temperature and wounding. J. inflexus, C. flagellifera, and I. cernua developed no or minor symptoms of SSR in field and controlled environments. Mycelia penetrated A. gramineus leaves 24 h after inoculation (HAI) and P. glaucum at 48 HAI, but did not penetrate J. inflexus at 24, 48, or 96 HAI. Oxalate oxidase was not detected in inoculated leaves of these ornamental graminoids. The results illuminate S. sclerotiorum's interactions with monocots and broaden the understanding of SSR resistance in ornamental grasses.