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.

White mold, caused by the necrotrophic fungus Sclerotinia sclerotiorum (Lib.) de Bary, causes stem rot, crown rot, wilt, and death of many common herbaceous ornamental plants. Relatively little research has been done on management of white mold and resistance to this disease in ornamental crops. Plant varieties from four genera of widely available annual bedding plants with no reported history of white mold susceptibility were evaluated for potential resistance to S. sclerotiorum. All plants were inoculated with three isolates of S. sclerotiorum and evaluated for disease severity in a controlled environment and under field conditions. Portulaca grandiflora Hook. ‘Sundial Scarlet’, P. grandiflora ‘Sundial White’, Pentas lanceolata Forssk. ‘Graffiti Pink’, and Scaevola aemula R. Br. ‘Whirlwind White’ were highly susceptible to white mold in the controlled environment but had significantly lower disease incidence and severity than Zinnia elegans ×angustifolia ‘Profusion White’, the susceptible control, under field conditions. Impatiens hawkeri W. Bull. ‘Sonic Red’, I. hawkeri ‘Sonic Amethyst’, I. hawkeri ‘Sonic White’, I. walleriana Hook. f. ‘Blitz 3000 Red’, I. walleriana ‘Blitz 3000 White’, and I. walleriana ‘Blitz 3000 Rose’ displayed abscission of diseased plant tissue as an unusual resistance response. Plants from all four genera that were evaluated became infected with S. sclerotiorum to a lesser extent than susceptible controls under field conditions and could be used as part of an integrated disease management program for white mold in ornamental plantings.

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.

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.

Sclerotinia sclerotiorum (Lib.) de Bary is a fungal pathogen that causes stem rot, crown rot, wilt, and death of many common annual flowering plants. Infested flower beds often suffer significant plant loss each year, and the identification of disease resistant plants would be a useful management tool. Caladium (Caladium ×hortulanum Birdsey), canna (Canna ×generalis L.H. Bailey), and elephant ear [Colocasia esculenta (L.) Schott] were evaluated for potential resistance to S. sclerotiorum. Plants grown in field conditions in Minnesota in 2012 and 2013 were inoculated through the application of sorghum grains colonized by S. sclerotiorum. The number of plants infected and percent of canopy dieback were recorded weekly for 3 months. The susceptibility of leaves, flowers, and below ground storage organs was also examined through direct inoculation of plant tissue with a mycelial plug of the pathogen in controlled environmental conditions favorable for disease development. Symptoms and progression of the infection were recorded after 24 days. Symptoms of infection on all three species were similar in field and controlled environments. Caladium plants were susceptible to S. sclerotiorum. Petioles, leaves, and corms developed a watery soft rot. Elephant ear was highly resistant to infection. Sclerotinia sclerotiorum infected only wounded or senescent tissue and did not result in significant symptoms under any conditions. Canna had partial resistance to the pathogen. Although canna petals were readily infected, infection of petioles was restricted to small necrotic lesions. Neither infection progressed to the main stem or resulted in plant death. This study indicates that canna and elephant ear have resistance to S. sclerotiorum and could be used in an integrated disease management program for infested landscape beds.