15 Sep 2025

Foliar Fungal Assemblages Associated with Diploid and Triploid Butomus umbellatus Populations in the United States

Purpose: Novel associations between plant invaders and fungi may moderate invader impacts if fungi are pathogenic or contribute to variation in invader response to management. Identifying and quantifying species associations with plant invaders can have management consequences. However, whether novel fungal associations and resulting assemblages are shaped by invader genetics is largely unknown. The goal of this research was to identify community patterns of foliar fungi associated with diseased and healthy diploid and triploid Butomus umbellatus (flowering rush) cytotypes in the United States. A total of 12 diploid and 9 triploid Butomus umbellatus L. populations in 10 states across the northern United States were surveyed, foliar fungi were isolated from healthy and diseased leaves, and a fungal assemblage structure analysis was conducted to determine whether assemblages were unique to B. umbellatus cytotypes. Differences in flowering rush–associated fungal assemblages and complex interaction between fungal taxa may promote uneven invasion between cytotypes in the United States and guide future management efforts to reduce the negative impacts caused by B. umbellatus invasions.

16 Sep 2022

Flowering Rush Control in Hydrodynamic Systems: Part 1: Water Exchange Processes

Abstract: In 2018, field trials evaluated water-exchange processes using rhodamine WT dye to provide guidance on the effective management of flowering rush (Butomus umbellatus L.) at McNary Dam and Reservoir (Wallula Lake, 15,700 ha). Additional evaluations determined the effectiveness of BubbleTubing (hereafter referred to as bubble curtain) at reducing water exchange within potential flowering rush treatment areas. Dye readings were collected from multiple sampling points at specific time intervals until a dye half-life could be determined. Whole-plot dye half-lives at sites without bubble curtain ranged 0.56–6.7 h. In slower water-exchange sites (≥2.6 h dye half-life), the herbicide diquat should have a sufficient contact time to significantly reduce flowering rush aboveground biomass. Other sites demonstrated very rapid water exchange (<1.5 h dye half-life), likely too rapid to effectively control flowering rush using chemical treatments without the use of a barrier or curtain to slow water exchange. At one site, the use of the bubble curtain increased the dye half-life from 3.8 h with no curtain to 7.6 and 7.1 h with a bubble curtain. The bubble curtain’s ability to slow water exchange will provide improved chemical control and increase the potential for other chemical products to be effectively used.