Field Dodder (Cuscuta pentagona) Control with Flumioxazin

Abstract

Greenhouse trials -2015Chateau (flumioxazin) was screened for preemergence activity against dodder (Cuscuta spp.) and two perennial grass species, collectively referred to as poverty grass (little bluestem (LBS; Schizachyrium scoparium) and broomsedge (BS; Andropogon virginicus)) in a greenhouse study. Improving controls for these weeds are listed as top-tier research priorities for the industry (Cape Cod Cranberry Growers Association, 2015).Square plastic pots (10 cm) were filled with a 3:1 sand:peat potting mixture. Each pot received a set of seeds from a single species. Sets of approximately 300 seeds of each grass species were measured by weight (0.50 g per pot of LBS seeds; 0.10 g per pot of BS seeds). Grass seeds were scattered on the surface of each pot, and covered with a light dusting of sand. Dodder seeds have physical dormancy and require scarification for germination to occur. Sets of 100 dodder seeds were mechanically scarified prior to being scattered on the surface of the pots, then covered with a light dusting of sand.Each pot received a single treatment (4 oz/A Chateau, 6 oz/A Chateau, or an untreated control) applied by a CO2 powered backpack sprayer in 400 gallons of water per acre to simulate application by chemigation. After treatment, pots were placed in the greenhouse. Dodder pots were evaluated every few days for one month after treatment. Emerged seedlings (≥ 2 cm) were counted and removed from pots at each observation. Grass seeds were allowed to germinate and grow for approximately 6 weeks. Grass plants were then counted, dried, and weighed.The experimental design was a randomized complete block with four replicates. The entire experiment was run twice (9 June and 16 June 2015). Data were analyzed using SAS (SAS version 9.4, SAS Institute Inc., Cary, NC). Each preemergence trial was tested with PROC GLM for a run*treatment interaction. The interaction was not significant, and data were pooled across both runs. Analysis of variance was performed on germination PROC GLM. Means were compared using Duncan's New Multiple Range Test (P ≤ 0.05).Chateau significantly reduced the amount of weeds seeds that germinated for all three species tested (see Table 1). The amount of LBS and BS biomass present after 6 weeks was also significantly lower than that of the untreated control (data not shown).