Establishment and management of switchgrass for forage and biofuel under irrigation

Switchgrass (Panicum virgatum) is a warm-season perennial grass that has been grown for seed for more than 30 years in the Columbia Basin. Switchgrass and other selected perennial warm-season grasses (WSG) can also be successfully grown in the hotter, irrigated regions of the Pacific Northwest (PNW) as feedstock for cellulosic biofuel or forage for livestock. Research studies were first established with switchgrass and other WSG at Washington State University Prosser in 2002. More than a decade later, this initial planting of switchgrass remained productive. After the establishment year, sprinkler-irrigated WSG fields were harvested twice per season for biofuel and as many as five times for pasture. By understanding and following the guidelines in this publication, we have maintained relatively dense, productive stands (specific to the species and variety) for years. We recognize switchgrass and many perennial WSG to be "sustainable" when properly managed. To accomplish the goal of long-term sustainable forage and feedstock production, the crop must be established properly, which is the focus of this publication. Variety differences for number of seeds per pound, optimum planting time, weed control practices, growth and development above- and belowground, and establishment year yields of switchgrass under irrigation in the PNW are compared. This publication encapsulates many of our experiences, research results, and recommendations with pre- and post-seeding management and early switchgrass seedling development under irrigation. Guidelines are provided so growers and researchers may avoid critical errors when establishing switchgrass in the irrigated Inland PNW. The goal is to have each planted acre of switchgrass result in a successful stand that overwinters to produce high biomass yields for many years. The principles discussed apply to either forage or biofuel feedstock production when grown under irrigation

An Investigation Into the Synergistic Interaction of Tridiphane and Atrazine (Cyanazine, Giant Foxtail, Glutathione-S-Transferase)

80 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.The primary purpose of this research was to investigate the herbicidal properties of tridiphane 2-(3,5-dichlorophyenyl)-2,2,2-trichloroethyl)oxirane in plants which contribute to the synergistic effect often observed when tridiphane is applied with atrazine 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine .The effect of tridiphane on atrazine metabolism and uptake was examined by in vitro and in vivo studies. Tridiphane inhibited isolated glutathione-s-transferase (GST) activity from corn and giant foxtail with an I(,50) of about 5 (mu)M. The specific activity of GST isolated from corn seedlings was 14 fold higher than the specific activity of GST isolated from giant foxtail seedlings. GST activity and reduced glutathione (GSH) levels were greater in leaf tissue than in stem tissue, and the amount of GSH/g fresh wt was greater in four-leaf giant foxtail seedlings (2.4 (mu)moles/g fresh wt) than in two-leaf seedlings (1.3 (mu)moles/g fresh wt).Tridiphane partially inhibited the metabolism of atrazine to water soluble metabolites in giant foxtail leaves but not in corn leaves resulting in the greatest amount of unmetabolized atrazine in giant foxtail seedlings (83 nmoles/g fresh wt). Tridiphane applied 12 hours prior to atrazine increased the uptake of atrazine in corn leaves and in five-leaf giant foxtail seedlings. Applying tridiphane with atrazine increased atrazine uptake in corn but not in giant foxtail seedlings.Tridiphane and atrazine combinations impaired photosynthesis more than atrazine alone in giant foxtail leaves, indicating greater levels of unmetabolized atrazine. Tridiphane alone did not lower photosynthetic rates in corn or giant foxtail leaves.Tridiphane also inhibited the growth of corn cells growing in liquid media with an I(,50) of approximately 5 (mu)M. Tridiphane was rapidly metabolized by corn cells to a compound which was more polar than tridiphane.Field studies indicated that tridiphane applied with atrazine improved the control of giant foxtail over that of atrazine alone, and allowed for the use of lower atrazine rates. The improvement was greatest when applied to giant foxtail in the 3- to 5-leaf stage of giant foxtail. The maximum synergistic effect between tridiphane and atrazine occurred when atrazine was applied 24 hours after tridiphane application.Larger giant foxtail seedlings (over 8 cm tall) were more difficult to control with single applications of tridiphane plus atrazine and two successive applications eight days apart resulted greater control.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Puncturevine

Puncturevine (Tribulus terrestris L.) is also commonly referred to as tackweed, puncture weed, Mexican sandbur, Texas sandbur, goathead, caltrop, and bullhead. This non-native plant of the southern Europe and Mediterranean region likely showed up in the United States and later the PNW due to seed movement. Since its introduction, human activity and animals have introduced and spread the plant throughout much of the United States and Pacific Northwest. Puncturevine fruits resemble the caltrop, a metal device used in medieval warfare which was placed on the ground with one spike up to slow advancing armies. This weed is a member of a small genus composed of about 12 species in the Caltrop family (Zygophyllaceae). The genus name, Tribulus, derives from the Greek word tribolus, “spiny plant,” which refers to the spiny fruits. This publication is intended to assist growers, crop advisors, pesticide applicators, and homeowners to effectively manage this weed