Preemergence Herbicides for Potential Use in Potato Production

Field trials were conducted in 2009 and 2010 near Paterson, WA and Ontario, OR to evaluate weed control and potato tolerance to PRE-applied pyroxasulfone, saflufenacil, and KSU12800 herbicides. Pyroxasulfone at 0.09 to 0.15 kg ai ha⁻¹ and saflufenacil at 0.05 to 0.07 kg ai ha⁻¹ applied PRE alone or in tank mixes with several currently labeled herbicides did not injure potatoes at either site in both years. KSU12800 at 0.15 kg ai ha⁻¹ injured potatoes from 18 to 26% for a period of about 4 wk after emergence at Ontario both years. In addition, KSU12800 at 0.29 and 0.45 kg ha⁻¹ injured potatoes from 17 to 38% at 17 d after treatment (DAT) at Paterson in 2009. Pyroxasulfone at 0.15 kg ha⁻¹ controlled barnyardgrass, hairy nightshade, and redroot pigweed 96% or greater, but control of common lambsquarters was variable. Saflufenacil at 0.07 kg ha⁻¹ provided greater than 93% control of common lambsquarters, hairy nightshade, and redroot pigweed at both sites in 2010. KSU12800 at 0.15 kg ha⁻¹ controlled common lambsquarters, hairy nightshade, and redroot pigweed 99% or more at Ontario, but only 87 to 93% at Paterson in 2010. These herbicides did not reduce yield of U.S. no. 1 tubers or total tuber yields compared to standard labeled herbicide treatments when weed control was adequate.Keywords: weed management, weed control, potato injury, Crop tolerance, herbicide injuryKeywords: weed management, weed control, potato injury, Crop tolerance, herbicide injur

Genetic variation and possible origins of weedy rice found in California.

Control of weeds in cultivated crops is a pivotal component in successful crop production allowing higher yield and higher quality. In rice-growing regions worldwide, weedy rice (Oryza sativa f. spontanea Rosh.) is a weed related to cultivated rice which infests rice fields. With populations across the globe evolving a suite of phenotypic traits characteristic of weeds and of cultivated rice, varying hypotheses exist on the origin of weedy rice. Here, we investigated the genetic diversity and possible origin of weedy rice in California using 98 simple sequence repeat (SSR) markers and an Rc gene-specific marker. By employing phylogenetic clustering analysis, we show that four to five genetically distinct biotypes of weedy rice exist in California. Analysis of population structure and genetic distance among individuals reveals diverse evolutionary origins of California weedy rice biotypes, with ancestry derived from indica, aus, and japonica cultivated rice as well as possible contributions from weedy rice from the southern United States and wild rice. Because this diverse parentage primarily consists of weedy, wild, and cultivated rice not found in California, most existing weedy rice biotypes likely originated outside California

Managing weeds and vegetation in Christmas trees

Controlling weeds that compete with Christmas trees is essential to producing quality trees. Weeds have several negative effectsFacts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Weed Control in Cabbage, Table Beet and Spinach

Mapping identified weeds and planning a year-round weed and crop management program offer the best methods for growing seed successfully. A combination of proper cultural practices, cultivation, and herbicides have been effective in controlling weeds in these seed crops. An efficacy chart rates herbicides on broadleaf and grass weeds. Herbicides listed were legal in Washington State at the time of publication. Verify current use with supplier, field representative, or county agent. 8 pages

Weed Control in Strawberry

Covers weed management, field selection, seedbed preparation, geese as weeders, crop rotation and competition, cultivation, and general management of strawberry beds. Includes a list of recommended herbicides for various seasonal and plant type applications. Analyses of production cost factors, budgeting, machinery, and other costs for a model cranberry bog. Offers tables and worksheets to help plan the production and marketing of the crop. Exhibits projected costs of chemicals [e.g., pesticides], labor, irrigation, analysis, and other factors to be considered. NOTE: Read all pesticide labels carefully before using. Pesticides listed were legal at time of printing. 8 pages

Western Washington Weed Control Guide: Weed Control in Wheat

Cultural practices, such as seedbed preparation, sanitation, use of clean seed, crop rotation, and encouraging a healthy, vigorous stand can reduce weed losses in wheat. Incorporating efficient, timely use of chemical controls with good cultural practices improves weed control efforts. Efficacy charts rate herbicides on broadleaf and grass weeds. Diagrams show stages when applications are most effective. Herbicides listed were legal in Washington State at the time of publication. Verify current use with supplier, field representative, or county agent. 12 pages

Responses of rice genotypes to foliar-applied metribuzin

The increasing development of herbicide resistance in weeds found in rice cropping systems has encouraged researchers to evaluate alternate herbicides to prevent and manage herbicide-resistant weed biotypes. Metribuzin is a photosynthetic-inhibiting herbicide that controls various important grass and broadleaf weeds. Several crops, including soybean, wheat, peas, and potato, have shown differential varietal responses to metribuzin. To determine whether rice has differential varietal responses to metribuzin for potential utilization in a rice breeding program, greenhouse experiments were conducted to evaluate the responses of 142 long-, medium-, and short-grain rice genotypes to the herbicide. Metribuzin was applied at 0, 22, 44, 88, 176, and 352 g ai ha-1 when rice plants were in the 3- to 4-leaf stage. Crop response regarding phytotoxicity, height reduction, and biomass reduction was evaluated. Metribuzin caused significant injury to all rice genotypes tested, but short-grain rice genotypes were, on average, more susceptible than medium- and long-grain rice genotypes. Short-grain rice genotypes generally had greater height reduction and produced less biomass than long-grain or medium-grain rice genotypes. Crop visual injury ratings were correlated with plant height reductions and biomass reductions. The results indicate that the level of metribuzin tolerance in rice is inadequate for commercial use; however, further research is needed to develop higher levels of herbicide resistance by mutagenized rice cultivars

Dissipation of pendimethalin in a water‐seeded rice field and implications for water management

Water-seeded rice (Oryza sativa L.) in California is produced near growing urban centers and a variety of neighboring high-value crops, which make water quality a paramount concern because of potential herbicide residue contamination in downstream surface waters. Pendimethalin is a potential herbicide for use in California water-seeded rice. A study was conducted to characterize pendimethalin's dissipation in water of a water-seeded rice field. A capsule suspension (CS), emulsifiable concentrate (EC), and granule (GR) pendimethalin were applied onto flooded rice plots at 1.1, 2.3, and 3.4 kg ai ha−1 rates. Water samples were collected periodically and analyzed with an high pressure liquid chromatography tandem mass spectrometry system for residues. Pendimethalin dissipation differed across formulations. The initial sampled concentrations recorded values from 3.0 to 125.6 parts per billion (ppb). First-order dissipation resulted in half-lives for the CS from 2.3 to 3.5 days, the EC from 0.6 to 0.7 days, and the GR from 3.5 to 6.9 days. Pendimethalin use in water-seeded rice is at low risk of contaminating downstream surface waters; however, early sampled residue concentrations could be concerning. The results can assist in generating management tactics like water-holding periods to avoid potential downstream off-target effects and ensure herbicidal activity in the applied area after a pendimethalin application in a water-seeded rice field