2001 Table of Contents

2001 STEEP III Final Report

RESEARCH PROJECT TITLE: Examine cropping systems including yellow mustard (Sinapis alba L.) in the Pacific Northwest.

INVESTIGATORS: Jack Brown, Donn Thill, John Hammel and Wesley Chun. PSES, University of Idaho, Moscow, ID 83844-2339, Tel.: (208) 885-7078, e-mail: jbrown@uidaho.edu.

PROJECT OBJECTIVES:

1. To determine the effect of row spacing and seeding rate on weed management, seed quality and seed yield of yellow mustard in no-tillage management systems.
   
2. Compare water use efficiency of yellow mustard with different row and seeding density with water use efficiency of spring wheat, canola, and pea under no-tillage systems.
   
3. Determine the rotational effect of yellow mustard, compared spring wheat, canola and pea with regard to soil physical structure, weed management, and disease incidence in the following winter wheat crop in no-tillage management systems.
   
4. Conduct annual surveys of yellow mustard growers to determine: seed yield potential; cultivars grown; cultural practices (including cultivation method, fertilizer, weed management, insecticide management); and identify problem areas for yellow mustard production in the region.

KEY WORDS: crop rotation, direct-seeding, weed seed, yellow mustard.

STATEMENT OF PROBLEM: Yellow mustard (Sinapis alba L.) has shown good adaptability to dry-land regions of the Pacific Northwest. This species can be grown with few (if any) chemical inputs. However, yellow mustard is a new crop to this region and little knowledge is available to growers on the best practices to maximize water use and optimize crop productivity. Similarly, very little is known of yellow mustard rotation effects on weed control and management, disease control in following crop, and physical soil structure. This project will examine the effect of yellow mustard row spacing and seeding density on water use management, crop productivity, weed control, and rotational effects.

AGRONOMIC ZONE OF INTEREST: Annual cropping, intermediate to high rainfall, non-irrigated.

ABSTRACT OF RESEARCH FINDINGS: Weed seed was harvested from three 0.25 m2 quadrats equidistantly spaced along the plot length and randomly spaced within the center in each half of each plot. Weed seed number was highly variable among subsamples within plots and among replications within treatments. Thus, few significant differences among treatments were detected. Individual and total weed seed densities were not reduced by herbicide treatments at Moscow in 1998 for all crops. Herbicide-treated canola plots had significantly more common lambsquarters seed than untreated plots. Individual and total weed seed densities in herbicide-treated plots were equal to untreated plots following herbicide treatment for all crops at Genesee in 1998. Individual and total weed seed densities in herbicide-treated plots were not different compared to untreated plots following herbicide treatment at Moscow and Genesee in 1999. In the mustard plots during both years at both locations, no three-way (seed rate by row spacing by herbicide treatment) interaction, two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions, or main effects were significant. For all previous crops, individual and total weed seed densities were not reduced by herbicide treatment during the 1998 crop year compared to the untreated plots at Moscow and Genesee in the 1999 winter wheat crop. Total weed seed density following mustard was not different in the herbicide-treated plots compared to the untreated plots in the 2000 winter wheat crop at Moscow. Herbicide-treated plots were not different for wild oat and total weed seed density compared to untreated plots at Genesee in the 2000 winter wheat crop.

RESULTS AND INTERPRETATION: See 1999 and 2000 STEEP reports for yellow mustard growers surveys, seed quality and yield, water use efficiency, soil physical structure, and disease incidence.

Year 1: 1998 and 1999 - Alternative crops
Each 20 by 150 ft plot at Moscow and Genesee in 1998 and each 20 by 120 ft plot at Moscow and 18 by 140 ft plot at Genesee in 1999 were divided into a untreated and herbicide-treated half. Weeds were counted in six 0.25 m2 quadrats equidistantly spaced across the 120, 140, or 150 ft plot length and randomly spaced within the center 9 or 10 ft (width) in each half of each plot. A crop-specific herbicide treatment was applied based on weed species, density, and growth stage (Table 1). Weed seed was harvested from three 0.25 m2 quadrats equidistantly spaced along the plot length and randomly spaced within the center in each half of each plot. Seed samples for each plot were combined, and were cleaned using a rub board, metal sieves, and a Dakota seed blower. Seed number was determined by counting all seeds in small samples and calculating seed number of larger samples based on the average weight of three lots of 100 seeds for each species at each location.

Weed seed number was highly variable among subsamples within plots and among replications within treatments. Thus, few significant differences among treatments were detected.

Weed seed species present at Moscow in 1998 included common lambsquarters (CHEAL), wild oat (AVEFA), redroot pigweed (AMARE), field pennycress, prickly lettuce, prostrate pigweed, downy brome, and volunteer wheat. The principal weeds present were common lambsquarters and wild oat. Individual and total weed seed densities were not reduced by herbicide treatments at Moscow in 1998 for all crops (Table 2). Herbicide-treated canola plots had significantly more common lambsquarters seed than untreated plots. In the mustard plots, no three-way (seed rate by row spacing by herbicide treatment) interaction, two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions, or main effects were significant.

Weed seed species present at Genesee in 1998 included common lambsquarters, redroot pigweed, henbit (LAMAM), mayweed chamomile (ANTCO), field pennycress, shepherd's-purse, prickly lettuce, catchweed bedstraw, annual sowthistle, and wild oat. The principal weeds present were common lambsquarters, redroot pigweed, and henbit. Individual and total weed seed densities in herbicide-treated plots were equal to untreated plots following herbicide treatment for all crops at Genesee (Table 2). In the mustard plots, no three-way (seed rate by row spacing by herbicide treatment) interaction, two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions, or main effects were significant.

Weed seed species present at Moscow in 1999 included mayweed chamomile, redroot pigweed, and common lambsquarters. The principal weed present was mayweed chamomile. Weed seeds were spare and variable throughout the entire study and no weed seeds were collected in canola. Individual and total weed seed densities in herbicide-treated plots were not different compared to untreated plots following herbicide treatment at Moscow (Table 3). In the mustard plots, no three-way (seed rate by row spacing by herbicide treatment) interaction, two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions, or main effects were significant.

Weed seed species present at Genesee in 1999 included common lambsquarters, hairy nightshade (SOLSA), interrupted windgrass (APEIN), downy brome, shepherd's-purse, mayweed chamomile, field pennycress, field bindweed, catchweed bedstraw, wild oat, henbit, and annual sowthistle. The principle weeds present were common lambsquarters and hairy nightshade. Individual and total weed seed densities in herbicide-treated plots were not different compared to untreated plots following herbicide treatment at Genesee (Table 3). In the mustard plots, no three-way (seed rate by row spacing by herbicide treatment) interaction, two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions, or main effects were significant.

Year 2: 1999 and 2000 - Winter wheat
1998 and 1999 plot areas at Moscow and Genesee were reestablished and seeded to winter wheat during fall 1998 and 1999, respectively. Weeds were counted in three 0.25 m2 quadrats as described previously. Herbicides were applied to winter wheat (entire plot area received the same treatment) based on weed species, density, and growth stage at Moscow and Genesee (Table 4). Weed seed was harvested from three 0.25 m2 quadrats equidistantly spaced along the plot length and randomly spaced within the center in each half of each plot. Seed samples were cleaned and seed number was determined as described previously.

The weed seed species present in winter wheat at Moscow in 1999 included mayweed chamomile, redroot pigweed, field pennycress, and wild buckwheat. The main weeds were mayweed chamomile and redroot pigweed. The weed seed species present at Genesee included interrupted windgrass, common lambsquarters, henbit, shepherd's-purse, mayweed chamomile, redroot pigweed, wild oat, catchweed bedstraw, field pennycress, downy brome, prickly lettuce, hairy nightshade, panicle willowweed, and prostrate knotweed. Interrupted windgrass and common lambsquarters were the principal weeds. For all previous crops, individual and total weed seed density were not reduced by herbicide treatment during the 1998 crop year compared to the untreated plots at Moscow and Genesee in the 1999 winter wheat crop (Table 5).

The weed seed species present at Moscow in 2000 included wild oat, downy brome, and interrupted windgrass. Wild oat was the main weed. Weeds were spare and seed samples were collected only in previous mustard plots. Total weed seed density following mustard was not different in the herbicide-treated plots compared to the untreated plots in the 2000 winter wheat crop at Moscow (Table 6).The weed seed species present at Genesee in 2000 included wild oat, smooth brome, California brome, and downy brome. Wild oat was the main weed. Herbicide treatment was not different for wild oat and total weed seed density compared to untreated plots at Genesee (Table 6).

Data are being analyzed to examine rotational crop by herbicide treatment interactions, and rotational crop and herbicide treatment main effects.

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