2000 Table of Contents

2000 STEEP III Progress 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. P.S.E.S., University of Idaho, Moscow, ID 83844-2339, Tel.: (208) 885-7078, e-mail: jbrown@uidaho.edu.

INTERIM REPORT: Year 3 report of project started in 1998

PROJECT OBJECTIVES:

• To determine the effect of row spacing and seeding rate on weed management, seed quality and seed yield of yellow mustard in no-till management systems.
• 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.
• Determine the rotational effect of yellow mustard, compared to wheat, canola, and pea with regard to soil physical structure, weed management, and disease incidence in the following winter wheat crop in no-till management systems.
• Conduct annual surveys of yellow mustard growers to determine: seed yield potential; cultivar 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, yellow mustard, canola, pea, and wheat.

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: The performance of winter wheat following four different spring crops (spring wheat, pea, canola and yellow mustard) was examined. At both locations, total weed density and biomass generally were equal to or lower in the treated versus the untreated plots (1999 crop year) following the herbicide treatment in winter wheat. However, in treated plots, total weed density and biomass were 2.7 and 2.1 times greater, respectively, following spring canola compared to the other three spring crops. Results from 2000 were in good agreement to those obtained in 1999 whereby highest yield of winter wheat planted after the alternative spring crops was after pea, followed by yellow mustard. Winter wheat yield following spring wheat produced lowest yield compared to other rotations. It was not possible to control volunteer spring wheat that survived the mild winter, in the spring wheat-winter wheat rotation. This contributed to the low yield in this rotation. Wheat yield after wheat was not significantly different compared to wheat after canola. There was no difference in winter wheat yield following yellow mustard with different seeding rates, wider row spacing of yellow mustard did, however, result in significantly higher winter wheat yields. This was in contrast to the 1999 trial where rotational benefits of yellow mustard in the following wheat crop was greatest at high seeding rates and closer row spacing.

RESULTS AND INTERPRETATION:

Year 2, 2000 -Winter wheat following alternative crops

After harvesting the 1999 alternative crops trials (see 1999 STEEP Report pp. 36), the plot areas at Moscow and Genesee were reestablished and seeded to winter wheat during fall 1999. Plot size was 20 by 100 ft at Moscow and 18 by 140 ft at Genesee. The winter wheat at both trial locations emerged and established well. It should be noted, however, that there was high survival of spring wheat volunteers that survived the mild 1999/2000 winter. It was not possible to control these volunteers in the winter wheat, and this must have affected the winter wheat following spring wheat performance.

Weed infestation

Prior to applying herbicides to winter wheat, weeds were counted in three 0.25 m² quadrats equidistantly spaced along the 100 or 140 ft plot length and randomly spaced within the center 9 or 10 ft (width) in each half of each plot (untreated and herbicide-treated in spring 1999). 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 1). Above ground crop and weed density and biomass were collected from three 0.25 m² quadrats as previously mentioned when wheat was heading. 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 a few days before grain harvest. Weed seed samples are being cleaned and seeds counted.

The weed species at Moscow included downy brome, interrupted windgrass, wild oat, catchweed bedstraw, henbit, tarweed fiddleneck, narrow-leaf montia, mayweed chamomile, and common lambsquarters. Downy brome was the principal weed, although weed density was variable and sparse (Table 2). Downy brome and total weed density and biomass in winter wheat were generally equal to or lower in the treated versus the untreated plots (1999 crop year) following the herbicide treatment at Moscow.

The weed species at Genesee included henbit, prickly lettuce, wild oat, shepherd's-purse, volunteer mustard, common lambsquarters, mayweed chamomile, volunteer canola, catchweed bedstraw, wild buckwheat, and tarweed fiddleneck (Table 3). Weed populations were moderate. Wild oat and total weed density and biomass generally were equal to or lower in the treated versus the untreated plots (1999 crop year) following the herbicide treatment in winter wheat at Genesee. Henbit density and biomass appeared unaffected by herbicide treatment. In treated plots, averaged over both locations, total weed density and biomass were 2.7 and 2.1 times greater, respectively, following spring canola compared to the other three rotational crops.

Seed yield and quality

Averaged over all treatments and sites, highest winter wheat yields were obtained following pea and yellow mustard, which were not significantly different from each other (Table 4). At Moscow, wheat following wheat was significantly lower yielding than following the other three crops. This was greatly influenced by the spring wheat volunteers that survived the mild winter and could not be chemically controlled. Spring wheat volunteers were not as dense at Genesee, where significantly higher wheat yields were obtained following pea. Wheat following yellow mustard was significantly higher than following canola or following spring wheat.

The effect of herbicide application on the 1999 spring crops was overall not significant (Table 5). Significant differences were observed in pea, where wheat following herbicide treated pea was significantly higher than no herbicide pea; this was due to a 6% yield increase at Genesee from the treated plots compared to non-treated. At Genesee, wheat following herbicide treated yellow mustard was significantly lower yielding compared to yellow mustard where no herbicide was applied. The difference in yield of wheat following yellow mustard with and without herbicide was greatest with lower seeding rates and wide row spacing in the yellow mustard crop (Table 6 and Table 7)

Averaged over herbicide treatments, lower yellow mustard seeding rates did not significantly impact wheat crops following (Table 6). Wheat following yellow mustard planted at 14-inch row spacing resulted in significantly higher yield (5% increase) over closer (7 inch) row spacing (Table 7). Averaged over sites and treatments, significantly higher wheat yields (103 Bu/acre) were obtained following yellow mustard planted at 5 lb/acre on a 14 inch row spacing, compared to the other yellow mustard seeding rates and row spacing. This result was somewhat similar to the 1999 trial, where this treatment was not significantly different from the best treatment that year (10lb planted on 7 inch rows).

Test weights were significantly lower at Moscow compared to Genesee (Table 8).
However, herbicide treatment, previous crop, and yellow mustard seeding rate and row spacing had no effect on winter wheat test weights.

Table 1. Herbicide applications in winter wheat near Genesee and Moscow, Idaho in 2000.

Table 2. Post-herbicide application weed density and biomass in winter wheat at Moscow in 2000.

¹ 1999 crop year

Table 3. Post-herbicide application weed density and biomass in winter wheat at Genesee in 2000.

Table 4. Seed yield (Bu/acre) of winter wheat grown after four species grown averaged over herbicide treatments at two locations (Moscow and Genesee).

Table 5. Seed yield (Bu/acre) of winter wheat grown after four species grown with and without herbicide treatment applied on the spring crops in 1999 at two locations (Moscow and Genesee).

Table 6. Seed yield (lb/acre) of winter wheat after spring wheat, and yellow mustard with two seeding rates grown at two locations (Moscow and Genesee) with and without herbicide treatment.

Table 7. Seed yield (lb/acre) of winter wheat after spring wheat, and yellow mustard with two row spacing at two locations (Moscow and Genesee) with and without herbicide treatment.

Table 8. Test weight (g/lb) of winter wheat grown after four species grown averaged over herbicide treatments at two locations (Moscow and Genesee).

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