1998 Table of Contents

1998 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.

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.

Statement of problem to be addressed

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.

Production system being investigated: Annual cropping, intermediate to high rainfall, non-irrigated

Abstract

Direct seeded wheat, pea, canola and yellow mustard resulted in rapid seedling emergence. Yellow mustard plots did not establish as might have been expected compared to canola. Pea used least water and did not deplete soil moisture content below 36 inches depth. Wheat utilized most moisture in the top 36 inches, but mustard was able to utilize moisture deep in the soil profile. Highest seeding rate and narrow row spacing of yellow mustard utilized greater moisture deep in the soil profile. Few pest or diseases were noticed in pea and wheat and no disease was observed on canola or yellow mustard. Without herbicides, least weed biomass was observed in wheat and most weed biomass in pea. However, when herbicides were not applied, yellow mustard had lowest total weed biomass. Highest seed yield was obtained from wheat followed by canola. Yellow mustard and pea yield was lowest and not significantly different. Row spacing and seeding density of yellow mustard had little effect on weed populations in the crop. The highest seeding rate of yellow mustard was associated with highest yield. Wheat and pea yield was reduced without herbicide application (1% and 13%, receptively) but canola and mustard yield showed a 7% and 11% yield increase without herbicide application.

Results and Interpretation

Plots of spring wheat (‘Penawawa’), pea (‘Colombian’), canola (‘Sunrise’) and yellow mustard (‘IdaGold’) were planted near Genesee (Zenner farm) on April 23 and at Moscow on May 4, 1998. All crops were planted using a Haybuster direct-seed drill. Wheat, pea and canola were sown at 120, 110 and 7lb/acre, respectively, on 7" row spacing. Yellow mustard was planted at 5lb on 7" rows, 10lb on 7" rows, 5lb on 14" rows, and 10lb on 14" rows. Pre-plant fertilizer (100 lb of 16-20-0) was banded below the seed. At Moscow 90 lb of nitrogen was broadcast applied and at Genesee 70 lbs of N was broadcast (both as 34-0-0).

Pests and diseases

Few insect pests were observed on plants throughout the growing season and no insecticides were applied to yellow mustard. Insecticide was applied to canola for flea beetle control and to wheat and pea for aphids.

Plots were assessed visually for disease symptoms during 1998. Each plot was rated on a scale of 0 to 5 where 0 = no plants, 1 = up to 10% of plants, 2 = up to 25% of plants, 3 = up to 50% of the plants, 4 = up to 75% of the plants, and 5 = up to 100% of the plants with symptoms. No disease symptoms were observed on canola or yellow mustard plants. Disease symptoms on wheat and pea were generally slight, and were located close to the soil line. Five plants were selected from each plot and isolations were performed for bacterial, fungal, and nematode pathogens. In 1998, while adequate moisture was present, disease levels were generally low with isolated incidence of diseases. Isolations were not performed on plants with no symptoms. Only pathogenic Fusarium spp. was found in some plots.

Water use by crop

Aluminum access tubes were placed in each plot following emergence for monitoring profile water use with a neutron moisture meter during the growing season. Volumetric water content was measured on five occasions from each plot throughout the growing season, approximately biweekly, basis at 6-inch increments to a depth of 60 inches.

Pea used approximately one third the water in the top six inches of soil compared to the other three crops. Soil depths greater than 24 inches were only slightly depleted of moisture by pea crops. In the top 30 inches of soil, wheat water use was greater than canola or yellow mustard. Similarly in this top 30 inches of soil, canola used more water than yellow mustard. At greeter soil depths yellow mustard used most water, canola intermediate and wheat depleted the soil moisture little at depths of 54 inches. The greater ability of yellow mustard to draw water from deep in the soil profile must be part of this crop's adaptability to drier regions. Some of the rotational benefits of including pea in rotation with other crops in the region might be related to the low water use of the crop not depleting soil moisture availability to following crops.

Different seeding rates and row spacing did not show as contrasting water use relationships compared to the differences among crops. All seeding treatments showed a similar trend with reduced water use by depth until 36 inches depth, and thereafter a slight rise in water use. There was a trend of greater water use in the top 36 inches of soil when mustard is seeded at wider row spacing. However, greatest water use treatment at deepest depth examined was from the highest seeding rate (10lb/acre) and 7" row spacing, and lowest water use was for the lowest seeding rate and widest row spacing.

Weed infestation

Each 20 x 150-ft plot was divided into an untreated and treated half. Weeds were counted in six 0.25m² quadrats equidistantly spaced across the 150 ft plot length and randomly spaced within the center 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). Above ground crop and weed biomass were collected from six 0.25m² quadrat as previously mentioned when wheat was heading and pea, canola and mustard were in the 50 to 75% bloom stage. Weed seed was harvested from three 0.25m² quatrats equidistantly spaced along the 150 ft plot length and randomly spaced within the center 10 ft in each half of each plot. Seed samples are being cleaned and seed counted.

The principal weeds present at the Moscow location included wild oat, common lambsquarters, and henbit. Individual and total weed density and biomass were lower in the treated versus the untreated plots following herbicide treatment for all crops at Moscow (Tables 2, 3, 4 and 5). In the mustard plots, no three–way (seed rate by row spacing by herbicide treatment) or two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions were significant. Herbicide treatment, the only main effect that was significant, reduced wild oat density and biomass and total weed density and biomass.

The principal weeds present at the Genesee location included henbit, redroot pigweed, and mayweed chamomile. Individual and total weed density and biomass generally were lower in the treated versus the untreated plots following the herbicide treatment for all crops at Genesee (Tables 6, 7, 8 and 9). In the mustard plots, no three–way (seed rate by row spacing by herbicide treatment) or two-way (seeding rate by row spacing, seeding rate by herbicide treatment, and row spacing by herbicide treatment) interactions were significant. Herbicide treatment, the only main effect that was significant, reduced mayweed density and biomass.

Averaged over both locations, wheat had lowest number of weeds per area and lowest weed biomass in herbicide treated plots. Herbicide treated canola had significantly fewer weed plants and lower biomass compared to yellow mustard or pea. Untreated pea plots showed over five-fold increase in weed biomass compared to treated plots. Similarly, untreated wheat had four fold and canola had two fold increases in weed biomass compared to treated plots. Yellow mustard showed lowest weed biomass in untreated plots compared to the other crops.

Seed yield and quality

The Moscow trial was harvested on August 12, and the Genesee trial harvested on August 25. After harvest, seed yield and moisture content was assessed and sub-samples of seed were taken from each plot for quality determination. Quality evaluation had not been completed at the time of compiling this report. Seed yield was significantly higher at Genesee compared to Moscow, despite a severe hailstorm at the Genesee site in mid-July.

Averaged over both locations wheat produced significantly higher yielded followed by canola, while yellow mustard and pea yields were not significantly different (Table 10). The low yield of yellow mustard was not expected from observation of past research plots and previous direct seeded grower fields. The 1998 growing season allowed for relatively early seeding of these trials. However, almost immediately after planting the weather became cold and very wet. Whereas yellow mustard has been observed to emerge and establish quickly (say compared to spring canola), yellow mustard establishment was very slow and plants stayed at the cotyledon to first leaf stage considerably longer than had previously been observed. This cold early growth was, at least in part, responsible for the poor performance of yellow mustard in these trials.

While the cool spring proved detrimental to the yellow mustard these climatic conditions favored canola. Similarly, the high spring moisture, despite high temperatures later in the season, meant that none of the crops showed any drought stress symptoms that can effect spring crops in the region.

Highest yellow mustard yield was obtained from planting 10lb/acre seed compared to 5lb/acre (Table 12). Highest yellow mustard yield was obtained from highest seeding rate and 7" row spacing. It should, however, be noted that there was no significant difference between 7" and 14" row spacing averaged over both seeding rates.

Wheat and pea yields were reduced by 1% and 12% when herbicides were not applied (Table 12). In contrast, canola and yellow mustard seed yield was increased by 7% and 11%, respectively, in untreated plots compared to herbicide treated plots.

1998/1999 winter wheat crop

After harvesting all the crops, the complete trial area was direct seeded to winter wheat. The winter wheat at both trial locations emerged and established well.

Grower survey

A survey of Pacific Northwest yellow mustard growers was taken using a similar questionnaire to that completed in the 1997 survey. At the time of writing this report, the results from this survey have yet to be summarized and we are presently waiting final (harvest) surveys to be returned. A full summary of this year’s survey will be presented in next year’s report.

Table 1. Herbicide treatments applied to crops grown near Genesee and Moscow, Idaho in 1998.

Table 2. Post-herbicide application wild oat and total weed density and biomass in spring pea at Moscow in 1998.

Table 3. Post-herbicide application principal and total weed density and biomass in spring wheat at Moscow in 1998 .

Table 4. Post-herbicide application principal and total weed density and biomass in spring canola at Moscow in 1998.

Table 5. Post-herbicide application principal and total weed density and biomass in yellow mustard at Moscow in 1998.

Table 6. Post-herbicide application principal and total weed density and biomass in spring pea at Genesee in 1998¹.

¹Only 3 replications were included due to missing data.

Table 7. Post-herbicide application principal and total weed density and biomass in spring wheat at Genesee in 1998.

Table 8. Post-herbicide application principal and total weed density and biomass in spring canola at Genesee in 1998.

Table 9. Post-herbicide application principal and total weed density and biomass in mustard at Genesee in 1998.

Table 10. Number of total weeds and biomass of weeds (oz) from herbicide treated and non-treated crops.

Table 11. Seed yield (lb/acre) of four spring crops grown at two locations.

Row and column means with different superscript letters are significant (P<0.05) according to Fishers protected LSD.

Table 12. Seed yield of four direct seed yellow mustard treatments.

Row and column means with different superscript letters are significant (P<0.05) according to Fishers protected LSD.

Table 12. Percentage difference in seed yield between herbicide treated plots and untreated plots ([non-herbicide yield/herbicide yield] x 100).