Corn

Prices paid for sweet corn are low relative to the cost of producing the crop, and every strategy possible must be used to maximize net return. Two strategies used to enhance profitability but that have received little research attention under Western Oregon conditions are the use of pop-up fertilizers and increased plant populations. Despite indications that popup fertilizers improve early-season growth, concrete evidence that these fertilizers ultimately enhance growth and yield are often lacking. Seeding density also can be increased to improve crop yield up to a point, but intraspecific competitive ability and the competitive stress tolerance of varieties currently produced in the Willamette Valley has not been demonstrated.

This project is evaluating interseeding of crop crops to improve cover crop establishment after late harvested crops such as sweet corn and processing squash. In Project 1 at the OSU Vegetable Research Farm, a cover crop of oat and crimson clover produced the most cover crop biomass when interseeded at V4 compared to V6 and V8 plantings but may have reduced corn yield slightly because of competition for water or nutrients. Applying Laudis herbicide immediately after interseeding of the cover crop had no impact on cover crop establishment, even when seeds were broadcast on the soil surface and incorporated lightly. Clover did not emerge well in interseeded plots, possibly because it was planted too deeply. Clover establishment was best when seed was broadcast on the soil surface and incorporated with shallow tillage. Cover crop biomass in mid-December averaged less in interseeded plots than in fall-planted plots because the oat cover crops began to senesce.

Oregon State University’s VegNet is a regional pest monitoring program that provides activity reports for 10 common insect pests that affect broccoli, cabbage, cauliflower, sweet corn, and snap beans. Crop pests are sampled weekly and raw data is compared to activity trends from previous years. Regional pest monitoring helps growers and agricultural field representatives adjust their scouting effort when an outbreak is detected, and the combination of area-wide monitoring plus field-specific scouting reduces risk of crop loss. Reports are available on www.oregonvegetables.com, and sent via an email newsletter that currently serves over 400 subscribers. In 2015, increases in pest pressure were noted for black cutworm, spotted cucumber beetle, cabbage white butterfly, bertha armyworm, and diamondback moth.

Urea is a common nitrogen fertilizer for sweet corn production. This two year project evaluated commercially available urea additives for their potential to provide crop production and environmental benefits. Specifically, experiments were designed to evaluate the efficacy of urea fertilizer products containing a urease inhibitor (Agrotain Ultra), or nitrification inhibitors, or a polymer coated urea product (ESN). Products containing nitrification inhibitors (SuperU and Instinct) were evaluated only in 2014, and found to have efficacy similar to ESN in slowing conversion of urea to leachable nitrate-N. The control treatment in all studies was granular urea without additives.

Prices paid for sweet corn are low relative to the cost of producing the crop, and every strategy possible must be used to maximize net return. Two strategies used to enhance profitability but that have received little research attention under Western Oregon conditions are the use of pop-up fertilizers and increased plant populations. Despite indications that popup fertilizers improve early-season growth, concrete evidence that these fertilizers ultimately enhance growth and yield are often lacking. Seeding density also can be increased to improve crop yield up to a point, but intraspecific competitive ability and the competitive stress tolerance of varieties currently produced in the Willamette Valley are poorly understood.

Enhanced efficiency fertilizer (EEF) technologies have the potential to improve the crop N use efficiency (NUE) as well as minimize negative environmental losses compared to conventional fertilizers. The EEF fertilizer products consist of urea plus additives (to inhibit N loss). The major pathways for N loss in our sweet corn cropping systems are 1) N leached below the root zone as water soluble nitrate-N (NO3-N), and 2) gaseous ammonia loss (NH3-N) to the atmosphere following a surface urea application.Field studies and a laboratory incubation study were conducted in 2014 to evaluate the potential for benefit from EEF products via reduced nitrate-N leaching. Three products were evaluated: ESN (polymer coated urea), SuperU (prilled urea containing both a urease and nitrification inhibitor), and Instinct (urea + nitrification inhibitor).

In 1978 a survey was done in the Willamette Valley to explore the relationship between soil nutrient values and tissue nutrient concentrations.

The following is a method for cheaply and quickly determining a soil’s nitrate status for the purpose of determining the midseason sidedress fertilizer rate for sweet corn. For information on the pre-sidedress nitrate test (PSNT), see OSU’s nutrient management guide EM 9010-E (Sweet Corn- Western Oregon). The ‘Quick Test’ (QT) has been in use for years in the Salinas Valley of California with good results. Compared to a traditional laboratory test, it is cheaper and test results can be obtained within hours of sample collection. Although this method is semi-quantitative, results from the QT are well correlated with laboratory results.