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ISSUE 13  July 30, 1998



    Listed below are useful Web page titles and addresses. These are useful to all involved in crop production, sales, crop consulting, ag. advising or crop marketing.

Title and WW Web Address

National Sunflower Association

Canola Connection

ProCrop 1998

North Dakota Small Grains Page

Weed-Pro 1998

Northern Crops Institute

North Dakota Agricultural Statistics Service

ND Weather Page

The National Agricultural Library

Ag Answers Home Page

AgriGator*Worldwide Agricultural SITE INDEX

National Association of Wheat Growers

New CROP Home Page

US EPA Office of Pesticide Programs

Farm Business Management Information Network

Sustainable Agriculture Network



    One very important management aspect of growing canola is estimating the correct time to swath and harvest. A canola grower must attempt to maximize yield and yet maintain quality with as little green seed content as possible in the threshed oilseed.

    Swathing canola at the optimum stage of ripening reduces green seed problems and seed shatter losses, and ensures the quality required for top grades and prices.

    Field inspections should be every "two to three days" when there is some color change in the first formed pods on the bottom of the main stem.

    To determine when a field of canola is ready to swath, plants from different parts of the field must be examined. The stage of maturity in an evenly maturing field will vary from plant to plant and from area to area within the field. When examining the plants, take into account varying soil types, low lying areas, available soil moisture and exposed early ripening areas.

    Examine only those pods on the main stem. Seeds in pods on the "bottom third" of the main stem were formed earlier and will turn color much sooner than seeds in the pods on the top third of the plant. When the overall moisture content of seed from the total plant averages 30 to 35 percent, about 30 to 40 percent of the seeds in pods on the main stem only will have changed color or have started to change color. Seeds with only small patches of color should be counted as color changed. Remember, the color of the seed is more important than the overall color of the field in determining the stage of maturity.

    Most of the seeds that have changed color will be from the bottom third of the stem. When seeds in the bottom pods slightly turn color, seeds in the top, last-formed pods are filled or nearly filled. At this time, most of the seeds will be firm and roll, as opposed to break, when pressed between the forefinger and thumb.

    Seeds in all pods on a plant complete filling (physiological maturity) at about 40 percent moisture and then slowly turn from green to light yellow, or reddish brown to brown, depending on the variety. Once filled, the seeds rapidly lose moisture at about 2 to 3 percent or more per day, depending on the weather.

Green Seed Problem:

    Temperatures at maturity is an important factor in chlorophyll breakdown. Swathing canola when air temperatures are in the mid-90’s and on hot-windy days, can dry and fix chlorophyll in the upper green immature seeds/pods. This can cause problems with turning and changing of seed color in the swath during the curing process.

On the opposite spectrum, cool temperatures and light frosts in late August and September slow the enzyme activity that breaks down chlorophyll. Frosts from 32 to 33 degrees F disrupts that system, more specifically it can reverse it and restart the synthesis process. This is very sensitive in the seed development stage, and the window is very narrow. This can cause differences between adjacent fields that are only days apart in maturity, or differ in uniformity of maturity. Even canola swathed four to six days before a frost will retain relatively high levels of chlorophyll. Two or more germination flushes and growth stages result in immature seed at swathing and green seed at harvest. Thin stand counts can result in plants with more branching and more variability in seed maturity and are more likely to have immature seed at swathing. Late seeded canola may be impacted by all these situations. When looking at uneven stands, its suggested that one do a count early on the ratio of early emerged canola which is bolting or starting to flower and the late emerged flush of young more immature plants.

    If one knows the ratio of early to late emerged canola plants, a better decision can be made as to how soon to swath or wait until the later crop catches up. If the stand is on 20-25% early and 75-80% late, then waiting to cut later may be the best strategy to reduce the amount of green seed.

    Research was conducted in 1996 and 1997 to study the effects of canola color change at swathing on yield and percent green seed.

Canola Swathing Research Results

Seed Color
at Swathing
(% change)




















Locations Averaged - 1996-97, Langdon, Minot, Carrington, ND and Roseau, MN

    The average green seed at the 0-5 seed color at swathing time resulted in 3.5% green seed content which is higher than the 2% allowed in the market place before a discount will occur. Approximately 200 lbs/A of yield gain was noted when swathing was delayed to the 30-35 percent seed color change.

    Another sign of canola being very near the swathing stage is the natural yellowing and senescence of leaves and leaf drop. When canola plants consist only of stems, stem branches and pods, it is probably very near the optimum time for swathing.

    Canola should be allowed to cure and ripen from ten to 14 days in the swath before combining. If combined too early, the chance of increased green seed in the harvested crop is much greater.

    "Be in a hurry to swath on time and prevent shattering, but take your time in moving the combine into the field to ensure maximum drying, maturation and quality of your harvested canola."

Duane R. Berglund
NDSU Extension Agronomist



    Earthworms are called the "intestines of the earth" because of their ability to break down plant litter, recycling nutrients, and enriching topsoil. Generally, a healthier turfgrass will be the result where earthworm populations are adequate. Their burrowing improves aeration and water penetration into the root zone, and significantly increases the total pore space in the soil. Their activity increases microbe populations that further enhance thatch decomposition and improve soil fertility.

    While their presence can go fairly much undetected in most home lawns, there are increasing inquiries about how to control what homeowners have called "excessive" earthworm activity - mounds of castings that make it difficult to mow, and in some cases, a dangerous task to even walk across the lawn.

    The inquiries come in asking what chemical will control these denizens of our soil. In turn, I must tell them that there is nothing labeled on the market for earthworm control. However, there are several products that will kill a portion of the earthworms as a non-target effect when they are applied to control insects or diseases in their lawns. Insecticides like Sevin® (carbaryl), Mocap® (ethoprop), or Crusade® (fonofos) are toxic to earthworms. Any of these products, applied at rates to control grubs as specified on the label, and watered in (at least ½ inch of irrigation), will generally give about an 85% to 95% temporary control of the earthworm population. The fungicide Cleary’s 3336® will provide similar suppression of the population. The impact of these products is greatest if used when the earthworm activity is highest - during rainy periods in the spring or fall when they are closer to the soil surface.

    Regular application of acidic fertilizers like sulfur, ammonium sulfate, or Sulfur Coated Urea (SCU), will also help to suppress the population, but not nearly to the extent of the above cited products.

Ron Smith
NDSU Extension Horticulturist
Turfgrass Specialist

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