ISSUE 14   August 2, 3006

CANOLA: SWATHING AND HARVESTING

The hot and sunny weather the past few weeks has caused canola to come on quickly and mature to the point that time for swathing is fast approaching. 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 made every "2 to 3 days" when there is some color change in the first formed pods on the bottom of main stem. Canola seeds within the pod will change color an average of 10 percent every 2 to 3 days. Under hot conditions, seed color changes can be very rapid.

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. Optimum time to swath is when 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 of variety. Once filled the seeds rapidly lose moisture at about 2 to 3 percent or more per day, depending on the weather.

Green Seed Problems

Cutting too early with high temperatures, hot winds and rapid drying can lead to excessive green seed count. Two percent or less green seed is currently the allowable limit. If green seed counts are higher than the 2 percent and market discounts can occur. The key to curing the crop is moisture. The enzyme responsible for clearing the chlorophyll requires moisture. Therefore, seed moisture is critical. If the stems and seeds dry too rapidly after swathing, then chlorophyll can be fixed.

Leaving canola in the swath longer can help eliminate some green seed problems or potential. A rain will also help reduce green count in canola. Once the moisture content of seed is 20 percent, chlorophyll will begin to be moved out. In some cases however, when swathed too green in hot weather the chlorophyll will not be reduced to any great extent. Cool temperatures and light frosts in August and September slow the enzyme activity that breaks down chlorophyll. Frosts from 32 to 33 F disrupts that system, and 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. 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.

Uneven Stands-mixed maturity

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. One would take the chance of shatter in the early maturing canola but would avoid the problem of green seed count and market discount. One could also swath at night or in the early morning hours to avoid shattering in the fields where portions of the canola are ahead in maturity and development.

Two years of NDSU research has shown that at 0-5 seed color at swathing time resulted in 3.5 percent green seed content which is higher than the 2% allowed in the market place before a discount will occur. Approximately 180 lbs/A of yield gain was noted when swathing was delayed to the 15-20 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 if 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 in the field to ensure maximum drying, maturation and quality of your harvested canola."

 

SPECIALTY CROPS- WHEN TO SWATH AND COMBINE

Hot weather and drought in many areas this summer of 2006, has tended to push many crops to mature at an increased rate. Questions on when to swath and harvest certain alternative crops are being asked. Below are some comments and suggestions:

Crop

Information to consider:

Lentil

Swath when lowermost pods are tan colored and rattle when shaken. Thresh when seeds test 18% moisture content or lower. Over dried lentils (8-10%) are hard and difficult to process or consume. Plants may still be green when pods are ripe. Crop typically matures in patches. Some shatter loss usually occurs.

Yellow Field Pea

Swath when peas are pea vines are yellow colored. Thresh when seeds are firm and can no longer be penetrated with thumbnail. 20% moisture content or lower. Some shatter loss usually occurs. Mixing wet soil with peas can cause staining - a discount grading factor.

Feed Pea

Swath when pea vines are yellow colored. Vines are often prostrate. Seeds are firm, but no longer penetrable with a thumbnail. Combine settings and operation are not as critical to feed peas as to human food peas. Admixture of various pea kinds are allowed. Some bleached peas, split, cracked or split peas, and earth tagged peas are accepted for feed peas.

Millet, Proso

Swath when seeds in the upper one-half of the panicle have matured. Seeds in lower portion will be in dough stage but will have less color. Harvest millet when its below 13% moisture. Shatters easily if not cut on time.

Mustard

Swath when seed moisture content is 25%. Oriental-75% yellow seeds. Brown-60% reddish brown seeds. Yellow (White)-100% yellow seeds. Straight combine yellow mustard whenever possible. Watch for cracked seeds. Moisture content of seed should be 13% or lower. Swaths are fluffy and subject to wind damage. Lay swaths in direction of prevailing winds. Immature green seed will not change in color in the swath. Use swath roller.

Safflower

Crop has finished blooming. Seeds heads are tan to brown in color. Leaves and heads are spiny with little green evident. Crop should be straight combined if evenly matured. Mature seed is striped or white and rubs freely from the heads.

Buckwheat

75% of the seed coats have turned brown. Flowering is nearly complete. Difficult to penetrate seed with thumbnail. Seeds continue to fill in the window or after light frost for about 3 days. Bottom seeds will likely be lost due to shattering.

Canaryseed

Straw is bleached, hulls are shiny and golden colored. Seeds are reddish-brown. Delay cutting canaryseed until it is fully mature. Canary seed will not thresh cleanly until the heads are dry. Canaryseed is resistant to shattering and weathering. Dehulled seed is severely discounted.

 

FLAX: HAYING AND GRAZING DANGER

This is an alert to the effect that grazing or haying of droughty flax can result in problems of HCN poisoning (Prussic acid). Had previous communication from Dr. Jack Carter the expert on flax and also former chair of our Plant Sciences Dept. Green flax straw should not be fed or grazed. The danger of prussic acid poisoning is much higher. Also if the immature flax is frozen and then fed to livestock according to the Canadian flax literature.

He recalled that cattle had died when breaking out of fences and eating the flax strips on fallow which had been planted for wind erosion. The test for HCN in flax is different than it is for Sudangrass or Sorghum-sudan.

Duane R. Berglund
NDSU Extension Agronomist
duane.berglund@ndsu.edu

 

OBSERVATIONS FROM THE WHEAT QUALITY TOUR

Last week, I participated in the annual Wheat Quality Tour organized by the Wheat Quality Council. This year there were 41 participants from various segments of the wheat sector. During the three day tour, most wheat producing counties were visited by at least one group and yields were estimated from more than 300 wheat fields. Estimates were based spike and spikelet numbers counted in random areas of the fields. For the state as a whole, the group estimated that yields were going to be down an average of 4 bu/acre from last year. This average figure, however, masks the tremendous variation observed in yields, which ranged from 66 to 0 bu/acre. Yields were lowest in the south central region of the state where drought has been severe and prolonged. Furthermore, there may have been an overestimation of yields in dryer regions as estimates were based on a standard kernel weight which will likely not be achieved due to poor grain filling. In eastern ND, yields were estimated to be relatively good given the high temperatures and limited rainfall this season (I just received a call from a grower near Fargo whose yields were in the 70-80 bu/acre range so maybe the tourís assessment significantly underestimated the crop in the east!). The good new for this region is that there is little or no scab.

In general protein levels will be high, but test weights may be light, especially in late planted fields. Winter wheat yields look to be very good this year and were estimated to be up 14 bu/acre from last year. Winter wheat because of it earlier development was less affected by the heat and drought than spring planted wheat. Early planted fields of spring wheat and durum showed a significant yield advantage over later planted fields. In fact, in the northwest, many participants described the wheat crop as the "tale of two crops", with the early planted crop looking reasonable and the late planted crop poor. Durum yields were estimated to be off by 6 bu/acre from last year, largely due to the fact that most of the durum fields visited had been planted late. Early planting was a management practice that will payoff big this year. Including some winter wheat also appears to have been a profitable practice for many areas of the state.

Joel Ransom
Extension Agronomist - Cereal Crops
joel.ransom@ndsu.edu


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