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      Tuesday, October 21, 2014

May 2012

This article is based on research conducted by Pab Orcajada, Provincial Wild Rice Specialist, Saskatchewan Agriculture and Food , and Dr. O.W. Archibold, Department of Crop Science and Plant Ecology, University of Saskatchewan.
Funded by: Agriculture Development Fund, Saskatchewan Agriculture, Food and Rural Revitalization, March 1989.

Introduction

Harvesting is one of the most important activities in the commercial production of lake wild rice. Propeller driven airboat harvesters were introduced in Saskatchewan in the late 1970's. While the operating principles remain the same, significant changes have improved performance and increased harvesting efficiency. Today, the most widely used design consists of a 12 ft long x 5 ft wide flat bottomed, aluminum hull fitted with a 10 ft collecting tray and powered by an air cooled Rotax engine.

The highest recorded production using a mechanical harvester was 214 pounds per acre in 1984. In 1988, an 11 acre stand, harvested 5 times at an interval of 4-7 days, produced a total of 6150 pounds, an average production of over 560 pounds per acre. Although some of this increase can be attributed to ideal growing conditions, correct handling of the lightweight boat ensured high yields.

Characteristics of the wild rice plant that have an impact on the harvesting operation

Seed shattering:

The most common characteristic of lake wild rice varieties is the high shattering nature of the mature grain. This means that when ripe, the kernels drop easily from the panicle, unlike the paddy wild rice varieties which require threshing. Because the kernels shatter readily, timely harvesting of the crop is required to prevent the grain from being lost.

Seeds mature in stages:

Wild rice seed mature gradually, starting from the uppermost part of the panicle. Depending on weather conditions, ripening begins in early August and will continue for a period of 15-30 days. About three to six percent of the potential yield matures each day. Maximum production can therefore be achieved if harvesting is done regularly during the ripening stage.


Tillers:

A wild rice plant can develop many stems, particularly in shallow water sites. These tillers are capable of producing the same quality of grain as the main stem. However, tillers generally come into flower later: this makes the timing of the first harvest critical. If harvesting is done too early, it could damage the tillers that are not fully mature, and a large percentage of the crop may be lost.

When to start harvesting

Harvesting in Saskatchewan starts generally around the fourth week of August. Traditionally, areas in the eastern part of the province begin to harvest about a week earlier than in other districts.

The most common indicators which will help wild rice growers decide when to start harvesting are as follows:

  • Determine the date when at least 75 per cent of the crop has reached the full flowering stage. Full flowering is indicated by the shedding of pollen from the male flowers and will normally occur between the third and fourth week of July, depending on weather conditions.
  • Get ready for harvest and check the stand again 3 weeks after full flowering. This visit will give you a good indication of when to start harvesting. Normally, the seed matures approximately 4 weeks after full flowering.
  • Some seeds will be mature when the male flowers below the seed head have started to wither.
  • The final step that should be done by the grower before attempting to run the harvester over the rice stand, is to paddle a canoe through a representative section of the area and check the kernels at the top of the panicle. If the grain is hard, and if it falls when the stem is gently shaken, it is mature. Harvesting should be started immediately. If the grain is still green and milky, it will require a few more days to ripen.

When to repeat harvesting

Once the first harvest is completed the stand must be repeatedly harvested. Maximum production per acre can only be achieved if the area is harvested at least 4 times. This means that harvesting would normally occur every 4-5 days depending on weather conditions.

  • If the weather has been continuously hot, repeat harvesting no later than 4 days.
  • If the weather has been cloudy and cool, harvesting could be delayed, but should be repeated no later than seven days.
  • It is not advisable to harvest when it is raining as there is a tendency for the plant to lodge easily and therefore get damaged.
  • Windy conditions can be hazardous for air boats.

Operating the harvester

Increased harvesting efficiency can be achieved if the harvester is run at the correct speed by a skilled and experienced operator.

  • Higher harvesting recovery and good crop quality have been found if the harvester maintains a speed of 20 kilometers per hour (kph) or 12-13 miles per hour.
  • If the speed is higher than 20 kph (13 mph), damage to the plant and crop loss have been noted as a result of: immature seeds being knocked off the panicles; plant stems being broken and whole panicles being cut off.
  • If the harvester is running slower than 12 mph, it does not create enough impact to knock the wild rice kernels into the table.
  • It is recommended that harvesters use a Global Positioning System (GPS) unit to measure their harvesting speed. The cost of these units has decreased substantially making them a good investment for harvesters.
  • Beater bars fitted across the table have been found to improve harvester efficiency, but their number, spacing, and angle can affect recovery.
  • Some harvesters use a plastic mesh with openings of 2 x 4 inches set at an angle inside the table. However, caution is advised when using the wire mesh because immature grains can be harvested if the speed is not correct.
  • The height of the table relative to the panicle is also important. A support mechanism which allows the table to be lowered close to the surface of the water is essential in short rice.

Harvesting technique

Wild rice harvesting is made difficult by the absence of a clear line of travel across the stand. If maximum production is to be achieved, it is necessary to harvest the crop efficiently, which means covering the entire wild rice stand during the operation with the least possible overlap. Skilled operators are able to achieve this by:

  • Organizing the harvest operation. The widely used practice is to start at one end of the stand and continue to harvest back and forth until the entire area has been covered. This method allows the operator to establish a reliable line of reference, partly because the plants recently harvested are still bent and wet, and also because he can recollect the last line of travel.
  • Another indicator that will be useful to the harvester operator in determining whether the area has just been harvested is the difference in the colour of the grain: mature grain looks darker, brownish or blackish in colour; immature grain that is still left on the panicle will be paler, often greenish in colour.

Care of freshly harvested wild rice

Cleaning the rice

Before unloading the rice, leaves, broken panicles, stems and other debris should be removed. Only clean rice should be bagged.

Storing the rice

It is important to let the harvesting crew know what the crop is going to be used for and advise them on how it should be handled.

Wild rice intended for seed

Bagged rice intended for seed should be tied tightly and kept moist until it is seeded. If it is not going to be seeded immediately, it should be stored under water in a protected site. The bags should be well secured to prevent them from drifting away.

Wild rice intended for processing

If rice is to be sold for processing, it should be delivered to the buying depot as soon as possible. If delivery is delayed, keep the bags open, standing up and in the shade. Wild rice can spoil rapidly if not handled properly. Spoiled rice should not be sent for processing.

A CALENDAR OF EVENTS FOR THE WILD RICE CROP YEAR IN SASKATCHEWAN

DEVELOPMENT
STAGES

GENERAL DATES

GROWER ACTIVITIES

Date

Day

Germination

May 15

0

Check water depth. Remove debris that obstructs water flow

Floating leaf

June 10

26

Changing water depth can be critical. Strong winds could seriously damage crop.

Aerial leaf

June 20

36

Check uniformity of growth. Watch for wildlife that could damage the crop.

Tillering

July 15

61

Observe tiller development. High water levels may reduce tillering.

Early flowering

July 20

66

Observe flower development. Uniform flowering is essential for a good crop.

Crop Insurance for Wild Rice

The Saskatchewan Crop Insurance Corporation (SCIC) has supported a wild rice crop insurance program since 2006. Coverage is based on the average production for the three wild rice production regions (Eastern, Central, and Western). Claims are triggered when the region reports annual production less than the average historical production, and is due to an insurable cause of loss, i.e. frost, wind, excessive rain, lightning, hurricane, tornado, insects, plant diseases or hail.

For more information on the wild rice insurance program, call the Saskatchewan Crop Insurance Corporation's toll free number 1-888-935-0000 or visit http://www.saskcropinsurance.com


For additional information contact:

  • The Agriculture Knowledge Centre at 1-866-457-2377; or
  • Email aginfo@gov.sk.ca


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