Harvesting seed crops for Certification

Harvest stages of Certified Seed, whole barley seed.

This is our third article on the Certification Seed process. We’ve taken a look at Inspection and Rogueing, which is the removal of unwanted plants by hand from the crop, and Crop Trials to observe the characteristics of crops and varieties and how they react to the Irish environment under Irish growing conditions. This month ISTA Former President Tom Bryan takes us through the process of harvesting outlining the key actions that need to be taken to ensure the seed collected is fit for certification.

After the crop has come to the end of its growing cycle, including thorough audits by Department of Agriculture (DAFM) representatives and the agronomists of the Seed Processors, the harvest period begins.

It is extremely important that every effort is made during the harvesting of the seed crops to retain the following which are the cornerstones of quality Irish certified seed:

  • Varietal Purity.
  • Freedom from invasive species (Wild oats, Brome and Canary Grass etc.)
  • Germination.

When to harvest
Harvest generally occurs from July to October and it is important not to delay harvest once the crop has ripened. When ripe, winter cereals are easy to thresh, and harvest can begin at moisture levels as high as 20%, although generally very little is harvested above 18% moisture.

A germination as low as 85% is acceptable but it is recommended that >98% should be the target at harvest. Harvest and handling is of particular importance for malting barley.

Before harvesting begins
There are a number of key activities that the grower must action. The grower must:

  • Ensure that the seed crops have not been desiccated through the use of any pesticide e.g. Glyphosate containing products.
  • Give adequate notice of intention to harvest (i.e. 24 hours’ notice) to the Seed Processor. The harvesting of Seed crops may be carried out when the required notice is given.
  • Ensure that all harvesting machinery and trailers for transporting the seed have been thoroughly cleaned out.
  • Ensure harvesting of seed crops will be supervised, if possible on a spot-check basis, by Department of Agriculture personnel.
  • Take care to ensure that there will be no contamination from any source of the seed grain if it has to be stored in the farmyard awaiting collection.

Harvesting underway
When operating the combine harvester, the driver has a bird’s eye view of the seed crop and, with due care and attention to detail, the operator aims to prevent any unwanted weed seeds or other contaminants entering into the harvested seed grains. This requires concentration and vigilance, which our expert seed growers, have in abundance.

The first run around the outer headlands of the field should be discarded when harvesting the crop. This is best practice for species purity reasons and will also further aid the cleaning out process of the combine.

Lodging can be a problem and it is recommended that these patches are also excluded when harvesting to prevent the possibility of reduced germination and the subsequent rejection of the sample.

Avoiding damage to the seeds during harvesting
Even minor damage to the seed can affect the ability of the seed to germinate. Cracked grains, skinned or partially-skinned grains, and grains killed through damage to the germ, cannot germinate properly in the subsequent C1 Seed crop.

When examining a barley seed sample for damage, look at individual grains not just a mass of grain. Always examine grain's back first and ignore the crease side. Severe cracking and germ damage are nearly always accompanied by a high degree of skinning (in barley).

  • The most common causes for this are:
  • Drum speed too high - only use the slowest drum speed that will effectively thresh the grain from the head. A higher drum speed is needed when harvesting crops not properly ripe and can cause serious grain damage.
  • An incorrectly-adjusted or warped concave - the initial header settings should have the concave set one notch wider for barley than for wheat. Check the setting frequently during the day. If the thresher drum speed is correct, concave adjustments should cope with the changes in temperature and other harvesting conditions met during the day.
  • The airflow may need to be increased slightly to obtain a clean sample.

It is essential that correct combining of the crop occurs as it is at this point that the potential seed crop can be irreversibly damaged. It is recommended that the grower should bring a sample of the threshed grain into his/her seed house to ascertain if the sample is acceptable and the crop is being threshed to the satisfaction of the purchaser.

Finally, post-harvest seed samples are checked for purity and quality and the seed grain makes its way to the Seed Processors. It’s this intricate process that guarantees the high standards expected of Irish Certified Seed.

For more information on Certified Cereal Seed production, see the Irish Seed Trade Association’s website.