Straw residue must be spread evenly to minimize potential frost injury.
Seed quality is critical for stand establishment, health and vigor. Seed quality includes genetic and mechanical purity, germination and vigour, and levels of seed-borne disease.
Seed purity is determined by the nature and amount of unwanted contaminants in the pure seed. Impurities include unwanted crop seed, weed seeds, and inert material. They can adversely impact crop yield and quality, as well as increase production costs.
Seed germination tests assess the ability of the seed to produce a healthy plant under favourable growing conditions. These tests are generally conducted under controlled conditions that provide ideal moisture, temperature, and light for a prescribed period of time. Seed lots with low germination often lack the ability to produce strong, healthy seedlings.
Seed vigour tests, conducted by some seed testing labs, are conducted under more adverse conditions than a germination test. Vigour tests are not standardized and conditions imposed upon the seed may vary from lab to lab. Vigour tests are an attempt to see how the seed germinates under less than ideal conditions and gives an indication of the vigour of the seedling.
Pea seeds are susceptible to mechanical damage during harvest, handling, storage, and seeding. Dry pea seed (14 per cent or less seed moisture) is brittle and difficult to handle without chipping and splitting the seed. All handling should be done as gently as possible. Even nearly invisible seed cracks can result in a reduction in germination. Seed damaged after a sample is submitted for germination and/or vigour testing will not perform as expected based on the results of the test(s). The final cleaned seed lot should be re-tested if handling damage is suspected.
Application of certain herbicides prior to harvest can also effect seed germination and/or vigour. Seed from fields treated with pre-harvest glyphosate should be avoided.
Contamination from seed-borne diseases should be as low as possible. Table 1 summarizes guidelines for seed disease levels when considering a lot for seed.
Table 1. Guidelines for Tolerances of Seed-borne Diseases in Pea Seed Intended for Planting
(These are guidelines only and should be considered along with farming practices and level of disease risk for the situation)
|Disease (Pathogen)||Tolerance and Factors Affecting the Level|
|Ascochyta (Mycosphaerella pinodes, Ascochyta pinodella, Ascochyta pisi)||
Up to 10 per cent ascochyta infection should not significantly affect plant establishment and yield, as long as the seed has good germination, and spring conditions promote quick germination and good seedling vigour.
Seed-to-seedling transmission of ascochyta in pea under field conditions is considered low.
In areas where pea production is common, the primary means of infection is air-borne spores from the overwintering stage of Mycosphaerella pinodes on pea residues.
|Seed Rots and Damping-off Pythium sp. & Phytophthora sp.||
These are soil-borne diseases and are not tested for at seed testing labs. Seed treatment in field peas may be beneficial when planting under cool, moist soil conditions or if using damaged or cracked seed.
Seed Rots and Seedling Blights
Rhizoctonia, and Fusarium species)
Sclerotinia, Rhizoctonia and Fusarium are primarily soil-borne. Botrytis and Fusarium are also often seed-borne and can be tested for at seed testing labs.
Up to 10 per cent infection (Sclerotinia + Botrytis) may be tolerable, but will result in significant seedling blight if a seed treatment is not used.
The importance of seed-borne Fusarium in seed rot and seeding blight in pulses is not known. Some labs will notify growers if greater than five per cent Fusarium infection occurs. If present, add the Fusarium value to the Sclerotinia + Botrytis value above (not to exceed 10 per cent).
The use of certified seed assures high quality seed with respect to purity, germination and disease level. A listing of Saskatchewan Pedigreed seed growers by variety is available in the Saskatchewan Seed Guide.