Seed quality is an issue for cereal producers in 2013. Results show that there are higher than normal levels of seed borne Fusarium. For producers and agronomists in Northwest Saskatchewan, this is a new issue to be faced with. In order to make informed decisions regarding this issue, one needs to understand a bit more about Fusarium and how seed treatments can help.
There are many different Fusarium species that can be found on seed, but the one that producers should be most concerned with is Fusarium graminearum. This species is very aggressive and causes a high degree of damage. Fusarium graminearum can affect cereals in two ways: the first by causing seedling blight or root rot during seedling and vegetative stages, or secondly by infecting the head at later stages causing Fusarium head blight. It is the later infection which leads to tombstone or fusarium damaged kernels. F. graminearum is also one of the strains that can produce a toxin known as deoxynivalenol (DON) or vomitoxin. This vomitoxin can cause significant issues when the infected grain is fed to livestock, especially swine.
Luckily, the presence of the organism on the seed does not lead to infection on the head in the same year that it is planted. Dr. Kelly Turkington, pathologist with Agriculture and Agri-Food Canada at Lacombe, explains that the fungus can infect the crown of the developing plant, it then can grow up the stem. Turkington commented that greenhouse research conducted by his colleague Dr. Kequan Xi has shown that F. graminearum can be found in the stem up to the third node, but none has been found to grow up to the head and infect the head directly. The infected stems or residue will then be a source of inoculum for future years. The Fusarium fungus present in the residue produces spores the next year, which increases the risk for development of Fusarium Head Blight. Turkington comments that the level of transmission from seed to the stem has been found to be 55 to 94 per cent based on studies in winter wheat at the University of Guelph in the 1980's. He calculated that at a seedling rate of 90 pounds per acre and a one percent level of infection, approximately 10,250 infected seeds per acre would be planted; and half to almost all of them could have some level of crown or stem infection during crop growth.
Germinating seeds and developing seedlings can become infected from seed borne Fusarium, but also from soil borne or infected residue on the soil surface. Early infections can cause the seedlings to turn brown and die which is termed seedling blight. Seed treatments can provide protection from both seed and soil borne inoculum during the germination and seedling stages, or up to 21 to 28 days after seeding. Fungicides can provide contact or systemic activity depending on the product. Contact type products do not move within the plant. They control disease where they come in contact with the organism such as on the surface of the seed and are used for protection and as a preventative before infection occurs. Systemic fungicides penetrate the plant tissues and have limited movement within the plant. They can control an organism after infection occurs, but have better effect on newer infections than older infections. With both contact and systemic fungicides, good seed coverage is important. Ensuring fungicide is on every seed and that each seed is completely covered at the right rate of chemical is important to maximize effectiveness.
Seed test labs are reporting high levels of F. graminearum across the province which means most of the province is dealing with higher than average levels on seed. Knowing what the levels are on your seed is important for making decisions pertaining to your farm. Saskatchewan Ministry of Agriculture recommends treating seed when levels of F. graminearum are two to five per cent and the seed is being seeded in an area where F. graminearum is already established. Levels above five per cent are at risk to have other quality problems. However, Dr. Turkington advises that if the germination is good (above 85 per cent) and vigor is good, research from western Canada and seed infection guidelines from the UK have shown that levels of ten per cent or more of F. graminearum can be planted successfully as long as a seed treatment is used. Turkington emphasizes that good germination and vigor are important no matter what the disease levels are. If germination or vigor is in question, then it is advisable to source new seed.
Remember, seed quality is the first step to a successful crop. The seed you put in the ground sets your yield potential, while inputs and environment dictate whether that yield potential is reached. Take extra time to make those informed decisions when it comes to seed quality.
For more information on seed quality or other crop related issues, I invite you to attend the Annual WARC Crop Opportunity and Scott Research Update on March 7 at the new Dekker Centre in North Battleford. Doors open at 8:15 a.m. and event occurs from 9 a.m. to 4:30 p.m. Cost is $30 per person and includes lunch. For more information or to register call 446-7964 or visit www.warc.ca.
