By Harry Brook
Whether to seed treat or not often comes up in the spring. It should be looked at as an insurance policy to protect against less-than-ideal growing conditions in the spring. If you have high germinating, vigorous seed planted into warm, moist soil, the crop is guaranteed to germinate quickly and be off to the races.
However, rarely does the weather cooperate where all the factors align for that kind of a perfect spring. Often spring comes in spurts between winter and summer. Soils warm up only to cool off. Long periods of cool, damp conditions hovering around 5 – 6⁰ C gives plenty of chances for root rots to take hold and kill off the plant. Early plant and root development is a crucial contributor to the overall yield that plant will deliver in the fall.
Other than weather conditions, what else can increase your risk of seedling losses? Smuts, bunts and fusarium are seed-borne diseases. Low levels on untreated seed can, under the right conditions, take over and cause significant yield loss in the crop. Treating your seed with fungicide kills off those potential damaging organisms and can protect the seed for up to 2 weeks in the soil. This protection also will extend to some of the common root diseases that attack the crop at the germination stage such as common root rot and seedling blights. Some seed treatments also have insecticides incorporated to prevent early feeding by insects on the seedlings. Seed treatment for flea beetle in canola has been common for many years and recently, treatment for wireworm in cereals is becoming more common.
Other farming practices that increase the risk to the crop includes slow soil warming, poor crop rotation and seed quality. A lot of the seeding done now is zero till. This is good in so many ways but it also slows soil warming in the spring. Plentiful crop residues insulate the soil surface and keep soils cooler and moister, ideal for slowing down germination and emergence and giving fungi a chance to affect the seedling.
Crop rotations with little variety. A lot of Central and Northern Alberta producers have moved to a canola-wheat crop rotation. Many diseases will overwinter on crop residues left on the soil surface and provide a source of infection for surrounding, susceptible crops for the next year. Reducing the spore source requires burial, which is not done with zero tillage. Blackleg on canola is a good example. Infectious spores are produced on the stubble for 2 -3 years after the crop. Highest spore production occurs 2 years after the crop which is a problem with a wheat-canola rotation.
Another factor to consider when applying seed treatment is the application method. Ideally, you want every seed to be adequately covered by the seed treatment. Some methods are better than others at getting it on each seed. Drip and gravity feed applicators are not good methods for application as they don’t allow for accurate volume control or seed coverage. To improve coverage you need an even volume of fungicide being applied over the whole stream of seed as it travels up the auger. Use an applicator tip with a known volume output and pressure.
Modern seed treatments have lower application rates with less physical product being used. Even if the seed doesn’t have as much colouring, the fungicides are still effective if applied properly. This makes seed treater calibration even more important, as a visual inspection of the seed is no guarantee of good coverage.
Seed treatment should never be used to replace good seed. Poor, diseased, low germinating seed will still be poor, diseased, low germinating seed with or without treatment. It is insurance and protection for, not replacement , of good seed quality
As with any insurance, seed treatment is a way of reducing the risk to the crop at the important, early stages of growth. With the uncertain nature of weather in the spring and tight crop rotations, seed treatment can be way of ensuring a healthy, vigorous crop stand. Or you can seed into warm, moist, soil. It’s all a matter of timing.
Created April 3, 2013 | Category: Industry