Seed Treatments

Table of contents

    Important tips for best management

    • Flea beetles and seedling diseases are major threats to canola crop establishment. Seed treatment is a targeted way to protect canola seed and seedlings, providing a significant increase in yield potential.
    • Use a seed treatment that combines protection from flea beetles and from all major seedling diseases. Certified canola seed typically comes pretreated with a combination of active ingredients that can provide this protection.
    • Protection from seed treatments will decline over time as active ingredients break down. In some cases this may happen before the crop has outgrown its most susceptible phase. Manage seeding to allow rapid germination and emergence, and keep seeding depth as shallow as possible to limit hypocotyl exposure to seedling disease fungi. Scouting is still required for treated crops and an insecticide spray may be necessary to control flea beetles.


    Fungicides

    Canola seed and seedlings are vulnerable to a broad range of pathogens. Fungicide seed treatments protect canola from the most common seedling disease-causing fungi, including Rhizoctonia solani and various species from the fusarium and pythium families. Without treatment, canola seedlings are at much higher risk of seed rots, seedling blight and damping off.

    Fungicide seed treatments also protect canola from seed-borne forms of blackleg and alternaria. Not only does this protect seed and seedlings from early infection, but this prevents the seed from introducing the pathogens to a field — or at a minimum, from increasing the inoculum levels for these diseases.

    Insecticide

    The seed treatments in widespread use for canola in Canada include an insecticide component to protect canola from flea beetles in the first 14 to 35 days — depending on the insecticide rate. Seed treatment is an effective way to provide this protection because flea beetles are widespread across the Prairies and young canola seedlings are so vulnerable to feeding damage. Flea beetles at high numbers can wipe out a crop quickly, and the damage can be done before a grower can respond with a foliar treatment. Seed treatments mitigate the risks associated with relying solely on foliar control — timing, coverage, and weather conditions such as rain or wind.

    Agriculture and Agri-Food Canada research found that seed treatments in general reduced flea beetle damage by 9-64%, depending on the product and the rate, when compared to untreated checks. By reducing damage, seed treatments improved seedling establishment by 2-75%, plant weight by 100-900% and yield by 3-100%. (See Table 1.) [1]

    On a per field basis, seed treatments use less insecticide than a foliar spray because only the seed is coated, not a lot of other surrounding area.  And seed treatments will limit damage to non-target and pollinator species. 

    The major disadvantage of seed treatments is that they are used prophylactically in anticipation of a pest problem. If the pest does not materialize, then use of the seed treatment was not warranted. Seed treatments can also be ineffective if they degrade before pest insects arrive and start feeding.

    Because canola stand establishment is so important and because canola seed is so valuable, fungicide and insecticide seed treatments are an economical way to provide the protection young canola seedlings need to survive. [1]

    Seed treatments with fungicide and the registered low rate of insecticide show a consistent benefit for canola stand establishment and yield when compared to fungicide only seed treatments and to bare seed. [2]

    Seed treatments that provide the longest flea beetle protection usually provide the best seedling establishment, highest plant weight and highest seed yield. Differences among seed treatments were greater when flea beetle infestations were high than when infestations were low. [1]

    In order to maximize seed treatment effectiveness, seed canola into warm soils (5 °C or higher) and to proper depth (1 to 2 cm) to ensure rapid emergence. Delayed emergence due to deep seeding or cool soil temperature prolongs the time required for the crop to grow beyond the vulnerable early seedling stage. If a crop germinates but stays below ground for 14 days or more before emerging, the likelihood that seed treatment protection will run out before the crop advances beyond the 4-leaf stage is greatly increased. Deep seeding also exposes the hypocotyls to more soil, increasing potential exposure to seedling disease fungi.  

    Bare seed is rarely a choice.Most new varieties, especially hybrids with herbicide tolerance systems, are only available as pre-treated certified seed. In fact, the most common treatments — Helix, Prosper and Acceleron — are for commercial treaters only. Gaucho CS is registered for canola and is available for on-farm application, provided the grower has approved set up for treating and that the seed is legal for farm re-use. A few varieties can be legally saved for a grower’s own use, but check first to make sure you don’t violate any legal obligations. Also, in addition to the insect and disease risks from planting bare seed, research has demonstrated the yield and economic advantages of hybrids and the agronomic disadvantages of growing F2 (farm saved) seed from hybrids. Therefore, planting certified treated seed is highly recommended.

    Other treatments

    Jumpstart

    JumpStart is a seed treatment of Penicillium bilaji, a bacteria that can make phosphorus from soil and fertilizer sources more available to the plant. JumpStart is active in soil temperatures as low as 4 °C, and can provide a benefit to early-seeded canola.

    Phosphorus is necessary for early plant growth. If growers have been applying moderate to high rates of phosphorus in recent years, growers may be able to utilize JumpStart to improve the availability of some of this residual phosphate to the plants.

    Jumpstart may benefit stand establishment in cases when phosphate availability to the crop is limited because the fertilizer is not placed directly in the seed row, seed is broadcast, or phosphate application rates are low and prills or droplets are not in immediate vicinity of each seed.

    Starter fertilizer treatments

    Some seed treatments provide a mix of starter liquid fertilizer, often including phosphorus and micronutrients such as zinc or boron. Before making a significant investment in these products, test them on limited acres on your own farm over a couple of years.

    Many fertilizer products are registered (http://active.inspection.gc.ca/eng/plaveg/fereng/fereng_dbe.asp), but the Canadian Food Inspection Agency (CFIA) rules for fertilizer products, including inoculants and enhancers, are not as strict as they are for pesticides. Controlled release coatings, urease inhibitors and inoculant extenders, for example, do not fall under the regulatory authority of the Fertilizers Act. But when mixed with a fertilizer, the end productis regulated. The CFIA’s Crop Inputs Division “encourages” manufacturers of these products to seek a “Letter of No Objection” (LONO) from the CFIA to ensure that their use in fertilizers and supplements results in final products that meet safety, efficacy and labelling standards. However, growers should note that any enhancers, extenders or seed-applied fertilizer products put into a custom fertilizer blend do not need to be registered, so they may have come into the marketplace without going through CFIA regulatory channels.

    Bulking agents

    Most drill tanks sold in western Canada are made to handle small seeds such as canola and deliver relatively uniform seed counts to each row. For a drill that cannot accurately meter small seeds and low flow rates, bulking agents such as elemental sulphur, seed-sized starter fertilizer prills, or cracked oat groats, may help.

    However, the Canola Council of Canada ran trials in 2001 and 2002 to evaluate pelletized elemental sulphur at 22.5 kg/ha (20 lb./ac.) as a seed-bulking agent. Research found no consistent stand establishment or yield benefit when using the bulking agent.

    The elemental sulphur will improve sulphur availability in following years. Bulking agents can also help when checking seed placement and drill performance. If you find the yellow sulphur prill, for example, you should be able to find canola seed on that same plane.


    References

    [1] “Effect of seed treatments on flea beetle damage and the performance of open-pollinated and hybrid Argentine canola,” R.H. Elliott, Agriculture and Agri-Food Canada, CARP Project # 2003-02-01-19.

    [2] “Impact of Decreasing Ratios of Insecticide-Treated Seed on Flea Beetle (Coleoptera: Chrysomelidae, Phyllotretaspp.) Feeding Levels and Canola Seed Yields,” Juliana J. Soroka, Larry F. Grenkow, and R. Byron Irvine, Agriculture and Agri-Food Canada, J. Econ. Entomol., 2008 .This 2002-04 Saskatoon study showed a consistent benefit for canola stand establishment and yield when using a seed treatment with fungicide and the registered low rate of insecticide compared to fungicide only seed treatments and to bare seed. Trends were similar when the study was replicated at Brandon, Man. However, flea beetle pressure was so high at both locations in 2002 and 2003 that the low rates of seed treatments used, with no subsequent foliar insecticide application after economic thresholds were reached, resulted in very low yields of all treatments.

    Table 1. Results from an AAFC study comparing performance of treated Argentine canola relative to untreated seed.a
    Year Conditions
    at seeding
    Damage
    (% reduction)
    Establishment
    (% increase)
    Plant weight
    (% increase)
    Seed yield
    (% increase)
    2001 moist 9-28% 2-26% 100-240% 4-35%
    2002 very dry 31-64% 45-59% 140-900% >100%
    2003 dry 10-64% 15-75% 180-900% 3-69%

    a Damage, establishment and plant weight assessed 21-28 days after seeding