July 31, 2013 – Issue 18

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  • Issues of the week

    Blackleg lesion on stem, found on a canola plant in late July.

    Swathing will likely start within a week or 2 for earliest canola fields. Keep in mind that the ideal time to swath is around 60% seed colour change (SCC). Some fields will have to be cut earlier for growers with a lot of canola to get down, but try to avoid cutting before 30% SCC.

    See this week’s top 10 list for diseases to look for ahead of swathing. The days leading up to swathing are an excellent time to identify diseases present. Once diseases are identified, growers can augment management practices to reduce specific diseases in subsequent years.

    Insect monitoring continues this week, with diamondback moth larvae, bertha armyworms and grasshoppers the most important.

    Tweet of the week:

    Tweet of week July 31

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  • Canola Watch quiz

    July 31 Quiz

    What caused these lesions?

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  • Top 10 diseases to look for in August

    They are:
    10. White rust
    9. Fusarium wilt
    8. Grey stem
    7. Alternaria black spot
    6. Downy mildew
    5. Root rot and foot rot
    4. Aster yellows
    3. Clubroot
    2. Sclerotinia stem rot
    1. Blackleg

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  • Why the missing pods?

    Missing or stunted pods at the top of this plant are likely due to heat stress. The plants look fine otherwise.

    Some canola fields are exhibiting missing or stunted pods at the top or middle of stems. Pods in some fields have been described as green on the ends and translucent in the middle. The most likely cause is environmental. The few days above 30°C in early July would certainly cause flower abortion, and the hormone response to a couple days of heat could stretch the effect on podding to a week or more. However, other factors can be at play…

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  • Diamondback moth larvae scouting and thresholds

    Diamondback moth larvae. Notice the spindle shape — wider in the middle than at the ends. Source: Saskatchewan Ministry of Agriculture.

    Diamondback moth larvae are showing up in canola fields. The most accurate method to estimate diamondback moth population density is to count larvae in several locations throughout the field, and determine the average population per unit area.

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  • Take a look for Swede midge damage

    Swede midge larvae feeding at the bud can stop stem elongation and leave pods in a cluster. Source: Owen Olfert

    Swede midge damage has been confirmed in canola fields in northeast Saskatchewan. The insect is not a major threat to canola in Western Canada, but it often causes extensive damage in Ontario. Entomologists want to keep on top of the insect in Western Canada, and would be interested to hear from you if you spot potential Swede midge damage.

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  • Ideal swath timing is 60% seed colour change

    swathing canola

    Delaying swathing while you wait for more plants to mature is generally positive for yield, especially at this stage of the season.

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