June 19, 2013 – Issue 12

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  • Issues of the week

    Flea beetles are worse that usual in some areas, with growers spraying more than once and with heavy feeding carrying on past the 4-leaf stage. Cutworm losses are low in general but flaring up in some areas. Aster leafhoppers are at much lower numbers than last year and the aster yellows threat is minimal based on what we know at this stage. Cabbage seedpod weevil numbers are picking up and some southern Alberta and southwestern Saskatchewan fields are close to flowering. Early flowering is the control stage for cabbage seedpod weevil adults — as long as they’re at economic thresholds.

    Growers who used elemental sulphur for their sulphur source this spring may need to top dress. Elemental sulphur will not address sulphur needs in the year of application. Keep an eye out for signs of sulphur deficiency in the bolt to bud stage.

    A possible answer for fields too wet for the sprayer: Aerial. Given the negative economics of late herbicide spraying on canola (see last week’s article), growers do have aerial options if weeds are getting away on them and the window is closing.

    Sclerotinia stem rot risk increases with rain. Moist soils during the two weeks before canola flowering begins will increase sclerotia germination in the soil, and increase the number of apothecia shooting spores into the canopy. Any rain at flowering will put canola growers at the same risk as last year, and last year was a heavy year for sclerotinia stem rot. Don’t bother spending the money on a petal test. With moisture, spores will be everywhere.

    Twitter is a valuable source of agronomy information from @CanolaWatch, the CCC’s Crop Production team and many others. Here’s a Tweet on cabbage seedpod weevil management from this week’s #ABbugchat:

    Tweet of the week June 19


  • Canola Watch quiz

    June 19 quiz

    What is this insect?


  • Top 10 things to look out for now

    You have to scout to know what’s going on in the fields. Here are 10 things to look for this week.

    10 – Gopher damage (Richardson ground squirrels or pocket gophers) Read more.
    9 – Environmental damage – frost or wind
    8 – Wild buckwheat. Read more.
    7 – Herbicide efficacy. Is weed control what you expected? If not, why not? Read more.
    6 – Flea beetle. Not all canola is safe at the 4-leaf stage. Read more.
    5 — Cutworms. Missing plants? Start digging. Read more.
    4 – Herbicide carryover issues. Read more.
    3 – Seedling diseases. Read more.
    2 – Cleavers. Read more.
    1 – Plant stand. What is the plant survival rate? Deep seeding is one issue causing establishment problems this year. Can definitely see areas in fields were drill settings were a problem. This leads to increased disease, delayed establishment, higher flea beetle risk as the treatment wears off, and generally low vigor. Read more.

    Listen to a podcast with CCC agronomy specialist Keith Gabert on what to scout for this week.


  • Insect update: Cutworms, flea beetles, CSPW, grasshoppers

    Cutworms are spotty but keep scouting. Flea beetles may need to be controlled past the 4-leaf stage in some extreme cases this year. Cabbage seedpod weevil numbers are building but only spray after first flower and only if sweep net results show them at thresholds. Hold off on early grasshopper control.


  • Bees and canola are good for each other

    Bees are good for canola. Canola is good for bees. Canola flowers provide an important source of nectar for honey producers in Western Canada: 80% of the honey produced in Canada comes from canola flowers. Honey bees and other pollinators can also increase canola yields. Although napus canola is self-pollinating, studies show that the extra level of pollination that bees and other pollinators provide can increase yields. This benefit should be considered when making management decisions in canola that could harm bees.


  • Aster yellows: No evidence of a problem in 2013

    Aster leafhopper numbers are quite low so far this year, down considerably from 2012. Aster leafhoppers carry aster yellows phytoplasma, so without leafhoppers to transfer the disease, there is no infection. Based on what we know at this stage, there is no evidence of a significant aster yellows risk for 2013.


  • Top dress: Identify N and S deficiency

    Sulphur deficiency symptoms include cupping and purpling of leaves, but soil tests and a knowledge of cropping history will help to confirm.

    Growers who used elemental sulphur as their only sulphur source may see deficiencies in this year’s crop. Elemental sulphur will not be available when the crop needs it. In following the 4-Rs of fertilizer, elemental sulphur applied at seeding is not the “right source” or the “right time.” Sulphur deficiency symptoms (see the photos) that appear at the bud to bolt stages can be fixed with a top-dress of ammonium sulphate, a highly available source of sulphur.


  • Aerial options for weed control

    Aerial spraying

    If weeds and crop are advancing toward the end of the application window and the ground is too soft and wet to support a sprayer, then aerial spraying may be the best economic response. Here are the options for aerial herbicide application in canola:


  • Rescue treatments for hailed crop

    Nutrient and fungicide top dress treatments have been promoted to help heal and restart canola after hail. We don’t have published studies on using these or any treatments for this purpose in Western Canada, so it’s buyer beware. Leave a check strip to see if they improved yield. For products that require foliar uptake to work properly, severe hail damage may have striped the leaves, reducing the surface area available for absorption by the plant.


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