Sclerotinia stem rot

  • Canola Watch quiz (survey actually) – Sclerotinia assessment

    Sclerotinia stem rot

    Predicting sclerotinia stem rot severity is difficult. This quiz is a review of management decisions for 2018, including a specific look at DNA petal tests. Please take a minute to do this quick survey.

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  • The disease triangle: Moisture means sclerotinia

    Sclerotinia stem rot

    The three points of the disease triangle are host, pathogen and environment. When it comes to sclerotinia stem rot in canola in Western Canada, the disease triangle hinges on one component: Environment.

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  • Sclerotinia stem rot timeline for infection

    Sclerotinia stem rot

    The sclerotinia stem rot infection cycle begins when sclerotia in the soil (left from the last time an infected crop was produced on that field) take up enough moisture to germinate and form little mushrooms known as apothecia. Spores are then released into the air from the mushrooms. Under ideal warm and moist conditions, it takes about two to three weeks for sclerotia to germinate and release spores.

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  • Sclerotinia stem rot: Late and second sprays

    Sclerotinia stem rot

    If conditions are dry at early flower and then it rains at 40% to 50% flower, spraying at the end of the window may be effective – as long as there was enough moisture before flowering to get apothecia germinating. In this situation, later sprays could be especially effective if moisture also promoted a longer flowering window due to later compensatory growth. With lower seeding rates resulting in more branching, canola fields can be at 50% flower for a week or more.

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  • Sclerotinia: Positive petal test may not mean “spray”

    Sclerotinia stem rot

    Small amounts of spores can lead to yield-robbing levels of sclerotinia in continued moist conditions. A petal test to confirm the presence of sclerotinia DNA on petals could be used to provide an indication of pathogen pressure at the time of petal collection.

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  • The sclerotinia spray decision: Moisture scenarios

    Sclerotinia stem rot

    The decision to spray or not spray fungicide to limit sclerotinia stem rot is rarely easy. Consider the following three scenarios as you assess the risk situation this year.

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  • Sclerotinia stem rot timeline for infection

    Sclerotinia stem rot

    The timeline from when sclerotia in the soil first take on moisture, to apothecia germination, spore release, petal infestation, petal drop and finally canola plant infection takes up to three weeks. This graphic shows the final 24 hours as the fungus on decaying petals enters the plant and creates a lesion.

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  • Sclerotinia risk assessment: Fungicide planning

    Sclerotinia stem rot

    As earliest canola crops start to flower, the annual sclerotinia stem rot management conversations begin. This article describes factors that increase risk and reduce risk.

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  • Quick comparison: Blackleg, clubroot, sclerotinia stem rot

    Sclerotinia stem rot

    Use this quick-reference table to compare key distinguishing features, mechanisms for spread, and management options for blackleg, clubroot and sclerotinia stem rot.

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  • Sclerotinia: Late-window sprays

    Sclerotinia stem rot

    If conditions are dry at early flower and then it rains at 40% to 50% flower, spraying at the end of the window may be effective. This would be especially true if moisture also promoted a longer flowering window due to later compensatory growth.

    READ MORE

  • Sclerotinia petal test

    Sclerotinia stem rot

    Small amounts of spores can lead to yield-robbing levels of sclerotinia in continued moist conditions. A petal test to confirm the presence of sclerotinia DNA on petals could be used to provide an indication of pathogen pressure at the time of petal collection.

    READ MORE

  • Sclerotinia stem rot … hot weather, variable crops, late sprays

    Sclerotinia stem rot

    Hot and dry or hot and humid? Hot, dry weather should reduce the risk of heavy sclerotinia infection, even if moist weather earlier promoted a lot of apothecia emergence and spore release. Hot, humid weather that leads to morning dew and a humid canopy can promote the disease. Keep in mind that even thought the sclerotinia fungus does not like to grow over temperatures of 30°C, night temperatures are often lower and will allow for fungal growth. But also keep in mind that hot weather during flowering can increase flower and pod abortion and reduce overall yield potential. Hot, dry weather during pod fill and ripening also reduces the progression of sclerotinia within the plant.

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  • Sclerotinia stem rot: Dry early, now moist. What’s the risk?

    Sclerotinia stem rot

    If conditions were dry, then turned wet, the sclerotinia risk depends on when this transition occurred.
    Early dry weather doesn’t matter as much as long as you have moisture within the canopy leading up to and during the flowering period.

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  • How to count 10-50% flower

    Sclerotinia stem rot

    Canola at 20% flower. Source: NDSU

    As a rough estimate, the 20% flower or “bloom” stage is when the main stem has around 15 “flowers”. Canola can reach 20% bloom in 4-5 days after first flower.

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  • Sclerotinia stem rot: Risk factors and spray timing

    Sclerotinia stem rot

    At risk: A moist canopy and good yield potential.

    Prevalence of sclerotinia stem rot has a direct correlation to above-average moisture. If a field has regular rains or high humidity or both from two weeks before flowering and through flowering, then infection will likely occur. If growers decide to spray, the window for most products is 20-50% flower. Earlier is usually better as early infection on the main stem tends to cause the most yield loss.

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