Pests & Crop Diseases

Your Land, Your Investment!

Why You Should be Always Scouting for Pests


Scouting your fields on a regular basis is crucial in comprehensive pest management decision - making. Why treat your field for Grasshoppers when there is no significant damage being done or vice versa when the damage is already done? Either side is most often environmentally and economically irresponsible. This is where solid scouting techniques come into play. During the growing season fields should be scouted on a weekly basis and even a daily basis depending on the economic threshold of the pest. When scouting you should be documenting what you find. If you do find a pest, you want to be able to have a short term and potentially long term plan. A good sweep net is a solid investment in your pest scouting management. 

Click here for an excellent guide for proper field scouting techniques.



Crop Diseases

  • Blackleg (Leptosphaeria maculans) Declared a Pest in Alberta

Blackleg is a fungal disease found in canola across the province and western Canada. In 2017, 25 fields in Saddle Hills County were surveyed and tested for Blackleg – one tested positive. Blackleg is characterized by white round to irregular shaped spots on the leaves; usually dotted with tiny black spots (pycnidia). Lesions on the stem are usually found around the base or at points of leaf attachment. Blackleg infection on leaves prevent proper absorption of sunlight while lesions on the stem prevent water and nutrients from reaching the pods and seeds – leading to reduced yield. Scout for Blackleg around swath timing, clip 10 – 20 stems just above soil level and using the Blackleg Field Rating Scale determine level of infection(Figure below). If blackleg is present (1 - 5), it is encouraged to have longer rotations (3-5 years) and use a blackleg resistant canola varieties when canola is seeded.

Blackleg

Video Blackleg Disease and Resistance Management - Click Here

  • Fusarium Graminearum Declared a Pest in Alberta

In 2017, 25 fields in Saddle Hills County were randomly collected and tested in the county for Fusarium Graminearum; 3 fields tested positive. It is a common fungal disease of cereal crops: wheat, barley and oats. F. Graminearum reduces yield as well as grain quality. Infected kernels may contain mycotoxins such as vomitoxin(Deoxynivalenol) that causes reduced feed intake, fertility and potentially death in livestock. The infection may not always be visible but is distinguished by early maturing reddish colored kernels in the head (Figure below). Managing F. Graminearum begins with clean, healthy seed along with regular seed health testing followed by treatment of seed, longer cereal rotations and growing varieties with higher levels of resistance. 

Fusarium


  • Clubroot (Plasmodiophora brassica) declared a Pest in Alberta

Clubroot was first discovered in Alberta around the Edmonton area in 2003. In 2017, the first confirmed case in the Peace Region was found in Big Lakes County and later that same year in Greenview. It is a soil – borne disease in canola that overwinters. The disease causes galls to form on the root system (Figure below). These galls cut of water and nutrient supply and lead to premature death. Currently there are no solutions for clubroot once the soil is infested. Management practices can be done to mitigate the chance of getting clubroot; not bringing equipment from infected counties (agriculture as well as oil and gas). Once the soil is infected; sanitation of equipment, longer crop rotations and the use of resistant varieties can be used to reduce spore load.  

Clubroot

Source:www.canolacouncil.org/canola-enclopedia/diseases/clubroot/about-clubroot

Clubroot Video Click Here.


  • Sclerotinia

Sclerotinia is one of the most destructive fungal diseases found in canola. It overwinters in the soil and crop stubble. The severity of infection is variable between years as well as regions and fields. Sclerotinia becomes more prevalent with tighter canola rotations (found commonly in the Peace), higher yield targets (increased crop density), rainfall (humidity) and timing of flowering. The infection is often discovered when it is too late. The infected pedals of the canola flower fall down onto the junctions of the canola plant (Figure below). Due to Sclerotinia being highly variable due to environmental conditions it is encouraged to keep track of field history as well as regular foliar fungicide spraying.
Sclerotinia

Source: Justine Cornelsen

Sclerotinia ChecklistClick Here.


Insects

  • Grasshoppers

There are 80 different species of grasshoppers in the Canadian Prairies alone; the most common pest grasshopper in recent years have been the two-striped grasshopper (Figure below) and the clear-winger grasshopper (cereal and grass). Crop pest grasshoppers hatch in late May and early June, are brownish black in color and have tiny triangular wing buds. Pest species of grasshoppers are also silent. Grasshopper pressure has an increased occurrence in drier climates. They are able to have multiple generations per year.

 

Economic Threshold: 10 grasshoppers/m2 and above if feeding is evident.

Grasshoppers

Source: insectsofalberta.com

Link to an excellent source of material on Grasshopper pressure - Click Here.

  • Diamondback Moth

In 2017, there was an increase infestation of Diamondback Moths in the Peace Region. Diamondbacks occur throughout North America in canola and mustard crops. They migrate northward from infested areas on wind currents and are able to produce as many as 4 generations/year. Crop damage occurs at the larvae stage (Figure 1) when they feed on the leaves as well as other green tissue. Scout for Diamondbacks in late July – August at least twice a week. To check insect pressure; remove plants in 12” square (0.1m) and beat the plants out onto a clean surface and count the larvae.

Economic threshold:  20 to 30 larvae/0.1 m2 (about 12” square) at the advanced pod stage. This works out to approximately two to three larvae/plant if plant population is close to 100 plants/m2).

Diamondback

Photos: Roy Ellis

For more on the Diamondback Moth – Click Here.

 


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