Weekly Update – Weather Synopsis

Ross Weiss, Owen Olfert, David Giffen and Erl Svendsen
Week 8

Across the prairies, weather conditions were warmer and wetter than long term average values for the period of June 6-13, 2016The average temperature was 15°C and was approximately 2°C warmer than the previous week. 

Across the prairies, weather conditions were very similar to long term average (LTN) values for the period of June 13-19, 2016. The average temperature was 14 °C and was approximately 1 °C warmer than the previous week. Temperatures in southern MB were 5-6 °C warmer than many locations in AB. 

The Peace River region was wetter than normal while most of southern AB and MB were dryer than normal. 

Soil moisture conditions are wettest in the Peace River region and across southern SK and MB. Southern AB and central SK have the driest soil moisture conditions.

The map below reflects the Accumulated Precipitation for the Growing Season so far for the prairie provinces (i.e., April 1-June 20, 2016):

Compared to last week, overnight temperatures were warmer during the past 7 days.  The map below shows the Lowest Temperatures the Past 7 Days (June 14-20, 2016) across the prairies:

The map below shows the Highest Temperatures the Past 7 Days (June 14-20, 2016):

The updated growing degree day map (GDD) (Base 5ºC, March 1 – June 19, 2016) is below:

While the growing degree day map (GDD) (Base 10ºC, March 1 – June 19, 2015) is below:

The maps above are all produced by Agriculture and Agri-Food Canada.  Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.


Weekly Update – Cutworms

John Gavloski, Scott Meers, Scott Hartley and prairiepest_admin
Week 8

Cutworms (Noctuidae) – Please refer to earlier cutworm posts describing scouting tips, monitoring protocols and fact sheets (including cutworm images plus action and economic thresholds).

For Manitobans….The  earlier Insect Update included great photos of dingy and redbacked cutworms plus monitoring tips including how to discern these two species from one another.  Reports of cutworm continued in the current Insect Update.

For Saskatchewanians…. Cutworms were reported in the recent Saskatchewan Insect Report (Issue 3).

For Albertans….. Additional reports of cutworms have occurred throughout the province the past week!  If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2016 Cutworm Reporting Tool”.  Once data entry occurs, your growers can view the live 2016 cutworm map.

A screen shot of the live map has been retrieved (22Jun2016) below for your reference.


Bertha Armyworm

Jennifer Otani
Week 8

Bertha armyworm (Lepidoptera: Mamestra configurata– Moths should have appeared in pheromone traps by now since all areas of arable prairie farmland are highlighted either yellow or orange in the map below.

Those monitoring BAW pheromone traps may want to compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture below:

Provincial staff coordinate BAW pheromone trapping across the prairies and summarize cumulative counts in report or map formats:
● Saskatchewanians.… Watch for future Insect Reports.  
● Manitobans.…. Exceedingly low numbers of male moths were intercepted during the first week of monitoring (Insect and Disease Report posted June 15, 2016, prepared by J. Gavloski).  

● Albertans.…..  Refer to the live 2016 map reporting Bertha armyworm pheromone trap interceptions.  A copy of the map (retrieved June 22, 2016) is below for reference.


Weekly Update – Grasshoppers

Owen Olfert, Ross Weiss, David Giffen and Erl Svendsen
Week 8

Grasshoppers (Acrididae) – Previous model predictions related to hatch and nymphal instar development can be reviewed here.  

For the week of June 19, 2016, warm conditions in southeastern Saskatchewan and southern Manitoba were predicted to result in enhanced grasshopper development. Across the prairies, grasshoppers should be between the first and fifth instars. The model predicted that approximately 15% of the population was predicted to be in the first instar, 35% second, 28% third, 13% fourth instar and just under one percent fifth instar.  Development is well ahead of average rates (22% first instar, 14% second instar and 10% third instar). 

In central Saskatchewan, grasshopper development is currently more than two weeks ahead of average development. The following graph shows grasshopper development at Saskatoon based on 2016 data. The model indicates that fifth instar grasshoppers should be present.

Now compare the above with the following graph which illustrates grasshopper development (for Saskatoon) based on long term normal (LTN) data.  The model indicates that  primarily first instars are predicted to be present with only the initial appearance of third instar nymphs. 

The following image showing various stages of the clearwinged grasshopper is provided below – note that adults have wings extending the length of the abdomen whereas nymphs lack wings but develop wing buds that will eventually mature to wings.  

Figure 1. Life stages of Camnulla pellucida  which including eggs, first-fifth instar nymphs and adult (L-R).

Biological and monitoring information related to grasshoppers in field crops is posted by the provinces of ManitobaSaskatchewanAlbertaBritish Columbia and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Weekly Update – Swede midge

Jennifer Otani
Week 8

Swede midge (Contarinia nasturtii)  – Reminder – Pheromone traps captured the first swede midge of 2016 between May 25 and 31 in northeastern Saskatchewan.  This is substantially earlier (6-7 weeks) compared to 2014 and 2015. 

The earlier emergence pattern is likely due to the mild winter and warm spring weather combined with adequate moisture levels. Emergence traps indicate a moderate number of swede midge have emerged near Carrot River, Saskatchewan, and producers should monitor their canola fields for damage symptoms

Figure 1. Swede midge infested canola buds which are enlarged with sepals fused together. 

Figure 2.  Swede midge large (~1mm long; yellowish-white) feeding within canola flower.

Swede midge scouting tips for in-field monitoring:
• Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae.
• The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
• Flowers may fail to open.
• Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
• Larvae can be seen with a hand lens.
• Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016.

Note the distribution map of confirmed symptoms and populations of swede midge (red dots) on the Canadian prairies  (Soroka and Andreassen 2015).


Weekly Update – Cabbage seedpod weevil

Jennifer Otani
Week 8

Cabbage seedpod weevil (Ceutorhynchus obstrictus–  There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo).  Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.

CSPW emerge from overwintering in the spring as soil temperatures warm to ~15°C.  CSPW utilize several flowering hosts including wild mustard, flixweed, hoary cress, stinkweed and volunteer canola.  CSPW move to canola during the bud to early flower stages and will feed on pollen and buds, causing flowers to die.

The map below reflects CSPW densities observed in 2015.  Growers situated within or adjacent to areas of the map highlighted yellow, orange and red will need to be scouting with a sweep-net as their canola fields initiate flowering.

 ● Begin sampling when the crop first enters the bud stage and continue through the flowering. 
 ● Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
 ● Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
 ● Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
 ● An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
 ● Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
 ● High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season these new adults migrate to overwintering sites beyond the field.

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and ForestrySaskatchewan Agriculture, or the Prairie Pest Monitoring Network.


Weekly Update – Cereal leaf beetle

Jennifer Otani
Week 8

Cereal leaf beetle (Oulema melanopus) – Back in May, the cereal leaf beetle (CLB) bioclimatic model was utilized to help predict when eggs and larvae might appear in fields along with its parasitoid, Tetrastichus julis

Recall the following (posted May 25, 2016) – Predicted dates of peak emergence of CLB eggs and larvae:

Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 1). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.  

Figure 1. Adult Oulema melanopus (~4.4-5.5 mm long).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.  

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 2).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 2.  Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Give priority to following factors when selecting monitoring sites:
   □ Choose fields and sections of the fields with past or present damage symptoms.
   □ Choose fields that are well irrigated (leaves are dark green in color), including young, lush crops. Areas of a field that are under stress and not as lush (yellow) are less likely to support CLB. 
   □ Monitor fields located along riparian corridors, roads and railroads. 
   □ Survey field areas that are close to brush cover or weeds, easy to access, or are nearby sheltered areas such as hedge rows, forest edges, fence lines, etc.

Focus your site selection on the following host plant priorities:
   □ First – winter wheat. If no winter wheat is present then;
   □ Second – other cereal crops (barley, wheat, oats, and rye). If no cereal crops are present then;
   □ Third – hay crops. If no hay crops or cereal crops are present then;
   □ Fourth – ditches and water corridors

Sweep-net Sampling for Adults and Larvae:
 ● A sweep is defined as a one pass (from left to right, executing a full 180 degrees) through the upper foliage of the crop using a 37.5 cm diameter sweep-net. 
 ● A sample is defined as 100 sweeps taken at a moderate walking pace collected 4-5 meters inside the border of a field.  
 ● At each site, four samples should be collected, totaling 400 sweeps per site.  The contents of each sample should be visually inspected for life stages of CLB and all suspect specimens should be retained for identification.  
 ● Because the CLB larvae are covered in a sticky secretion, they are often covered in debris and are very difficult to see within a sweep-net sample. 
 ● To help determine the presence of CLB, place the contents of the sweep net into a large plastic bag for observation.

Visual Inspection:
Both the adults and larvae severely damage plants by chewing out long strips of tissue between the veins of leaves (Fig. 2), leaving only a thin membrane. When damage is extensive, leaves turn whitish. 

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.


Weekly Update – Alfalfa weevil

Julie Soroka and Jennifer Otani
Week 8

Alfalfa Weevil (Hypera postica)  Earlier predictive model outputs can be reviewed by searching the Blog for “Alfalfa weevil” or use the Label Index located to the right of the screen to sort and review all “Alfalfa weevil” posts for 2016.

Reminder – The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”.  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long.  Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).

Economic thresholds for Alfalfa weevil (adapted from Soroka 2015) vary by crop type (hay or seed), area fed upon and larval densities.

In hay fields, forage losses can be economic if one or more of the following symptoms are noted:
● if 25-50 % of the leaves on the upper one-third of the stem show damage, or
● if 50-70% of the terminals are injured, or
● if 1 to 3 third or fourth instar larvae occur per stem (with shorter stems having lower economic thresholds and 3 or more larvae requiring treatment no matter what the alfalfa height), or 
● 20-30 larvae per sweep occur when 12% leaf loss is acceptable.
● Also consider these two points:
      1. Early cutting of the first growth of alfalfa or insecticide treatment will reduce alfalfa weevil populations.
      2. If the hay crop value is high and weevil injury is seen or 2 or more larvae per stem reappear in regrowth after cutting, insecticide may be necessary (if a second cut is anticipated). 

In alfalfa seed fields:
● Economic thresholds are 20-25 third to fourth instar larvae per sweep or 35-50% of the foliage tips showing damage. 
● Thresholds increase with the height of the alfalfa, and decrease in drought conditions. 
● Also know that several small wasps parasitize alfalfa weevil larvae and adults, and in the past these natural control agents kept the weevil in check in most years. One of these wasps, Bathyplectes curculionis (Thomson), parasitizes alfalfa weevil in Alberta and Saskatchewan, and is now found in Manitoba.


Provincial Insect Pest Reports

Scott Meers, Scott Hartley, John Gavloski and prairiepest_admin
Week 8

Provincial entomologists provide insect pest updates throughout the growing season so we have attempted to link to their most recent information: 

– Manitoba’s Insect and Disease Update (June 15, 2016, prepared by John Gavloski and Pratisara Bajracharya).

– Saskatchewan’s Insect Report which contains a reminder for cutworms (Issue 3, prepared by Scott Hartley).
– Watch for Alberta Agriculture and Forestry’s Call of the Land for updates from Scott Meers  who recently provided an update (posted on June 16, 2016including cabbage seedpod weevil on early canola in southern Alberta but also incidences of blister beetlesred turnip beetles, and  small scarab beetle larvae.


Insect of the Week – Cotesia margeniventris

Jennifer Otani
Week 8

Cotesia margeniventris (parasitoid)

Last year, the focus of the Insect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] 

This week’s Insect of the Week is Cotesia marginiventris (sorry, no common name), a braconidid wasp parasitoid. Female C. marginiventris lay their eggs in the larvae of cabbage looper, black cutworm, corn earworm, variegated cutworm, armyworm and fall armyworm.

For more information about C. marginiventris, the pests it controls and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).

Cotesia marginiventris parasitoidizing beet armyworm larva.
Photo cc-by-nc Debbie Waters, University of Georgia, Bugwood.org


Weekly Update

Jennifer Otani, David Giffen, Ross Weiss, Erl Svendsen, Kevin Floate and Owen Olfert
Week 8


A downloadable PDF version of the complete Weekly Update for Week 8 (June 22, 2016) can be accessed here.  

This edition includes the “Insect of the Week” featuring beneficial arthropods in 2016!

Subscribe to the Blog by following the instructions posted here!  You can receive automatic updates in your inbox through the growing season.

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Owen Olfert or Jennifer Otani.  Past “Weekly Updates” are very kindly archived to the Western Forum website by webmaster, Dr. Kelly Turkington.  


Weekly Update – Small scarab beetle

Kevin Floate and prairiepest_admin
Week 8

Small scarab beetle (Coleoptera: Aphodius distinctus) – This is the time of summer that farmers will be seeing larvae of a small scarab beetle (Aphodius distinctus) in their fields.  There have been scattered reports each June of large numbers of beetle grubs in crops associated with crop damage (e.g., canola, corn, dry bean, onion, pea).

Please help researchers compile information related to this species so they might confirm its pest status!  Information is posted about the beetle and the survey.  Here’s how you can help:

1. Please send reports of high white grub densities and associated crop damage to Kevin.Floate@agr.gc.ca (403-317-2242). 

2. Live larvae accompanied by the following field information would be extremely helpful please – contact Dr. Kevin Floate if you have a sample!

3. Include answers to the following so the pest status for this species can be ascertained:  
     – Previous crop?
     – Legal land location or latitude+longitude?
     – Irrigated or not?
     – Was composted manure added this spring?
     – Surface residue in spring?