Week 6 and things are hopping – literally! Be sure to catch the Insect of the Week – it’s bertha armyworm! This week find updates to predictive model outputs for grasshoppers, wheat midge, bertha armyworm, cereal leaf beetle, and alfalfa weevil plus a lot more to help prepare for in-field scouting!
Access background information for how and why wind trajectories are monitored in this post.
1. REVERSE TRAJECTORIES (RT) This past week (in particular June 9 and 10) there were an increasing number of reverse trajectories moving north from the Pacific Northwest (Idaho, Oregon and Washington), Texas, Oklahoma, Kansas and Nebraska (Fig. 1). Though these US regions can be a source of diamondback moths (DBM), the ECCC models predict air movement, not actual occurrence of diamondback moths. Fields (and DBM traps) should be monitored for DBM adults and larvae.
a. Pacific Northwest (Idaho, Oregon, Washington) – This week there have been 106 trajectories (53 last week) that have crossed Alberta, Manitoba and Saskatchewan. This growing season, PNW trajectories have crossed all parts of the prairies (Fig. 2).
b. Mexico and southwest USA (Texas, California) – Compared to previous years, there has been a noticeable increase in the number of trajectories from the southern US. The majority of these trajectories have crossed Manitoba and eastern Saskatchewan (Fig. 3). This week there have been 10 trajectories (0 last week) that originated in Mexico or the southwest USA that have crossed the prairies (Fig. 3).
c. Oklahoma and Texas – This week there have been 13 trajectories (0 last week) originating in Oklahoma or Texas that have passed over the prairies (Fig. 4).
d. Kansas and Nebraska – This week there were 19 trajectories (versus 1 last week) that originated in Kansas or Nebraska that passed over the prairies (Fig. 5). Relative to the reverse trajectories associated with Oklahoma and Texas (Fig. 4), the trajectories from Kansas and Nebraska have crossed further into Alberta (Fig. 5).
2. FORWARD TRAJECTORIES (FT) a. Continuing a trend that began last week, this week there was an increase in the number of forward trajectories predicted to cross the prairies (Fig. 6). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line). The data suggests that there will be increased potential for introduction of DBM to the prairies.
TEMPERATURE: This past week (May 31 – June 6, 2021) extremely warm conditions resulted in weekly average temperatures that were well above normal (Fig. 1). The warmest temperatures were observed across Manitoba and eastern Saskatchewan (Fig. 1).
Across the prairies, the average 30-day (May 8 – June 6) temperature was almost 2.5 °C warmer than the previous week and 1.3 °C greater than climate normal values. Warmest temperatures were observed across southern Manitoba (Table 1; Fig. 2).
The 2021 growing season (April 1 – June 6) has been characterized by near-normal temperatures. Temperatures have been warmest for southern Manitoba and southern Alberta (Table 2; Fig. 3).
PRECIPITATION: This week, the highest rainfall amounts were reported across northwest Saskatchewan and central Alberta while weekly rainfall amounts less than 2 mm was reported across a large area that extended from western Manitoba, across most of Saskatchewan, to southern Alberta. Extreme dry conditions were reported across the Peace River region (Fig. 4).
Rainfall amounts for the period of May 8 to June 6 (30-day accumulation) were above normal (110 % of long-term average values). Rainfall amounts have been near normal to above normal for large areas of Alberta as well as northwest and southeast Saskatchewan. Well-above-normal rain was reported for Edmonton and Regina. Below normal rainfall amounts were reported for central and northern areas of the Peace River region and across Manitoba (Table 1; Fig. 5).
Average growing season (April 1 – June 6) precipitation was 94 % of normal with the greatest precipitation occurring near Edmonton and across eastern Saskatchewan, including Regina. Most of Manitoba and the Peace River region have had 60 % or less than normal precipitation during the 2021 growing season (Table 2; Fig. 6).
Access Environment and Climate Change Canada’s weather radar mapping interface. Options to access preceeding precipitation events include clicking off either an 1 or 3 hours time interval, using an 8-colour or 14-colour index. or changing the base map.
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 6, 2021. Average development of eggs is 86 % and is well ahead of the long term average of 73 %. Last week’s warm conditions across southeastern SK and southern Manitoba have been responsible for advanced development of eggs near Regina, Saskatoon, Brandon, and Winnipeg. Egg development is predicted to exceed 90 % across most of the southern prairies (Fig. 1).
As of June 6, hatch was predicted to be occurring across most of the prairies (overall average was 26 %) with hatch rates approaching 30-45 % across southern Manitoba and Saskatchewan (Fig. 2). The model was projected to June 22 to determine potential development at Regina and Swift Current over the next two weeks (Figs. 3 and 4). Results suggest that by June 22, Regina populations will primarily be in the third instar, with first appearance of fourth instars. Development near Swift Current is predicted to be slower, with populations being mostly in the first and second instars.
Warm, dry conditions continue to persist across Manitoba. This may result in conditions conducive to crop damage from grasshoppers as hatch progresses in June. Producers are advised to monitor roadsides and field margins to assess development and densities of local grasshopper populations.
Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. The Olfert et al. (2020) model indicated that dry conditions may result in: a. Delayed adult emergence and oviposition b. Reduced numbers of adults and eggs
As of June 6, 2021, wheat midge model runs indicate that recent rainfall in central Alberta and northwestern and southeastern Saskatchewan has resulted in movement of more than 30 % of the larval population to the soil surface (Fig. 1). Dryer conditions in other parts of Saskatchewan, Manitoba and most of the Peace River region continue to delay movement of larvae to the soil surface. If dry conditions persist, this should result in delayed pupation and adult emergence.
More information about wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Model simulations to June 6, 2021, indicate that bertha armyworm (BAW) (Mamestra configurata) pupal development ranges from 60-90 % across the prairies (Fig. 1). BAW traps should be placed in fields when pupal development exceeds 80 %. Table 1 provides guidelines to determine when traps should be deployed. Based on weather data up to June 6, 2021, BAW adults should begin to emerge by mid to late June.
Model projections to June 30 predict that development near Winnipeg will be more advanced than at Lacombe (Figs. 2 and 3, respectively). The model predicts that egg hatch will begin in mid-June near Winnipeg.
The cereal leaf beetle (CLB) (Oulema melanopus) model predicts that larval development is progressing across the prairies. The graphs below provide a comparison of development at Saskatoon (Fig. 1) and at Lethbridge (Fig. 2). The simulation indicates that populations are mostly in the second instar with the initial occurrence of third instar stages expected to occur this week. The simulation predicts that larval development will be complete by the end of the month across central Saskatchewan.
Model simulations for alfalfa weevil (AAW) (Hypera postica) predict, as of June 6, that alfalfa weevil populations should be primarily in the second larval instar (Fig. 1). The following graph indicates the predicted development near Brandon (Fig. 2). This week, larval populations in southern Manitoba should be primarily in the second instar. Simulation runs indicate that by June 22, southern Manitoba populations will be in the fourth instar with initial appearance of pupae.
The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3). The green larva features a dorsal white line down the length of its body, has a dark brown head capsule, and will grow to 9 mm long.
Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon). Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (2018; accessible in either English-enhanced or French-enhanced versions).
The European corn borer (ECB; Ostrinia nubilalis), has been an important pest of corn and other crops in eastern Canada for nearly a century now but is also known to be a sporadic pest in western Canada. Despite its name, ECB is actually a generalist feeder, having a wide range of hosts. With so many new emerging crops being grown in Canada that are also hosts for ECB (eg. hemp, cannabis, quinoa, hops, millet and others), there is no better time to look at this pest across the Canadian agricultural landscape.
To monitor for ECB nationwide, the Surveillance Working Group of the Canadian Plant Health Council has developed a harmonized monitoring protocol for European corn borer in both English and French. The project aims to generate real-time reporting and annual maps – access a full description of the project and list of key contact persons. The protocol can be used to report ECB eggs, larvae or damage in any host crop across Canada. This harmonized protocol has been designed to complement protocols already in use to make management decisions in order to generate data to compare ECB presence across all of Canada and across host crops.
When scouting corn, quinoa, hemp, millet, potatoes, apples, or other crops susceptible to ECB, the Surveillance Working Group of the Canadian Plant Health Council encourages the use of the harmonized monitoring protocol and reporting of the data from fields or research plots using the free Survey123 app (available for both desktop and mobile devices): • Early to Mid-Season ECB Survey (Before July) – https://arcg.is/0qCCHH (applicable for use in eastern Canada). • Later Season ECB Survey (July to Pre-Harvest) – https://arcg.is/fSODf (applicable for use in both eastern AND western Canada).
Track the migration of the Monarch butterflies as they move north by checking the 2021 Monarch Migration Map! A screenshot of the map has been placed below as an example (retrieved 10Jun2021) but follow the hyperlink to check the interactive map. They have reached Dauphin MB!
Provincial entomologists provide insect pest updates throughout the growing season so link to their information:
MANITOBA’SCrop Pest Updates for 2021 are now available! Access the June 9, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Also, bookmark their insect pest homepage to access fact sheets and more! • Bertha armyworm pheromone trap monitoring update for MB – Cooperators are deploying pheromone traps and weekly data will soon be available. • Diamondback moth pheromone trap monitoring update for MB – Refer to the summary updated twice a week. So far, only 38 traps have intercepted moths and only double-digit cumulative counts! Access the summary (as of June 8, 2021).
SASKATCHEWAN’SCrop Production News will soon be available. Be sure to bookmark their insect pest homepage to access important information! • Bertha armyworm pheromone trap monitoring update for SK – Cooperators are deploying pheromone traps at sites across the province. • Diamondback moth pheromone trap monitoring update for SK – follow this link to find current DBM counts. At this point, extremely low numbers have been intercepted but monitoring continues. Province-wide, <45 moths have been intercepted so far (2021Jun10 Carter, pers. comm.).
ALBERTA’SInsect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am. • Bertha armyworm pheromone trap monitoring update for AB – Cooperators are deploying pheromone traps so refer to the Live Map as data becomes available. • Diamondback moth pheromone trap monitoring update for AB – Refer to the Live Map which reported extremely low numbers of moths intercepted so far (<45 province-wide as of 10Jun2021). • Cutworm reporting tool – Refer to the Live Map which reported four sites with cutworms (as of 10Jun2021).
This week’s Insect of the Week is the bertha armyworm (Mamestra configurata), a crop pest with the potential to do serious damage when populations run high. Though these insects are harmless to crops as adults, bertha armyworm larvae primarily consume canola, mustard, and alfalfa. Larvae may also consume plants like flax, peas and potatoes. The bertha armyworm is prevalent across the Prairies.
Prior to reaching their mature larval size, bertha armyworms feed on the underside of leaves. In canola and other plants that drop their leaves prior to the bertha armyworms’ larval maturation, the growing larvae move on to eat seed pods, stripping the pods and in extreme cases, consuming the seeds inside them. Even when the seed pods are not eaten through, stripped pods risk shattering and can hinder crop development.
Adults are 20 millimeters long moths with a greyish body and 40 mm wingspan. Wing markings on the forewing include prominent white, kidney-shaped markings near the midpoint, and an olive and white irregular marking extending along the wing tip. Mature larvae are 40 mm long black (though sometimes light green or light brown) caterpillars with a light brown head and an orange stripe along each side, with three broken white lines down their backs.