David Giffen, Ross Weiss, Owen Olfert and prairiepest_admin
Weather synopsis – Weather conditions continue to be warmer and dryer than average across most of the prairies. This past week, (May 22 – 29, 2018) the average temperature was approximately 4 °C warmer than long term average (Fig. 1). The warmest weekly temperatures occurred across MB.
The 30-day average temperature (April 29 – May 29) was approximately 2 °C warmer than long term average (Fig. 2).
Weekly precipitation was below average and 30-day total rainfall was approximately 50% less than average (Figs. 3 and 4).
Accumulated precipitation for the growing season (April 01-May 30, 2018) is shown below.
The map below reflects the Highest Temperatures occurring over the past 7 days (May 24-30, 2018) across the prairies.
The map below reflects the Lowest Temperatures occurring over the past 7 days (May 24-30, 2018) across the prairies – it got a bit chilly for our newly seeded crops!
The growing degree day map (GDD) (Base 10ºC, March 1 – May 30, 2018) is below:
The growing degree day map (GDD) (Base 5ºC, March 1 – May 30, 2018) 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.
Background: Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories to deliver an early-warning system for the origin and destination of migratory invasive agricultural pests.
We receive two types of model output from ECCC: reverse trajectories (RT) and forward trajectories (FT):
(i) ‘Reverse trajectories’ (RT) refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date.
(ii) ‘Forward trajectories’ (FT) have a similar purpose; however, the modelling process begins at sites in USA and Mexico. The model output predicts the pathway of a trajectory. Again, of interest are the winds that eventually end up passing over the Prairies.
Since May 21, 2018, the number of incoming trajectories (RTs) crossing the prairies has increased, particularly from California, Texas and Mexico (Fig. 1). The increased number of reverse trajectories could result in increased introductions of insects into the prairies.
Flea Beetles (Chrysomelidae: Phyllotreta species) – The Insect of the Week features flea beetles!
Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Cutworms (Noctuidae) – A field guide is available to help growers scout and manage Cutworms! Cutworm Pest of Crops is available for free in either English or French and is posted on the Cutworm Field Guide page! Also be sure to check the Insect of the Week through May – it highlights cutworms. Several species of cutworms can be present in fields. They range in colour from shiny, opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms. The following page extracted from the new “Cutworm Pests of Crops on the Canadian Prairies” (Floate 2017; Page 5) shows the seasonal occurrence of lifecycle stages for different species of cutworms. To aid scouting, the seasonal chart outlines what time of year larvae of different pest species are present (i.e., when to scout) but it also describes larval feeding habit (i.e., where to look for them relative to the plant host). For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2018 Cutworm Reporting Tool”. Once data entry occurs, growers can view the live 2018 cutworm map which is updated daily (see below for screenshot of map retrieved June 5, 2018).
David Giffen, Ross Weiss, Owen Olfert and prairiepest_admin
Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
Above normal temperatures have advanced grasshopper development (Figs. 1 and 2). As of May 28, 2018, predicted hatch was 31% (up from 6% last week).
Figure 1. Grasshopper embryological development (%) based on model simulations (April 1-May 28, 2018).
Figure 2. Grasshopper hatch (%) based on model simulations (April 1-May 28, 2018).
Reminder – The Prairie Pest Monitoring Network’s 2018 Grasshopper Forecast Map was released in March (Fig. 3). Spring temperatures, soil moisture conditions, and precipitation all have an impact on survival of overwintered grasshopper eggs. Growers in areas highlighted orange or red in the map below should be vigilant this spring.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that oviposition is occurring across southern and central regions of the prairies (example Swift Current – Fig. 1).
Figure 1. Predicted pea leaf weevil phenology at Swift Current SK.
Values are based on model simulations (April 1-May 28, 2018 and projected to July 1, 2018).
Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight. Adults are slender, greyish-brown measuring approximately 5 mm in length (Fig. 2, Left). The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout.
Figure 2. Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).
Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June. Reminder – The 2017 risk map for pea leaf weevils was released in March 2018. The map is based on the number of feeding notches observed in peas (Fig. 3).
Figure 3. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in
peas grown in Alberta and Saskatchewan in 2017.
Cereal leaf beetle (Oulema melanopus) – Model output indicates that CLB are primarily in the larval stage (example Lethbridge – Fig. 1).
Figure 1. Predicted cereal leaf beetle phenology at Lethbridge AB.
Values are based on model simulations (April 1-May 28, 2018 and projected to June 21, 2018).
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 2). 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 2. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).
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. 3). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 3. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).
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.
David Giffen, Owen Olfert, Ross Weiss and prairiepest_admin
Alfalfa Weevil (Hypera postica) – The AAW model runs for Swift Current SK indicate that oviposition is well underway in southern Saskatchewan (Fig. 1). Larvae should be primarily second and third instars. Fourth instar larvae may be occurring as well.
Figure 1. Predicted alfalfa weevil phenology at Swift Current SK.
Values are based on model simulations (April 1-May 28, 2018 and projected to June 21, 2018).
Degree-day maps of base 9°C are produced using the Harcourt/North Dakota models (Soroka et al. 2015). Models predicting the development of Alfalfa weevil (Hypera postica) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below (Fig. 2).
Figure 2. Predicted development of alfalfa weevil as of May 30, 2018.
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.
Use the photo below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
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” (Philip et al. 2015). The guide is available in both a free English-enhancedor French-enhanced version.
Updated phenology models for insect pests on the Canadian prairies will be posted to our new Predictive Model Update page during the growing season, as they become available. This information is intended to supplement the Weekly Updates while providing the most current information to further support in-field scouting.
Whenever items are posted to this page, @vanbugsky will be Tweeting and using #PPMNblog to help users access this most up-to-date information.
This week, an updated table of predicted emergence dates for bertha armyworm was posted for across the Canadian prairies (May 30, 2018). Those in charge of coordinating deployment of pheromone traps will need to pay particular attention to these dates.
Bertha armyworm (Lepidoptera: Mamestra configurata) – The BAW model is predicting that pupae are developing rapidly in the soil and that development is well ahead of average (Fig. 1). Development is expected to be 5 – 6 days faster than average.
Figure 1. Predicted bertha armyworm pupal development (as of May 30, 2018).
Pupal development is approximately 72% (long term average is 47%). Model output predicts that emergence may begin as early as June 6, 2018 (Table 1).
Table 1. Projected dates for bertha armyworm adult emergence as of May 28, 2018 and projecting to June 30, 2018.
Reminder – Review the 2017 bertha armyworm distribution map for the Canadian prairies which reports cumulative pheromone trap counts intercepting male moths during the 2017 growing season.
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.
Monitoring: ● 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.
Remember – Health Canada’s Pest Management Regulatory Agency launched a mobile app to access pesticide labels registered for use in Canada. The App helps homeowners, farmers, industry, provincial and federal organizations access details for pest control products from a smartphone or tablet (Fig. 1). Users can save searches, download product labels to their ‘Favourites’ which can even be accessed while offline. ‘Favourites’ will also auto-update when accessed online. Pesticide labels can be searched based by product name or active ingredient (e.g., to review detailed explanations on proper product use and necessary precautions). Users can download the app on their mobile device. If you have any questions, please contact the PMRA’s Information Service.
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 for 2018 will be posted soon. Review the most recent updated (May 30, 2018) prepared by John Gavloski and Holly Derksen. The insect update notes flea beetles in canola and cutworms. Saskatchewan‘s Crop Production News for 2018 is now posted. Access Report #1 posted May 31, 2018, and be sure to review the articles posted for flea beetles and pea leaf weevils to prepare for field scouting. Also know that Saskatchewan growers can review diamondback moth pheromone trap counts in the upper right of the diamondback moth page. Access Alberta Agriculture and Forestry’s Call of the Land for insect pest updates from Scott Meers. The most recent Call of the Land (posted on May 31, 2018) and highlights scouting for flea beetles with the warmer weather, glassy cutworms in perennial forages crops and more recently in the irrigated acres to the south of the province (please report using online cutworm reporting tool), relatively low numbers of diamondback moth on pheromone traps in the 4th week of monitoring and relatively low pea leaf weevil numbers so far based on field assessments completed in southern Alberta to date.
Crop reports are produced by: • Manitoba Agriculture, Rural Development (May 28, 2018) • Saskatchewan Agriculture Crop Report (May 22-28, 2018) • Alberta Agriculture and Forestry Crop Report (May 22, 2018) The following crop reports are also available: • The United States Department of Agriculture (USDA) produces a Crop Progress Report (view the May 29, 2018 edition).
We again track the migration of the Monarch butterflies as they move north by checking the 2018 Monarch Migration Map! A screen shot of the map has been placed below as an example (retrieved 29May2018) but follow the hyperlink to check the interactive map!
This week’s Insect of the Week is the Flea Beetle (Phyllotreta species). This group of beetles is typically oval and 2-3 mm long. In canola, the most common flea beetles are either bluish black (crucifer flea beetle or Phyllotreta cruciferae) or black with two wavy yellow lines running down the length of its back (striped flea beetle or Phyllotreta striolata). They overwinter as adults under plant material along field margins and females lay eggs in the soil near the host plants. Striped and crucifer flea beetles feed on canola, mustard and related cruciferous plants and weeds. Their damage results in a shot-hole appearance in cotyledon leaves. They also feed on stems under windy or damp conditions, causing wilting or breakage. Remember, the Action Threshold for flea beetles on canola is when 25% of cotyledon leaf area is consumed.