Sunflower: Sclerotinia was reported in sunflower.

 

Cereals: Low levels of Fusarium head blight (FHB) is being reported in cereal crops. 
  

 

Some have been noticing Lygus bugs in flax and wondering if they could be an economic issue. Adults move into flax from nearby host plants in July when flax produces buds and flowers.

Although Lygus bugs can reach high densities in flax, flax is quite tolerant of their feeding damage under good growing conditions. A study in Manitoba found that under good growing conditions, populations of up to 100 per 10 sweeps were not economical. Whether this tolerance extends to flax growing under less favourable conditions in uncertain. Flax can compensate for insect injury by producing additional flowers.

                                             
                                                 Figure 1. Lygus bug on flax

 

 

 

Some have been noticing what usually (although incorrectly) get described as eggs on the heads of cereal plants (Figure 2 below). These are not eggs, but clusters of pupal cases of parasitic wasps, likely a species of Cotesia. They are often parasitizing caterpillars such as armyworms, and before the caterpillar dies it climbs to the top of the plant. When you see a large armyworm near the top of the plant during the day, that could mean they are infected with either a parasitoid of pathogen. Healthy older armyworms prefer to take cover on the ground during the day. Many Cotesia larvae will emerge at roughly the same time from the armyworm (Figure 3), and quite rapidly after emergence form these silky pupal cases in a cluster, often high on the plant. So if you are seeing a lot of these, this is a sign that parasitic wasps have been actively working in the field.

      
   Figure 2. Pupal cases of parasitoid                        Figure 3. Cotesia emerging from armyworm

  

Bertha armyworm: Cumulative trap counts for bertha armyworm are mainly in the low risk range (less than 300). Out of 83 traps, 72 are in the low risk range, 10 are in the uncertain risk range (300 to 900 moths), and 1 traps is in the moderate risk (900 - 1,200 moths). No traps are in the high risk range (1,200 plus moths). Most of the counts above the low risk range are in the western regions of Manitoba. The table below shows the highest counts as of July 26:

 

In the map below, green=low risk, yellow=uncertain risk, and orange=moderate risk

                                     

 

A reminder for those monitoring traps that the week of July 24-30 is the last week of data entry; traps can be pulled after data for that week is collected.

 

For uncertain risk the precaution we use is that economic levels of larvae may not be widespread, but fields that were particularly attractive to egg-laying females could have higher levels. Check your fields.

Note that there are times when we get to these levels, and no economic levels of larvae occur.
Also, higher levels of larvae, should they occur, may or may not be in the fields that the traps are in.

So far there have been no reports of high levels of larvae of bertha armyworms.

 

Compiled by: 

 

John Gavloski, Entomologist                    Pratisara Bajracharya, Field Crop Pathologist        

Manitoba Agriculture                                    Manitoba Agriculture

Phone: (204) 745-5668                               Phone: (204) 750-4248      

 

To report observations on insects or plant pathogens that may be of interest or importance to farmers and agronomists in Manitoba, please send messages to the above contacts.

 

To be placed on an E-mail list so you will be notified immediately when new Manitoba Insect and Disease Updates are posted, please contact John Gavloski at the address or numbers listed above.