Category Archives: Insecticides

Corn Earworm and Late Planted Sweet Corn

Corn earworm pressure often increases as we head into September. With turbulent weather patterns originating in the Gulf of Mexico, flights of airborne moths are generally quite high.  As the tradewinds mix with the cooler air of the great lakes, these high populations are dropped into Southern Ontario.  Any sweet corn at the green silk stage is highly susceptible to corn earworm infestation.

For earworm control, cover green silks with an insecticide such as Coragen or Voliam Express.  Avoid insecticides from the pyrethroid family.  Corn earworm are known to be resistant to the pyrethroids.  Lannate TNG is a good rotational partner for Coragen and Voliam Express.

Heliothis trap for corn earworm monitoring

Matador/Warrior/Silencer and Imidan proposed phase out

The PMRA have proposed to cancel the registration of both lambda-cyhalothrin (Matador/Silencer/Warrior) and phosmet (Imidan). The decisions can be found here:

Lambda-cyhalothrin
Phosmet

The decisions state that lambda-cyhalothrin poses an unacceptable risk from dietary exposure (worst case scenario cumulative food residues would be too high), while phosmet poses a risk during application and post-application activities. The proposed precautions such as revised restricted entry intervals would not be agronomically feasible (e.g. 12 day REI for scouting carrots, 43 days for moving irrigation pipe).

Public consultation is now open until September 23 (lambda-cyhalothrin) or September 30 (phosmet) so if growers wish to make comments on these proposed decisions you can submit them to pmra.publications@hc-sc.gc.ca, or talk to your growers’ association who can comment on your behalf.

 

Scouting for onion thrips

Onion thrips (Thrips tabaci) feed on more than just onions; they also feed on cabbage, leaf lettuce, a variety of other vegetables and fruits, field crops, and many weed species. Thrips are unique from other insects as they have rasping-sucking mouthparts that allow them to scratch the cell walls of leaves, suck up the cell contents including the chlorophyll, and leave behind a shiny, translucent trail on the leaf. A single female can produce Continue reading Scouting for onion thrips

Time to Scout for Asparagus Beetles

Asparagus beetle activity is on the rise. The adult beetles hide in soil cracks or underneath residue during the heat of the day.  Egg laying is often the most obvious sign of their activity. The presence of eggs on the harvest spears, may affect marketability. On young fern, heavy amounts of larval feeding has a negative impact on growth and development.

As harvest concludes, scout plantings regularly as the spears begin to elongate and develop a full canopy of fern. Spray thresholds are as follows:

Eggs:   2 /10 spears with eggs
Larvae:   50% of plants with   larvae OR 10% Defoliation
Adults:   5-10% of   plants infested

If controls are required during the harvest season, play close attention to the pre-harvest intervals.  Products with a 24-hr pre-harvest interval include: malathion (Malathion 85E), cypermethrin (Mako, Upside 2.5 EC), and acetamiprid (Assail 70WP).

Spotted Asparagus Beetle (Hannah Stevens, retired MSU)
Common asparagus beetle (Hannah Stevens, retired MSU)

Cabbage Maggot; An old pest with limited options

The cabbage maggot (Delia radicum) is the larvae stage of the cabbage root fly which can cause severe damage to all Brassica crops. The adult cabbage maggot is a fly that is about half the size of a house fly and is grey in colour.

In the early spring, cabbage maggot flies emerge from the soil and the females lay small, white eggs ~2-10 cm below the soil line. Depending upon the temperature, eggs hatch 3-7 days later as larvae that immediately start boring Continue reading Cabbage Maggot; An old pest with limited options

Potato Insects – Insecticide Activity Table

Here is a quick reference guide for insecticides registered on potatoes in Ontario. Use it as a guide only, always refer back to the label. Remember to rotate insecticide groups for resistance management.

Potato Insecticide Activity Table Final

Printable Potato Insecticide Activity Table

Continue reading Potato Insects – Insecticide Activity Table