Coming soon to an area near you - European apple sawfly
Did you see this damage at harvest? A spiral russetted scar that goes from the calyx to the stem end across the body of the fruit. This is typical damage that was created early in the season from European apple sawfly (EAS).
Figure 1. Spiral russetted scar that extends from the calyx is typical damage from European apple sawfly.
This invasive insect has moved slowly westward across Ontario since monitoring began in the late 1980's. While it is not uncommon to find EAS damage in orchards east of Toronto, it is not expected in the western part of the province. In 2014, damage was reported as far west as the Georgian Bay region. However, while doing harvest assessments in the Niagara region this year, I came across a young orchard block with this:
Figure 2. European apple sawfly damage found in the Niagara region in 2016.
Why is it important to make note of this damage? It is an indication that European apple sawfly has become established in a new area and/or in your orchard. While it takes a few years for the population to build up in an orchard, commercially available traps set up at pink will track the adult emergence and help determine if petal fall control is needed.
From full pink to petal fall, EAS is present as an adult and lays its eggs into the base of the blossoms. After hatching, larvae feed beneath the skin of developing fruitlets, creating a russetted, ribbon-like scar that spirals out from the calyx end.
- If larvae cease feeding early for whatever reason, the damage will likely be seen on mature fruit at harvest. However, the tunneling scars may be short and indistinguishable from damage caused by tarnished plant bug.
- If larvae continue feeding during development, they will tunnel into the fruit towards the seed cavity and reddish-brown frass is often seen protruding from an exit hole. This sort of damage will often cause fruit to abort during June drop.
- Delegate (Group 5) was just recently registered for control
of EAS. This is the third insecticide group registered for this
pest, which also includes:
- Group 4 (neonicotinoids): Assail, Calypso
- Group 28 (diamides): Altacor (petal fall only), Exirel
Research is continuing to look at the potential use of the biopesticide, Quassia for control of EAS and other potential petal fall pests.
For more information on scouting, thresholds and management of this insect, refer to the EAS module on Ontario AppleIPM.
For more information:
Toll Free: 1-877-424-1300
|Author:||Kristy Grigg-McGuffin - Horticulture IPM Specialist/OMAFRA|
|Creation Date:||21 December 2016|
|Last Reviewed:||21 December 2016|