Green Oak Moth, Tortrix viridana

Tortrix viridana, Green oak moth is an economic insect of oak. It is also known as the European oak leaf roller and tortrix moth.

Tortrix viridana, Green oak moth is an economic insect of oak. It is also known as the European oak leaf roller and tortrix moth. It is a distinctive green moth whose larvae feed on tree leaves of Quercus (main host), Acer, Betula, Carpinus, Fagus and Populus. They also feed on shrubs including Vaccinium and Urtica. It is distributed in Europe, northern Africa, Cyprus, Iran and Israel. An infestation of the larvae can defoliate an oak tree.

Russell IPM manufacture and supply pheromone lures, traps and complete monitoring systems for Tortrix viridana, Green Oak moth. Pheromone trap data gives early warning of the infestation and also exhibits the density of the insect population.

Biology

Adult moth’s forewings are pale-green or yellow-green; hind wings are brownish-gray to grayish; both wings have a white, frayed outer edge. The wingspan is approximately 18 to 23 mm. The head is yellowish and adults have a grayish, 8 mm long abdomen. Larva: Younger larvae are gray coloured with dark heads. Older instar larvae turn gray-green. Larvae are 15 to 19 mm long and 2.5 mm wide. Egg: Eggs are round, with a diameter of about 0.7 mm. They are initially light yellow, later changing to brown. Each female oviposits approximately 50 to 60 eggs in pairs within a cement-like mass. Eggs are deposited on branches, leaves, and branch forks, within the entire crown. A dust and algae lining make the eggs nearly invisible.

Nature of Damage

Emerging larvae bore into open buds, since closed buds cannot be penetrated. Therefore, emerging larvae can only survive if the buds are in synchrony with their development. As the buds flush, the larvae move to young leaves and flowers and continue feeding. Larvae construct shelters by rolling leaves with silk webbing Third instar larvae become more mobile and are thus more visible. Similar to other tortricids, when larvae are disturbed, they will drop on a silken thread. Last instar larvae feed upon the expanded foliage as well as the bark of tender young shoots. Tortrix viridanais part of a Quercus dieback complex that results in thinning foliage, progressive die-back, cambial necrosis, epicormic shoot development and tree mortality. Successive defoliation can cause growth loss and can also weaken trees and predispose them to mortality by other organisms (Canadian food inspection agency).

Monitoring

Russell IPM manufactures and supplies pheromone lure – the Qlure, traps and complete monitoring systems for Tortrix viridana, Green Oak Moth.

Pheromone trap data gives early warning of the infestation and will also alert the user to a low level of population before it becomes serious.

The lure can be best applied with the Mothcatcher trap or Delta trap.

Application Guidelines

Lures
Lures can be changed every 4-6 weeks to get the most accurate results.

Lures Handling
Pheromone lures are a very sensitive tool. They can be affected by exposure to elevated heat and direct sunshine. Direct touching by hand may cause cross contamination leading to mixed catches in the trap. Some contaminants such as Nicotine May have repellent effect reducing trap catch.

Lure Storage
Store in a cool dry place. Shelf life can vary from 3-36 months depending on the storage temperature. See Technical Data Sheet for further details.

Trap Selection

The Deltra trap is the most sensitive trap to use for monitoring this insect. However, Moth catcher may be used in dusty conditions or in high moth population density.

Trap Density

Do not re-use the trap to monitor different insects as this may lead to mixed catches. One trap for every two hectares of large scale fields of homogenous lands.

Two traps per hectare (2trap/ha) for small holdings and in field of uneven topography.

Trap Position

Place traps near the highest point of the plant using supporting posts approximately 1 meter high, or higher if the crop is higher.

Data and Interpretation

Collect data weekly from the start of the flight of the over wintering generation. During the height of the population more frequent reading may be needed. Decisions on pesticide application should not be taken solely on the trap catch data. Climatic and biological considerations should be taken in account.

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