Wednesday, September 11, 2013

Curculio Weevil Damage in Willunga - UPDATE 11/9/2013

A hollowed out bud suspected to be caused by Curculio weevil.
Growers are advised to be on the look out for weevil damage (buds hollowed out or shoots stripped of foliage as shown above). These symptoms can be be caused by garden weevil, which is a problem in Langhorne Creek and the Adelaide Hills, or Curculio weevil more commonly found in McLaren Vale.

Both Curculio weevil and Garden weevil emerge for the soil and at night and chew leaves and even whole buds. They are also known as Apple Weevil, or Apple Beetles.

This week some possible Curculio weevil or Garden weevil activity has been seen damaging vines (and olives) In some vineyards in the areas west of Willunga significant damage has occurred.

Both types of weevil are difficult to see during the day where they hide the soil. They can also shelter in bark during the day. Keep your eyes out.

Description

• Larvae - are soil dwelling, legless and have a brown head with black jaws. The
larva of apple weevil is similar to garden weevil, spotted vegetable weevil and
sitona weevil. A microscope is required to identify the actual weevil type in the
larval stage.

• Adult - medium sized about 8mm long and uniform brown weevil. It has a
slightly bulbous abdomen. The adult weevils are flightless and all are females.

Habits

• Adult weevils feed at night. They are inactive during the day and shelter under
bark, in the crotch of branches, between fruit and leaves, and burrow into soil
around the base of trees.

• When disturbed they fall to the ground and quickly walk away.

Life cycle

• Eggs are laid in loose organic matter on the soil and hatch in 10 - 14 days.

• Young larvae are mobile; they immediately burrow into the soil to feed on plant
roots.

• Larvae develop slowly during winter and more rapidly as soil temperature
increases in spring. They pupate in October/November.

• The length of the pupal stage depends on weather conditions. It usually lasts three
to four weeks.


If you are seeing these symptoms and need specific advice please contact us.

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