Friday, 23 June 2017
Walnut Tree Juglans regia and Walnut Leaf Gall Mite - Aceria erinea
Walnut Juglans regia
Walnut is a deciduous broadleaf tree native to south-east Europe to south-west China.
The walnut's botanical name, Juglans, originates in Roman mythology. According myth, Jupiter, who was also known as Jove, lived on walnuts when he lived on earth. Therefore Romans called walnuts Jovis glans, meaning 'the glans of Jupiter.' The botanical name of the English walnut, Juglans regia, means the 'royal nut of Jupiter'.
Description to 35m. They typically have a short trunk and broad crown, though can be narrower if grown in a woodland situation. The bark is smooth and olive-brown when young, developing fissures and fading to silver-grey with age. Twigs are stout, green and curving.
Leaves: shiny and pinnate (feather-like), with 5-9 paired oval leaflets and one 'terminal' leaflet at the end.
Flowers: male flowers are drooping yellow-green catkins 5–10 cm long, and the female flowers appear in clusters of 2-5.
Fruits: pollinated by wind, female flowers develop into a fruit with a green, fleshy husk and a brown, wrinkled walnut.
Aceria erinea is a mite that causes galls to form on the leaves of Walnut. Large yellowish blisters appear on the upper surface of the leaves with corresponding hollows on the underside which are lined with whitish or pale brown hairs among which the mites live and feed