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Meria laricis

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Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.

From Scion publication Forest Research Bulletin 220,
An Introduction to The Diseases of Forest and Amenity Trees in New Zealand,
G.S.Ridley and M.A. Dick 2001.

Species: Meria laricis (Ascomycete anamorph)

Common name: None

Country of origin: Northern Hemisphere

Host(s): This needle-infecting fungus causes premature needle cast of a number of species of larch. Larix decidua (European larch) is extremely susceptible. In New Zealand L. kaempferi (Japanese larch) is considered to be resistant although there have been records of minor damage in Europe. The hybrid L. x eurolepis can suffer from severe attacks but generally it is less susceptible than L. decidua.

Symptoms: First symptoms are a patchy yellow-brown discoloration of the needles; the needles then brown off and are readily shed.

Disease development: Meria laricis overwinters in fallen needles; conidiospores are produced in spring and these infect the new season's needles. Only immature needles are infected and they become resistant with maturity. The fungus penetrates through the stomata and later the white fruit- bodies emerge through the stomata on the under-surface of needles. These fruit-bodies can look very much like the white waxy stomatal plugs. Disease progress is favoured by warm wet weather, with an optimum temperature of 17°-20°C. The spores cannot survive drying and germinate only when RH>90%, with the result that in dry years the disease is not apparent at all.

NZ distribution: Found throughout New Zealand.

Economic impact: All ages of plants can be affected, from nursery seedlings to mature trees. In New Zealand it is seldom a problem in the nursery, but can cause considerable defoliation in older trees, usually in mid to late summer. Although it has been recorded as causing defoliation in stands up to 50 years old, there is generally little damage on trees greater than 8 years old. In the United States where L. occidentalis is also highly susceptible, extensive loss of foliage on even big trees can slow growth.

Control: Not considered necessary.

References: Gilmour 1966; Sinclair et al. 1987.

This information is intended for general interest only. It is not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. Scion will not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, loss of profits, or any other intangible losses that result from using the information provided on this site.
(Scion is the trading name of the New Zealand Forest Research Institute Limited.)


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