engleski

Research update on Mycosphaerella dearnessii Barr. on Pinus halepensis Mill. in Croatia

Brown-spot needle blight caused by Mycosphaerella dearnessii kills foliage and retards growth of many pine species. Diseased needles typically show dead tips, central zones with spots in green tissue, and green bases. After severe attack the whole needle initially turns brown, then light brown to grey, and abscises prematurely. Heavily infected pines typically show twigs with only last year's needles, giving a paintbrush appearance. The pathogen has a wide host and habitat range and occurs on pines in tropical to temperate zones. In Croatia it has been found only on Aleppo pine (Pinus halepensis) on individual older trees and mostly self sprouting young forests developed in former gaps and dense forest plantations. Although it was found in several locations along the Adriatic sea cost, the forest area Kožino near Zadar is considered to be the permanent centre of the disease, because pathogen continuously exists there causing faint to relatively strong infections, depending on the year and climatic conditions. Research was conducted in 5 localities in the Kožino forest area which differ in the age of pines and level of infection. Field inspections included collecting and counting all discarded dead needles from the 1 m2 wooden boxes placed under the groups of pine trees once per week for a year and collecting 5 shoots from all four expositions in each locality once every two weeks for a year in order to compare the number of healthy and diseased needles. Infected needles were microscoped to determine the number and maturity of fruiting bodies of Mycosphaerella dearnessii and other occuring fungi. Results gave insight into dynamics of needle defoliation caused by the disease, infection occurence and progress during the year and pathogen biology.

Mycosphaerella dearnessii ; Pinus halepensis ; Kožino

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