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This article focuses on a study in which the effects of thinning, fertilization and pruning on the vigour of douglas fir and its susceptibility to armillaria root disease were explored, as of January 1998. Tree vigour was defined as the relative capacity for tree growth, expressed as the above-ground hiomass increment per unit of photosynthetic tissue or growth efficiency. It has been hypothesized that trees with higher growth efficiency can better resist pathogen attack and that growth efficiency can be used as a predictor of tree susceptibility to disease. In a previous study, four douglas fir plantations were thinned, fertilized and pruned in all combinations and the effects of these treatments on tree vigour were measured after 10 years. Root disease was not a factor in the initial study design and mortality was ignored until 8 years after the treatments were applied. The results of an earlier study were utilized and the correlation between armillaria root disease incidence and the effects of earlier stand treatments on tree growth was tested.

In vitro antagonism of three root-disease pathogens, Phellinus weirii, Heterobasidion annosum and Armillaria ostoyae by Ulocladium botrytis is discussed in the article. On solid medium, areas of inhibition were characteristic of antagonism, whereas, in liquid medium, antagonism resulted in the reduction of the colony dry weights of the pathogens. The antagonistic effect of Ulocladium botrytis was fungistatic.

This article focuses on characteristics of canopy gaps caused by Armillaria root disease and their management implications in Lowveld forests of South Africa. Armillaria root disease is caused by Armillaria (Fr) Staude sp. is one of the most forest tree diseases in South Africa. Pinus elliottii was the most commonly infected host, followed by Pinus kesiya, P. roxburghii, P. caribaea, P. taeda, and P. patula, in describing orders. Gap incidence rapidly increased to age 10, after which it remained constant.

Armillaria root rot, or the shoestring root rot, caused by Armillaria mellea, is an important fungal disease of Canadian forests and it has attracted considerable interest of researchers as well as foresters during the past few years. Under field conditions, particularly in temperate regions, A. mellea regularly produces rhizomorphs which serve as the principal means of subterranean spread and perpetuation of the fungus in soil. This article describes the results obtained from investigations conducted to determine the effects of three different types of site and soil conditions, and four host species on the growth and distribution of rhizomorphs in Newfoundland forests in Canada.

This article presents a brief information on Armillaria root rot, a kind of tree disease which is responsible for root and butt rot, and tree mortality of a wide variety of softwood and hardwood species, by way of artificial inoculation and development of this disease in greenhouse. This disease is caused by the fungus Armillaria mellea. Inoculation of five softwood provenances have revealed that they vary considerably with regard to their percent infection, percent mortality, severity of disease symptoms and progress of infection. Sitka spruce was found the most susceptible species which served as a better substrate for further development of mycelium and rhizomorphs as compared to Norway and black spruces and Scots pine. Based on a survey, it was found that there was a conspicuous reduction in the total and annual growth in height in Armillaria mellea-infected seedlings in North America and Europe.

The article reports that various soil treatments with chemicals, sodium pentachlorophenate and/or pentachlorophenol failed to protect seedlings of the tree, Pinus radiata from the fungal Armillaria root rot infection. In the treatment, container grown Pinus radiata seedlings were inoculated with either Armillaria novae-celandine or A. Limoniae. With these chemicals, it gave no reduction in seedling infection or mortality. In conclusion, it is stated that there is an increase in seedling infection and mortality and a decrease in the vigor of surviving seedlings occurred in some treatments.

The article presents information on the report of the Forest Research Institute for duration January 1 to December 31, 1980. The areas covered in the report are: aerial spraying for control of Dothistroma needle blight, nursery application for the control of Terminal Crook Disease and Armillaria root rot and its prospects for control.