Bibological control and ecology of Armillaria mellea (vahl) fr

Abstract

1 Problems of controlling Armillaria root disease in young and old plantation crops are discussed with special reference to tea estates in Nyasaland. 2 A method is suggested for curtailing the normal course of the disease in young plantations. 3 The basic means of control is by preventing the infection of the remaining roots of forest tree roots after the land is cleared. Ring-barking is still considered to be the best method of biologic control. Observations and experiments are described upholding this conclusion. 4 The ecology of Armillaria mellea is discussed. An experiment showed that nearly all the indigenous trees can be invaded by the fungus though the roots of a few species only are commonly associated with Armillaria root disease of tea. The roots of most species can normally localize the infection but when the roots are severed the fungus travels freely. 5 The rate at which tree roots die after felling is thought to be the factor which controls the distribution of Armillaria in cleared forests. Roots which die quickly and become invaded by saprophytes are considered to restrict the spread of Armillaria , while roots which die slowly facilitate the spread of that fungus. 6 Further work is needed on the part played (if any) by spores, in starting centres of infection in virgin forest.