Survey ofFomes annosusin East Anglian Pine plantations

The incidence of killing by Fomes annosus in first-rotation crops was studied in relation to some soil characteristics and forest management. Killing was closely correlated with soil reaction in the major lateral rooting zone, extensive damage occurring only on areas with a pH greater than 6. Neither soil reaction at 50 cm. nor soil depth was correlated with root rot losses under the conditions of this survey. Losses were high on agricultural land only where the addition of lime had raised the soil reaction above pH 6. Damage was severe in many stands growing on calcareous grass-heath with a naturally high soil reaction. Losses were erratic in young stands but became more uniform by the age of 30 years. Disease incidence increased in proportion to the number of thinnings only where the soil pH was greater than 6. Losses from F. annosus in pure stands of Corsican pine (Pinus nigra var. calabrica) were relatively low, as compared with those in Scots pine (P. sylvestris).