Infection of Pinus radiata needles by Dothistroma pini

Abstract

Summary Seedlings of Pinus radiata were sprayed with conidial suspensions of Dothi‐stroma pini under controlled conditions. Germination of conidia was virtually complete within 48 hours. The mycclium grew on the needle surface for 7‐10 days and produced secondary conidia before entering the needle tissues through stcmata. tlyphac grew inter‐ and intra‐cellularly and caused disruption of the mesophyll cells. Hulbary's (1941) observations on stromatal development were confirmed. Stromata of D. pini appeared on the needle surface 3 1/2‐4 months after inoculation. Some evidence of exotoxin or exo‐enzymc production by D. pini hyphac was obtained.