Infection of lettuce by Microdochium panattonianum.
On lettuce leaves most conidia of M. panattonianum germinated by producing short appressoria which penetrated epidermal cells directly. Extensive colonization of leaf tissue occurred within 72 h, necrotic lesions were visible after 96h and sporulation occurred on and within the leaf tissues. The pattern of colonization and sporulation on Lactuca serriola was similar to those on L. sativa. At temp. >5°C, infection levels increased with increase of leaf wetness period following inoculation. Opt. infections occurred following leaf wetness periods > 8 h at 15°. The control of overhead irrigation to minimize infection periods in the field is discussed.