Pythium irregulareAssociated withPinusSeedling Death on Previously Cultivated Lands

Abstract

Linde, c., Kemp, G. H. J., and Wingfield, M. J. 1994. Pythium irregulare associated with Pinus seedling death on previously cultivated lands. Plant Dis. 78;]002-1005. A serious root disease of Pinus patula seedlings has occurred in the northeastern Cape forestry region of South Africa during the past 3 yr. Mortality as high as 100% was experienced 4-5 rno after seedlings were planted on previously cultivated agricultural lands. No mortality, however, occurred in plantings on virgin lands. Where seedlings survived on previously cultivated lands, their growth compared poorly with those on virgin lands. PYlhium irregulare was consistently isolated from diseased roots of Pinus parula. as well as from the soil of previously cultivated lands. P. irregulare was highly virulent when artificially inoculated onto 4-mo-old Pinus parula and 2-mo-old Eucalyplus grandis seedlings. P. irregulare. therefore, appears to be an important factor associated with deaths of Pinus parula on previously cultivated agricultural lands. South Africa is a country character