01379nas a2200133 4500008004100000245008200041210006900123300001100192490000700203520088400210100002101094700001501115856011501130 1957 eng d00aA leaf and twig disease of English holly caused by Phytophthora ilicis N. sp.0 aleaf and twig disease of English holly caused by Phytophthora il a95-1010 v473 a

This is an expanded account from Oregon State College, Corvallis, of a disease of holly caused by Phytophthora sp. [34, p. 328], for which the name P. ilicis n.sp. is proposed. It was shown that the defoliation which accompanies the disease is due to the production of ethylene by infected leaf tissue. The disease develops from October to May, and is inactive in the summer. The pathogen is distinguishable from P. porri by its smaller oogonia, and from P. hibernalis and P. syringae by the consistent presence of amphigynous antheridia. On diseased holly tissues the sporangia have a shallow apical thickening and no papilla, and measure 18 to 30 by 30 to 50 (average 24 by 39) µ, with persistent pedicels, 5 to 15 µ long. Oogonia average 21 µ and oospores 18 µ, with a slightly yellow wall; antheridia average 13 by 1µ.

1 aBuddenhagen, I W1 aYoung, R A uhttps://forestphytophthoras.org/references/leaf-and-twig-disease-english-holly-caused-phytophthora-ilicis-n-sp