A Comparative Study of Phytophthora Infestans on Tomato and Potato (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. Excerpt from book: The Fungus times irregularly,, scattered over fhe leaf surface. In the case of the youngest leaves these spots may "be larger and coalesced about the tip. These spots develop slowly at first, turn brown, and tend to cause a small amount of leaf curl. No rapid softening, water soaking, or rotting, however, occurs, as with infected potato plants. After a few days time the spots, now enlarged to dark areas, may exhibit the white down of conidiophore g growth on the surface. This does not occur as soon with the tomato as with the potato. The tomato plant will not succuuib under these conditions for a long while. Potted potato plants. Such plants usually developed the symptoms as commonly described. The blackening of margin and tip of leaf, the subsequent water soaking, and general darkening, were the ordinary signs noticed. In contrast to infected tomato plants the potatoes were much more rapidly and extensively diseased. Conidiophore growth usually appeared on their leaf surfaces two or three days earlier than upon tomato leaves. Tomato fruit. The fungus in infecting ripe fruit first caused small discolored areas in the skin, but because of the red oolor the subsequent darkening was not observed to be so plain in ripe as in green fruit. A dull, dark spot is developed on fruit infected in damp chambers, and this area sometimes become slightly sunken. About one week after inoculation small tufts of aerial mycelium and conidiophores appear on the surface of the now darkly splotched fruit. If left in the damp-chamber the fruit finally completely rots, mostly as a result of soft rot organisms. Brief account of the morphology of Phytophthora infeatane While no special study was devoted to the morphology of this fungus, the important characterlatics of its form and development should "be closely understood befo...