Tomato Anthracnoses

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University of Wisconsin--Madison, 1915 - Anthracnose - 102 pages
 

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Page 12 - Glceosporium on tomato, as well as from those of Col. lagenarium. There is a scant development of decumbent, spreading mycelium, with a strong tendency to concentric markings in the growth, where the mycelium is more erect and in tufts, surrounding black, spherical perithecialike bodies which produce long setae. These, so far as has yet been determined, are sterile. The conidia formed freely on the mycelium do not mass up in large heaps.
Page 6 - RIPE ROT" OR ANTHRACNOSE OF THE TOMATO. Colletotrichum lycopersici Chester. SYMPTOMS. The diseased spots may vary from small, sunken, smooth areas, sometimes darker in color than the surrounding healthy tissue, again yellow and dotted with the small fruit masses or acervuli of the fungus, to large roughened areas, brown to almost black, covering an entire side of the fruit. A great many of the older spots have a characteristic which is very noticeable, that is, the zonation rings. These are plainly...
Page 5 - ... destruction of fruit. So far as observed it does not affect the green tomato, but rather at the point when it just begins to color, and from that on to complete ripening. When, however, an attack is once made, the malady spreads so rapidly as to occasion serious loss before the fruit can be gathered. The disease shows itself upon the tomato as sunken, discolored spots, each with a dark center, becoming black. These spots increase in size, or by confluence cover a large portion of the decaying...
Page 13 - The appressoria (PI. VII, fig. 18) as found in this species are oval bodies, smooth in outline or with knob-like projections, dark brown, and contain a few large oil drops. They are invariably the first objects to come into focus when a hanging drop preparation is examined. Certain hyphae seem to grow up towards the cover glass and when it is reached, thru mechanical stimulus or otherwise, these attachment organs are formed.
Page 5 - An anthracnose causing a ripe rot of the tomato is manifested at first by a small, circular, depressed area. Older spots show a lighter central portion surrounded by a dark marginal band 2 to 3 cm.
Page 37 - In parts recently affected the contents of one or more cells were browned and changed from the normal vacuolar structure into a brown mass containing oil globules and sometimes crystals not found in normal cells nearby. The radius of transformation of the cell contents extended at times over about ten cells. Hair bases from which the hairs are broken off are often browned in that way.
Page 13 - VI, flg. 17). This process gradually continues until the entire acervulus is one blackened heap (PI. VI, fig. 16). The setae apparently break or fall off, as little or no evidence was found of their previous existence. The conidia also disappear, falling upon the surrounding tissue or scattering elsewhere. At times these blackened heaps occur upon the anthracnose spot from the time the epidermis is ruptured by the fungus. In such a case few typical acervuli are developed. The spherical dark aggregations...
Page 18 - ... of the colony where the new growth continues. As these darkened masses are developed, the conidia formation ceases. The spores which have been produced germinate and grow into a new mycelium. The latter, due to lack of nutrition, does not produce spores a second time. The blackened areas gradually heap up until they are more or less spherical and somewhat confluent. They are sterile and may or may not produce setae. At times, especially in freshly isolated cultures, small pinkish heaps precede...
Page 6 - I. figure 1. In such a concentrically arranged spot the acervuli will be massed together in circles, while a portion of firmer tissue with no external evidence of disease intervenes. This zonation may be noticed in the first photograph taken of this anthracnose by Chester.8 In Plate I, figure 3, the diseased area either presents a homogeneous surface with the acervuli arranged promiscuously, or only a slight zonation is noted. In the several isolations and inoculations made, it...
Page 13 - ... confluent. They are sterile and may or may not produce setae. At times, especially in freshly isolated cultures, small pinkish heaps precede the formation of the black aggregations. These seem to be the typical acervulus with setae and spores. Under natural conditions, an examination of the tissues of an anthracnose spot which has not yet produced acervuli, shows an abundant production of primary spores which are formed in the same manner as that of the conidia in cultures. As the spot becomes...

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