Pathogenesis in the Wilt Diseases

A rapid laboratory method for assessing the biological control potential of Penicillium oxalicum against Fusarium wilt of tomato

“…Many authors have demonstrated that vascular wilting of tomato is caused by the impairment of water movement through the xylem of diseased plants. Decrease in water transport may be caused by collapse of xylem vessels (Chambers & Corden, 1963) or obstruction of the vascular system (Dimond, 1955). Xylem obstruction may be caused by air (embolism) (Sperry & Tyree, 1988), polysaccharides (Hodgson et al, 1949) or other materials released from plant cell walls by action of cellulases (Husain & Dimond, 1960), polygalactouronases (Van Peer et al, 1990) or pectic enzymes (Cooper & Wood, 1973;Guy & Baker, 1977) released by the pathogen.…”

Electron microscopy of elm infected with Ceratocystis ulmi (Buism) C Moreau

“…Tyloses have also been reported in wilt diseases of tobacco (Powers, 1954), hops (Talboys, 1958), grapes (Esau, 1948), bananas (Beckman et al, 1962), watermelons (Sleeth, 1933) and sweet potatoes (McClure, 1950). The occurrence of tyloses was noted less commonly in wilt diseases of tomato and mint (Dimond, 1955).…”

“…Several general reviews are Gaumann (1951), Dimond (1955), Sadasivan (1961), Beckman (1964) and Dimond (1967). Few investigations have been concerned with Dutch elm disease and the amount of information that is applicable remains to be established.…”

“…The discoloration of xylem parenchyma may result from oxidation of phenols to produce melanoid pigments which ultimately spread to other xylem elements or become trapped in occluding gums (Dimond, 1955). The exact mechanism by which the fungus induces the "browning reaction" is unknown.…”

Phytotoxic action of Endoconidiophora fagacearum Bretz

“…Since the last comprehensive review of wilt induction (Dimond 1955), a wide variety of metabolic products have been implicated, particularly with reference to tomato wilt (Gaumann 1957) . Formation arid func tion of some of these substances are well understood (Dimond ii and Waggoner 1953b;Gaumann 1957) .…”