Diseases of economic plants (1921) Diseases of economic plants diseasesofecon00stev Year: 1921 404 Diseases of Economic Plants lower sides of the leaf spots arc small, concentrically ar- ranged, black acervuli. The disease has been troublesome on black-walnut in Delaware, Iowa, Maryland, and West Virginia. Blight â -''- (Pseudomonas juglandis Pierce).âThis blight known in 1901 only on the Pacific coast is now recorded in California, Oregon, Texas, Louisiana, Maryland, Delaware, Pennsylvania, and New York on English-walnut. Black cankered spots upon the young nuts, which fall pre- maturely, o
Diseases of economic plants (1921) Diseases of economic plants diseasesofecon00stev Year: 1921 404 Diseases of Economic Plants lower sides of the leaf spots arc small, concentrically ar- ranged, black acervuli. The disease has been troublesome on black-walnut in Delaware, Iowa, Maryland, and West Virginia. Blight â -''- (Pseudomonas juglandis Pierce).âThis blight known in 1901 only on the Pacific coast is now recorded in California, Oregon, Texas, Louisiana, Maryland, Delaware, Pennsylvania, and New York on English-walnut. Black cankered spots upon the young nuts, which fall pre- maturely, or similar spots upon the young, green shoots are characteristic. Chief damage is to the nuts, l)ut in seasons Fig. 215. â Bacterial blight of walnuts. After R. E. Smith. favorable to blight much of the terminal growth is killed and the succeeding crop is thereby reduced. Spraying is of questionable value. Care should be taken to select resistant trees for propagation. Melaxuma -' (Dothiorella gregaria Sacc). â In this dis- ease, reported from California, black sunken cankers develop on the trunk and larger limbs, and the leaves on the smaller limbs suddenly wilt. The first indication of disease is often a black area like a blotch of tar on the gray ])ark. Excision and disinfection should l)e practiced. Other walnut troubles are: Die-back, often due to lack of or
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