@article {Perala:1965:0015-749X:347,
	author = "Perala, Donald A. and Sucoff, Edward",
	title = "Diagnosing Potassium Deficiency in American Elm, Silver Maple, Russian Olive, Hackberry, and Box Elder",
	journal = "Forest Science",
	volume = "11",
	number = "3",
	year = "1965",
	abstract = "Ulmus americana, Acer saccharinum, Elaeagonus angustifolia, Celtis occidentalis, and Acer negundo were grown in solutions containing +K+Na, -K+Na, +K-Na, -K-Na. In addition Ulmus americana seedlings were grown at all possible combinations of +K or -K and three levels of P. The -K seedlings grew less; their old leaves became necrotic and their young leaves, chlorotic. The leaf discolorations and reduced growth were associated with definite low concentrations of K in the leaves. Na and P concentrations in the supply or in the leaves did not affect deficiency, except that plants supplied low P had no terminal chlorosis. The origins of the terminal chlorosis are discussed.",
	pages = "347-352",
	url = "http://www.ingentaconnect.com/content/saf/fs/1965/00000011/00000003/art00018"
}