RUSTS OF PINES IN NORTH AMERICAL = RUSTS OF PINES IN NORTH AMERICAL

다국어 초록 (Multilingual Abstract)

The rust fungi infecting North American pines fall into four genera: Cronartium, Endocronartium, Cnleosporium, and Melampsora. Those in the genus Cronartium cause the majority of economic losses. Included in this genus are the introduced species C. ribicofa on white or soft pines, and the native C. quercuum f. sp. fusiforme, on the southern hard pines. These two rusts are the most damaging tree diseases in northwestern and southeastern United States, respectively. Other important Cronartium rusts include comandra (C. comandrae), sweetfern (C. comptoniae), eastern gall (C. quercuum f. sp. banksianae), and southern cone rust (C. strobilinum). Western gall rust or $quot;pine-to-pine rust$quot; (Endocronartium harknessii) is also a serious disease of hard pines in both the western United States and Canada, and eastward across the continent to the Atlantic coast. This rust is interesting because it possibly poses a threat to the commercially important southern pine forests in the southeastern United States. Needle rusts of hard pines are caused by many different species of Coleosporium, all but a few having herbaceous alternate hosts. Several other needle rusts of western hard pines are caused by Melampsora species. With few exceptions the needle rusts cause only slight to moderate economic losses, although no critical studies have been made on the impact of these diseases. In general, the various stem rusts are by far the most economically important of rust fungi, with cone rust occasionally causing heavy losses in seed orchards. Current research on North American rusts is heavily oriented toward work on white pine blister rust in the north-central and western United States and Canada and on fusiform rust in the southeastern United States. There is increasing interest, however, in western gall rust on several species of western pines, including Pinus radiata. This latter work is related to the extensive plantings of P. radiata in New Zealand and Australia. Another recent area of interest is the damage being caused in Central America by a rust, possibly cone rust, in forest tree nurseries.