The rosette disease affects many kinds of peaches, both budded fruit and seedlings. Probably the same disease occurs on many varieties of plums and almonds.
The disease was first described as a probable southern variation of peach yellows, but later it was referred to as a distinct disease. The earliest record dates back to 1879, when it was observed in the State of Georgia. Ten years later it appeared in Kansas. It has subsequently been reported from South Carolina, Arkansas and elsewhere.
Affected orchards are lost within a few years. The trouble is regarded as second to peach yellows in point of obscurity and destructiveness. The rosette disease is more rapid in its destruction than is yellows, and in Georgia, a prominent peach state, it has a wider range than yellows.
Peach-rosette is recognized by the development of a rosette or whorl of sprouts on affected limbs. The whole tree, or only one or two limbs, may be diseased. Within six to twenty-four months the tree dies. First evidence is noted in the early spring when the buds open. Instead of only a few winter buds pushing out, a great majority of them grow into shoot - axes in compact tufts or rosettes. Such are only two to three inches long, and they bear numerous small leaves. When older and larger leaves are affected, they show an inrolling of the margins and a peculiar stiffening due to the midrib becoming straight. Smaller leaves are seldom rolled. Affected foliage turns yellow early in the summer and falls prematurely. Often leaves are blotched, browned and deadened at the ends and margins from the attacks of secondary leaf fungi. Fruit on rosette trees falls prematurely. Diseased trees show less tendency to develop sprouts on the trunk and main limbs.
Peach - rosette differs from yellows in the more tufted character of the growths; in the absence of premature ripening of the fruit; more rapid destruction; and usually rosette is confined to the tips of branches, occurring but rarely on trunks and at the base of main limbs. It resembles yellows in the pushing out of dormant (adventitious) buds which develop diseased branches; the dormant buds tend to unfold in the summer and autumn; and only a portion of a tree may be affected, whereas the remainder is normal.
This disease does not seem to be due to plant or animal parasites, nor to any chemical ferment. On the other hand, there is the slight possibility that it is caused by a bacterium which as yet has not been seen. The disease is contagious; the causal factor, whatever it may be, is readily spread by bud-inoculation, by root - grafting, or by blowing leaves. There are doubtless other ways by which it is spread, but as yet they have not come to light. Within two to ten months after a tree is inoculated first signs of the rosette disease are apparent.
The prevention of rosette is not known to be possible. All affected trees should be promptly destroyed. This should be done early in the spring as soon as the disease appears, and before the leaves fall. In those regions where the disease is present, attention should be given to the plum, which at times shows symptoms of rosette similar to those described for the peach.
Smith, E. F. Additional evidence on the communicability of peach yellows and peach rosette. Part II. - Peach rosette. U. S.
Agr. Dept. Veg. Path. Div. Bul. 1: 45 - 58. 1891. Smith, E. F. Peach yellows and peach rosette. U. S. Agr. Dept.
Farmers' bul. 17:5-20. 1894. Smith, E. F. The peach rosette. Journ. Myc. 6: 143-148. 1891. Smith, E. F. Additional notes on peach rosette. Journ. Myc. 7:226 - 232. 1893