The objectives are to prevent further spread of the diseases by adequate nursery and budwood (mosaic) inspection and quarantine enforcement; to control peach mosaic in the commercial areas; and to suppress and hold the phony disease in check in the commercial area of the generally infected States. The first aim, properly executed, assures the production and shipment of disease-free nursery stock.

The second and third are measures of control in areas where the two diseases have ravaged commercial production of peaches. The operational programs differ somewhat by States to fit local conditions and requirements.

Several factors bear directly on the effectiveness of phony disease control: Abundance of the primary vector, density of peach and plum trees, and ecology. Certain latitudes, elevations, and soil types result in distinct types of agricultural crops and native plants, which have their effect on the abundance of vector population. The disease is most destructive in areas where Homalodisca triquetra, the primary vector of phony, is abundant and where peach and plum also are dense. As an example, in the Fort Valley, Ga., area, where phony was first discovered, those conditions favorable for the rapid development of the disease are present, and phony has taken its heaviest toll.

To be effective, control in commercial areas of high incidence must be on an area-wide basis. Experience has demonstrated that inspections made in that way will reduce or retard the annual increase in infection to the extent that peach production continues to be profitable. Annual inspections of only scattered orchards in such areas do not produce the maximum benefit.

In a phony-infected area it is a sound procedure to remove wild plums from a 300-yard zone around a new planting site at least a year before the orchard is set. That will prevent or retard vectors from picking up the disease from infected wild plums and establishing the disease in such new plantings at an early date. New orchards should not be set immediately adjacent to old infected orchards. When an old infected orchard is removed, it is not advisable to reset to Peaches immediately because infected vectors may be present. At least a year should elapse between removal and replanting.

By means of chemically testing twigs of wild plums, surveys have been made in 83 counties of 11 States. In making the surveys, 16,104 plum twigs have been tested from 550 locations. The presence of phony was indicated in 611 twigs, an average incidence of 3.8 percent. Phony disease is known to occur generally in wild plums in substantially the same area as it is known to occur in peach. Orchardists in an infected area are requested to remove wild plums from the environs of their orchards as a prerequisite to having their orchards inspected.

The following reductions in disease incidence from the peak years to 1951 indicate the effectiveness of mosaic control: California, 5.78 percent in 1936 to 0.52 percent in 1951 (90 percent reduction); Colorado, 4.43 in 1935 to 0.22 (95 percent reduction); Oklahoma, 2.59 in 1941 to 0.005 (99 percent); Texas, 0.80 in 1937 to 0.04 (95 percent); Utah, 1.60 in 1936 to 0.38 (76 percent).

QUARANTINES regulating the movement of peach and related nursery stock from and within known affected areas have been in effect for both phony and mosaic since the beginning of control operations. Products have been regulated under uniform State quarantines.

The phony quarantine in 1952 had the following requirements: Each nursery in the regulated area producing the regulated products peach, plum, apricot, nectarine, and almond shall apply to the State quarantine official for approval of proposed nursery-growing sites on or before August 15 of each year; selected nursery sites shall be at least 300 yards from wild or domesticated plum, one-half mile from phony-infected commercial orchards, and one-half mile from urban areas; the 1/2-mile environs of the nursery site shall be inspected before October 1, and all phony trees found within such environs shall be removed prior to November 1; and all budding shall be restricted to the slip-bud method.

The mosaic quarantine provides for certification of nurseries when no mosaic infection is found in the nursery stock and when mosaic-infected trees found within a mile of the nursery are removed before May 16 of each year. Because mosaic may be transmitted by means of buds from infected trees, all budwood sources must meet the same requirements as the nursery stock. The California quarantine prohibits movement of nursery stock from the regulated area.

Through the application of inspection and elimination of infected trees over a period of years, substantial reductions in the incidence of both phony and mosaic have been achieved. The practice has resulted in the apparent eradication of phony disease from Illinois, Indiana, Maryland, Oklahoma, and Pennsylvania, and from more than 100 counties in other lightly infected States. Mosaic has apparently been eliminated from 21 counties of the known infected States. All areas in which eradication apparently has been accomplished were lightly affected by the diseases when controls were first applied. In areas of general infection, control has been more difficult, but a persistent application of approved practices has achieved and maintained a sufficiently low level of infection that commercial fruit production has continued to be profitable.

A. E. CAVANAGH is the project leader on the phony peach and peach mosaic control project, with headquarters at Gulfport; Miss. He joined the Department of Agriculture in 1921. Since 1936 he has worked in Atlanta, Ga., Little Rock, Ark., and San Antonio, Tex., in connection with the phony peach and peach mosaic project.

C. H. ROTHE was born on a ranch in Texas and is a graduate of the Agricultural and Mechanical College of Texas. He Joined the Department of Agriculture in 1925 and is now assistant project leader engaged in peach mosaic disease control at Riverside, Calif.