Our Domestic Quarantines

Herbert J. Conkle.

An important function delegated by the Congress to the Secretary of Agriculture is the responsibility for preventing or retarding the spread of insects and plant diseases that are new to the United States or that have not become widely distributed here.

In 1905 the Congress passed the Insect Pest Act ,which provided authority to regulate the entry and interstate movement of injurious insects. It came none too soon the foreign insects already here had had years in which to establish themselves so thoroughly that one group of them eats up nearly one-tenth of our grain crop and all of them cause losses of millions of dollars every year. About go percent of the introduced pests had come in with shipments of plants and seeds and most of the others with plant products the most effective methods of inspection will not always reveal all injurious insects or plant diseases they may carry. There was need for regulating the importation and interstate movement of pest carriers, and recognition of that need resulted in the passage by the Congress in 1912 of the Plant Quarantine Act. The Act authorized the Secretary of Agriculture to promulgate and enforce quarantines and regulations needed to regulate the entry and interstate movement of known carriers of insect pests and plant diseases.

Soon a domestic plant quarantine was established to prevent further spread from New England of the gypsy moth and the brown-tail moth, destructive defoliators of trees, which had spread in New England and caused fears that the expanding commerce in materials that carried them would spread infestations unless quarantine action was taken promptly. Quarantine and control efforts by Federal and State Governments and local organizations greatly reduced the numbers of the moths in most infested areas and helped to keep them from becoming distributed over large areas of the United States.

At about the same time a quarantine was promulgated to prevent the further spread of two imported date palm scale insects from infested areas in Arizona, California, and Texas. One of these, the red date scale, was removed from consideration in 1932 as it was found to be commercially unimportant. The quarantine, and control measures were so effective that the other one, the parlatoria date scale, was apparently eradicated and the quarantine was revoked in 1936.

Several other major agricultural insect pests of foreign origin later became established here. The existence of enabling legislation, however, permitted prompt and decisive action through quarantines to attempt to prevent their further spread while control and eradication measures were carried out.

Some of the insects spread rapidly despite quarantine and control efforts and eventually reached a status of distribution that made continuance of the Federal quarantines impracticable. For that and other reasons the Federal quarantines on account of the European corn borer, the satin moth, the Asiatic garden beetle, the oriental beetle, the thurberia weevil, and narcissus bulb pests were eventually revoked.

A quarantine on account of the Mediterranean fruit fly was put into effect in April 1929, soon after it was discovered in Florida. Quarantine action prevented its spread to other States. Control work was so effective that it was eradicated. The quarantine was revoked in November 1930.

Federal domestic plant quarantines were in effect in 1952 to assist in preventing further spread of six introduced insects, the gypsy and brown-tail moths, Japanese beetle, pink bollworm, Mexican fruit fly, and white-fringed beetles. Some spread of these insects has occurred beyond the areas of introduction, but their more extensive dissemination has been prevented through the quarantine and control measures.

Domestic plant quarantines are also in effect to prevent or retard further spread of two seriously destructive introduced plant diseases, the black stem rust of grains and the white-pine blister rust.

WHEN PLANT PESTS new to this country are found here, the Department of Agriculture determines the extent of infestation and the potential hazard to the agricultural and related interests of the Nation. When it seems apparent that a newly introduced pest would become a hazard to agriculture if it should spread, and that quarantine measures could be expected to prevent or retard the spread, the Secretary of Agriculture calls a public hearing. Interested persons present their views and arguments for or against quarantine action. If it is determined from evidence presented at the hearing that quarantine action is necessary in the public interest, the Secretary promulgates a quarantine. In general, such a quarantine regulates the interstate movement of articles that might serve to spread the pest. Intensive measures to attempt eradication or control of the infestation usually are put into effect immediately. They may include application of insecticides, eradication of host plants, or cultural practices known to be effective in reducing infestations. Such measures usually reduce the hazard of spread materially even though they may not eradicate the pest.

QUARANTINE REGULATIONS normally include four items : A description of areas from which the interstate movement of carriers of the pest will be regulated; a list of the articles the movement of which will be prohibited or regulated, including the live insect in any of its stages and things upon or in which the pest may be carried normally; the conditions under which regulated articles may be moved; and the provisions under which certificates or permits may be issued for movement of regulated articles.

The regulated area is primarily determined by the extent of infestation. Entire States in which infestations occur are placed under quarantine, but the regulated area is usually restricted to the infested area and a surrounding safety border. If the infestation is general throughout the State, the entire State may be included within the regulated area. Annual surveys are usually made to determine the limits of the infested areas or to discover incipient infestations that may occur at a distance from the known infested areas through natural spread of the pests or because of accidental artificial spread.

Quarantine regulations are amended or revised as often as necessary to include additional areas in which the pests may be found.

It is possible sometimes to reduce the regulated areas when infestations apparently have been eradicated from an area and intensive inspection over a period of several years discloses no further infestation.

The regulated areas are kept as small as possible consistent with conditions that will permit effective prevention of spread of the pests and reasonable quarantine enforcement procedures. One requirement is regulation by the State concerned of the intrastate movement of regulated articles to prevent further spread within the State. Federal quarantine action with regard to infestations in some States or parts thereof sometimes is withheld because of the effectiveness of State quarantine and control measures in preventing spread.

Most Federal quarantines prohibit the interstate movement, except for scientific purposes, of any stage of the live insect subject to quarantine. Such action, authorized by the Insect Pest Act of 1905, is taken primarily to bring the restrictions of that Act pertaining to the specific insect involved to the attention of shippers within the regulated area who may become familiar with the quarantines applicable to them but who are not so generally aware of the Insect Pest Act.

The movement of articles is regulated when they are known to be general carriers of the pest in any of its live stages. It would be impracticable to regulate movement of every article that might be a carrier of such pests, because under some conditions almost anything could serve as a carrier. The list of regulated articles is therefore restricted to include only the ones that ordinarily may be considered hazardous in spreading the pests. Because other articles might be carriers at times, the newer quarantines usually include an additional feature to permit regulatory action by quarantine enforcement officers in regard to any other articles, products, or things, the movement of which may involve a hazard.

WHEN QUARANTINES involve insects that feed on a wide variety of plants or that are soil inhabiting, the movement of a wide variety of items may be regulated. Quarantines involving insects that are restrictive in their feeding or life-cycle habits and plant diseases that are restricted in their host relationships may regulate the movement of specific plants, fruits, or products. The gypsy moth and brown-tail moth quarantine regulates movement of woody nursery stock and forest products because the insects are pests primarily of forest and shade trees. Stone and quarry products also are regulated because the gypsy moth frequently lays its eggs on such materials. The Japanese beetle and the white-fringed beetle are soil inhabiting in their larval stages and in the adult stages feed on a wide variety of plants. With both insects it is necessary therefore to regulate movement of soil and related materials as well as plants and other things upon which the adults may be carried, and, in regard to the white-fringed beetle, several articles on which it may deposit eggs.

The pink bollworm harms cotton and okra. Therefore the quarantine on it regulates the movement of cotton plants or parts thereof and unmanufactured cotton products and things or machinery associated with the handling or processing of cotton. The pink bollworm quarantine also regulates the movement of okra.

As the Mexican fruit fly is a pest primarily of certain citrus and other fruits, the quarantine regulates the movement of the citrus fruits in which its larvae normally live and prohibits the movement from the infested area of other host fruits.

Sometimes articles that may carry plant pests cannot be freed from infestation satisfactorily by known methods of treatment, or freedom from infestation cannot be determined satisfactorily by inspection. Quarantines therefore have to prohibit movement of such materials from infested or regulated areas. Such prohibitions often impose serious hardships on shippers, but research organizations constantly are seeking ways to treat such materials effectively; when they are found and have proved satisfactory, they are put into use immediately. Prohibitions on movement can then be relaxed to permit movement after specified treatment.

The conditions under which regulated articles may move depend on the degree of hazard of pest spread represented. In general, no regulated articles may be moved from the regulated areas unless they are free from infestation.