BUREAU OF ENTOMOLOGY AXD PLANT QUARANTINE 31 
when these plants have been grown in soil treated with this dosage 
of DDT. . -^^ 
Chlordane has not been used so long or so extensively as DDT for 
control of Japanese beetle grubs, but most plants seem to tolerate the 
recommended dosage. When freshly applied, 10 pounds of chlordane 
per acre has had no noticeable effect on 7 varieties of azaleas or 21 
varieties of evergreens grown in treated nursery soils, or on 11 varieties 
of grasses, 19 of garden vegetables, 2 of strawberries, and 18 varieties 
of annual plants, spring rye. soybeans, and hybrid corn in special tests. 
However, it has retarded the *gr° wtn f celery, Massey strawberry. 
oriental poppy, and snapdragon plants. 
Quarantine and Control Activities 
Principal modifications in the regulatory program to prevent the 
spread of the Japanese beetle through the movement of infested host 
material consisted in an extension of the regulated area, provision for 
more flexibility in starting and terminating the seasonal quarantine on 
fruits, vegetables, and cut flowers, and approval of two new chemicals 
for treating plants and soil as a means of securing certification. 
Additions to the regulated areas in Maryland, Virginia, and West 
Virginia were made on April 18, 1949. With these extensions there 
are now included within the regulated areas of these States all of 
Maryland., the eastern third of Virginia; and three more counties in 
West Virginia. 
Another modification permits delay in establishment of the summer 
quarantine on fruits, vegetables, and cut flowers until actual appear- 
ance of adults or their known imminence in a particular locality. 
When such conditions are determined by on-the-spot observations of 
an inspector, the certification procedure can. be started on short notice. 
Aircraft was included in the revised regulations as a type of carrier 
subject to regulation. 
An ethylene dibromide-chlordane dip for soil about the roots of 
plants was authorized September 21, 1948. With this treatment 
nurserymen are permitted to obtain certification for most -of their 
stock on a year-round basis. Treatments have previously been avail- 
able by which plants could be certified at all seasons except the summer 
period when beetle eggs are present. Eggs proved stubbornly resist- 
ant to insecticides tested until the ethylene dibromide-chlordane dip 
was developed. 
Use of chlordane as an alternative treatment for bulk soil, surface 
soil, or ground planted with nursery stock was authorized on January 
6, 1949. A dosage of 10 pounds of technical chlordane per acre applied 
in an approved manner is sufficient to qualify stock in treated areas 
for certification. 
A total of 6,176 commercial and 6,484 military aircraft were given 
aerosol treatments to eliminate Japanese beetles during the 1948 season. 
The nonpassenger compartments of 421 commercial and 703 military 
aircraft were given, in addition, residual spray treatments. Super- 
vision of these treatments was given at 37 airfields located in 9 States 
and the District of Columbia. 
