BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 47 
Quicker Vapor-Heat Sterilization Treatment Under Test 
A modification in the vapor-heat treatment used in certifying cer- 
tain fruits from areas infested with the Mexican fruit fly employs a 
run-up to higher temperatures without the holding period previously 
required. Out of more than 4 million immature flies in test fruit there 
was no survival after fruit temperature exceeded 117° F. Manila 
mangoes and three varieties of grapefruit were sterilized to 117° F. 
without detectable change in flavor or measurable loss in ascorbic 
acid. 
TRUCK-CROP AND GARDEN INSECTS 
Control Campaign Against Sweetpotato Weevil Continued 
Growers and packers benefit from control of sweetpotato weevil 
Utilizing the treatment for control of sweetpotato weevils developed 
last year, in cooperation with the Louisiana Department of Agricul- 
ture and Immigration, storage operators in Louisiana dusted with 
DDT more than 1.5 million bushels of sweetpotatoes. The sweet- 
potatoes were washed to remove any hazardous residue before they 
were marketed. The new treatment proved practical and economical. 
By destroying the weevils it prevented the severe losses that occur in 
infested sweetpotatoes during storage. Now that sweetpotatoes in 
storage are no longer a source of infestation to nearby plantings and 
the April 1 storage clean-up deadline has been extended indefinitely, 
sweetpotatoes are being marketed in a much more orderly fashion. 
The DDT treatment was of particular benefit to growers and pack- 
ers in the heavy producing areas of southwestern Louisiana. In 1946 
as high as 20 percent of the sweetpotato crop there was weevil-infested. 
This year DDT treatments and sanitary practices reduced infestations 
to oelow 3 percent. 
The treatment also assures to the growers an adequate supply of 
weevil-free planting stock. Before it was developed the growers in 
heavy producing areas required such large quantities of planting 
stock that they were unable to obtain enough weevil-free certified seed 
sweetpotatoes. To fill this need in the Louisiana control areas, more 
than 300.000 bushels of seed sweetpotatoes were dusted with DDT at 
the time of storage in the fall of 1950. 
Extensive farm areas freed of sweetpotato weevil 
More than 1,70;) farms were rid of sweetpotato weevils as a result 
of eradication and control measures carried on during the year in 
cooperation with the States of Alabama, Florida. Georgia, Louisiana, 
Mississippi, South Carolina, and Texas. This farm land included 
all properties in three counties. Approximately 12,000 farms have 
been freed from weevil infestation since the cooperative eradication 
began in 1937. Thirty counties once infested are now free from the 
weevil. 
Educational campaign stimulates control efforts by growers 
An educational campaign like that used effectively in 1950 in Louisi- 
ana to reduce losses from the sweetpotato weevil and prevent further 
spread of the pest was extended to Georgia, Florida, and South Caro- 
