76 ANNUAL REPORTS 01 DEPARTMENT 01 AGRH I Lit KK. 1 
Excellent results have been obtained in controlling white-frii . 
beetles since I > I >T was introduced Since 1946 approximately 50,000 
acres of agricultural land have been soil-treated with 1" pounds of 
DDT to the acre. The residual effects of the insecticide are expected 
to remain for at leasl 3 years. Since L948 more than 2,500 acn 
i iv land have been soil-treated al the rate of 50 pounds of I >I >'Y an 
acre. This treatment assures destruction of beetle Larvae in the 
and allows the movement of Qursery plants from such Land to non- 
infested localities without further treatment. 
Use by farmers of DDT in fertilizer- to replenish the DDT residue 
in farm land treated in previous years was authorized in the spring of 
L951. This was too late to obtain maximum results in 1951 si] 
large part of the commercial fertilizers had been mixed before that 
date. However, some 600 tons of commercial fertilizer- containing 
0.5 pei-reiit DDT were used during the year for this purpose. 
Soil Insecticides Give Effective White-Fringed Beetle Control 
Foliage applications of approximately 10 pounds of toxaphene an 
acre for control of cotton insects during a single season have provided 
excellent control of white-fringed beetle larvae in the soil for the fol- 
lowing 2 years. DDT mixed with the soil at 25 pounds an acre gave a 
complete kill of newly hatched Larvae for 5 years after application and 
98 percent kill the sixth year. The application of ;>0 and LOO pounds 
to the'acre gave complete control I'^r the sixth year. Other insecti- 
cides that continue to loolc promising when used as -oil treatments 
t<> destroy the larvae are chlordane, toxaphene, aldrin, dieldrin, and 
heptachlor. This work- was in cooperation with tin 1 Alabama State 
I department of Agriculture and Industries and the Florida State Plant 
Board. 
Cultural Practices Fail To Influence Beetle's Development 
Studies of the development of the white-fringed beetle as related 
to cultural practices showed that the addition of stable and green 
manure to the -<>il for 2 years did not cause any appreciable change 
in the time of adnlt emergence or in the survival of immature larvae 
in either L950 or L951. 
NEMATODES INFESTING POTATOES 
Cysl Forming Nematode Found <>?i Tobacco 
A significant development during the year was the reportii g of a 
specie of //' '' / odi i <i on t he roots of tobacco in i he State of Connect- 
icut. A cooperative Federal State -oil survej conducted in Connecti- 
cut revealed infestation on four properties, three of which were 
uiow ing shade tobacco and one potatoes. Specimens submitted to the 
Division of [SJematoL y, B Itsville, Md., were found t<» k> morpho- 
Eilly indistinguishable from //- '*. This in- 
festation is particularly important since tobacco varieties have been 
I for susceptability of HeU >dera rosi w with negative 
re uh . Research workers are investigating the host range of this 
tobacco c\ st nematode. 
