BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 21 
Beet Leafhopper and Associated Curly-Top Disease 
Controlled on Cantaloups 
Experiments in Arizona on the beet leafhopper as a pest of canta- 
loups showed that when leaf hoppers infected with curly-top disease 
feed on cantaloup plants in the cotyledon or two-leaf stage of develop- 
ment, the plants usually die. Feeding of these insects on cantaloup 
plants in the four-leaf stage of development caused severe stunting 
of these plants resulting in very low yields. Plants fed upon in the 
six-leaf stage or later were only slightly retarded in growth, followed 
by a slight reduction in yield. In some cases there was also a slight 
reduction in the sugar content of the melons produced on affected 
plants. The investigations showed that there is a definite relation- 
ship between the occurrence of certain species of weeds in cantaloup 
fields and the prevalence of the beet leafhopper and the curly-top 
disease in such fields. These weeds are known to be preferred hosts 
of the beet leafhopper. It was shown further that in cantaloup 
fields where clean cultural practices were followed to destroy these 
species of weeds the beet leafhopper populations and resultant curly- 
top disease remained at a low level. 
In further experiments in Arizona, wherein various insecticides 
were tested against the beet leafhopper on cantaloups, it was found 
that DDT and parathion dusts are effective against the leafhoppers 
as well as against associated infestations of thrips. The application 
of DDT, however, often caused an increase in the populations of 
spider mites and leaf miners on the treated cantaloups, and also 
caused a reduction in the number of parasites and predators of the 
leaf miners and red spiders. In view of these complications a 2-per- 
cent parathion dust is now being recommended for beet leafhopper 
control. 
Seed Treatment Effective Against Seed-Corn Maggot 
Research in California and Idaho on the biology and control of 
the seed-corn maggot as a pest of beans showed that three types of 
seed treatment — dry coating, wet treatment in the form of a slurry, 
and spraying an insecticide in the furrow simultaneously with the 
seed-planting operation — were effective against this insect. Aldrin, 
chlordane, dieldrin, and lindane were used for the purpose. All of the 
treatments caused injury to the sprouting seed under conditions of 
high soil moisture, high soil alkalinity, or deep planting. The spray 
method appeared to be safest, due to lower and more uniform concen- 
tration of the insecticide in contact with the seed. The fungicide 
Arasan was found to be safer than Spergon when used on the seed 
in combination with an insecticide. Studies on other phases of this 
problem disclosed that fields where cover crops, manure, or refuse 
from preceding crops are plowed under are attractive to seed-corn 
maggot flies until this organic matter disintegrates, indicating that 
these materials should be plowed under several weeks before beans 
are planted. 
