s oil. When inges ted by a foraging beetle grub they multiply prodigious ly in its blood, caus ing it
to turn an abnormally white color, hence the popular name, ‘milky disease’.
Milky disease was discovered in New Jersey in 1933. By 1938 it was rather widely prevalent in
the older areas of Japanes e beetle infes tation. In 1939 a control progra m was launched,
directed at s peeding up the s pread of the dis eas e. No method had been develope d for growing
the disease organism in an artificial medium, but a satisfactory substitute was evolved; infected
grubs are ground up, dried, and c ombined with chalk. In the s tandard mixture a gra m of dus t
contains 100 million spores. Between 1939 and 1953 some 94,000 acres in 14 eastern states
were treated in a cooperative federal s tate progra m; o the r areas on federal lands were treated;
and an unknown but extens ive area was treated by private organizations or individuals. By
1945, milky s pore dis eas e was raging among the beetle populations of Connecticut, New York,
New Jers ey, Delaware, and Maryland. I n s ome tes t areas infection of grubs had reached as high
as 94 per cent. The dis tribution progra m was dis continued as a governme ntal enterp ris e in
1953 and production was taken over by a private laboratory, which c ontinues to s upply
individuals , garden clubs , citizens ’ as s ociations , and all others interes ted in beetle control.
The eas tern areas where this program was carried out now enjoy a high degree of natural
protection from the beetle. The organism remains viable in the soil for years and therefore
becomes to all intents and purpos es permane ntly es tablis hed, increas ing in effectiveness , and
being continuous ly s pread by natural agencies. Why, then, with this impres s ive record in the
Eas t, were the s ame procedures not tried in Illinois and the othe r mi d- western states where the
chemical battle of the beetles is now being waged with s uch fury?
We are told that inoculation with milky spore disease is ‘too expensive’—although no one
found it s o in the 14 eas tern s tates in the 1940s. And by what s ort of accounting was the ‘too
expens ive’ judgment reached? Certainly not by any that as s ess ed the true cos ts of the total
des truction wrought by s uch programs as the Sheldon s praying. This judgment als o ignores the
fact that inoculation with the s pores need be done only once; the firs t cos t is the only cos t. We
are told als o that milky s pore dis eas e cannot be us ed on the periphe ry of the beetle’s range
becaus e it can be es tablis hed only where a large grub population is already pres ent in the s oil.
Like many othe r s tateme nts in s upport of s praying, this one needs to be ques tioned. The
bacterium that caus es milky s pore dis eas e has been found to infect at least 40 other s pecies of
beetles which collectively have quite a wide distribution and would in all probability serve to
establish the disease even where the Japanese beetle population is very small or nonexistent.
Furthe rmore, becaus e of the long viability of the s pores in s oil they can be introduced eve n in
the complete abs ence of grubs , as on the fringe of the pres ent beetle infestation, there to await
the advancing population.
Thos e who want immediate res ults , at whatever cos t, will doubtles s continue to us e chemicals
agains t the beetle. So will thos e who favor the mode rn trend to built-in obs oles cence, for
chemical control is self-perpetuating, needing fre que nt and c os tly repetition. On the other
hand, those who are willing to wait an extra season or two for full results will turn to milky
disease; they will be rewarded with lasting control that becomes more, rather than less
effective with the passage of time.
An extens ive program of res earch is under way in the United States Departme nt of Agriculture
laboratory at Peoria, Illinois, to find a way to culture the organism of milky disease on an
artificial medium. This will greatly reduce its cost and s houl d encourage its more extens ive us e.
backadmin
(backadmin)
#1