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Wisconsin State Cranberry Growers Association / Wisconsin State Cranberry Growers' Association. Forty-seventh annual meeting, Wisconsin Rapids, Wisconsin, December 14, 1933. Forty-seventh summer convention, Wisconsin Rapids, Wisconsin, August 8, 1933

Goldsworthy, Vernon C.
1933 insect situation in Wisconsin and control methods,   pp. 33-39 PDF (1.7 MB)

Page 34

for its control has ever been worked out. Sanding, destruction of
wild fruit surrounding the marsh in which they breed, putting water
on early in the fall for two weeks when the water is warm (60' F)
all help some, but none of these methods give very good control.
Trichagamma parasites were tried the last two years and while they
seemed to be of a benefit, I found they did not give as good a control
as hoped for, although it is extremely difficult to check closely.
The cranberry leaf-miner (Coptodisca negligence) which is strictly
a Wisconsin cranberry insect and has never been reported on any
other cranberry marsh, except in Wisconsin, is increasing particularly
on the northern marshes. Excellent method of control has been
worked out by the author which consists of a nicotine sulfate spray
applied shortly after the moths emerge and before they have a chance
to lay eggs for the next year's brood of leaf-miners. Usually three
sprays must be applied at intervals of three or four days as the moths
do not all emerge at the same time. The adult moth appears about
July 4th. There is one brood a year.
The leaf-hopper population on Wisconsin marshes is increasing and
false blossom is spreading. Do not think for one minute because you
cannot note its spread readily with the naked eye that it is not spread-
ing. False blossom is an insidious thing and is spreading unquestion-
ably on every marsh in the state to some extent and will continue to
spread as long as the blunt-nosed leap-hopper (Euseelis striatulus) is
present and diseased vines are available as a source of the virus. Some
marshes do not have many of the blunt-nosed leaf-hoppers, the only
carriers of the disease, but on any marshes where the hoppers are pres-
ent in any numbers they must be fought at once. Do not wait until
there is a fair percentage of false blossom in a section, or leaf-hoppers
three hundred to four hundred in a hundred sweeps-it is too late
then for control, just like locking the stable after the horse is stolen.
When 50% of the vines become infected it is merely a question of
time when the balance will become worthless, unless, of course, dras-
tic conditions alter its spread. Moreover, remember false blossom
vines, once they become badly diseased, do not bear fruit and never
recover. Just stop and think-suppose a section is 50%e false, you are
only getting one-half a crop, and you will never get any more, but
less and less. Suppose you have a section of good Searls Jumbo and
they yield 100 barrels to the acre. If the section becomes 50% in-
fected, you lose fifty barrels and even at the low price of $8.00 per
barrel that means you are losing $400 an acre, and on a marsh of
twenty acres that would mean $10,000 a year. Do not trust your eye
to tell you if the disease is increasing-there is no man on earth, no
matter who he is, that can positively tell the current year's infection
and the only way an infection can be detected is by waiting at least
one year and seeing the symptoms which we are all so familiar with,
and when we see the symptoms the vine is hopelessly lost. Once
again, let me caution you not to wait before practicing control if you
have the leaf-hoppers in any quantity.
Vines vary in their susceptibility to false blossom. but no vines or
variety are immune. McFarlin vines are quite resistant, but in the
author's thesis an experiment reported and conducted under the di-
rection of Mr. Bain and suggested by him proved verv conclusively
that the McFarlin will take the disease when exposed to the feeding
of hoppers which have been infected by first feeding on diseased vines.
Dr. Franklin in the East has proven the disease is insect borne, and a
repetition of his experiments in Wisconsin bv Bain, Rogers and Golds-
worthy uphold this fact. Some growers still believe that cultural con-
ditions cause false blossom, such as dryness or wetness. I will def-
initely state that I will give any cranberry plant that anyone in the
world may pick out the disease of false blossom absolutely every time

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