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Wisconsin State Cranberry Growers Association / Wisconsin State Cranberry Growers' Association. Forty-fifth annual meeting, Wisconsin Rapids, Wis., December 2, 1931. Forty-fifth summer convention, Wisconsin Rapids, Wis., August 18, 1931

Rogers, L. M.
Cranberry culture in Wisconsin in 1931,   pp. 18-22 PDF (1.4 MB)

Page 19

Burning over the marshes to renew the vines is very good if con-
ditions are just right. Otherwise injury to the roots may follow.
Late in the fall when the ground has been frozen should be an excel-
lent time for burning. I have burned in December in Massachusetts
many times with the best of results.
Destructive insects do not appear to be particularly abundant in
the marshes this year. The black-head fireworm. as usual is present in
many localities, but its habits are pretty well understood by the grow-
ers and a good control is generally maintained. I think where the
first crop is not heavy enough to brown the vines, good work can
be done without risk of injuring the hooks by waiting until the worms
are about full grown and making a short flood of twelve hours.
Where the water can be put on quickly it would be well to start early
in the morning and have the vines all under as soon after daylight as
possible. This should be done in cloudless weather. If flooding is done
this late in the season it will also serve as a leaf-hopper control, and
if intended as such, after the vines are covered a film of oil should be
spread over the water, where it will float to leeward among the hop-
pers on the dikes. Otherwise a spray should be put on the dikes and
An insect that I think has attracted little notice as a cranberry pest
in any state has been called to my attention by northern growers. It
is the leaf miner. For some time I gave it scant attention, thinking
it would do little harm as it worked only in the old leaves and then
only in the springtime. But this season it was so numerous in some
marshes that it took all the leaves in places, and the affected plants
were obviously weakened by the attack. I have seen little of it in the
south or central part of the state. I will give a rough description of
it that growers may know if it gets plentiful on their marshes.
The insect overwinters in the egg stage. The eggs hatch in May,
and the larva feeds entirely within the leaf, mining between the up-
per and lower leaf surfaces. The larva matures early in June. It
then cuts a clean oval disk about 3/32nds of an inch long from the
leaf, sewing the upper and lower leaf surfaces together to form a
case in which to pupate. The case drops to the ground or may lodge
among the vines, where it is firmly attached by one end to stand at
right angles to the stem. The moth emerges soon after July 1. It is a
tiny, shiny creature, most active among the vines about sundown. The
moths fly for at least ten days and probably longer. They insert their
eggs inside the leaf, seldom more than one but occasionally two hatch-
ing in one leaf. The eggs are not injured by the winter flood. Soon
after the larva cuts off its case the leaf dies and falls off.
Apparently the only stage in the insect's life where we may hope
to secure control is with the millers. These are flying in mid bloom,
which practically eliminates flooding as a controL Mr. Goldsworthy
is trying some sprays which we hope may give good results.
As most of you know, in the past two seasons I have been trying
to kill weeds with some preparation that will not harm the vines.
The only compounds used to which the vines are resistant are copper

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