The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1924-05-09
Little Nema Big
Problem on Farm

or by opening it with green crops
turned under and by thorough culti-
walton.
Attacks Variety of Crops.
Among the many crops attacked by
the root-knot nematode, the most i'm
portant are alfalfa, clover cotton,
COW peas with the exception of few
varieties), field peas, fax, fig, grape.
peach, soy beans with the exception
of the Laredo Variety, pumpkins,
sugar beets, sugar cane, sweet pota-
toes, tobacco, vetch, large number of
truck crops, ornamental plants and
trees. Some of the plants attacked
are legumes which normally have no.
dulles produced by beneficial bacteria
but usually it is not difficult to dis
tinguish between these growths and
those chickering's on the roots made
by the gall nematode. The former are
more or less globular and easily re-
moved, while the latter are usually
club-shaped or irregular masses, real
'ly enlargments of the roots and root
lets themselves.
When the soil freezes large numbers
of the nematodes are killed off and,
as consequence, the pest is not so
bad In the northern states as in the
southern. However, enough of the
organisms get down below the frost
line so that they never are annihilated.
In greenhouses they become bad pests
in any part of the country, but by
treating the soil with hot water or
steam ii is possible to destroy them
along with fungi and many undesir-
able bacteria 1t is now recommend
ed that new greenhouses be construct
ed In the first place with tile or pipes
in the beds with view TO steaming.
Although nemas exist in enormous
numbers and kinds in the soil and are
of great Importance in crop produc-
ton, there are important species which
infest different animals, insects and
man. The hookworm is a nema, and
there is one infesting fox which is
blood red in color and attains length
of several feet. Investigations are be-
ing made by the department to learn
if these parasites can be used to COM
bat certain insects of economic impor-
lance. 1t has been found that a GER
tain nema has prediction for grass
hopperS, and Doctor Cobb is of the
opinion that it is this enemy, in some
cases, which causes the hopper"
scourge to rise and subside in great
waves. This nema, which attains
length of 20 inches or more and is
about the thickness Of coarse thread,
makes the host insect sterile, and in
that way reduces the increase enor-
plentiful the parasites increase and cut
down their numbers; then through
lack of grasshoppers the nemas de-
crease, and the cycle repeats. Inves-
tigators are now trying to find out II
it will be practicable to introduce this.
particular nema in regions where the
choppers" are not infested, and in that
way help protect the crops.
Have Economic Possibilities.
There are many other possibilities
for utilizing these natura, enemies in
the interest of the farmer. There is
nema parasite infesting the cucumber
beetle and study is being made of
the problem of introducing them in
localities where this beetle is abun-
dant and not already badly infested.
Practically all the injurious insects,
and the beneficial ones as well, are
thought to have their nemas, and 1t
is possible that some day these para
sites will be used for our benefit just
as insect parasites Of insects are
now being used in efforts TO control
such economic pests as the Japanese
beetle, the European corn borer and
various caterpillars.
In the soil and in water there are
nemas which prey on other species OF
their own kind and it is thought pos
sible that some day we may be able
to increase the numbers of those pre-
datory nemas which prey on the eco
nomically destructive ones.
This field of nematology is one which
it is thought may be cultivated with a
great deal of promise for the farmer.
1t is certain that much more work
must be done in the control of those
that are reducing the yield of crops,
particularly that widespread one
which produces root-knot on so many
valuable plants.