Report on the Agricultural Experiment Stations, 1951 Page: 90
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90 REPORT ON EXPERIMENT STATIONS, 1951
cide. The new strip method removes the danger of milk contamination
since the screening may be dipped and dried outside the barn, and
fastened to the ceiling out of reach of livestock.
Mist concentrate sprays profitable on fruit
One of the costliest operations in commercial fruit growing has
been that of applying spray schedules that would reduce both insect
and disease damage. Research at the Pennsylvania station, in cooperation
with commercial growers, extension specialists, and chemical
spray manufacturers has developed mist concentrate sprays that have
reduced spraying costs. In concentrate spraying, air-blast sprayers
are used and larger quantities of chemicals are put in a smaller amount
of water. This mixture is then atomized through nozzles with fine
openings into an air current that drives it into the trees. By this
system air is used as a substitute for most of the water required
formerly. Instead of applying 15 to 20 gallons of coarse spray to an
apple tree, a grower blows 3 to 4 gallons of fog-like mist into it.
Growers in southern Pennsylvania used concentrate spraying on
about 500 acres of fruit in 1949 and on more than 1,000 acres of apples,
peaches, and cherries in 1950. No wasteful drip was found underneath
trees sprayed the new way. Spray chemicals applied with
air-blast sprayers stay on the trees. Actually, growers used 40 percent
less spray material than was necessary by the old method. They
hauled only 20 percent as much water and used only 30 percent as
much labor. Their savings ranged from $50 to $60 per acre. There
are over 30,000 acres in the area in blocks large enough to be suitable
for concentrate spraying.
Ant control reduces fruit pest
The California station reports that killing ants on orange trees increased
the amount of foliage and fruit as well as the size of the fruit.
The ants attack the parasites of insects that feed on orange trees. Killing
the ants allowed the natural insect enemies to establish biological
control of plant-feeding insects. Naturally the removal of these pests
improved the health and vigor of the tree, which resulted in an increase
in the number and size of the oranges.
The experiments got under way by making comparisons between
ant-free and ant-infested trees in a number of groves. The groves had
been untreated for periods of several years and natural enemies had
been given a chance to establish themselves without interference from
applications of insecticides. For example, one of two orange trees
was kept ant-free for 2 years. At the start pest populations on the
two trees were very similar. The condition of the two trees was virtually
identical. Since then the ant-free tree has become more and more
free of pests until now it is exceptionally clean and very vigorous.
The ant-infested tree, although never too heavily populated by any
given pest at any one time, has suffered cumulative damage from increasing
numbers of citrus mealybugs, red scale, soft-brown scale,
black scale, citrus red mites, and aphids until real differences between
it and the ant-free tree were evident after 2 years. The ant-infested
tree now has considerably less foliage than the ant-free tree and 70
percent as much fruit. The fruit is smaller, averaging 344 per box
compared with larger sized oranges (200 per box) on the ant-free tree.
Noticeable differences between the insect infestations on the two trees
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1951, book, January 1952; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5991/m1/92/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.