Ottumwa tri-weekly courier. [volume] (Ottumwa, Iowa) 1903-1916, 1912-08-08
PEAR THRlPs, A NEW ORCHARD PEST
THE PRoDUCTIvENEss OF MANY ORCHARDS IN
THE FRUIT GROWING STATES HAS, FOR
SEVERAL YEARS, BEEN GREATLY
REDUCED BY THIS INSECT.
BY p. J. PARROTT.

| For = number Of years pear bios
SONS In orchards in the state of New
York and other parts of the east have
blighted, resulting in more or less ex-
tensive losses in fruit yields.
Careful studies during the past
year have shown that the injury Is
caused BY the pear thrips. new
orchard pest, which has attracted con-
siderable attention in recent years IN
California because Of its destructive
ness to various deciduous fruits.
Tho adult thrips. which is largely
responsible for the injuries to the
trees. is small, darkish brown
winged insect measuring about one
twentieth Of an inch in length. 1t APP
pears in destructive numbers when
the buds are opening. attacking the
tenderest of the flower parts. The
eggs are mostly deposited beneath the
epidermis of the blossom and fruit
stems Matching takes place within a
few days, and the larvae seek prefer
ably the calyx cups, undersides OF
calyces, and the folds or under sur
faces Of the tender, expanding leaves.
The larvae feed for about two weeks
and drop to the ground, in which they
form a protecting cell. In this cell
the insect completes it's transforma-
tons and emerges from the ground In
the spring as an adult. The thrips Is
single brooded; and the most active
and destructive stages are coincident
with the period that includes the life
events of the swelling and opening OF
the buds and dropping OF blossoms
and calyces.
Injuries by the thrips in the Hudson
Valley have apparently occurred over
q period Of five yeal During the
past three years fruitgrowers gener-
ally have noticed blighting Of blossom
clusters Of pear trees. although the
nature Of the causal agent seems not
to have been suspected. According to
statements Of fruitgrowers the most
severe attack of the thrips occurred
during 1910, when the pear crop in
many orchards was much reduced.
Besides losses in yields the trees were
seriously checked by injuries to leaf
buds and leaf clusters; and In some
orchards tho season was much adj
venced before the trees resented nor
NAL conditions Of growth. The pro-
OuCl1V0I1eS3S u pear O1SAAoA 10 uuA AAAo
1911 was greater than the preceding
year. but blighting of blossom clusters
was general and orchards suffered
losses In yields according to the sever
ity Of the attacks by the thrips.
Severe attacks by me thrips are a
serious drain on the vitality and pro-
ductiveness Of the trees. In their
weakened state they are also moro
subject to injuries by adverse weather
or environment and to attacks by var
ious wood boring insects. The needs
Of tie orchard with respect to cultiva-
ton, fertilizers, pruning and spray
ing for other insects and diseases
should be carefully considered in
order that the most favorable condi-
lions for recovery to health and pro-
ductiveness may be afforded to the
trees.
The thrips l. q difficult pest to COM
bat because Of the nature and sudden
ness Of its attacks. Spraying Is the
most efficient method Of control. The
period for effective spraying Is during
the time when the buds are breaking
and until they are entirely opened at
the tips. The most promising spray
ing mixtures are the nicotine prepare