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THESIS.

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60 what extent the insect is

of aid in fertilizing the Pomes. ;

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Ruther Buches. 1896. f
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THESIS

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- EXPERIMENTS TO LEARN TO WHAT EXTENT ;-
the

-: INSECT IS OF AID IN FERTILIZING THE POMES :-

Luther Hughes.

Ausust 15th, 16896.
Tre.

 
EXPERIMENTS TO LEARN TO WHAT EXTENT
Insect is of Aid in Fertilizing the Pomes.

Crossing, 2s a means of causing variation in plants and
affording opportunity to develope new varities is by no means
anew practice. Recent scientific investigation has given
additional motives for crossing. Darwin showed that many
plants are benefited by an occasional cross, in fact, seem
to require it. But the sterility of some of our plants to
their own pollen has attracted marked attention to this sub-
ject; for a few of our best fruits have been found to have
this weakness.

From a scientific standpoint this need occasion no
surprise. Our fruits have been improved by specializing cer-
tain parts, that is some part was developed at the expense of
some Other part. Not only does the orchardist seek the hi¢h-
est improved variety, but he is also careful to thin out the
branches and prune hack new growth that all possible energy
may be thrown into tne fruit. In the natural state roots,
limbs, folilare and fruit were in halance with each other; no
one part was specialized at the expense of another. Hence

the plant was in the hest condition to care for itself, but

nature readily respondinsto man's touch has piven him a host

101°741
of varietiesas a reward for his labors. But each of these
varieties is necessaruly weaker in some respects than were the
natural plants. Increased susceptibility to disease, short-
ness Of life, etc., have been known to be inherent in some
cultivated plants, hut when the weakness shows itself in the
pollen of the plant so thet it is unable to bring about self
fertilization, it hecomes a question of importance to know
by what means the plant is to be made to mature fruit. Pol-
len must be secured from some nearly related plant or such
plants will have to he discarded for cultivation.

But nature has provided against such contingency by |
furnishing a host of insects to cross fertilize by carrying
pollen from plant to plant; so much so is this the case that
if one wishes to secure a true cross, the flower crossed must
be covered to preclude the insectcoordinating her work by
furnishing other pollen.

But aside from the question of the weakness of the
pollen in many cases it may be doubted as to whether nature
intended that the pollen of a flower should fo to fertilize
that self-same flower. Indeed, with out large number of
insects this would secem improbable; also many have their
parts so thet they tend to favor crossing. In the pomes
under investigation the stigma is found to mature before tre

anthers do. This must greatly tend to favor crossing. Hence
-%3-
if the weather be fair when the flowers b gin to open it is
likely that the insects will already hive supplicd the stigma
with pollen before the anthers of the sane flower have been
able to do so. No sooner are our orchards in blossom than
the insects begin to do their work of so much value. Occasion
ally we are mde to realize the importance of their work, in
@ negative way, when prolonged cloudy weather keeps the
insects away till the flowers have passed the critical state
and a poor set in the furit is the result.

To determine what would he the result if the insects
Were excluded from tne flower and to gather suggestions rel a-
tive thereto was largely the purpose of the experiments to
be discussed in ‘his paper.

Por the carrying out of this plan a certain number of
flowcr clusters were crossed and covered with paper ba;;s, and
an equal number merely covered and left to self fertilize.

The crossed ones would represent the work which the insect
would perform and the covered ones those which the insect
nevor visits. These clusters were selected, so far as could
be judged, in equally favorahle locations on the tree. For
convenience of reference each cluster was tagred and numbered,
By this means when successive visits were made there was no
confusion of one cluster with another and progress or retro-

grade was easily noted. From two to three weeks after
the flowers were covcred, they were visited, bari removed, and
results noted. No doubt some of t':ese recorded at this date
wer: not properly fertilized and would soon fall. Hence

at the end of two more wecks they were arain visited to ret a
final record es at this stare there could te no doubt as to
tie promise of fruit to come to maturity.

In crossinr no especial attempt was made as to what
pollen was used except that the trees were thought sufficient-
ly nearly related to easily admit the crossing; the trees in
blossom at the desired time fenerally determined the pollen
used. In other words, the work was ::ade so far as feasible,
to correspond to that which would take place when insect
passes from flower to flower.

It was found that the work of crossing could he best
done at one operation-- that is to emasculate the flowers
and apply the pollen at once, leaving it to do its part when
the stipma bec:me mature. This was a great ssving of time
and prevented danrer of damaging the younrs parts by too much
handling. It is true thet the covers placed the flowers in
somewhnrt ahnormal conditions. However, no difference in
those under cover and those not covered could be observed.

As the bass much increased the surface of exposure, those
this covered mu:t have been moved ahout somewhat more by theo
wind, so that if any difference existed between the self-fer-

tilized ones under te covers and those not covered, the
helence would be din favor of the former as tke wind shakin;
the twirs would aid in scatterinzs the pollen. At any rate
the rood or ill effects of the bers were halanced in hoth
crossed and self frrtilized between which all comparisons were
made.

We will now consider the experiments, consid-ring the
pears first.

Bartlett Pear crossed by pollen from Keiffer. Six
clusters were crossed and six covered, each cluster havins
five blossoms.

Results observed on May l2th.

No. 1 emasculnted-- fruit set 4

n 9 n " n 5
n 3 " " rn o4
n 4 " " n 3
n 5 " " n 5
nw o£ " " n 4
25
No. 1 covered--- fruit set. 3(?)
n 9 " " nm  9(9)
n 8 " n n Oo
n 4 " " y QO
n 5 " " n Oo
n ¢ " " " 0

 

on

On May 23rd, they were ecain visited. The five covered
ones marked doubtful, hecause of poor aprearance, had fallen,
Of the crossed ones seventeen remained and were sufficiently
large and vigorous to leave no doubt as to their comins to
maturity. Thus we have 57% of the crossed ones arainst none
of the self-fertilized ones.
Pear, Flemish Beeuty.

This was pollenized hy the Bartlett pollen. -The Flemish
Beauty blossomed at ahout the snme time as the Bartlett, but
hy selecting some of the clusters thet were a little late in
opening and tekins the earliest of the Bartlett the cross
was effected. Five were placed under each bag. May 12th,

pave the following record:

 

No. 1 emasculated-- fruit set 3 No.1 covered ---fruit set 2
nO " n a) nO " " a)
n 8 " " n 8 n 2 n Nn n 3
no oA " " "oy "4 " " aa)
nS n " "3% RS n n a |

Total 8 Total 12

At this early d:-te it could not he told but that the
self-fertilized ones were equally healthy as the covered ones.
On Mav 23rd, they were asain visited. It was found that the
wind storm had so damared the fruit that it was thought inadvi-
ahle to try any farther comparson. Byt aside from the fact

that the crossed ones were 33 1/39, ereater in set the fact
_7-

trat the Bertlett pollen was enahled to fertilize the ovules
of this t-ee shows that the failure of te Bartlett to self
fertilize was not due to tne fact trat the pollen grein will
not serminate.

Sheldon.

Tris was polenated by Bloodpood. Six clusters each
containing six flowers were crossed aiid 48 inany covered. This
tree was well filled with blossoms. On May l2th, the tree
was visited, but comparatively few rruit on the tree were
set. The result of the experiment was as follows on May 13th

No. l omasculsted-- fruit set O No. 1 covered-- fruit set O

n 2 " " " 1 ” oO " 9 " 1
" 3 n " we 2 a 3 " w " O
" A nw " La] 1 " A J " " a
wo " " n 9 wo S w n rn oO
" 5 " " " 1 " 6 " " " O
36) 7(20% 36)2_
BY
2?
In tne case of the crossed ores 20% h-d set while te
4 . \
covered ones set but 6%. May 23rd, tre record was four of
the crossed ones to one of the covered. Perhaps it was owin;

to some defect in the tree that’ so few fruit were set. How-
ever the record shows that the crossed ones were ;;re:.tcer in
number as 7:2 in the first case and 4:1 on May 23rd. At

this date the [fruit was so large as to lenve no doubt of mat-
urlty.
Bonssock.
Five clusters each having six blossom buds were crossed
by Keiffer, and as many covered. May l2th, gave tne follow-

<

ing result.

No. 1 covered---fruit sct.0O No. 1 emaculated-- fruit set 5
n 9 n n re) nr) n " nm 4
L 3 " " " 1 " 3 " mv 5
| " n nr) n" 4 n " "4
nm 5 n n a | mos " " n 0

6) Ts-

On May 23rd, tne number set was 6 Of the crossed and
O of the self fertilized ones. This tree was fully e::posed
to the neavy wind wnicn will account for the reason thi:t so
many failed to hant. However, the first record showed a ratio
of 1826 in favor of tne crossed ones.
Beann Gin Ahines.
This was crossed by Keiffer pollen. The tree was

especially full. of bloom, "so tnat eisht were placed under each

cover.
May 12th.

1 cov. O frt. set. No.l Fer. frt. set l
2 vt O | 2 ve ” A] 5
3 w O re 3} rv " | 3
4 ve O ® A w v8 | 4
5 " O ts 5 " " " 1

0 14

Te above would indic: te that tnis tree is infertile
-10-

to its own pollen. The large amount of blossoms wnich it
produced no doubt weakened the tree to some extent and may
have played some part in decreasing the yield of fruit. On
May 23rd, five of the crossed fruit still remained. As this
tree wns also exposed to tne windstorm it may he reasoned
that tne loss of tne other nine m&y '::ve been largely due to
this cause.
Sovernia De Espe.

This tree was crossed by pollen from another dwarf tree

of a different variety but tne name was unknown. Each clust-

er had four flowers under cover.

l crossed fruit set 2 l covered fruit set O

2 " n " O 2 n " n 0

3, " " n 3 3 tt n n 0

4 n n ar) A " " n 0
a

This tree was fully exposed to the wind storm yet
three of the crosscd ones were found in good condition May
2ord.

Out of the total 186 ilowers crossed 82 were set on
May 1l2tn. 38 on May 23rd. On May leth, tnere 21 of the 183
covered ones set. On May 23rd, but one of the covered ones
renained. While tiie severe windstorm tended to decrease the
number of fruit, it must be remembered that tre crossed and

seif-fertilized ones were equally exposed. Hence if there
-ll-

was a greater decrease of tne self fertilized ones owin;; to

the wind, it would go to show that they were of weaker growth

Aprles.
Crab in Asboretier.
This was crossed by pollen by a crab of another variety.

Five under each cluster.

l emasculated 1 fruit set. 1 covered fruit set 2(?)
2 Y 9 " " ) " fe n Oo
3 " 1 oo. " 3 " " n QO
4 w 3 " " 4 " ” | O

~ 7 “2

On Mav 23rd, there were six crossed ones remaining.
The two self fertilized ones which were we:k appearing on
May 12th nad dropped by May 23rd. At the present time the
fruits nave shown no superiority over tne others on the trec,
and probably will not snow any noticeable dffference.
Wild Crab.
This wascrossed by pollen from another crab about 1/4

mile removed from th:ec former.

1 crossed fruit set 6 1 covered 4,
2 " " " 4 2 " 5
3 # we ” 4 3% " 4
A " " nA 4 " 5
5 " " yn OS 5 n 5

25 20
Then the crossed and covered onesS were equally balanced.
On May 23rd, it stood 12 to 8 in -avor of the crossed.
Siberian Crab.
The name of this tree unknown. The pollen for crossin;
was taken from another variety of crab. Five clusters each.

l crossed fruit 3.

2 " n 2
3 " n 2
A " " 3
5 " no 5
6 " a ae
16

Tne covered ones set none. This tree being exposed
to the wind storm no farther record could be taken.
Greening Sweet.
This was crossed by pollen from "Seek No Farther,"
When the first record was taken but two each of the crossed
and self fertilized could be found. These gave 4:0 in favor
of the crossed. May 23rd, gave the same record.
Golden Sweet.
This was fertilized by Greeniny, Sweet. May l2th.
1 crossed fruit set 0
2 " w " 4

3 " 8 ]
~13-

5 crossed fruit set 2
6 # " " 4
15

Pive in eacn clister. None of t':e covered ones
snowed any signs of setting fruit, as on May 12th, the young
fruit hed turned yellow and wilted. On may 23 five of the
covered ones were hanging and apreared perfectly healthful.
Apples of Unknown Name.
This was crossed by taking pollen from an apple tree
of unknown name. Four were taken under each cover. May

lith, showed the following results.

No. l crossed fruit set 3 1 self fertilized fruit. set O
n 9 " " " 4 2 6M n " a |
n 2 " " n yj 3 ON " n n 0
n 4 " " " o£ 4" " O nr Oo

127 ~

They were again visited May 22nd, but tne wind storm
had damaged the fruit clusters so that no farther compariosns
were made.

Siberian Crab.

This cross was made by using pollen from an unknown

variety . Five blossoms were placeu under each cover.

1 crossed fruit set 3 No. 1 self fertilized O
2 " " " " 9 W "

3 " wn "

1
a " l
2

,
 
-~]4-

This was likewise injured by the wind.
Falcon Sweet.

Crossed by pollen from "Seek No Farther."

No.l crossed fruit set 4 1 self fertilized fruit set 0
"9 " " n 3 5 oo. " " " 0
n 3 n " n 5 3 OM " n " 0
| " " a) 4 6 n n " 0
nH 5 " " e 3 5 ON " " n 0

17

The above would indicate that this tree was somewhat
infertile to its own pollen. The cross was somewhat a
wide one but yet gave good results so far as number of fruit
sets were concerned. On May 23rd, the fruit was examined.
The crossed were all in good condition. 15 yet remained.
Early Harvest.

Pollen used for the cross was obtained from the Falcon
Sweet. Four were placed under each cover. May llth, guve
the followin; record.

No. 1 crossed fruit 2 set. No. l self fertilized 2 sect.

w 2 " " ] " ” 2 n " O 8

" 3 ] " 3 " a 3 ” " O "

w 4 Lf " 2 " w 4 Rn " 0 "
8 ~ 20

On May 2lst, five of the crossed ones were still hang-
ing and the self fertilized ones also. These all came to
maturity but no noticeable difference was observed between

them and the fruit of the rest of the tree. The ratio of
~15-

fruit would be 5:1.
Pall Junetin.
This was crossed by using pollen of Seck No Farther.

Pour blossoms were placed under each cover.

1 crossed 3 fruit set. l self fertilized fruit set O

2 L 2 ” | 2 | | Ls] # O

3} ” O " ” 3 # 0 ” a] O
a: a

But three out of the eight were left on May 23rd, but
these were in excellent condition somewhat superior to the
rest of the fruit so far as could be judged.

Northern Spy.

Pollen fer cross was gotten from Fal on Sweet. This

tree was highly set in blossom. Three were placed under

each cover. On May llth, the following record was gooten.

No. 1 crossed fruit set 3 1 self fertilized 0 set
# 2 ” Ls] | 3 2 . 0 O . #
Ww 3 ” La] Ls 3 3 w e O |
“3 —_—

On May 23rd, five of the nine remained. These were
plump and healthful, but the fruit of this tree was hardly far
enough advanced to make any comaprison in size of fruit.

Out of the total 200 apple blossoms crossed 132 were
hanging Lay 12th. Of the self fertilized 200 but 32 remained

on the same date. The ratio is nearly 4:1 favor of the
crossed ones. May 23rd, there were 73 of the crossed and 15
of the self fertilized ones or a ratio of nearly 5:1 in favor
of the crossed ones. The high degree of self fertility in
the wild crab h6elps sustain the above record. If we were to
subtract from both sides the records which it gave us would
have a final ratio of 85:1.

If we recur to the figures given on the pear there is
left no doubt as to the good to he derived from crossing.

“he improvement noed was of a double character.

lst, An increase in the number of fruit sets.

end, Increased vigor over the self fertilized ones,
vhich in almost evcry instance lost a good snare of those
which were found to be hanging on May 12th. The highest
degree of self fertility was found in the wild crab. But
even here time showed a gain in favor of the crossed ones, as
May 23rd, gave a ratio of 3:2 in favor of the crossed ones.

If such good is to be gooten fro m cross-fertilization
it stands the orchardist in hand to, so ‘ar as practicable,
Open up the way for the insect to perform her important work.
Perhaps the greatest hinderance to crossing has been the pra-
ctice of planting together those trees of the same variety,
s0 that the distance for the insect to carry pollen was so
great that few, if any of the flowers were crossed. In plant

ing out an orchard generally there are suificient varities
~17-

so that where the rectangular planting is used, one half of
those trees adjacent to any one tree could be of a different
variety. Under any circiwpstances a judicious scattering of
the trees should be practiced. Ihe inconvenience of having
the varieties scattered when harvesting or ;iving some es-
pecial care is of small consideration when increased vigor and

number of fruits are concerned.
 

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