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THESIS.
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of aid in fertilizing the ap rer

a, §. Hughes. 1896.

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-~-? EXPERIMENTS TO LEARN TO WHAT EXTENT :-
the

-: INSECT IS OF AID IN FERTILIZING THE DRUPES 3-=

A. F, Hughes.

Ausust 15th, 1896.
EXPERIMENTS TO LEARN TO WHAT EXTANT
tne
Insect is of Aid in Fertilizinz the Drupes.

It has heen well said that everything in nature perforss .
‘its part. No sooner are our flowers opened in the spring,
than virious species of insects are ohserved flying from
flower to flower. It is well known th..t besides securing
nectar and pollen for their own use that they are of service
to the plant hy distrubuting pollen to other flovers

A superficial glance at any insect reveals the fact that
tney have contrivances Whicn necessitate pollen being carried
away by them. These appendages doubtless serve some iirect
purpose in the insect economy. But «is ne passes f-om flower
to flower they take on and give off pollen continually. This
constitutes onc of nature's great plans for distributing
pollen.

In tne ahsence of the insect the pollen may come in
contact with tiie stigma by being carried by the wind or
falling from flowers ahove, etc. Indeed, with some of our
trees they depend altorether upon the wind to fertilize
themselves, notably the pines. But with the drupes the
distribution of the pollen themselves accomplished is never
SO general and thorough, for the stigmas are small and com-

3

paratively smooth and the pollen is produced in small quanti-

ties. 101°742
Sclentific investigation has miven us much information
along this line but has yet left gpen a broad field of
inquiry. Orchardists frequently attribute a "poor set" in
fruit to lack of proper fertilization of the ovules, caused
by raln washing away the pollen or prolon:red cloudy weather
precluding the insects' work.

To determine to whet extent tne insect is of aid in
fertilizing our fruits, and to gather such suggestions as
arise therewith, was largely te purpose of the experiments
to be discussed in this paper.

To gain this end a certain number of flower clusters on
a tree were crossed and an equal number were merely covered
and left to set fruit by self fertilization. The crossed
ones would represent those to which the insect carries
pollen from other trees, and the self fertilized ones those
which the insect never visits. the covers used were
manilla paper bags, which precluded alJ insects and vet
admitted sufficient lisrt so that at no time was there any
noticable difference in the twigs under cover and the tilgs
on the rest of the tree. The bass were allowed to remain
on until it wascertain that fertilization had teken nlace,
ns indicated by tie dyin; of the stigmas.

It was found difficult on account of the cloudy and
rainy waether. But thiis difficulty was overcome hv maturins
pollen in the house, which was easily accomplished by placing

the twircs of openin;: hlo:soms in wator. To prevent the
mixing of the pollen of the different kinis each twig was
labled and wranppned in paver. By tris means polten could be
kevt for several darvs. In gathering the rnollen it was
selecte?] somewhat promiscuously, tuat is, no special attenpt
was made to cross certain varieties. In some cases the
relntion was close in others different snecimens were crossed
azccin early and late varieties were crossed and vice versa,
In other words, the work was msle to represent to a certain

extent that which takes place when tne insevt does the cross-=

Plum---- Speer.
This was fertilized hy taking pollen from the Wolf. Eight
clusters each containing six blossoms were chosen, of which
one-half were costated. On May 12th, tne followin; record

was taken,

No. 1 Cross fertilized 6 set. ,
n 9 n " 4
vt 5 " ve O
" 4 " 1
Total “Il = 46%
No. 1 Self Fertilized 5
n 9 n w 6
w % . " " O
n 4 " n 4
Total 15 = 62%

In the ahove exrcriment Numbers 324 of both fertilized
and sclf fortilized were chosen on the trunk of the trea.
The higher per cent of the self fertilized was propably
due to a lack of suffictent pollen on theother lot. On
May’ 29th, the tree was aprin visited and tye following record
was taken. None of the self fertilized ones were -et; 50%
of the crossed ones stil’ remained. The fruit at this
sta..e was of rood color; but no attempt was male to compre
the size on account of the early stace of tne fruit.
Plum--- De Soto.

FPertilized with pollen from t*:e Robinson. Ten clusters
each having six blossoms were selected, five of which were
crossed. On May 12th, they were visited with the follow-

ing results.

No. 1 crossed had 5 set.
n 9 r ho 5 on
n 3 " nog of
n 4 n n 6 of
nm 8 n " A of
Total 26
No. 1 Self fertilized 2 set.
n 9 " " 5 8
n 3 " " 3 ON
n 4 " " 5 ON
no5 " O 1 of
16

On May 1°th, the self fertilized were not lookinyg: as

well as were thosr> which hed heen crossed. . The eorssed
 

 

 
Ones were lookins finely, even larver than were those hang-
ins upon the tree. On May 30th, the trees were 27ian
visited and none of the self fertilized were found hanging.
35% of the crossed ones were still lookin:; well, and gave all
indic:tions of remeéaining until ripening.
Plum-- Moriana. |

This was crossed witn pollen from a Japan plum. Eight
Clusters of five buds each were chosen, four of which were
crossed and the others were covere:! with hars. On acconnt
of lack of pollen these blossoms were allowed to stand for
five days before they were pollenatcd, whih caused no trouble
as the followins wi'l show.

On May 14th, they were visited with the following result

No. 1 Cross Fertilized 3

 

nm 9 8 " 3
n 3 of " 9
nm A on 8 a

Total Tr - 55%
No. 1 Self Fertilized O
n 9 " " 0
” . " a] 1
"4 " " 1

Total 2- 10%

June lst, they were apain examined and of the sclf fert-

ilized none were hanging. Of the crosscd 40% were still
still hanging and gave socd prospects or comin to maturity.
Lombard Plum.
This tree was exceptionally full of blossom buds.
Eicht clusters, each containing; ecisht blossom buds were
Selected and four of these were trossed with pollen from the
Wold plum.
On May 15th, they were examined with the following;

results.

No. 1 Crossed 7 set.
n 9 n A on
" 2 " a ON
no oA. tt 2 oN
Total 16 —- 50%
No. 1 Self Fertilized 6
n 9 n " 4
n 2 n n 6
n oA " on 1
Total “17 = 53%

The numbers four were placed on the trunk of the trec,
which accounts for tne small number set. At this time all
of both the crossed and self fertilized were the same Size
and looked as well as any of the others on the tree. June
end, the tree was arzain visited and 38% of the crosses were
still. hanging and 35% of the self fertilized were still on,
and all pave cocd evidence of comings to maturity. The
above experiment shows th:t tnis tree is capable of self-

fertilization.
a

Rollin:stone Plum.
Crossed with pollen from the Wolf. EKisht clusters with
six buds on each cluster were chosen. The following is the
record tzken on May 1°th,.

No. 1 Crossed 5 set.

" 2 " 3 ”
" 3 a] 4 "
w 4 " 2 "

Total 14 - 58%

No. 1 Self Pertilized 2 scat.
ar) n " ZOOM
n 2 " " zs On
" 4 " " O ud
Total “8 - 32%

Oi, May 30tn, the tree was a,,ain examined, and tne tree
itself had a poor set of fruit as compared with the number
wnich the tree had after the blasoms had fallen. Twelve of
the crossed ones were still han,;ing and were of larser size
than any others on the trec, wWiicr would leave 50 % for the
crossed ones. Of the self fertilized none were set.

Wild Plum (Prunus Americana)

A small cluster of th se trees being hear at hand,
and heing ready to oren just as the Wolf was beginnin; to
blossom, it was crossed with pollen from the Wolf. Six
were put under each bag. On Mey 18th, the trees were vis-

ited with te followinz- result.
No. 1 Cross Fertilized 5 set.

no9 " " 5 oN
n 2 " n 2 on
n 4 " n lo.
Total 13
No. 1 Self Fertilized O
ar) " " 1
n 8 n n 1
n 4AM n 0
Total “2

On June 4th, the trees were opgain inspected and 65% of
the crossed ones were still hanjing and cave all evidence
of coming to maturity. But one of the self fertilized ones
was hanging at the sme date or 5%. It wes expected tht
these trees being of a wild variety woutd set quite well
to its own pollen. Pernaps the lack was owing to the fact
that the trees were crowded quite closely together and in a

blue grass sod.
Cherry---May Duke.

This tree being unusually full in blossom eight buds
were put under each bape. There being several trees of the
May Duke around, t':e crossed and self fertilized ones were
chosen on different trees. On May lst, the trees were in-

spected with the following result.
No. 1 Cross Fertilized 4
en 9 " " 0
n 3 ft " 5
"” 4 a] ve 2
n 5 n " l
n 6 " " 4

Total 167

No. 1 Self Fertilized 1
n 9 n " 0

own 3 99 re 1
n 4 " n 0
nm 5 " " 0
n 6 " n 1

Total ~ 3.

On May 29th, the trees were again visited and all of
tne crossed fertilized ones were ripe, but no special diff-
erence was noted except that they seemed to be in advance of
the others. On the same date the self fertilized had but
one hanging ard it was of inferior size.

Cherry--- Kentish.

This tree was fertilizéd with pollen from the May Duke
The tree being well filled with blossoms, ten clusters, each
containing four blossoms were chosen, of which number five

were crossed and the others were covcre dad with bars.
-~10-

They were visited on ‘tiay 2nd, giving the following: results.

No. 1 Self Fertilized 1
nH" 9 on " 0
a n 1
mn aon n 0
hn 5 on n 1
Total a

No. 1 Crossed 2
n 9 " 2
nr 3 " 1
rn 4 0 2
a) " 1

Total ~ 8.

All these came to maturity but no special difference
wis noted in the size or otherwise except that the tree rip-
ened rather unevenly and the crossed Ones ripened all at the
same time.

Choke Cherry.

There being no near relative of this tree in blossom
pollen was taken from a tree of the same species about 1/4
of a mile distant. Eigsht clusters of six blossom buds on
each were chosen. On May 18th, the tree was visited and
the following is the tabulated result.

No. 1 Cross Fertilized 3

" 2 ba ] ve 4
nv 63 7] Ca] 4
" 4 | " 4
Total I5 - 62 1/2 %
-ll-

No. l1 Self Fertilized 5

] 2 ww a) 5

" 3 " v 1

" 4 ve wr _ 3 / ,
Total 4 - 58 1/3 &

It can be seen from the above that the increase is not
materially in favor of the crossed ones. No chance was
given to watch the further developement of the fruit as the
tazs were pulled off by the children.

The wild black cherry was crossed with pollen from one
of its own variety; hut neither the crossed nor the self
fertilized ones set a single fruit. Perhaps this was due
to the fact that all of the eight clusters were selected in
the center of the tree, and the tree being large and spread-
ing hindered the ones in the center from receiving the sun-
light which is necessary for all fruit to form. The out-
side limbs were hanging full while tiie center of the tree
had no fruit at all. If the above is true it certainly
stands the orchardists in hand to prune his trees s0 as to
admit the sunlight into the center of the trees.

Out of the total 225 plum blossoms crossed, 125 were
hanging May 13th. Of the self fertilized 125 were hanging
at the same date. The ratio being nearly 2:1 in favor of
the crossed. Jure Ist, 85 of the crossed ones were still

hanging and gave all evidence of coming to maturity. Of the
-12-

16 self fertilized which were remaining but 10 gave promise
of coming, to maturity. . And if we were to remve the record
of the Lombard from the above it would five us a final ratio
of 9:2 in favor of the crossed oncs.

To recur to the figures of the cherry; we find that the
total 68 crossed ones that 38 were still hanj;ing May l2th,
and that 30 of the self fertilized were still hanging. And
at the last visit, May 26th, 36 of the corssed ones were
still hanging; and of the fertilized 9 were still hmgping,
which would give us a ratio of four to one in favor of the
crossed ones.

While the above record may be exapperated in a few
cases, taken as a whole it would leave no doubt as to the god
to be derived from crossing. As already intimated nature
has made abundant provision for this work in tne host of
insects which play about our flowers. Just how far the
insect may be depended upon to carry pollen is hard to de-
termine. However, in small orchards there is generally no
difficulty experienced as there are upwards of a dozen or
more varieties. But frequently in planting large orchards
the mistake is made in planting a great many of the sane
variety together, a large share of which do not receive
pollen from other varieties. The more such trees are
sterile to their own pollen the greater is the loss, at any
rate there can be no doubt as to the propriety of scattering

the varieties. I}. the experiments recorded above over 50%
of the plum trees were found to mature no fruit by self
fertilization. It would not be inferred from the limited
ranee of the experiments that such trees were wholly sterile.
But the trend of the experiment is emphatic in indicating the
benefit of crossing.

On account of the warm weather hastening the opening of
the cherry blossoms there was not given as much an oppor-
tunityfor working on the cherry blossoms as was hoped. It
was surf;rested that £t would be well to try the effect of

crossing on some of our cultivated currants, accordingly the
work was befun and the same methods werc used as in crossing
the drupes. tne currants did not open their blossoms even-
ly, so those wnich were not ready to open were pulled off,
care being taken not to injure the clusters.

Tne Currant Riber naguim.

This was crossed with pollen from the wild currant of
the same variety. Right clusters were chosen, four of
which were castrated. The remaining were self fertilized.

On May 16th, the following record was taken.

No. 1 Cross fertilized 6
n 9 " " 7
n 3 n " 5
n 4 n " 5

All the bags and tags were pullcd off from the self

fertilized ones except No. 4, which had none. On June lst,
-14-

it was again inspectcd. ~hree or four of the crossed fert-
llized ones were still hanging and were much larper than
the averare.

Currant--- Dakota.

This was crossed with pollen from the wild species (R.
nigrum) Four clusters were crossed each having five blossoms
and an equal number were covered. On May 26th, they were

visited and the following is the record.

| No. 1 Cross fertilized 3 set.

n 9 " " 5 on
n 3 " n 3 ON
n" 4 " " lo."
No. 1 Self Fertilized O set.
n 2 a " O " |
n 3 n " 1."
n 4 n " Oo "

On June 2nd, they were agin inspected and of the self
fertilized ones none were hanging. Of the crossed ons
eleven were still hansing and were twice as large as others
on the bush; they also were rmch ecrlier in maturing. Near-
ly all of the fruit which had first set dropped off hefore
attaining size. the Fact thet no other currant bush was

close at hand, so thnt insects would probably carry pollen
~15-

will probably account for so few fruit maturing on the hush,
as the ahove record will indicate that the tree is sterile
to its own vollen.

Suming wp the results of the currants we have the
following: Of the 36 crossed ones 24 came to maturity; and
of the same numher of self fertilized ones hut three came to
maturity the ratio heing as @:l

The self fertilized ones were small and were quite letea
coming to maturity. One the other hand tre crossed ones

were twice as larrse and matured a couple of weeks in advance

of either the self fertilized or those on the hushes.
Junjo é”

-”~ ? . ‘

_ : o_o

 

 
 

T581.1 H892 101742
Hughes

 
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