LIBRARY

0,30-7

NOTICE: Return or renew all Library Materials! The Minimum Fee for each Lost Book is $50.00.

The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below.

Theft, mutilation, and underlining of books are reasons for discipli- nary action and may result in dismissal from the University. To renew call Telephone Center, 333-8400

UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN

Y

L161— O-1096

Some Effects of Severity of

Pruning on Growth and

Production in the

Concord Grape

By A. S. COLBY AND L. R. TUCKER

UNIVERSITY OF ILLINOIS

AGRICULTURAL EXPERIMENT STATION

BULLETIN 393

CONTENTS

TYPICAL GROWTH AND FRUITING HABITS 179

OUTLINE OF EXPERIMENT 180

SHOOT GROWTH AND FRUIT PRODUCTION 182

PRUNING AND GENERAL VINE GROWTH 189

PRUNING AND VINE YIELD 191

GROWTH AND PRODUCTION RESPONSES 191

GROWTH AND PRODUCTION ALONG THE CANE 194

EFFECTS OF PRUNING ON FRUIT-BUD FORMATION 201

SUMMARY 204

PRACTICAL APPLICATION 204

LITERATURE CITED 206

DEFINITION OF TERMS.. . 206

Urbana, Illinois July, 1933

Publications in the Bulletin series report the results of investigations made

by or sponsored by the Experiment Station

Some Effects of Severity of Pruning on

Growth and Production in the

Concord Grape

By A. S. COLBY, Chief in Small Fruit Culture, and L. R. TUCKER, formerly Scientific Assistant in Pomology

GRAPEVINE has been subjected to many methods of I pruning and training by growers and investigators, to all of "^ which it has adapted itself readily, giving constant and definite responses. If the grower is to determine the most economical and profitable degree of pruning to use, he must be able to recognize the re- sponses which a grapevine makes to different pruning treatments. He should be able to interpret the condition of a healthy vine by observing its previous season's growth and fruiting activities, if that season was normal. He should be able to tell whether a vine has been pruned cor- rectly, or whether it has been pruned too little or too severely; he should know what results will be obtained by varying the pruning treatments.

The investigations reported in this bulletin deal with the cumu- lative effects on the growth and fruit production of Concord grapes of consistent winter pruning to varying degrees of severity during the five years 1924-1928.

TYPICAL GROWTH AND FRUITING HABITS

In any pruning experiment the typical growth and fruiting habits of the plant must be taken into consideration. As a grape bud de- velops into a shoot in normal vine growth, a leaf bud is produced at each node on alternate sides along the shoot. A bud forms in the axil of each leaf, and sometimes a secondary shoot or lateral is later pro- duced near this bud. A tendril or a flower cluster may be found opposite the leaves at some of the basal nodes. After these inflorescences have been produced up to five in number, the shoot may continue to grow for several feet with no more blossoms.

The following year the buds vary in size along the portion of the shoot that was selected as a cane at pruning time. Some do not grow, but remain latent, while some produce weak and others vigorous shoots.

179

180 BULLETIN No. 393 [July,

Some time during the late summer of the season previous to fruit- ing, flowers begin to be differentiated in the fruit bud in the axil of the leaf on the shoot.6* The number of these inflorescences in the different buds along the shoot varies, fewer being found near the base than farther out. This habit has been widely studied, usually by meas- uring the fruit production the following year on the shoots originating from these buds.2> 7> 8> 9> "» 14* These studies, indicating that the basal buds are less fruitful than the buds farther from the base, resulted in the recommendation of the so-called "long-cane" system of pruning (leaving canes with five or more nodes each) rather than the "spur" system (leaving approximately three nodes per cane). Again, buds on some shoots contain more flower clusters than those on other shoots. A study of this variation has shown that the shoot of medium vigor will make the most productive cane the following year.10' "*

When a bud contains more than one flower cluster, the clusters usually vary progressively in size along the fruiting area of the shoot produced from this bud, the tip cluster being the smallest.4* This in- dicates that the clusters nearer the base in the fruit bud increase in size as extra clusters are set, and that the buds carrying the largest number of inflorescences are potential producers of large clusters.

OUTLINE OF EXPERIMENT

In the experiment reported in this bulletin the 4-cane Kniffin sys- tem of training was followed. Data were secured from 48 vines in 1927 and from 64 in 1928. The plants used in the experiment are growing in the Station vineyard in Urbana. They were planted in 1917 and are of average size for their age in that locality.

The vineyard is located on the eastern slope of a recessional mo- raine characteristic of the Early Wisconsin glaciation. The soil is brown silt loam of morainal type merging into a black clay area at the base of the slope. The vines are so distributed over the plot that soil differences are minimized. Clean cultivation is practiced during the early part of the growing season, followed by a cover crop of oats, buckwheat, and soybeans sown in August and disked under the fol- lowing spring.

The number of nodes to which any vine in this experiment was pruned varied not more than 15 in any two of the six years 1922-1927. In 1922 the vines were classified into seven groups according to degree

*These numbers thruout the text refer to literature citations on page 206.

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

181

of severity of pruning, the number of nodes that were left in the re- spective groups ranging from 20 to 90 in multiples of 10.* This treat- ment was consistently followed for five years and detailed comparisons made of vine growth and production in 1927 at harvest time. The treatment was continued and comparisons again made in 1928.

TABLE 1. — SUMMARY OF GROWTH AND PRODUCTION OF CONCORD VINES, ILLINOIS EXPERIMENTS, 1927 AND 1928

Item		Year	Node-number range to which vines were pruned	Total
20-29	30-39	40-49	50-59	60-69	70-79	80-89
1	Number of vines in each range	1927 1928	7 9	3 24	15 17	11 11	9 3	2 0	1 0	48 64

Vine averages

2	Average number of	1927	17.6	30.3	37.7	47.5	54.6	61.5	65
	shoots produced	1928	17.1	25.8	35.2	43.1	50.3
	per vine
3	Percentage of nodes	1927	29	19	26	27	21	29	28
	dormant	1928	28	28	26	24	23
4	Percentage of nodes	1927	8	15	12	15	11	16	8
	producing two	1928	8	11	11	8	10
	shoots
5	Percentage of	1927	15	8	5	3	2	1	2
	shoots broken off	1928	16	12	8	5	6
6	Total growth of	1927	130	166	200	226	233	241	264
	main (primary)	1928	144	183	204	205	233
	shoots in feet
7	Total growth of lat-	1927	92	56	91	90	78	95	64
	eral (secondary)	1928	168	150	140	88	100
	shoots in feet per
	vine
8	Total growth of	1927	223	223	291	316	310	336	327
	main and lateral	1928	312	333	344	293	334
	shoots in feet per
	vine
9	Number of laterals	1927	61	83	99	111	122	156	146
	per vine	1928	109	124	138	114	155
10	Total number of	1927	13	53	60	74	90	96	96
	clusters per vine	1928	18	35	54	63	78
11	Average weight of	1927	19.9	122.8	173.1	198.6	250.6	247.0	275.0
	fruit per vine in	1928	48.1	99.7	135.2	167.3	211.5
	ounces
12	Average size of	1927	1.36	2.35	2.66	2.64	2.70	2.46	2.86
	cluster in ounces	1928	2.22	2.66	2.48	2.59	2.68
1 3	Number of spur	1927	4.0	7.7	12.9	17.0	19.8	24.0	45.0
	buds left per vine	1928	4.3	8.1	10.7	18.8	22.3
(Table is concluded on next page.)

*The small buds at the base of the cane were included in making the counts. These buds are dormant or produce a nonfruitful shoot.** In this experiment both fruitful and nonfruitful shoots were considered.

182

BULLETIN No. 393 TABLE 1. — Concluded

[July,

Item		Year	Node-number range to which vines were pruned
20-29	30-39	40-49	50-59	60-69	70-79	80-89

Shoot averages

14	Average length of	1927	88	67	66	59	51	48	49
	main shoot in	1928	102	89	70	59	56
	inches per vine
15	Average length of	1927	63	22	33	24	17	20	12
	the laterals in	1928	123	80	49	26	24
	inches from each
	main shoot
16	Average length per	1927	151	89	99	82	68	68	60
	shoot in inches of	1928	225	169	119	85	79
	terminals and
	laterals combined
17	Average number of	1927	3.4	2.8	2.8	2.4	2.3	2.6	2.2
	laterals from each	1928	6.6	5.2	4.0	2.8	3.1
	main shoot
18	Average number of	1927	.66	1.73	1.53	1.59	1.65	1.56	1.48
	clusters per shoot	1928	1.02	1.34	1.54	1.47	1.55
19	Average weight of	1927	1.0	4.1	4.4	4.3	4.6	3.9	4.2
	fruit in ounces	1928	2.7	3.8	3.8	3.9	4.2
	per shoot

Growth and fruit production were studied both separately and col- lectively in each pruning group, both the shoots and the cane being used as units of comparison. The location and length of each main shoot on the vine, the number and length of its laterals, and the number and weight of clusters produced were noted. From these data the effects of pruning to varying degrees of severity were determined.

SHOOT GROWTH AND FRUIT PRODUCTION

Growth. — The 48 vines from which data were secured in 1927, ranging from the 20-to-29-node to the 80-to-89-node group (Table 1, Item 1) produced 2,003 shoots ranging in length from less than 1 foot to more than 50 feet per shoot (Table 2). The 64 vines in the 1928 test ranging up to the 60-to-69 node group (Table 1, Item 1) pro- duced 1,995 shoots. The shoot growth per bud in this group varied in length from less than 1 foot up to 100 feet (Table 2).

The shoots were first grouped according to length of terminals and laterals (Table 2). About half the shoots were less than 5 feet long. The short ones had very few and short laterals. The more vigorous shoots were longer wTith an increase in both length and number of

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

183

	1						1	o	3	JO
	_g 01	o					2 -H	-H 5	+i	^	S o
	CO						ss	— CO	OCM	•»•*	— CO
	S							CM CO	ss	8S
		t-	CO			t^-	•0	a>
		O>								OO
	•§	*~l	"*			O	°.	CO	"^	a
	S.	M		g	oo			§	!M	»o	O
	o>	- +i	+1		+1	"H	CO -f-]		_1J	-H	.
	A	So	ss	c^	OO-*	00 1- " *	s§	ss?	— 0	OS-^f	to to — CM
	00	0-.	— ICM		S5	is	*•"*	•*-*	00 CO	|S
	J	S	CO to		o	8	i	s CO	s	CO
	B	S -H	+1	o» CO eq	+1	+^ ^ *	§ +i	s	CO	HH	CM
	i	** CM	CO tO		ooo	CMCM " 2	88	ss	OCO	O>CM	— —
J3	i		CO-*		2"	COCO	««	•«••«•	to co	s*
o Si	J	8i	00 t-		ooo	S5	11	>o-< •* CO	3>o	CM 00
	c			<O	^ CO	•^ CO to		CO	CM CM	CO CM	r*.
j~	g	S +i+i	+1+1	*"J	+1+1	+1+1 ^ 2	S +1+1	+1+1 S	+1+1	+1+1	to to
"I	I	8.8	««		ooo	cot-	CM O	cooo 00 CO	COO	00 O	S —
			CM CO		OlO	CM 00
[Z	CO								'--	co4r
J	8	OCO	t-o>				-.0	coa>
o	J	2o	5<co		'-«O	S 5	00	CMCM	— >o	2S
^*	J	CO		s	CM—i	CM ^H CO •* O>		ao	CM —	CM —	oo
.5	§»	•0 +1+1	+1+1		+1+1	+1+1 ^ ^	2 -H+l	+1+1 ^	+1+1	+1+1	0> CO
			COO
g	0	**!*"!	coco		O>00	OOh-	COO	IQ^<	*H	OCM
*	<M				1C ?4	«N			•*•»	CM CO
I	1	II	Sg		CO«	OO CM	(Mr- 3.8	S2	§^	— is
M	_B	2 +!+!	+1+1	s	+I+H	^-t ^H CO +I+! o "	Oi	+1+1 ^	44+^	+1+i	00 CM
J	1	£2	SCM 0>	04			00-fl<	COCJ	CM O	CMCM	*~ 2
GO	2	-'-'	*••*		CO CM	ss	-•	••*	Sco	00 CO
	1	II	t~Q §2		0§	sg	ii	S2	ss	oS
	_o			M	^	^ C4		^	1^t	^	oo
	g	8 «*	+1+1	•«	+1+1	+1+1 ^ ^	oo o +1+1	-H+l "•	+1+1	+1+1	•«r co to oo
		OO O	82		CMV	«ca	°s	ooS	•oo	cooo
	d	*-* ^H	toto		CO ^t*	OjV	^ «_4	^3* CO	^- Tf*	to *O
	"				O!M	^1-C^I			OCM	TCM
	1	||	32		f><3>	si	CO CM	5§	S5	sl
	.S at	S +i+i	+1+1	3	+1+1	** S 2	2 +|-H	+1+1 ^	+1+1	+1+1	5 o
		OOh-	COCO				Q'T	OCO
	j				•^* oo	a>co	So	r-co	CO OO	to ao
	S	-•—•	««		S£:	0000	'	«•«	=o£:	§2
	J	§s	II		82	SS	is	||	Ii	oS <— < o
	O			s		• •	oo "	' ' CM			^
	.3	2 -H+1	+1+1	' '	+i+i	+1+1 « »	00 "^"^	+1+1 ~	+i+i	-H-H	CO OO
	OS	r~oo	CO GO			CO	Tl OS	— CO			CO
	*9	CO »	•«-C»		00 •*	6MOO			CO OO	tO ^f
		~"	COCO		09	-if	•^	CM CO		S.
					J :	.S . .	; 1 ;		J3	.	J I
		: «	-t> .		o .	§ : : :	: *	•g : S	.1	0	-g ^
		1 1	§ : •a 8	a	•S :	1 8* -' ';	j J	1$ i	-J	1 8	g. .1
		1 J	— - 51	a	J-g XI C c •—	J9 '!) J3 JS J.5 * |	i 1	&| .s .^ ° E	"S a C"*	"I -3	1 1
		i ii J II •s !•«	Dunces of fru deviation in	\	length of mai: deviation in	B $ « -5 & J =5 1 i 2 ^ .3 | |	's 1.2 1 J53 •s s 5	ounces of fru I deviation in size of clustei	length of mai 1 deviation in	length of late ea i deviation in	number of la length per lai
		sis si	4>	/		"« -fi"^ - ^*	-vi *- ®"H	V M »	« ii	aj -C j^	& 9
					fta
		~-"s 2*32	2~2	L:		2 — "2 g 'S	~" 3 *"c	g-o 2	2"§	£'="2	S S
		z II	4l	|	<:»2	4 1 z j	z <!	•<! 4	<!	> 5	4 4

184

BULLETIN No. 393

[July,

laterals (Fig. 1). Lateral shoot growth occurred, therefore, at a more rapid rate than growth of the central or main shoot. Since the laterals produce many of the leaves, a larger proportion of the leaf surface on the very vigorous shoots must have been formed later in the season than on the less vigorous shoots. Both the very weak and the very

800

(O LJ

I

O

Z 700

600

< 500

LJ

5

300

200

100

• LATERAL LENGTH 1926

TERMINAL LENGTH 1928

H ll 1927

200

300 400 500 600 700 TOTAL SHOOT GROWTH IN INCHES

900 1000

FIG. 1. — RELATIONSHIP BETWEEN LENGTH OF TERMINALS AND OF LATERALS ON SHOOTS OF DIFFERENT DEGREES OF VIGOR, 1927 AND 1928

An increase in shoot vigor resulted in an increase in both length and number of laterals.

vigorous shoots produced slightly fewer clusters and slightly less fruit than did the shoots of medium vigor (Table 2). Similar and less vari- able results were previously reported by the authors.4*

The variation in vigor and fruitfulness between groups was so slight and the variation within each group was so large, as shown by standard deviations in Table 2, that there seemed to be little relation- ship in these shoots between vigor and fruit-bud formation or fruit production.

Clusters. — The shoots were also classified according to the number of clusters they produced (Table 3). The number of clusters per shoot during the years 1927 and 1928 ranged from 0 to 5 and 0 to 4 re-

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

185

Z		X				o		o
O	g		l-» ON	oo	(^	IO ON	|	00 t-*	ON NO	IO	0 -
			CS 00	rs	s	CS ON			R 3	B	•* PO
.
I			•	O •	o •	CM
J		2	iO	CM •	r-» .	10 •#
*
		8$	00.0	«cs	PO.O			S3	oo oo cso	NO
2			10 PO'	•*PO'	00 NO				NO"T(< POa	O^PO
						CS		CS			o
8 3		+1+1	• +1+1	+1+1	+1+1		^4	+1+1 PO	+1+1 +1+1	+1+1
3 0								•* cs			CS IO
		PO ON	IO NO	O ON	*o 9>				00 O ^NO	csoo
a		(SPO	ss	2S	zz			CSPO	ScS ^NO	— ON
5		ON 00						•H 00
- 2 u S		2S	Sjo	gg	3*				8^ ^^	toS!
"o g	ON	+1+1	"*• +1+1	+1+1	+1+1	IO CS	CS	+1+1 ~?	+1+1 +1+1	+1+1	00 00
^ 0		NO 00 ONO	r~ cs	— -H	OOO			S8	•*CS CSNO	NOO	—
s "* 3			IO PO	ON^'	•*'oo				PO NO IO O	X*
fl					— 1				s	— < -H
O
M — f°		r*. 10 00	So	SS!	POO			ss	3% S»	CCOX
=3 ^			~ — <	,-1	PN — •	t-.			-H CS-<	fOCS	NO
	$ NO	+1+1	s +l+l	+1+1	+1+1	CS 00	00 NO	+1+1 2	+1+1 +1+1	+1+1	«* cs
		POOO						IO CS
rt es		-«NO	ON 00	PONO	PNO»			CSPO	foes es«*	10 •*
1		IOCS	ONIO IO ^	•HOO	-HOO			iocs	00 IO 10 O	CSNO
I		ON ON						POO
			—100	•*o\	12 10			33	O-* OOO	2o^
				CS 00					NO »H • •
o E						PO			• • cs cs	»*cs
						NO CS		00			cs -<
J3 3	PO	+1+1			+1+1		t^		+1+1	+1+1
M u		SPO	3*	ss	O-H			•HOO 00 PO	si sa	§3
1			£2	1$	SN^				NO ^H 00 O	•HOO
|			^H ^H	CS *H	PO CS				•H ^ CS CS	•*cs	t^.
1 "o	ON •*		+1+1	-H+l	+1+1	-I CS Tj"	1 IO		+1 +1 +1 +1	+1+1	t^ O cs •*
			IO«O	PO r~	ft : :				1010 WON	-A
			: s: : £ :	4) ' Si ' O B •	i					i'l
			8 'f :		3	8 %		: : 8	'Z a '	i	8 $
	i	8 :	3 8 : 0 « '	8 :	et	to u	i	Ij 1	$ i:- m O .	c cd	1* C & . •:
	7P27 Number of shoots in each cl	Average ounces of fruit per Standard deviation in ounce	Average weight per cluster i Average terminal length per Standard deviation in inches	Average lateral length per si Standard deviation in inches	Average combined termina per shoot in inches Standard deviation in inches	Average number of laterals Average length per lateral ii	192S Number of shoots in each cl	Average ounces of fruit per Standard deviation in ounce Average weight per cluster i	Average terminal length per Standard deviation in inche Average lateral length per s Standard deviation in inche	Average combined termina per shoot in inches. . . . Standard deviation in inche	Average number of laterals Average length per lateral ii

186

BULLETIN No. 393

[July,

spectively (Table 3), while the amount of fruit on a shoot ranged from none to more than a pound. Since this number had been determined in the flower bud, this grouping was used as an index to the amount of flower formation that took place. The number of clusters was also a very good index of the amount of fruit produced (Tables 2, 3, and 4). Even under the wide range of pruning treatments for the

FIG. 2. — CONCORD VINE SEVERELY PRUNED TO 16-25 NODES, 1924-1929

Severe pruning of the above vine for six years resulted in too vigorous shoots with long internodes. Very little fruit was in prospect from this vine for the 1929 season. (Photographed June 5, 1929)

two years, 1927 and 1928, the production of any of the growing buds left on the vines after pruning seemed to be largely determined by the number of embryonic flowers differentiated the previous season.

In accordance with the findings of Partridge,10* Schrader,12* and the authors,4* the average cluster size in a given area became larger as the number of clusters increased (Table 3).

As shown by the standard deviations, a wide range of shoot vigor existed among those shoots having the same number of clusters

1933}

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

187

(Table 3). There seemed to be little relationship between shoot vigor and the previous year's fruit-bud formation, tho the extent of fruit-bud formation appeared to have considerable effect upon the production of a shoot the following year.

FIG. 3. — CANE FROM CONCORD VINE PRUNED TO 16-25 NODES, 1924-1928

Vigorous shoots with considerable lateral growth, much of which occurred late in the season, developed on this severely pruned cane. One shoot has been broken off near the end of the old cane.

Yield. — The shoots were again classified and studied according to the number of ounces of fruit they produced (Table 4). Under this method of grouping, average growth was similar to that shown in Table 3, where the number of clusters was taken as the unit. Under

188

BULLETIN No. 393

[July,

	7	OPO oo	t-oo 0010	— «— PO oo	1O	O-O 00	POO	oo POO	OO. POO
	TO M						Ot-	c««	O* PO
										in
	A^ c2	PO -H-H	-H-H	-H-H	-H "! «•	- -H-H	•H-H	-H-H	-H-H	10	"1
										«•»	(N
	>d o u	M^§	t~oo	— o>	0*0	SPO	M-*	•«oo	10 0>
	' 1	PO	M«0 OOPO	POO> POPO	£S	PO	SlO	$%	2g
		^0	oooo	-M		%*	0-	00 O*
		00				oo
1	ui S 11	2 -H-H	-H-H	•H-H	£5 s	S +1-H	-H-H	-H-H	-H-H	M O	o>
3	04 0	•>*<o
I			^<o	Ml--	IOM	0\PO	r-oo	oooo	^1*^
		cs
a			t-ro	PO-*	cxo		CMO	t-Ov	-2
g		MO				— •*
		OO	KM	oo M	MM	00	S§	•*O Tj<o	253
o	°i to		— —	— —	POM oo		ts —	TJ<PO	O'l"	00
e	il	M ^^	-H-H	-H-H	-H-H PO r-	8 •"•"	-H-H	-H-H	-H-H	wj	M
§	00 °	010	r~oo	10-*	(NO	0-*	00 (S	00	001^
o		M	K5!	IN 3	woo	cs	<£!o	58	s§
c		t~M				•*o
|		OO	%%	Ol-	csK	oo	•* —	«o	oa
g	°:S		j, '	^ '	CN— 10		— —	N«	•* (S	00
S	1 c	•10 -H-H	-H-H	-H-H	-H-H f>- "!	° -H-H	-H-H	-H-H	-H-H	oc	PO
•o	®. s									*#	M
1		— Jo	OO	10 —	100	- -	•*0	OOO	MOO		**
3		M	»PO	oo M	t^Ov	«s	POPO	ao>	POO
i			10 •*	— PO	**		0010	1/1	— —
2		POO				•* o
				MOO
H		oo	— oo		— 1O	oo	•*o	OOO	r-O
	O; g		—	—	N~ § -		— —	cs —	PO ts
	PO jit	M -H-H	-H-H	-H-H	•H-H	PO -H-H	-H-H	-H-H	-H-H
		10 PO
		PO IO	O* M	o o*	o. o*	PO1O	T* O	— 00	10 ^
		—	OlO	S3	t^OO	—	M'lO	oo	2§
			— 0	— 00	oo-*		PO-*	t^ —	Ot^
			t^ —		l-O		o —	OOO	— 00
	1	2	-H-H	-H-H	PO es o -H-H *• I	s	-H-H	-H-H	-H-H	•	O
	O	"*	MOO	O 9>	OOO —	IO	•4< Tf	c- x	POOO		^^
			.0.0	sa	— , C • •		1O1O	oo 10 POOv	%% vN C • •
					1 ; ; ; •				X : : m >->
			e •	u	* : : : 1 :		1 :	O	§ : 2
		: 8	.2 •	•5	S § »	g	.5 •	•S		'S	05
			| ;	|	— J= JS	' B	| ;	1		i	|
		1 1	£p	« 0>	•3 1 JS ~	jtf » "y QO	sP	•S8	- 8 <« £	«	.5
		o •*•* 2 3. c °	II	V - RJ 5C	•S " 2 I? '| 'S - JB	•g 5	J3 C IS		c ti E -S S .5	1 s	I
		1927 mber of shoots i ;rage number oi ndard deviation	:rage terminal 1< ndard deviation	:rage lateral len ndard deviation	1 1 ° S 1 1 1 § 8S£ § •§ all a a 2 -S *t3 55	/P2* mber of shoots i srage number of ndard deviation	srage terminal 1< ndard deviation	srage lateral len ndard deviation	erage combined inches ndard deviation	erage number oi	erage length per
		'Z <(n	<w	<w	< w •< <	Z <5j	<tf>	<tn	< w	<	<

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

189

this range of consistent annual pruning, individual shoot vigor had very little apparent effect on the same year's fruit production.

PRUNING AND GENERAL VINE GROWTH

The growth and fruiting activities of the different groups of vines varied with the treatments they received (Table 1 and Figs. 2, 4, and 6). The number of shoots was limited in proportion to the number

FIG. 4. — CONCORD VINE PRUNED TO APPROXIMATELY 60 NODES DURING 1924-1929

Moderate pruning of the vine as shown above resulted in shoots of medium vigor and with sufficient bloom to yield a good crop. (Photographed June 5, 1929)

of buds left at pruning time (Table 1, Item 2). This limitation, how- ever, did not seem to affect markedly either the percentage of nodes producing two shoots (Item 4) or the percentage of nodes remaining dormant (Item 3).

At harvest time a survey of the activity of these vines showed that the amount of their new wood or shoot growth was not limited by the severity of the pruning treatment (Item 9). Even where the more se- vere pruning reduced the number of buds and thus limited the possible number of potential shoots, each shoot was usually longer than the shoots on vines less severely pruned (Item 7) and produced more laterals of greater vigor (Item 15). As a result the total vegetative growth of the vine remained about constant even tho the type of growth varied.

190

BULLETIN No. 393

[July,

Two other conditions resulting from the pruning need to be taken into account in this connection. First, more severe pruning resulted in an increase in the percentage of shoots broken by various causes, such as storms and tools used in cultivation (Item 5). This may be ex- plained by the fact that the smaller number of shoots afforded less

FIG. 5. — CANE FROM CONCORD VINE PRUNED TO 56-65 NODES, 1924-1928

Shoots of medium vigor with few laterals resulted on this moderately pruned cane. Compare with the too vigorous shoots resulting from severe prun- ing as shown in Fig. 2. Polarity along the cane is illustrated by the shoot growth.

protection to one another while the resulting vigorous and tender growth offered a greater exposure. Next, the 4-cane Kniffin system of training, as previously mentioned, theoretically involves leaving four spurs at pruning time for renewal purposes. With the vines in the very severely pruned group, spurs were often unattainable in the desired

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

191

location (close in to the trunk). The severely pruned canes were short and in some cases behaved similarly to spurs in that they furnished some of the shoots for canes the following year. On the other hand, where the very light pruning (Item 13) was followed consistently, it was often impossible, at pruning time, to find four canes long enough to furnish the required number of buds, and a few extra spurs were necessarily left on the vine.

PRUNING AND VINE YIELD

The average yield per vine in the different groups declined as the severity of pruning was increased (Table 1, Item 11). Since pruning has long been practiced as a method of thinning the fruit of the grape, this result was expected.

The average production per shoot was also slightly smaller with this decreased total yield (Item 19). Shoot production was determined by size and number of clusters (Items 12, 18), both of which varied in a more or less similar manner.

GROWTH AND PRODUCTION RESPONSES

Effects of Cane Length on Shoot Growth and Fruit Production of Vines Similarly Pruned. — Grape production is related to the fruiting pattern of individual canes, as previously discussed. In this experi- ment the cane length of the vines, which were trained to the 4-cane Knirnn system, necessarily varied under the different pruning treat-

TABLE 5. — AVERAGE GROWTH AND FRUIT PRODUCTION PER SHOOT FROM CANES

PRUNED TO DIFFERENT NUMBERS OF NODES AND ORIGINATING FROM

VINES PRUNED TO A SIMILAR NUMBER OF NODES

Number of nodes per cane left after pruning	Termi- nal length	Lateral length	Total length	Number of clusters	Weight of fruit	Size of clusters	Nodes forming shoots
	inches	inches	inches		OS.	02.	perct.
Vines with 40 to 49 nodes (1927)
Canes with 1 to 8 nodes	68	29	98	1.81	5.18	2.86	69
Canes with 9 to 16 nodes	66	30	97	1.88	5.96	3.17	79
Increase due to extra cane length	-2	+ 1	-1	+ .07	+ .78	+ .31	+10
Vines with 40 to 49 nodes (1928)
Canes with 1 to 8 nodes	78	63	141	1.68	4.20	2.50	72
Canes with 9 to 16 nodes	68	41	108	1.87	4.80	2.56	78
Increase due to extra cane length	-10	-22	-33	+ .19	+ .60	+ .06	+6
Vines with 50 to 59 nodes (1928) Canes with 1 to 8 nodes	53	26	79	1.57	4.13	2.63	70
Canes with 9 to 16 nodes	65	30	95	1.92	5.45	2.84	81
I ncrease due to extra cane length	+ 12	+4	+16	+ .35	+ .32	+ .21	+11

192

BULLETIN No. 393

[July,

ments. The effects of pruning on yield may be studied thru the activi- ties of the canes as well as thru those of the vine.

To determine the effect of cane length upon growth and produc- tion, all of the canes in one group of vines were divided according to their length, as shown in Table 5. This treatment was repeated with three groups in order to obtain three measures of the average variations. The canes with nine or more nodes formed a noticeably larger number of shoots per node than did those with fewer nodes.

TABLE 6. — EFFECT OF DEGREE OF SEVERITY OF PRUNING ON GROWTH AND FRUIT PRODUCTION PER SHOOT FROM CANES WITH SIMILAR NUMBERS OF NODES

Number of nodes per cane left after pruning	Termi- nal length	Lateral length	Total length	Number of clusters	Weight of fruit	Size of clusters	Nodes forming shoots
Canes with 5 to 8 nodes on vines pruned to — (1927)	inches 80	inches 48	inches 128	1.33	OS. 3.26	OS. 2 45	percl. 71
45 nodes or more	60	26	86	1.80	4.74	2 63	71
(1928)	91	88	180	1.60	5.18	3.24	71
40 nodes or more	70	52	122	1.66	4.15	2.50	72
Canes with 9 to 12 nodes on vines pruned to — (1927) 49 nodes or less	68	30	99	1.86	5.94	3.20	77
50 to 59 nodes	60	23	82	1.83	5.20	2.85	75
	55	17	72	1 83	5 24	2 85	84
(1928) 39 nodes or less	95	74	170	1.63	4.42	2.71	79
40 to 49 nodes	70	44	114	1 85	4 84	2 61	72
50 nodes or more	68	34	102	1.85	5.27	2.85	77

The average productivity of these shoots was also greater in both number and size of clusters. The shoots consisted of about the same length terminals and laterals in each cane class. The variations in yield in the 9-to-16-node section were actually larger than they appear at first glance, since the average is taken on all shoots of the cane and not on the shoots of this area alone.

It is concluded, therefore, that increased length of cane increased the average yield per shoot, but did not affect shoot vigor.

Effects of Severity of Vine Pruning -on Shoot Growth and Fruit Production of Canes With Similar Node Numbers. — The effects of severity of vine pruning upon growth and production of buds on canes with similar bud numbers were next determined (Table 6). The num- ber of buds forming shoots did not vary consistently with the differ- ent pruning treatments, nor was there a consistent variation in the average yield per shoot. As the severity of pruning was increased,

1933] GROWTH AND PRODUCTION IN THE CONCORD GRAPE 193

growth and production of the remaining buds were affected in the following manner: Shoot growth consistently increased with a pro- portionately wider variation in length of laterals than of terminals. Production was not markedly affected within the divisions made.

Growth and Production Relationships. — Results of the experiment having indicated that shoot vigor is determined by the severity of winter pruning and production by the number of nodes left and by the number of flowers formed in the buds the previous season, an effort was next made to determine if any correlation exists between produc- tion, number of clusters, and growth on like portions of canes similarly pruned. Shoots grown in 1927 from the fifth to the eighth node on canes 9 to 12 nodes long on vines pruned to 49 to 63 nodes were studied. This was the closest selection possible if a dependable number of shoots was to be retained.

A study of these selected shoots is summarized in Table 7. A cor- relation of -f- .319 rh .043 was found to exist between terminal shoot

TABLE 7. — RELATIONSHIP BETWEEN GROWTH AND FRUITING OF SHOOTS FROM STH TO

STH NODES ON CANES 9 TO 12 NODES LONG ON VINES PRUNED TO

49 TO 63 NODES, 1927

Correlation between number of clusters and —	+ .778	±	.019
Terminal length per shoot	4- .351	-	.042
Lateral length per shoot	+ .142	-	.047
Combined terminal and lateral length per shoot	+ .275	-	.044
Correlation between ounces of fruit and —		-	.043
Lateral length per shoot	+ .142	~	.047
Combined terminal and lateral length per shoot		-	.046

length and ounces of fruit. Since the correlation between length of laterals and production was still lower, altho positive ( -f- .142 ± .047), it seems unlikely that the same year's growth and production have much in common. A correlation of -(- .351 ± .042, which is fully as high as the one just mentioned, between number of clusters and termi- nal shoot length indicates that the relationship that does exist may continue from the earlier existing relationship between fruit-bud for- mation and bud vigor. This is further substantiated by the much higher correlation of + .778 ± .019 between number of clusters and yield. The relationship resulting between shoot vigor and fruit-bud forma- tion as measured by number of clusters is related to parallel patterns of activity along the cane. These patterns appear in the section on growth and production along the cane, page 194 to 201.

194 BULLETIN No. 393 [July,

To check still further the relationship between fruiting and growth the same summer (1928), the factor of vigor as it affects fruit-bud formation was eliminated as much as possible by selecting shoots with two clusters. The effect of vigor as induced by pruning was also largely nullified by choosing shoots with the same range in primary length (80 to 99 inches). The weight of fruit on these shoots with similar fruit-bud formation and similar vigor at pruning time was cor- related with lateral length in inches. The variation in lateral growth as measured by the standard deviation was 45.4 inches, and in produc- tion was 2.4 ounces. These variations were larger than the limitations placed on terminal growth and number of clusters. After thus limiting the factors of fruit-bud formation and early vigor, a correlation of no significance ( -f- .096 ± .076) was found between fruit development and lateral growth during the summer. This correlation indicates that under the conditions existing in this experiment the amount of fruit normally produced by a shoot seems to have little or no effect on growth. Since this is a shoot study, it does not take into account the effect of production by one shoot on the growth of another, which may partially explain why these data appear to disagree with those of Chandler and Heinicke,1* who found that fruit production decreased top growth on the vine as a whole.

In order to measure the relationship between fruit-bud formation and the vigor of the buds the following spring, one vine (Fig. 6) was left unpruned in 1929 and at blooming time, June 5, the number of flower clusters present and the vigor in terms of shoot length were determined. Since the vine was left unpruned in 1929, the in- dividual buds were expected to show the same relative vigor as they had the previous season. The correlation between fruit-bud formation and growth at blooming time was + -444 ± .026. This is similar to the correlation found by Schrader13* between shoot length on May 22 and size of bunch on shoots that were thinned to one cluster before set- ting. The correlation was, however, slightly higher than that of termi- nal growth and fruiting, as previously presented, and shows that the relationship between growth and fruiting is one of bud vigor and fruit-bud formation continuing on to fruit development.

GROWTH AND PRODUCTION ALONG THE CANE

Vines trained to the 4-cane Kniffin system and pruned to different degrees of severity would, judging from the above data, be expected to vary in cane length somewhat proportionately to the severity of prun-

1933}

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

195

ing. The distribution of the 199 canes left on the 48 vines in 1927 and the 225 canes of 1928, according to length in number of nodes and pruning treatment of the vine supporting them, is shown in Table 8. The average activity of the different length canes proved to be directly

FIG. 6. — CONCORD VINE MODERATELY PRUNED TO 50 NODES IN 1928, WITH No PRUNING IN 1929

A large number of weak shoots beginning growth with too many fruit clusters resulted from moderate pruning in 1928 and no pruning in 1929. (Photographed June 5, 1929)

related to the pruning range followed the preceding winter and also, altho to a less extent, of the winter before that.

Shoot Growth Along the Cane. — The number of shoots produced per node along the cane was larger as more nodes were left on the cane and vine at pruning time (Table 9). Examination of the canes from base to tip indicated that this growth pattern was due primarily to greater activity of buds on more distal nodes in starting shoots.

The average vigor of shoots or growth per bud as measured by length of terminals (Table 10) and of laterals (Table 11) decreased with length of cane. The growth of laterals diminished more rapidly than that of terminals, as would be expected from the conclusions drawn from the data in Table 6 (page 192).

196

BULLETIN No. 393

[July,

TABLE 8. — DISTRIBUTION OF CANES ACCORDING TO NUMBER OF NODES TO WHICH VINES WERE PRUNED AND ACCORDING TO NODES PER CANE

Nodes per vine	Nodes per cane	All canes
1-4	5-8	9-12	13-16
Number of canes in each group, 1927
20-29	3 3 3 2 2 5 0 18 51.2	23 6 31 13 9 1 1 84 42.8	0 3 25 24 20 4 2 78 54.9	0 0 3 6 7 2 1 19 60.3	26 12 62 45 38 12 4 199
30-39
40-49
50-59
60-69
70-79
80-89
Number of canes in each group, 1928
20-29	10 4 1 2 0 17 31.6	22 77 35 17 4 155 38.3	2 15 31 21 6 75 46.4	0 0 2 4 2 8 54.5	34 96 69 44 12 255
30-39
40-49
50-59
60-69
Total number of canes
Average nodes per vine
TABLE 9. — AVERAGE NUMBER OF SHOOTS PER NODE IN CANE SECTIONS PRUNED TO DIFFERENT NODE NUMBERS (Data for same canes as in Table 8)
Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes
Number of shoots per node, 1927
1-4	.71 .56 .60 .54 .58	1.03 1.08 1.00 1.04	i.'ii 1.19 1.15	1.36 1.36	.71 .74 .91 .97 .86
5-8
9-12
13-16
Average for all canes
Number of shoots per node, 1928
1-4. . .	.66 .54 .51 .62 .54	.96 .97 .91 .96	i!oo 1.15	i!66 1.00	.66 .71 .82 .87 .76
5-8
9-12
13-16
Average for all canes

1933}

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

197

TABLE 10. — AVERAGE TERMINAL GROWTH PER SHOOT IN CANE SECTIONS PRUNED TO

DIFFERENT NODE NUMBERS (Data for same canes as in Table 8)

Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes

Terminal growth per shoot, 1927

1-4	inches 65	inches	inches	inches	inches 65
5-8	65	74			70
9-12	51	60	70		61
13-16	42	52	59	71	56
Average for all canes	57	64	67	71	63

Terminal growth per shoot, 1928

1-4	86				86
5-8	82	84			83
9-12	65	72	88		75
13-16	36	36	50	59	45
Average for all canes	76	77	82	59	77

TABLE 11. — AVERAGE LATERAL GROWTH PER SHOOT IN CANE SECTIONS PRUNED TO

DIFFERENT NODE NUMBERS (Data for same canes as in Table 8)

Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes

Lateral growth per shoot, 1927

1-4	inches 37	inches	inches	inches	inches 37
5-8	30	42			36
9-12	18	19	34		23
13-16	15	20	21	43	24
Average for all canes	14	27	34	43	28

Lateral growth per shoot, 1928

1-4	106				106
5-8	69	77			73
9-12	39	44	58		46
13-16	6	6	7	14	8
	61	60	50	14	59

198 BULLETIN No. 393 [July,

Both terminal and lateral shoots from each group of canes were shortest at the base of the cane and increased in length as they origi- nated nearer the tip. Apparently the shoot- vigor pattern of a vigorous cane, like its productiveness, tends to increase with the buds farther out from the base to at least the sixteenth node. This probably ex- plains most of the correlation found between shoot growth and produc-

FIG. 7. — FLOWERING SHOOTS FROM A HEAVILY PRUNED, A MODERATELY PRUNED, AND AN UNPRUNED CONCORD VINE

The vine pruned severely to 16-25 nodes (1) shows a more vigorous growth than the vine pruned moderately to 56-65 nodes (2). The vines that received no pruning (3) was much less vigorous than either of the pruned vines.

tion (Table 7). As pruning treatments become more severe and shorten the cane accordingly, they also increase the vigor of the remaining buds nearer the base (Figs. 3 and 5).

Production Along the Cane. — In some of the earlier studies on cane production the node was used as a unit instead of the shoot, which is usually considered as the unit in this study. The node is used as a unit in Tables 12 and 13, in which production results are shown.

In general, the findings in this experiment confirm duplicate studies in other states. That is, they show that the production per shoot tended to be low at the base of the cane and increased to about the ninth to sixteenth nodes (Table 15), and that the production per node varied in the same direction, altho more widely, owing to the differences in number of shoots produced at the various nodes (Table 16). This variation in the production of the different areas of the cane in the

1933}

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

199

TABLE 12. — AVERAGE NUMBER OF CLUSTERS PER SHOOT IN CANE SECTIONS PRUNED TO DIFFERENT NODE NUMBERS (Data for same canes as in Table 8)

Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes

Number of clusters per shoot, 1927
1-4	1.31 1.59 1.75 2.03 1.67	1.55 1.98 1.96 1.83	1.70 2.09 1.81	2.' 07 2.07	1 1 1 2 1	31 .57 84 04 74
5-8. . .
9-12
13-16
Number of clusters per shoot, 1928
1-4	.63 1.50 1.66 2.00 1.50	1.73 1.91 2.17 1.82	l!74 2.25 1.82	2.35 2.35	1 1 2 1	63 62 80 19 71
5-8
9-12
13-16
Average for all canes

TABLE 13. — AVERAGE NUMBER OF CLUSTERS PER NODE IN CANE SECTIONS

PRUNED TO DIFFERENT NODE NUMBERS

(Data for same canes as in Table 8)

Number of nodes per cane left after pruning

Section of cane from base to tip
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes

Average for all sections

Number of clusters per node, 1927

1-4.. 5-8.. 9-12. 13-16.

Average for all canes .

.93

.89

1.05

1.10

.98

1.60 2.14 1.96

1.90

1.94 2.50

2.90

2.82 2.82

.93 1.17 1.68 1.98

1.53

Number of clusters per node, 1928

1-4. . .	.42				.42
5-8	.82	1.66			1.15.
9-12	.84	1.85	2.06		1.48
13-16	1.25	1.97	2.25	2.35	1.90
	.81	1.75	2.10	2.35	1.30

200

BULLETIN No. 393

[July,

TABLE 14. — AVERAGE WEIGHT OF FRUIT PER CLUSTER IN CANE SECTIONS

PRUNED TO DIFFERENT NODE NUMBERS

(Data for same canes as in Table 8)

Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes
Weight of fruit per cluster, 1927
1-4	oz. 2.64 2.36 2.65 2.92 2.57	oz. 2'.73 3.18 3.31 3.06	oz. 2.88 2.89 2.88	oz. i!68 2.68	oz. 2.64 2.56 2.97 2.97 2.86
5-8
9-12
13-16.
Weight of fruit per cluster, 1928
1-4	2.62 2.54 2.23 2.08 2.50	2.91 2.91 2.87 2.91	2. 'SO 3.14 2.87	2^46 2.46	2.62 2.75 2.72 2.74 2.70
5-8
9-12
13-16
TABLE 15. — AVERAGE WEIGHT OF FRUIT PER SHOOT IN CANE SECTIONS PRUNED TO DIFFERENT NODE NUMBERS (Data for same canes as in Table 8)
Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes
Weight of fruit per shoot, 1927
1-4	oz. 3.45 3.76 4.65 5.91 4.51	oz. i'.23 6.31 6.48 5.60	oz. 4.91 6.05 5.22	oz. s!s3 5.53	oz. 3.45 4.02 5.48 6.06 5.18
5-8
9-12
13-16. .
Weight of fruit per shoot, 1928
1-4	1.66 3.80 3.72 4.15 3.74	5.04 5.57 6.23 5.30	4.87 7.07 5.23	S. 79 5.79	1.66 4.46 4.91 6.00 4.71
5-8
9-12. .
13-16
Average for all canes .

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

201

TABLE 16. — AVERAGE WEIGHT OF FRUIT PER NODE IN CANE SECTIONS PRUNED TO

DIFFERENT NODE NUMBERS (Data for same canes as in Table 8)

Number of nodes per cane left after pruning	Section of cane from base to tip	Average for all sections
lst-4th nodes	5th-8th nodes	9th-12th nodes	13th-16th nodes

Weight of fruit per node, 1927

1-4... .	01. 2.46	ot.	oz.	oz.	oz. 2.46
5-8	2 09	4 35			2 99
9-12	3 79	6 81	5 58		4 99
15-16	3.20	6.48	7.22	7.54	5.89
Average for all canes	2 64	5 90	6 02	7.54	4 45

Weight of fruit per node, 1928

1-4	1.10				1.10
5-8	2 07	4 82			3 16
9-12	1.88	5 38	5 78		4 04
13-16	2.59	5 64	7 07	5.79	5.20
Average for all canes	2 03	5 09	6 02	5 79	3 58

Illinois studies, as in those in other states, was determined largely by the number of clusters produced but was also somewhat affected by the size of the clusters.

EFFECTS OF PRUNING ON FRUIT-BUD FORMATION

The data in Tables 12 and 14 show that the shoots on each section of the short canes consistently produced both fewer and smaller clusters than did the shoots on the same regions of the longer canes. These data include a larger range of variables in vine pruning than do the data in Tables 5 and 6, where this variation does not show con- sistently.

Keeping in mind that the severity of pruning within the limits of this experiment did not affect the current year's cluster production of the buds left, and that the ability of a bud to produce was determined largely at the time of fruit-bud formation, the authors began studies to determine the effects of the severity of pruning on fruit-bud formation.

The number of clusters produced by a shoot during the growing season was considered an index of the ability of the bud to form in- florescences, since practically no aborted flowers were noted. Any discrepancy caused by the polarity of cane activity was overcome by

202

BULLETIN No. 393

[July,

as DM

w

M

a! O

a

Q

H

~ H 5

W

	19 and 20	3 fa. Q S5.S-S	ooo • ooo •	000 • ooo •	000 • ooo •	S§ 8 • o COCO CM — — O •	000 • ooo •	000 ooo
	oo	-3 1* O zj-g	000 • ooo •	ooo • 000 •	ooo • 000 •	oooo CO CM CM CM	To" CM 0>00 •	ooo 000
	15 and 16	III	ooo • ooo •	000 • ooo •	OS CM	:::s	oc»oa> •a- :	ooo ooo
	f	in i £	S SS	ss g	5S82	So1^	5S82
•8	1	in	OCM O •	CMCMO ;	^CM" •	W:	O-f CO • CM>0— •	ooo
|	•	a"° A £	- S	CMX5 CM	— 0000 »	OO CO CO OO •»00 —	CM OO IT- OS	S
1 I	i OS	III		0..0 ;	SS>:	— CO— • — -<r co •	fSSSco :	oot-
		|-0i2	coo —	gp-gg	Tl CC ~ — •	— r-oocM >O 3500 —	" — — -	..s
I 3 8	i as	HI	•- •- — •	CM -*00 •	C3 tO t^- •	Bas 1	S2S :	oo>o
1		SJoo Sg-S	SS525	S55S	2S8SS	>- -. ( ~	•* CO<M — (MOOOOO	: :ff
2		•S'S"1
it		KlB	ssss	sgss	C^ OS O> O	S2S2	SSS2	00^
Js S "8	a	ZJ=^-	2S= :	sis :	68! i	IIS :	S§S:	ooco
		12I|	oooo OCM	-S5SS	CO i-H M CO CM O OO O	gSSS§	(M O> OO O	oo".
	T3 § iO	III	SSg:	§iS:	Hi i	sii ;	CO if3 CO •	ooos
		a"2 A E	SSS55	SS5^	ssn§	ssss	«2SS	oo 00 •
	1 CO	a^"!	SiS:	Sis :	OOOOCM • COCOCM •	OJt-— •	S5co :	OO CO
		123-1	?§r:s	S«2S	— 00 — t-	SSSfc	OCO^JO	8
		III	irt OSCM •	CO — CM •	WBi		— CO CM • CM CO 10 •	oo — CM
	!rt A '	JB|	. . . y	: : :d	: : :«	: : :„•	: : :»
	*4*	Jj	ocot- £	222-5	222-S	lill	222-<	lOCOt- (M CXI CXI O3 CS OS
	1}	If	1	1	|	a>	i	OS 1

1933]

GROWTH AND PRODUCTION IN THE CONCORD GRAPE

203

numbering all nodes progressively outward, starting with the basal node at the trunk. The clusters on the shoots from each two nodes of all canes of the vines in each group were averaged separately, as shown in Table 17. The averages of the shoots in the first four groups, including those from the first eight nodes, were then averaged as an

20-29

30-39

40-49

50-59

60-69

70-79

BUDS PER VINE FIG. 8. — EFFECTS OF PRUNING ON FRUIT-BUD FORMATION

The rate of fruit-bud formation per node was low when severe pruning was practiced and increased with the decrease in severity of pruning up to 56-65 nodes.

index of fruit-bud formation. Data for the other nodes were listed but not averaged owing to the small number of shoots in some classes. Since this study covers a period of three years and includes thous- ands of shoots, the indexes may be considered as representative. They result in a very smooth, even graph (Fig. 8). The rate of fruit-bud formation per node was low when severe pruning was practiced and increased at a constantly diminishing rate with the decrease in severity of pruning until the peak was reached at 56 to 65 nodes per vine. At this point the rate apparently started to decline. Since these curves are so consistent in direction for each of the three years, it may be concluded that under conditions similar to those of this experiment 56 to 65 nodes is the optimum number to leave in pruning Concord grapevines for maximum flower-bud production.

204 BULLETIN No. 393 [July,

SUMMARY

1. The total amount of shoot length produced by a Concord vine was little affected in these experiments by the severity of the previous winter's pruning. The vigor of individual shoots was, however, in- creased proportionately as the severity of pruning increased. The in- creasing vigor of weak shoots was evidenced mainly by their greater length and of very vigorous shoots by the growth of laterals. The average length of the growth per shoot varied inversely with the num- ber of buds left on the vine at pruning time.

2. The total yield produced by a vine was greatly influenced by the severity of the previous winter's pruning, the possible number of fruit clusters being limited by such pruning. Where fewer buds were left at pruning time and where the number of potential shoots was reduced, the number of clusters resulting was automatically lessened. The yield of individual shoots from the buds left to grow was not noticeably changed.

3. The patterns of shoot growth and of fruit production along the cane varied similarly from base to tip within the groups having a similar number of nodes per cane. The degree of severity of winter pruning treatment given a vine changed proportionately the vigor of all the shoots on a cane, the more severe pruning increasing the vigor of the shoots but having little effect on their production.

4. The degree of severity practiced in dormant pruning had a marked effect upon the formation of inflorescences in the buds along the shoots growing the following summer. With the more severe pruning, fewer inflorescences were formed.

5. Except under very unusual conditions during the fruiting season, the yielding ability of a shoot was largely determined in the bud the previous year, while its vigor was increased or decreased by the number of nodes left on the vine at pruning time, the smaller num- bers resulting in an increase in vigor.

6. In this experiment vines pruned to about 56 to 65 nodes pro- duced a profitable yield and also produced the largest number of flower primordia in the buds of the young shoots for the following year's crop.

PRACTICAL APPLICATION

The grower's problem is to secure high annual yields of marketable fruit and at the same time to cause the vine to form the largest in- florescences possible in the buds along the growing shoot for the future crop. Usually conditions that favor the formation of large flower

1933] GROWTH AND PRODUCTION IN THE CONCORD GRAPE 205

clusters also favor a large number of flower clusters.4* Winter prun- ing modifies the immediate crop, mainly by limiting the number of clusters that can be produced. It influences the following year's crop by affecting the condition of the new shoots and their ability to form flower buds.

The grower should look upon his vines as individuals and, allow- ing for gradations in vigor resulting from the presence of insects or diseases, soil differences, and weather conditions, should handle them in such a way that vine growth and yield of well-matured clusters are balanced yearly.

The plants should have sufficient vigor and enough shoots, properly located, that will ripen into desirable canes, to produce a good crop. Since the condition of the crop cannot readily be determined while in the bud, the best available index that can be used at pruning time during the dormant season is the growth of the last season's shoots.

If most of the shoots were short and were too weak to produce laterals, the vine was pruned too lightly ; that is, too many nodes were left the previous season. More severe pruning should be practiced, de- pending on the degree of weakness found.

If the shoots were so vigorous that they produced more than a third of their combined terminal and lateral length in laterals, the previous winter's pruning treatment was too severe and more nodes should be left in order to obtain higher yields the coming season and maximum fruit-bud formation for the next crop.

Concord vines grown under conditions similar to those occurring in the University vineyard and pruned to about 56 to 65 nodes will bear shoots that are vigorous but not sufficiently vigorous to produce much, if any, lateral growth. Vines with such a type of growth can carry large-sized bunches to full maturity and at the same time they have enough vigor to differentiate large flower clusters in the nodes along the growing shoots for the following year's crop.

After the severity of pruning treatment for the individual vine has been determined in terms of number of nodes to be left, the canes should be selected which will bear the following year's crop. Colby and Vogele5* found that shoots with a diameter of about ^ inch measured between the third and fourth nodes and well matured out to the tip will make the most productive canes the following year. Canes of this type, with few laterals, should be selected as arms to form the frame- work of the vine since the buds on these canes carry many and large inflorescences.

206 BULLETIN No. 393

LITERATURE CITED

1. CHANDLER, W. H., and HEINICKE, A. J. Some effects of fruiting on the

growth of grape vines. Amer. Soc. Hort. Sci. Proc. 22, 74-80. 1925.

2. CLARK, J. H. Some effects of pruning on grape production. Amer. Soc.

Hort. Sci. Proc. 22, 80-84. 1925.

3. COLBY, A. S. Additional notes on pruning and training grapes. Amer. Soc.

Hort. Sci. Proc. 22, 415-420. 1925.

4. — and TUCKER, L. R. Growth and fruit production studies in the

grape. Amer. Soc. Hort. Sci. Proc. 25, 210-216. 1928.

5. — — and VOGELE, A. C. Notes on pruning and training Concord

grapes in Illinois. Amer. Soc. Hort. Sci. Proc. 21, 384-387. 1924.

6. GOFF, E. S. Investigation of flower-buds. Wis. Agr. Exp. Sta. Rpt. 18,

304-316. 1901.

7. KEFFER, C. A. The fruiting habit of the grape. Tenn. Agr. Exp. Sta. Bui. 77.

1906.

8. MANEY, T. J. Grape pruning — the spur and long cane systems compared.

Iowa Agr. Exp. Sta. Bui. 160. 1915.

9. PARTRIDGE, N. L. A note on the fruiting habit of the Concord grape. Amer.

Soc. Hort. Sci. Proc. 18, 193-196. 1921.

10. — The fruiting habits and pruning of the Concord grape. Mich.

Agr. Exp. Sta. Tech. Bui. 69. 1925.

11. SCHRADER, A. L. Growth studies of the Concord grape. Amer. Soc. Hort.

Sci. Proc. 20, 116-122. 1923.

12. The Concord grape — Pruning and chemical studies in relation to

the fruiting habits of the vine. Md. Agr. Exp. Sta. Bui. 286. 61-118. 1926.

13. The effect of fruiting on the shoot growth of the Concord grape.

Amer. Soc. Hort. Sci. Proc. 27, 170-174. 1930. 14. SWARTWOUT, H. G. Fruiting habit of the grape. Amer. Soc. Hort. Sci. Proc.

22, 70-74. 1925.

DEFINITION OF TERMS

Shoot. The young growing branch originating from a bud. All fruits are borne on shoots, but not all shoots bear fruit.

Terminal or main shoot. The one central or principal shoot starting at the bud.

Lateral. A secondary growth arising from the main shoot the same year that the shoot grows.

Cane. A shoot of the previous season which may be left as an arm at prun- ing time.

Node. The enlarged portion or joint of the shoot at which the tendril, leaf, bud, and cluster are or may be borne, or the joint of the cane where the bud or shoot may be attached.

Internode. The part of the cane or shoot between two nodes.

Spur. A short piece of the base of a cane, having one to four nodes with one or more buds each, where renewal wood may be obtained at pruning time. Sometimes known as a renewal spur.

Bud. An undeveloped shoot.

Fruit bud or mixed bud. A bud in which a shoot bearing flowers originates ; a bud containing rudiments of both shoot and flowers.

UNIVERSITY OF ILLINOIS-URBANA

- ,

-

.

• •

•

'

-

.

•

.

.

•