I

I

J

]

]

J

]

]

]

]

]

]

I

I

I

J

]

J

MANAGEMENTSYSTEMSFORHIGH DENSITYWALNUTORCHARDS

D. Ramos,W. Olson, J. Osgood, W. Krueger,G. S. Sibbett, W. Rei1, L. Hendricks, R. Snyder and K. Ryugo

ABSTRACT

Chico walnut trees planted in 1974 in hedgerows (22' x 11') trained into afruiting wall and mechanically pruned since 1978 continue to-yield as much ormore crop than standard spaced and pruned trees. In 1986, the yields were asfollows: annual hedging -- two sides, 2.22 tons per acre; annual hedging --one side (alternate), 2.90 tons per acre; and conventional spaced (22' x 22')and pruned, 2.54 tons per acre. A third hedging procedure in which the treeshave been hedged on two sides each year, but were left unpruned in 1982 and1983, and again in 1986 yielded 3.36 tons per acre. A fourth treatmentinitiated in 1983 consisting of alternate year hedging (even years) on twosides yielded only 2.12 tons per acre. This significant drop in production isexplained by 1986 being a year in which the trees were pruned. Variety trialsto measure the performance of various walnut cu1tivars in a high densitymanagement system have been established in Tulare, Merced and Yolo Counties.Preliminary vegetative growth ratings made in a hedgerow variety trial inVisa1ia showed that Sun1and, Tehama,Serr, Hartley, Ashley and Vina exhibitedexcessive wi110wing of shoots which present training/pruning problems.

OBJECT!VE

To develop and implement more efficient high density management systems forearly economic production and sustained high yield and quality of walnuts,examine pruning systems and how they influence tree physiology and produc-tivity, and determine adaptability of various walnut cu1tivars and proper treespacing for hedgerow p1antings.

PROCEDURE

The Chico hedgerow trial (221 x 11') established in 1974 near Vina was main-tained and the two hedging treatments initiated in 1978 (one side hedged vs.two sides hedged each year) were conti nued in 1986. Yi e1d data were alsoobtained from two other hedging treatments in which the trees are being leftunpruned either on even or odd years. As in previous years, mechanicalpruni ng of the hedgerowed trees was performed with avert i ca1 boom hedgi ngmachine positioned to cut about 4 feet from the trunk. No tree topping wasperformed in 1986, 1985, or 1984 in contrast to previous years. Productionwas compared with standard spaced (22' x 22') hand pruned trees.

Variety trials designed to measure the performance of various walnut cu1tivarsunder a high density hedgerow management system are being developed in Tulare,Merced and Yolo Counties in cooperation with Farm Advisors Sibbett, Hendricksand Rei1, respectively. The Visa1ia trial (20' x 10') was planted in 1982 andgrafted in 1983 to fifteen cu1tivars in three replications of nine trees perplot. The trial near Gustine was planted in 1983 and consists of twelve acresat a 30' x IS' spacing, comparing five cultivars -- Payne, Chico, Vina,

45

-- --

IJJJJJ]

J

J

]

]

]

J

j

]

I

: j

Chandler and Howard. There are two trials in the Winters area. The first oneincludes five cultivars (Chico, Vina, Chandler, Howard and Amigo) at twodifferent spacings (221 x II' and 18' x 9'). The 350 trees in this trial wereplanted as Black walnut seedlings in 1983 and 1984 and allowed to grow oneyear before grafting in 1984 and 1985. The second Winters trial (22' x II')consists of 520 Black walnut trees planted in 1984 and grafted in 1985 tothirteen cultivars -- Amigo, Ashley, Chandler, Chico, Howard, Payne, Pedro,Sunland, Tehama, Vina, 67-11, 67-13 and 68-104. There are four replicationsof ten trees per pl~t in this trial.

RESULTSAND CONCLUSIONS

Vina Hedgerow Trial

Yields obtained from the Vina hedgerow trial (cv. Chico) in 1986 were lowerthan the record crop obtained the previous season but still in excess of 2tons per acre in all treatments (Table 1). Individual treatment yields wereas follows: annual hedging -- two sides, 2.22 tons per acre; annual hedging-- one side (alternate), 2.90 tons per acre; standard density -- hand pruned,2.54 tons per acre. The data show that these original hedgerow pruningprocedures (hedging either one or two sides each year) are continuing to yieldas much or more crop than the standard spaced and pruned trees. A thi rdhedging treatment initiated in 1982, in which the trees were unpruned for twoconsecutive years (1982 and 1983) and again in 1986, yielded 3.36 tons peracre. The yield of a fourth hedging treatment consisting of alternate yearhedging (even years) on two sides was 2.12 tons per acre. This sharp reduc-tion in crop after the significant increase in production in 1985 was expectedsince this is the year in which the trees were pruned. The most promisingpruning procedure to this point based on the five-year cumulative yield dataappears to be hedging alternate sides of the tree wall each year. Thisconclusion is supported by on-tree crop observations made in August, 1986. Itwas noted at that time that the non-pruned trees and non-pruned sides of thealternate side hedged trees appeared to have substant~ally heavier crop. Thisobservation was borne out by the harvest data where those treatments hadsignificantly greater yield, 3.36 and 2.90 tons per acre respectively. Also,the trees in the alternate side hedging treatment had 37% more yield on theside left unpruned in 1986 as compared to the side that was hedged. Maximumsustained production seems to be dependent on being able to take advantage ofthe cropping potential of the new shoot growth generated each year in responseto the hedging.

Performan~e of Walnut Cultivars in Hedgerow Configuration

The trees in the Visalia variety trial have completed their fourth year ofgrowth following field grafting. They were mechanically hedged at three feetfrom the trunk on both sides and topped by cutting back one-third to one-halfof the previous season's growth last winter.

In 1986, early and late season vegetative growth ratings were made in theVisalia trial to gain additional information with these cultivars as to theirpotential suitability for hedgerow planting. The ratings were made on May 22,1986, during the period of rapid shoot growth (Table 2) and on September 17,1986, after the cessation of growth (Table 3).

46. !

I]

J

J

]

]

]

]

)

J

1

I

I

I

I

----

The May growth ratings indicated that Serr, Ashley, Tehama, Hartley andSun1and exhibited vigorous shoot growth and some IIwillowing" as compared tothe other cultivars in the trial. By September, the problem of excessivewill owing was accentuated with the additi ona1 shoot growth and it becameevident in Vina as well. As observed last year, 67-11 is interesting in thatthe shoots tend to remain upright in spite of being among the longest by theend of the season. These data are still very preliminary and will be col-lected over the next several years in order to determine the response ofvarious walnut cu1tivars to a hedgerow training and pruning system.

Catkin density ratings were made March 12, 1986, on the various cu1tivarsunder test to measure their precocity (Table 4). 67-13 and Sun1and standoutas prolific catkin producers based on these initial data.

47

]

J TABLE1. YIELDOFHEDGEROWWALNUTS-- CV. CHICO,PLANTED1974

J

J Dry Tons per Acre

Treatment 1982 1983 1984 1985 1986 X

] Hedged one side(alternate) 3.09 a 2.77 a 1.79 a 4.24 ab 2.90 ab 2.96

-]

Hedgedtwo sides 3.03 a 2.76 a 1. 73 a 3.61 c 2.22 c 2.67

Hedgedtwo sides

]except unpruned 3.42 a 3.06 a 1.34 b 3.75 be 3.36 a 2.99in' 82, '83 & '86

"]

Hedged two sidesexcept unpruned in 3.00 a 3.19 a 1.34 b 4.65 a 2.12 c 2.86'83 and '85

] Standard density andhand pruned 2.34 b 1. 78 b 1.26 b 3.64 be 2.54 be 2.31

1

-J

J

-J

oJ4

-]

-J

-j

-J

-j 48

- - - -- -- -

JJJJJJJJ

J

]

"J

]

J

J

J

I

J

J

1

--

TABLE2. VEGETATIVEGROWTHRATINGS OF WALNUTCULTIVARS IN HEDGEROW

CONFIGURATION- MAY, 198&1/

11 Ratings made 5/22/86.Data represent averages of 9 trees per replicate.

~ Vigor: 1 = no new growth2 = few new shoots; one foot of new growth3 = moderate no. of newshoots; 2-3 feet of newgrowth4 = large no. of new shoots; 3-4 feet crt new growth5 = profuse new shoots; 4-5 feet of new growth

1/ Wiliowiness: 1 = normal (upright)2 = some willowing of new growth3 = excessive willowing of new growth

49

- -

VigOr-2/ Willowiness1/

Replicate Replicate

1 2 3 X- l 2 3 X--Amigo 1.8 2.0 2.6 2.13 1.1 1.0 1.1 1.06Payne 2.6 3.0 2.7 2.77 1.7 2.1 1.9 1. 90Serr 3.5 4.0 3.5 3.67 2.0 2.1 2.1 2.07Ashley 3.0 3.4 3.3 3.23 2.2 2.2 2.3 2.23Chico 2.0 2.1 2.7 2.27 1.1 1.1 1.0 1.07Vina 2.7 2.5 3.1 2.77 2.0 1.6 1.7 1. 7767-13 2.4 2.5 2.8 2.57 1.3 1.0 1.0 1.10Tehama 3.3 3.4 3.5 3.00 2.0 1.8 2.1 1.97Hartley 3.8 3.6 4.4 3.93 1.7 2.1 2.7 2.1767-11 2.8 2.2 2.6 2.53 1.2 1.2 1.0 1.1368-104 2.7 2.1 3.0 2.60 1.2 1.0 1.4 1.20Howard 2.6 2.4 2.5 2.50 1.3 1.0 1.1 1.13Chandler 2.3 2.0 2.6 2.30 1.0 1.0 1.0 1.00Pedro 2.7 2.2 3.3 2.73 1.7 1.1 2.0 1.60Sunland 3.5 3.4 4.3 3.73 1.5 1.7 2.6 1.93

11 Ratings made 9/17/86.Data represent averages of 9 trees per replicate.

~/ Vigor: 1 = < 4' average current season's shoot growth2 = 4'-6' average current season's shoot growth3 = > 6' average current season's shoot growth

1/ Wi11owiness: 1 = < 45° average angle of current season's shoot growth2 = 45°-90° average angle of current season's shoot growth3 = > 90° average angle of current season's shoot growth

50

TABLE3. VEGETATIVEGROWTHRATINGSOFWALNUTCULTIVARSIN HEDGEROW

CONFIGURATION- September, 198&1/

Vigorl/ Willowinessll-Replicate Replicate

1 2 3 X- l 2 3 X--Amigo 2.0 1.9 1.7 1.87 1.4 1.5 1.5 1.47Payne 1.9 1.9 1.8 1.87 1.6 2.2 2.2 2.00Serr 2.9 2.7 2.5 2.70 2.2 2.4 2.2 2.27Ashley 2.1 2.0 1.9 2.00 2.5 2.4 2.4 2.43Chico 1.5 1.5 1.6 1.53 1.1 1.2 1.4 1.23Vina 1.5 2.1 1.9 1.83 2.1 2.5 2.6 2.4067-13 1.7 1.9 1.9 1.83 1.4 1.9 1.9 1. 73Tehama 2.2 2.0 2.6 2.27 '2.1 2.2 2.1 2.13Hartley 2.1 1.6 2.4 2.03 2.1 2.0 2.4 2.1767-11 2.8 2.4 1.8 2.33 2.1 1.9 1.9 1.9768-104 2.5 1.6 1.9 2.00 1.9 1.9 2.1 1.97Howard 1.1 1.0 1.2 1.10 1.4 1.1 1.3 1. 27Chandler 1.9 1.9 1.8 1.87 1.6 1.8 1.7 1. 70Pedro 1.7 2.1 1.3 1.70 1.6 2.3 1.9 1. 93Sunland 2.2 2.6 1.9 2.23 2.3 2.9 2.3 2.50

]

]

J

J

J

J

]

]

]

]

]

]

]

]

]

]

)

J

)

TABLE4. CATKIN DENSITY RATINGS OF WALNUTCULTIVARS IN HEDGEROWCONFIGURATIOnl/

1/ Ratings made 3/12/86.

..

Scale: 0 = absent1 = < 10 per tree2 = approximately 20-per tree3 = adequate4 = plentiful5 = abundant

51

---

Replicate

1 2 3 X

Amigo 2 2 2 2.0

Payne 3 4 3 3.3

Serr 3 2 3 2.7

Ashley 3 1 4 2.7

Chico 2 3 4 3.0

Vina 3 2 4 3.0

67-13 5 5 5 5.0

Tehama 2 2 3 2.3

Hartley 1 1 1 1.067-11 3 2 2 2.3

68-104 2 3 3 2.7

Howard 1 2 2 1.7

Chandler 2 2 3 2.3

Pedro 2 2 4 2.7

Sunland 5 5 5 5.0