Research Note

vm Souther Forest

f

SO-293

Experim nt Station May, 1993

Performance of Willow Clones on Sharkey Clay

Robert B. Ferguson

SUMMARY

Random clolnes of black willow (Salix nigra) and

sandbar willovir (S. exigua) from near Stoneville, MS

and of S. argebtinensis and S. babylonica X S. alba

were gro\Nn dn Sharkey clay near Stoneville, MS

for 11 years. US. babylonica X S. alba grew best

throughout the period. S. nigra, severely damaged

by the cottonqood leaf beetle at age 1, was performing well by age 11, while the single clone of S. X

argentinensis and 2 of the 3 clones of S. exigua had

died.

Additional k/eywords: interspecific hybrids, selection, asexual propagation, Salix sp.

INTRODUCTION

Black willov$ (Salix nigra Marsh.) abounds along

streams and iln wetlands throughout the eastern

United States and adjacent parts of Canada and

Mexico (McKn~ight 1965). Because of the tolerance

to flooding, it thrives where little else grows. Along

the lower reaches of the Mississippi River, the better specimens1 are sawed and the lumber brings

prices as high ias $lOOO/mbf. Occuring in stands too

dense for good growth, the majority of the trees are

never harvested because of hidden defects, primarily ring shake.

Black willow is dioecious, easy to cross, easy to

propagate by seedlings or asexually from dormant

cuttings, and sexually mature as early as age 1 or

2. Its early sexual maturity interests tree breeders.

Abundant genetic variability and the general low

quality of the species suggest that it would benefit

from improvement efforts. Insufficient demand for

the present low quality material fails to justify tree

improvement for a species so naturally abundant.

Nevertheless, breeders will likely want to work with

willow, if only as an experimental tool. Growers of

other hardwood species may be interested in it as

a potential species to plant in areas too poorly

drained or otherwise unsuitable (sewage disposal

plants) for other species.

To supply information on growth potential, a small

willow clonal test was established by the Southern

Forest Experiment Station near Stoneville, Mississippi in anticipation of this need. Performance

through age 11 is reported here.

MATERIALS AND METHODS

Experimental materials consisted of unrooted

cuttings of 49 Salix sp. clones as follows:

43 black willow (Salix nigra) clones

14 female

16 male

13 of unknown sex

Southern Foreist Experiment StationIT-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

Serving Alabarn&, Arkansas, Louisiana, Mississippi, E. Oklahoma, Tennessee, E. Texas, Puerto Rico, U.S. Virgin Islands

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3 sandbar willow (Salix exigua Nutt.) clones’

3 interspecific hybrid clones

1 Salix X arg ntinensis (Salix babylonica L. X

Salix humb $ Diana Willd.)

2 Salix baby/olnica x s. alba L.

The black willow and sandbar willow clones all

come from random trees from natural stands in the

general vicinity of! Stoneville. The hybrids were received from Dr. Arturo Ragonese of the National

Center of Agricultural Investigations at Cestellar,

Argentina and maintained in a ctonal nursery at

Stoneville.

Cuttings of the female and 16 male black willow

clones came directly from 30-40 year old trees. The

13 black willow clones of unknown sex and the 3

sandbar willow clones were obtained directly from

2-3 year old tree$. Cuttings of the hybrid willows

were made from one year old regrowth taken from

2 year old nursery rootstock.

The experiments was installed in 1970 as a randomized complete block design with six replications of single tree plots using unrooted cuttings

planted at 10 by 19 feet spacing. The site was a recently cleared Sharkey clay (a very fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) on the

Delta Experimental Forest at Stoneville, MS. Internal drainage is poor, and the very low site is subject

to summer flooding.

Nineteen of the clones were planted from dormant

cuttings on Marchm12. The 30 black willow clones of

known sex were blanted as freshly collected, nondormant branch duttings from 30-40 year old trees

on May 1. Because of the differences in cutting materials and planting dates, the two groups are not

directly comparabhe and should probably be considered as two separate interspersed experiments.

Data were collscted on cottonwood leaf beetle

(Chrysomela scriflta F.) defoliation, height at age 1,

and diameter at breast height (dbh) at ages 4 and

11. At each age, data were subjected to missing plot

computations (using Yates’ approximation, Steel

and Torrie, 1960) sfter exclusion of the clones with

poorest survival but prior to computation of means

and analysis of variance. At age 11, severe mortality

excluded two entire replications.

Age 4 dbh data’ were subjected to more detailed

analysis in comparing black willow, sandbar willow,

S. X argentinensis and S. babylonica X S. alba. The

‘These clones were cllassified as Salix interior Rowlee by Randall (1971).

30 late-planted black willow clones were considered

separately and only means were computed. Analyses of variance for each of the other groups was

conducted separately. Comparisons among groups

of clone means were made using an unequal variance, unequal replication “t” test (Steele and Torrie 1960) at the -05 level.

RESULTS

Age 1 height and defoliation results (Randall

1971) are included here for comparison and discussion. Only 45 of the original 49 clones survived

to the end of the first growing season. The total remaining clones dropped to 40 by age 4 and further

decreased to 31 clones by age 11.

Results of t-test comparisons of age 4 dbh revealed that each group mean was significantly different from each other group mean at the .05 level

(table 1).

The S. baby/mica X S. alba hybrid clones outperformed all other species/hybrid groups and individual clones tested. When examined closer, these

clones also proved to be quite branchy and of general poor quality. The age 11 mean dbh adjusted

for missing plots was 7.6 inches (table 1). The best

tree of this hybrid averaged 10.9 inches, 4.4 inches

better than any other clone. The elimination of two

replications resulted in a low mean for the other

hybrid clone.

The single S. X argentinensis clone showed early

promise of performing as well or better than the native group of black willow clones planted from cuttings of 2 or 3 year old trees, but it died out by age

11.

The sandbar willow group of clones ranked best

for age 1 height and high for cottonwood leaf

beetle resistance, but, like the S. X argentinensis

clone, this trend did not carry through to age 11.

Only 1 of the original three sandbar willow clones

was still alive at age 11 and that one ranked lower

than the means of the other groups planted from

comparable material. The best tree of the sandbar

willow was only 5.6 inches for age 11 dbh.

The native black willow clones were poorest for

age 1 leaf beetle resistance, but performed adequately for growth throughout the experiment. A few

individual clones ranked above the experiment mean

for both age 4 and age 11 dbh. The best tree at age

11 was 8.7 inches dbh. When only those clones

Robert B. Ferguson, lormerly Research Support Geneticist at the Forest Sciences Laboratory, which is maintained at Starkville,

MS, and currently Stetistical Assistant, RWU 1102, Alexandria, LA, Southern Forest Experiment Station, USDA Forest Service.

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Table I.--Summary of character means by species or hybrid group for Delta Experimental

Forest willow planting

Character

Species or hybrid Age 1 Age 1 Age 4 Age 11

defoliation height dbh dbh

(%I (ft) (in) (inches)

Black willow (Salix nigra) 69 5.6 2.0 4.9

Male 7 6 5.0 1.6 4.6

Female 5 5 4.6 1.9 4.4

Juvenile (sex unknown) 7 1 7.0 2.5 5.4

S. X argentinensis 5 2 6.1 3.1 . . . . .

Sandbar willow (S. exigua) 9 9.4 2.2 5.2

S. babylonica X S. alba 5 6.6 4.7 7.6

planted from 2 to 3 year old trees are considered,

the potential of black willow appears more favorable. The mean of these clones was 0.5 inche dbh

better than the mean of all black willow clones at

age 11. A few individual clones planted from younger material exceeded 6 inches for age 11 dbh. The

black willow clones planted later from cuttings of

older trees never equalled any groups planted early

from younger material. A few individual clones of

this older group did rank above the experient mean.

The performance of the willow species and hybrids in this study compare favorably with other species planted onthe same soil type and within a mile

of this experiment. One such study involving 40 families of sweetgum (Liquidambar Styraciflua L.) reported a mean dbh of only 3.3 inches at age 11 (Ferguson and Cooper 1977). A study of 80 clones of

eastern cottonwood (Populus deltoides Bartr.) reported a mean dbh of only 5.7 inches at age 14

(Cooper and Ferguson 1979).

DISCUSSION

Willows, known to grow much better on soils other

than Sharkey clay, can be grown on sites such as

used in this ca$e. Few alternative uses for this type

of site exist.

The small number of clones representing each

species or hybrid group or a single testing site

severely limits the conclusions that can be drawn

from the data. Nevertheless, the failure of sandbar

willow and S. ti argentinensis suggests they are unsuitable in the area where tested.

S. babylonica X S. a/h appears to have some potential. It is excessively branchy, but its extremely

rapid growth rate suggests that other hybrids involving one or both of the same parent species

should be examined.

The best bliack willow clones performed well

enough to suggest that a selection program would

be effective in identifying suitable black willow

clones. Experience with sycamore, Platanus occidentalis L., indicates that material from south of the

planting site outperforms northern and local material (Cooper et al. 1977 and Ferguson et al. 1977).

Other work with eastern cottonwood, P. deltoides,

a more closely related species to Salix, indicated the

same geographic trend.* Therefore, selected clones

from possibly as far as 150 miles south of the planting site might perform considerably better than the

unselected, local clones in the present study.

LITERATURE CITED

Cooper, D. T. and Ferguson, Robert B. 1979. Avoid

early selection for growth rate in cottonwood.

Proc. South. For. Tree Improv. Conf. 16: 52-58.

Cooper, D. T., Filer, T. H., Jr. and Wells, 0. 0. 1977.

Geographic variation in disease susceptibility

of American sycamore. Southern Journal of Applied Forestry. 1: 21-24.

Ferguson, Robert B. and Cooper, D. T. 1977. Sweetgum variation changes with time. Proc. South.

For. Tree Improv. Conf. 14: 194-200.

Ferguson, Robert B., Land, S. B., Jr. and Cooper,

D. T. 1977. Inheritance of growth and crown characters in American sycamore. Silvae Genetica 26:

180-l 82,

McKnight, J. S. 1965. Black willow (Salix nigra

Marsh.) In: Silvics of forest trees of the United

States. H. A. Fowells, editor. U.S. Department of

Agriculture Handbook No. 271. p. 650-652.

Randall, W. K. 1971. Willow clones differ in susceptibility to cottonwood leaf beetle. Proc. South. Tree

Improv. Conf. 11:108-111.

Steel, Robert G. D. and Torrie, James H. 1960. Principles and Procedures of Statistics. McGraw-Hill

Book Company, Inc. New York. 481 p.

zpersonal communication with D. T. Cooper, Southern Forest

Experiment Station, Starkville, MS.

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