NORT 

No. 1 

OCTOBER 

EARCH NO 

IMENT STATION 

0 

1951 

TES 

I R W . MARQUIS DIRECTOR 

> I ( IN HYBRID PINES TESTED I 

'f 

Hybrid trees, like hybrid corn, may have I 

I 

exceptionalqualities their parents did not have. I 

But extensive tests are needed to pick out the 11 

hybrids that have desirable characteristics such I 

as exceptionally fast growth and good form. 1 

I 

Crosses of'pitch x loblolly pine and shortleaf x pitch pine have been made by the California Forest and Range Ekperiment Station, and 

in 1943 hybrid seed from these crosses was sent 

to the Northeastern Forest Experiment Station 

for testing. Through the cooperation of the New 

Jersey and Delaware state foresters, the seedlings were grown in state nurseries. I 

i 

The seedlings aere planted in 1945 at the 

Eastern Shore Experimental Forest near Pittsville, Md., and in the Lebanon State Forest near 

Mount Misery, N. J. For comparison, ordinary 

stock of shortleaf pine and loblolly pine was 

also planted, but no pitch pine because neither 

nursery had any. 
I: Survival 

The pitch x loblolly hybrids usually survived the best of any of the stock planted in 

this study (table 1). Vhen planted, these hybrids had well-developed, extremely fibrous root 

systems; and they had suffered little winter injury or damage in lifting. 

But most of the shortleaf x pitch hybrids 

have died. Only 2 percent are still alive in 

New Jersey, no more than 29 percent in Maryland. 

When planted, most of these seedlings nere very 

small, had suffered extensively from winter injury, and many were prostrate. I P I k 

The ordinary seedlings of shortleaf and ! 

loblolly pine generally survived better than the f 

shortleaf x pitch hybrids--even though the % 

former had been injured more before planting. -, 

2 

g 

The plantings in Maryland have survived 

better and grown more than those in New Jersey, 

apparently because of the moister site. 

Growth 

The pitch x loblolly hybrids grew better 

than any of the other stock in the New Jerse 

plantings. They also grew well in the Maryla 

plantings, but here the ordinary loblolly gr 

better. 

The shortleaf x pitch hybrids exhibited the 

poorest growth--in both New Jersey and Maryland 

Many of these trees are still prostrate and les 

than 1.5 feet in heirht. 

None of the stocks planted in this study- 
Table 1.4urvival and growth of hybrid pines and ordinary 

nursery stock, 1945-50 

( 3-0 stock. All other 1.8 2-0. 

Mrsery 

Nmber Per- - Feet peet cent 

WTWN SHQRE E][PERR!ENTAL FORPST, HARYLAW) 

Rtch(V6) x loblolly( V22) 245 79.6 10.8 10.1 

E: W. J. { Loblolly 196 30.1 13.1 12.1 

Shortleaf 1% 56.1 7.8 7.1 

Pitch(V28) x 

loblollg(~22) 49 '77.6 9.7 9.2 

Pitch(V27) x 

loblolly(V22) 49 36.7 7.0 6- 5 

'bl. * Pitch(V29) x loblolly(v22 ) 28 n-4 7.6 6.9 

nilford, 

Shortleaf(*Lb) x 15 

pitch(V29) 13.3 0.6 0.3 

Shortleaf(V22) x pitch(~29) 1% 28.6 6.3 5.8 

shortlea8 147 3.4 6.7 4.8 

Loblolly 47 46.3 13.2 12.4 

LEBAM3A STATE mEIEST, !@EM JgRSEP 

Pitch(V6) x 

loblolly (~22 ) 439 62-9 5.0 4.3 

~hortleaf(V22)x ,,, pitch(V29) 2.0 1.2 0.9 

II. J. ~hortleaf (W6) x 

pitch(V29) 47 2.0 3.6 3.3 

Loblolly 392 12.5 4.5 3.5 

Shortleaf 196 42.9 4.0 3.4 i 1 

stock Phnted 

(19h5) KT Average 

E$f. Avenge 

2;; 
have grown as fast as natural reproduction. In 

the Eastern Shore plots, some native loblolly 

and pond pines became established and overtopped 

the pitch x loblolly hybrids in the 5 years between examinations. In New Jersey the fastest 

growing stock in this study, the pitch x loblolly hybrids, grew 4.3 feet in height in 6 

years, but in a nearby area the tallest natural 

seedlings of shortleaf and pitch pine on stocked 

quadrats grew 11 feet in 6 years. 

Conclusions 

None of the hybrids tested in this stud 

showed any evidence of exceptional vigor. 

The shortleaf x pitch hybrids have bee 

quite unpromising. The seed from the crosses o 

these species produced very few seedlings, a 

they have survived and grown poorly. For e 

ple, 650 seeds of the shortleaf (~46) x p 

(~29) cross produced only 15 s 

planted; and only two of those 

0.5 and 0.8 feet tall. Only a 

leaf x pitch hybrids have grown pas 

The pitch x loblolly pi 

value for reforestation work 

obtained economically--because they have a we1 

developed, fibrous root system that enables th 

to survive well. However, these hybrids are d 

veloping into trees that have larger limbs a 

are not quite so straight as ordinary lob101 

pine. 

--S. LITTLE and H. A. SO 

AGRICULTURE - FOREST SERVICE - UPPER DARBY, P