Table 1. - -Three-year survival and height growth of pine seedlings re- 

 leased from overtopping scrub oaks 



Time of release 



Loblolly pine 



Slash 



Dine 



Survival 



Average 

 height 



Survival 



Average 

 height 





Percent 



Feet 



Percent 



Feet 



Immediately after planting 



86 



4. 3 



46 



3. 4 



One year after planting 



62 



3. 2 



36 



2. 3 



Two years after planting 



39 



2. 5 



31 



2. 1 



Not released 



33 



2. 2 



27 



1. 6 



Girdling was as effective as poisoning in removing the oaks and 

 releasing the pine. Girdled trees, sprouted more than poisoned ones, 

 but the pines outgrew the sprouts. Therefore, the cheapest method of 

 release is recommended. Other studies have indicated, however, that 

 where longleaf is being released, poisoning is necessary to prevent the 

 hardwood sprouts from resuppressing the seedlings before they are out 

 of the grass stage. 



The pines that were released immediately after planting sur- 

 vived well during 1948. In contrast, the severe drouth of 1948 killed 

 nearly all seedlings planted in adjacent open areas. Survival was good 

 in 1948 because there was very little competition for available moisture 

 --the hardwoods were dead and the grass stand under the hardwoods 

 was only one -third as heavy as that in the open. The benefits of this 

 reduced competition continued for at least 3 growing seasons. By then 

 the pine trees were well established and above the grass. 



Forest Tree Improvement 



The Alexandria Research Center is participating in a South-wide 

 genetics program that seeks to breed fast-growing, well-formed, 

 disease-resistant pines, including hybrids. Work at Alexandria is con- 

 centrated on crossing trees that possess outstanding characteristics. 

 One such tree is a longleaf pine that, as a seedling in the nursery, dis- 

 played high resistance to brown spot infection. Now that it is large 

 enough to produce cones, its flowers are being carefully self -pollinated. 

 Seedlings from this tree will be watched to see if they also can with- 

 stand brown spot. 



- 14 - 



