Growth and Fusiform Rust Responses of Piedmont Loblolly Pine After Severa1 Site Preparation and Regeneiation Methodsl

Cutover pine-hardwood s i t es in the Piedmont of central Georgia were prepared by prescribed burning or drum chopping and regenerated to loblolly pine (Pinus taeda L.) by planting or directseeding. Site preparation had Little effect on soil physical properties. After an average of 12 years, trees were larger in dbh and total height, the merchantable stand was greater, and distribution was more uniform on planted than on seeded areas. Regeneration from direct-seeding was enhanced more by intensive site preparation than was regeneration from planting. Neither fusiform rust incidence nor rust associated mortality 1 The authors thank the industrial cooperator, Inland-Rome, Inc. (formerly Georgia Kraft Comnanv). Rome. GA, for proviiing land, equi’pm&t, personnel, and protection of the study areas, and Earle P. Jones, Southeast. For. Exp. Stn., Macen, GA, for locating historical information pertaining to this study. Trade names mentioned in this paper are for information only and do not constitute an endorsement by the USDA Forest Service. 18 S J A F 14(1990) was affected consistently by the intensity of site preparation, but both rust incidence and rust associated mortality were generally higher in the direct-seeded than in the planted plots. South. J. Appl. For. 14(1):18-24. A fter natural stands containing mixtures of pine and hardwood are harvested from upland sites on the Piedmont Plateau, most foresters recommend mechanical site preparation and planting of 1-O loblolly pine seedlings. The purpose of mechanical site preparation is to reduce competition from residual, unmerchantable hardwoods as well as sprouts of harvested hardwoods. Particularly for nonindustrial private forest owners, however, foresters should be offering a range of options that may vary in effectiveness as well as cost and appearance. Prescribed burning and direct-seeding can reduce costs, but at some price in productivity of the new stand (Brender 1973). Of equal importance to seedling establishment is how the intensity of site preparation and the regeneration method affect the subsequent incidence of fusiform rust caused by Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. @iforme. In slash pine (P. elliottii Engelm. var. elliottii), both height growth and rust incidence generally have been greater with increasing intensity of site preparation (Burton et al. 1985, Miller 1977). Studies on loblolly pine, however, have failed to demonstrate a consistent relationship between intensity of site preparation and rust incidence (Miller 1977). Recent research by Zutter et al. (1987) found that herbaceous weed control increased the incidente of stem galls in loblolly pine plots on six of seven sites in North Carolina, Georgia, and Alabama that had received severa1 different mechanical site preparation treatments, but the increases after 5 years were statistically greater at only two sites. The purposes of our study were to: (1) compare regeneration of loblolly pine by direct-seeding and by hand planting, (2) determine if intensive site preparation is needed to obtain well-stocked pine stands, and (3) assess the influence of site preparation and regeneration methods on subsequent infection of seedlings by fusiform rust. Damage by tip moths (Ryacionia frustrana Comst.) for l-3 years after stand establishment was reported by Thomas et al. (1982). In this paper, we present 12th-year results. Reprinted from the Southern Journa of Applied Forestry, Vol. 14, No. 1, February 1990. SITE DESCRIPTION AND METHODS In 1968, 1969, and 1970, two blocks containing al1 study treatments were installed per year at a total of six locations (Table 1) on timberland controlled by the industrial cooperator in the lower Piedmont of central Georgia (Figure 1). In Monticello, in Jasper County, at the same latitude and about midway between the field locations, mean temperature is 46°F in January and 8 1°F in July. The growing season averages 232 days. About half of the annual precipitation of 50 in. occurs during the growing season, mostly from thunderstorms. Brief periods of drought are common during the late spring and fall. Al1 study sites were located in the area of Georgia designated by Squillace (1976) as high hazard for fusiform rustJones and Putnam Counties 7’71Y%, M e r i w e t h e r C o u n t y Are& from which mature natural stands of pine and hardwood recently had been commercially clearcut were selected for study. The harvested stands were typical of nonindustrial private holdings that are being harvested on the Piedmont. Loblolly pine had been t h e p r e d o m i n a n t o v e r s t o r y species, but scattered shortleaf pines (P. echinata Mill.) were also p r e s e n t ( T a b l e 1 ) . I n b o t h numbers and basal area, the hardwood stand component was dominated by sweetgum (Liquidambar styracijlua L.) and flowering dogwood (Cornos florida L.). Soils are Figure 1. Counties in the Georgia Piedmont where the study was conducted. well-drained, sandy loam to sandy clay loam Ultisols, in the Cecil, Madison, and Davidson series (clayey, kaolinitic, thermic Typic Hapludults, and Rhodic Paleudults). Slope gradients ranged from about 5 to 20%. A representative 6-ac block was selected at each site. Each treatment block was divided into two sub-blocks, with each sub-block prepared by one of two methods. Preparation treatments were made by the industrial cooperator under operational conditions: 1. Burn. Prescribed strip headfires during the late growing season were timed for maximum reduction of litter and logging debris. Prior to burning, hardwood stems Table 1. Location, treatment date, and characteristics of the six experimental sites in the Piedmont of Georgia.