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Artificial regeneration is successful when high-performing seedlings are transported with care to the planting site, stored for a short period in an environment without desiccation or fungal growth, and planted in a deep hole, so roots are in contact with moist soil. One of the requirements for success is the ability to avoid common planting mistakes. Due, in part, to the use of container stock plus an increase in rainfall, the average first-year survival of pine seedlings (89%) in the southern United States is about 15% greater now than 45 years ago. However, when survival is less than 50% six months after planting, some landowners seek reimbursement for their loss. Some assume poor seedling quality was the cause without realizing that anaerobic soils or sudden freeze events, shallow planting holes, pruning roots, a lack of rain or underground insects can kill pines. With a focus on pines planted in the southern United States, we list non-nursery factors that have killed seedlings in North America, Africa and Europe.

This review provides information and opinions about irrigation practices in pine nurseries. Even when nurseries receive more than 15 mm of rainfall week-1, managers irrigate seedbeds to increase germination, increase seed efficiency, and increase root growth. In the southern United States, a 7-month old pine seedling in an outdoor nursery typically receives 2 to 6 kg of water supplied from either sprinklers (39 nurseries) or center-pivot irrigation (12 nurseries). Most nursery managers do not intentionally subject the crop to moisture stress, since most reforestation sites receive adequate rainfall, and many studies show that reducing root mass does not increase seedling performance. In fact, nursery profits can be reduced by more than $13,000 ha-1 when deficit irrigation reduces average seedling diameter by 1 mm. Although some researchers believe that failure to properly drought stress pine seedlings might increase outplanting mortality by up to 75%, research over the past 40 years does not support that myth. When pine seedlings average 5 mm (at the root-collar), water stress is not a reliable method of increasing tolerance to an October freeze event. In several greenhouse trials, researchers grew and tested seedlings that nursery managers would classify as culls (i.e., dry root mass < 0.5 g). Unfortunately, it is common for researchers to make irrigation recommendations without first developing a water-production function curve.

Copper has been used by nursery managers for more than 100 years to suppress fungi and as a fertilizer for more than 50 years. Consequently, nursery seedlings with copper deficiencies are rare, especially for broadleaf species. In many nurseries, soil contains

This review covers most of the published literature on potassium (K) fertilization in bareroot seedbeds with the intent to concentrate on the southern United States. The timing and rates of K fertilization for bareroot seedlings are often based on logic and myths and, as a result, K recommendations vary considerably. Some recommend bareroot pine seedlings be fertilized with twice as much K as nitrogen (N) while others apply less than 100 kg ha-1. It was determined that several long-held claims about K fertilization are invalid. Nursery seedbeds do not need to contain four times as much available K as N and the belief that extra K fertilization will increase freeze tolerance or drought resistance of non-deficient seedlings is invalid. There are no data to support the claim that K fertilization increases root growth or assists in the formation of terminal buds. For sandy seedbeds, there is no need to apply K before sowing. Adding extra K during the fall does not increase seedling morphology or seedling performance when loblolly pine seedlings, at lifting, have more than 0.5% K in needles. A reduction of K fertilization can be achieved by reviewing foliar tests prior to K top-dressings.

Two schools of thought address the optimum soil pH (measured in water) for growing hardwood seedlings in bareroot nurseries. One school uses nutrient surveys in non-fertilized forests to determine the best pH range for growing seedlings in fertilized nurseries. Some students of this school believe hardwood seedlings grow best at pH 6.0 to 7.5. In contrast, another school relies on research from pH trials to conclude that fertilized hardwoods can grow well in soils that range from pH 4.5 to 6.0. This article compiles some of the findings from seedbed and greenhouse trials and attempts to use data to dispel a few myths about the “optimum pH” for growing hardwood seedlings. Greenhouse trials suggest many fertilized hardwoods grow better in acid soils (pH 4-6) than in nearly neutral soils (pH 6.0-7.5). The optimal pH for growth differs among species and, therefore, it is a myth that all hardwood seedlings grow best at pH 6 to 7.5. Most nursery managers in the southern United States grow bareroot hardwoods between pH 4.8 and 6.0.

In North America, most tree nursery nutrition publications during the past two decades involved either container-grown stock or stock grown in greenhouses. In contrast, most bareroot nursery fertility trials in North America were published during the last century. As a result, some bareroot fertilization recommendations have remained the same since 1980 and some practices continue to be based on myths and assumptions. The bareroot nursery industry in the USA might benefit if the next generation of graduate students will consider testing old and new theories about nursery fertilization. Hopefully, they will discover new facts so that future fertilization regimes will be based on science. This paper provides various fertilizer trials that should be established in bareroot nurseries.

Although the production of commercial products of vegetative Pt (Pisolithus tinctorius (Pers.) Coker & Couch) inoculums has ceased in North America due to a lack of demand by consumers, the number of products that contain Pt spores has increased. The quality, quantity and price of these products vary considerably. The cost of inoculating 1,000 tree seedlings with Pt basidiospores can vary from $0.45 to more than $30. The cost of treating with Pt spores is lowest when seedlings are inoculated in a container nursery using rates that are less than 0.4 mg per seedling. However, with some products the cost to treat 1,000 bareroot seedlings is greater than $500 when spores are applied in the planting hole. Three decades ago, 1 g of Pt spores could be purchased for $0.13 and now the price of 1 g can exceed $14. Although many research papers provide data on the biological response to inoculating seedlings with spores, few document the cost of inoculation. Commercial products that are marketed toward homeowners containing both ectomycorrhizal and endomycorrhizal spores are more expensive than products that contain only ectomycorrhizal spores. In situations where survival and growth of seedlings are not increased, the benefit/cost ratio will typically be less than one.

Two pH experiments were conducted at a sandy, bareroot loblolly pine (Pinus taeda L.) nursery in Texas. A sulfur trial (0, 813, 1626, 2439 kg ha-1 of elemental sulfur) was installed to determine if lowering soil pH would result in nutrient toxicity symptoms and affect seedling morphology. Although soil acidity in the sulfur study ranged from pH 3.9 to pH 5.0, none of the treatments resulted in micronutrient toxicity and none affected height growth, root-collar diameter, root mass, shoot mass or the root-mass ratio (root dry mass/total dry mass). Acidifying soil with sulfur increased leaching of calcium, potassium, magnesium, manganese and zinc but there was no effect on seedling morphology. The objective of the liming trial (0, 813, 1626, 3252 kg ha-1 of dolomitic lime) was to determine if increasing alkalinity would result in an iron deficiency and reduce seedling growth. As expected, applying lime increased the calcium and magnesium levels but had no effect on soil levels of iron, phosphorus, potassium, sulfur, zinc and sodium. However, the root-mass ratio was reduced by applications of dolomitic lime (pH ranged from 5.3 to 6.0). Differences in soil properties (i.e. plot location) had a greater effect on seedling morphology than lime applications. Foliage levels of manganese and boron were reduced by the highest rate of lime and sulfur, respectively.

This review compares fall acclimation patterns and lift/store practices for Pseudotsuga menziesii var. menziesii, Picea glauca (Moench) Voss x P. engelmannii Parry ex engelm and Pinus taeda L. seedlings. Spruce seedlings achieve budset and an endodormant state in late summer, coastal Douglas-fir in early fall, while loblolly pine achieves a less endodormant state with a limited amount of mitotic activity. Natural chilling during the fall reduces days to budbreak (DBB) and increases freezing tolerance, with northern species achieving greater freezing tolerance. Although root growth potential (RGP) in some years may increase from early fall to mid-winter, this trend does not always occur. Chilling hours and/or freezing tolerance status is used to initiate storage of Douglas-fir and spruce seedlings but there is no proven attribute to make the lifting decision for loblolly pine. When properly hardened, all species can be cooler stored to meet lift/store requirements of a few months, though fall lifted interior spruce seedlings are typically freezer stored for up to six months. Lengthy storage can cause declines in DBB, freezing tolerance, RGP, and carbohydrate reserves. Douglas-fir and interior spruce seedlings require an appropriate length of fall acclimation, typically including chilling, to develop a level of hardiness for lengthy storage and high survival after outplanting. Loblolly pine seedlings benefit from chilling, though non-chilled, hardened seedlings may exhibit high survival after four weeks of cooler storage. Each species has a unique fall acclimation pattern making it difficult to define universal culture practices across all regional forest regeneration programs.

Two studies were established to determine the effects of planting depth on early performance of bareroot shortleaf pine seedlings (Pinus echinata). The studies involved planting seedlings either with the root-collar slightly below the groundline (GL) or with the root-collar planted about 11 cm below the soil surface (DEEP). After transplanting, DEEP seedlings had about 7.9 cm of shoot remaining aboveground. In one study, seedlings were planted in open sand pits where seedlings received 352 mm of rain by April 30. The second study involved planting seedlings in boxes (containing sand) in a roofed shade-house. Without rain, survival of DEEP seedlings in April was 96% which was significantly greater (P>F =0.007) than survival of GL seedlings (67%). With rainfall, survival (95%) was the same for both planting depths (P>F = 0.39). Therefore, planting seedlings with the root-collar level with the soil surface can, in some years, increase mortality. This might help explain why bareroot survival of shortleaf pine in some forest districts averages less than 80%.

Cold storing bareroot southern pine (Pinus spp.) seedlings for greater than one week after lifting in the fall can lead to poor outplanting survival when compared to seedlings that are lifted and stored in winter. In contrast, container-grown seedlings typically do not experience adverse effects from storing for periods greater than one week. The practice of lifting bareroot seedlings can cause wounds to root systems, which could allow soil-borne pathogens such as Pythium species to be used as infection sites. Once seedlings are placed in storage, the cool, moist environment may be conducive for zoospore activity, leading to root disease and outplanting failure. Bareroot and container-grown longleaf pine (Pinus palustris), loblolly pine (Pinus taeda), and slash pine (Pinus elliottii) and container-grown shortleaf pine (Pinus echinata) were inoculated with either Pythium dimorphum or Pythium irregulare, cold-stored for 3, 4, 6, or 12 weeks, and outplanted. Both Pythium species reduced survival of bareroot longleaf pine but not bareroot slash pine. Length of storage decreased survival for both seedling stock types. Pythium species did not affect the survival of container-grown seedlings. These results suggest that P. dimorphum and P. irregulare are more virulent to bareroot longleaf pine than the other pine species tested.

Many root hydrogel compounds are available for seedling nurseries for root treatment at the time of packing. They can differ based on composition (starch-based versus polyacrylamide), grade (fine, medium, or coarse), or by their range of particle size distributions. While the use of root hydrogels at the time of lifting, packing, and storing is a visual indicator to customers that something has been sprayed on the roots, trials with loblolly pine ( Pinus taeda L. [Pinaceae]) indicate that the effect of hydrogels on seedling survival is dependent on the particle size, composition, and soil moisture availability. When subjected to moisture stress following outplanting, root hydrogels do not increase seedling survival, and in some cases may increase seedling mortality, counter to manufacturers’ claims. Cross-linked polyacrylamide gels with a peak particle size distribution 1000 microns (μm) caused significant reduction in survival when seedlings were outplanted in sandy soils. For optimal seedling survival, nurseries should evaluate their hydrogel to determine the particle size and target a product with a peak particle size distribution around 300 μm.

Pinus taeda L. plantations in the United States are typically established using rows that are spaced 3 to 4 m apart. Although one company now plants pines in 6.1 m rows, reports on performance using this row spacing are rare. This paper provides a case study (established at the Solon Dixon Forestry Education Center) that compares two densities (672 vs 1344 seedlings per ha (SPH)) when fixing the between-row distance to 6.1 m and using either 2.44 m or 1.22 m within-row distances between the planted trees. At age 13-years, the aboveground biomass mean annual increment on this old-orchard site was 13.5 green Mg/ha/yr. Planting half as many pine seedlings as typical (for this region) did not reduce dominant height (P=0.22), basal area/ha (P=0.58) or total merchantable tonnes/ha (P=0.67). As expected, the higher density produced trees that were smaller in mean diameter at breast height DBH (25 vs 22 cm) and had more pulpwood than 672 SPH plots. However, planting pines 1.2 m apart within the row reduced survival, soon after two severe summer droughts. Apparently this stress increased the risk of attracting bark beetles. An economic analysis indicates that 672 SPH produced more valuable timber (at age 13 years) and had the highest Net Present Value (NPV). In contrast, the Ptaeda3 model indicated 1344 SPH would have the greater NPV. The conflicting results are related to Ptaeda3 predicting one sawtimber-sized tree while 156 were present in the 672 SPH plots. Although these findings should not be extrapolated to cutover sites, it appears there may be several advantages to planting pines in wider than traditional rows. The reluctance to plant Pinus taeda in 6.1 rows on flat, agricultural lands might be due to a lack of field data and/or a reliance on output from growth and yield programs that were developed using data from cutover sites.

Yellow nutsedge (Cyperus esculentus) is a difficult weed to control in conifer nurseries. Soil fumigation with methyl bromide has been used to control yellow nutsedge for years but may not be available in the future. For this reason, the objective of this research was to identify herbicides that can control yellow nutsedge but do not injure loblolly (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) when used over-the-top of seedlings. Yellow nutsedge tubers and loblolly and slash pine seedlings were potted separately, and treated with three rates of the herbicides mesotrione (Callisto®), imazosulfuron (Valent-V10142), and halosulfuron (Sedgehammer®). Imazosulfuron and halosulfuron provided the best suppression of nutsedge, but imazosulfuron injured loblolly and slash pine. Slash pine diameter and height growth were reduced by imazosulfuron. Halosulfuron did not affect loblolly pine but it reduced slash pine height growth and the number of new leaders (spring flush growth) the following spring. Mesotrione injured slash pine but provided intermediate control of yellow nutsedge. Halosulfuron applied at 35 to 140 g ai·ha−1 (active ingredient per hectare) over the top of loblolly pine (≥ 60 cm height and ≥ 8 mm diameter) can control yellow nutsedge without injuring pine seedlings.

Summary Cold storing bareroot pine (Pinus spp.) seedlings grown in the southern U.S. for as little as 1 week in a cooler (just above freezing) in the fall (November to mid-December) has been shown to reduce seedling survival after outplanting. In contrast, survival of container-grown seedling is typically not affected when stored for 4 weeks in coolers in November and December. Wounds sustained by seedlings as they are lifted from nursery beds may allow Pythium spp. to infect bareroot seedling roots. Once in the cool, moist storage environment, Pythium multiplies and may result in seedling mortality after outplanting. Bareroot loblolly pine (Pinus taeda) and container-grown loblolly, longleaf (Pinus palustris), slash (Pinus elliottii) and shortleaf pine (Pinus echinata) seedlings were inoculated with either Pythium dimorphum or Pythium irregulare, cold stored with or without peat moss and monitored for survival after outplanting. Peat moss did not increase bareroot loblolly pine survival or reduce Pythium populations when seedlings were inoculated with Pythium prior to storage. Pythium irregulare reduced survival of longleaf and shortleaf pine grown in peat moss and perlite, respectively. Pythium did not affect loblolly or slash pine, but wounding their roots did reduce seedling survival when grown in containers.

Scalping is a mechanical process whereby the soil is peeled back in a shallow (5 to 10 cm [2 to 4 in]) furrow that is 75 to 90 cm (30 to 35 in) wide. Scalping is often recommended prior to planting longleaf pine ( Pinus palustris Mill. [Pinaceae]) on pastures and land formally occupied with row crops; however, some reports suggest that growth of pines is reduced when seedlings are planted on scalped areas. A study was implemented in southern Alabama to determine the effect of scalping on early survival and growth of bareroot and container longleaf pine. In this study, scalping reduced seedling survival of bareroot stock by an average of 18 percentage points, which is contrary to findings from results on well-drained soils. On this relatively flat site (Greenville Fine, kaolinitic, thermic Rhodic Kandiudult), I speculate that scalped areas collected water and some seedlings died from waterlogging. This detrimental effect appeared to be greater on bareroot stock than on container stock. In contrast, early height growth at this site was excellent and scalping increased growth by an average of 0.9 m (3 ft). Stocktype affected both survival and growth with bareroot seedlings outperforming container stock.

Managers are typically interested in using equations that provide accurate volumes for large, merchantable trees while modelers are often more interested in equations that meet statistical assumptions. Therefore, modelers often use weighted (WLS) rather than ordinary least squares (OLS) to fit individual tree volume equations since the random error variance is not constant. Since OLS and WLS produce different parameter estimates, perhaps the method chosen will impact the predicted optimum economic rotation age. To address this concern, individual tree volumes were obtained from plots established in an unthinned loblolly pine plantation in southeastern Arkansas. Parameters of the combined- variable function were then estimated using OLS and WLS for the same dataset. Stand-level projections and predicted diameter distributions for two planting densities (748 and 2,692 seedlings per hectare) were then obtained from a growth and yield model (PTAEDA 3.1) and individual tree volumes were predicted using the two parameter estimation approaches. When conducting economic analyses, we found the optimum rotation age between OLS and WLS can differ by as much as 11 yrs (i.e. 10 yr clearcut vs 21 yr clearcut).

An assumption of ordinary least squares (OLS) is constant variance across the domain of a regressor. Often, however, the random error term variance is not constant when modeling biological data and therefore weighted least squares (WLS) is commonly used to estimate parameters. Less emphasis is placed on observations of the dependent variable with larger variances when using WLS, which is thought to produce more “efficient” parameter estimates. Statisticians often use WLS instead of OLS when the random error variance is not constant. However, as natural resource managers, we are often most interested in values of the dependent variable where the variance is greatest. What then are the biological, economic, and management implications of using WLS versus OLS in natural resource modeling? In this article, parameters of the combined-variable volume equation were estimated for individual trees in loblolly pine plantations using both OLS and WLS. A growth-and-yield model was used to predict stand development over time of two planting densities (303 and 1,090 seedlings/ac) and individual tree volumes were predicted using OLS and WLS parameter estimates. Economic analyses were then conducted. Our results show that the choice of OLS or WLS can have a substantial impact on predicted economic returns. Thus, when using WLS, landowners may decide to invest in additional management treatments that may, in fact, not be economically feasible. This study provides further evidence that landowners need to be aware of model structures when basing harvest-age decisions on growth and yield projections.

Only a few growth and yield programs allow users to model the effects of hardwood competition on yields from pine plantations. Several of these programs were developed with the assumption that reducing hardwood competition would consistently produce a Type 2 growth response where pine volume gains increase over time. However, the actual response is not always a Type 2 response. To determine growth response types resulting from woody control treatments, plot volume data were analyzed from 14 trials (on 13 sites) measured over a period of 2 decades (The COMProject). The “age-shift” method of growth analysis and regression analyses were used to classify the types of responses. After 20 years, stand volumes of loblolly pine (Pinus taeda L.) were increased after woody control at 13 of 14 trials when compared to no controls. At four trial locations the age gain ranged from 0.7 to 1.6 years and the growth response was classified as a pseudo-Type 1 response (i.e., pine growth was increased while the total above-ground biomass of the mixed-stand was not altered by the species shift). At nine trial locations a true Type 2 response was observed (i.e., increase in total above-ground biomass of the pine dominated mixed-stand) and the age gain ranged from 0.9 to 5.1 years. At a site in Louisiana, woody control on two similar blocks resulted in a reduction in both early and mid-rotation pine volumes (termed a Type E response) while two other blocks resulted in an early reduction that changed to a mid-rotation volume increase (termed a Type F response). Thus, four types of growth response were associated with woody control treatments.

Because of concerns over the ozone layer, the annual amount of methyl bromide used for soil fumigation for crop production is decreasing. A promising alternative soil fumigation treatment involves applying 300 lb/ac of chloropicrin (CCl3NO2) under a plastic tarp. Although this soil fumigant does not control weeds as well as an equivalent amount of methyl bromide, chloropicrin is an effective strategy for controlling many soilborne pests. The total amount of chloropicrin used for fumigation in southern pine nurseries will likely increase as use of methyl bromide fumigation declines.

Pot-binding can adversely affect the performance of container-grown stock. One factor that affects potbinding is the size of the root system in relation to the size of the container. The aim of this study was to determine if an objective root-bound index (RBI) would be useful when evaluating the quality of pines grown in various types of containers. A RBIdia was determined by dividing the root-collar diameter (RCD) by the cavity diameter (i.e. the distance from one container wall to the opposite container wall, measured at the top of the container cavity and passing over the centre of the cavity) and a RBIvol was determined by dividing the RCD (mm) by the container volume (ml). Field assessments of seedlings produced in six container types in the United States indicate that both RBI methods produced similar results for survival of Pinus palustris (stock with the highest RBI values exhibited the lowest survival). However, the RBIvol method did a better job of separating the performance of two types of peat pots. Both indices were also related to outplanting performance of P. patula cuttings grown in South Africa. When sorting container stock, P. elliottii x caribaea cuttings with RBIvol values greater than 7 might be culled while P. palustris seedlings might be culled when the RBIvol index exceeds 11. Therefore, the target RBIvol value will vary with species and plant type. When tree planting guides cover a range of container types, listing a maximum RBIvol value would provide some indication of when root-binding might reduce plant quality. In addition to RBI, the age of the roots also appears to affect field performance of pot-bound stock. We rejected the hypothesis that age is not related to post-planting survival of Pinus elliottii x caribaea cuttings. Keywords: cuttings, pot-bound, root-collar diameter, container volume, seedlings, survival, Pinus palustris, Pinus patula, Pinus elliottii x caribaea Southern African Forestry Journal Vol. 207 2006: 47-54

When the landowner's objective is to maximize the net present value of a longleaf pine (Pinus palustris P. Mill. [Pinaceae]) plantation, most tree planting recommendations can be placed into 1 of 2 schools of thought. Those from the "plant-'em thick" school recommend planting more than 1483 longleaf pine trees/ha (600/ac). Some from this school say the extra costs associated with establishment will result in more profit when selling pulpwood, chip-n-saw, sawtimber, pine straw, and poles. When the landowner's objectives include producing chip-n-saw, sawtimber, wildlife, and maximizing profits, some from the "plant-'em thin" school recommend planting less than 1235 trees/ha (500/ac). For example, some might recommend planting 1100 container-grown seedlings/ha (445/ac). Most longleaf pine articles published prior to the turn of the century are from the "plant-'em thick" school. In contrast, this paper provides landowners with some of the logic for planting longleaf pine seedlings at wide spacings.

Although gravitropism of maize (Zea mays L.) roots is dependent on light, it is not known if light affects the gravitropism of pine radicles. Therefore, seeds of slash pine (Pinus elliottii Englm.) and loblolly pine (Pinus taeda L.) were germinated under constant light or constant darkness. A gravitropic set-point angle (GSA) of 90° indicates the radicle is pointed horizontally while a GSA of 0° indicates the radicle is growing toward the center of the earth. After 20 days from sowing, the GSA was less than 10° in both light and darkness. Therefore, gravitropism of both pine species occurred in the dark. The presence of light initially stimulated gravitropism but this effect was ephemeral. After 25 days from sowing, there was no significant difference in radicle growth among light treatments, suggesting that darkness did not affect pine radicle gravitropism. However, light did increase germination of both species. Radicle length was slightly increased when seeds germinated in the dark.

Integrated Pest Management is a system that combines cultural, biological and chemical technologies to reduce insect, fungal and weed populations to levels below those that result in economic damage. Nursery managers in the southern United States currently use many practices to control pests of southern pine seedlings. Over the last three decades, improvements in chemical, cultural, and biological pest control practices have increased seed efficiency (defined as the number of plantable seedlings produced divided by the number of pure live seed sown) and reduced the percentage of production costs associated with pest control. As crop values increase, the economic thresholds for applying control measures decrease. However, since the statistical power of most trials in bareroot nurseries is low, the likelihood of experiments that detect “real” treatment difference (e.g. those that consistently increase seed efficiency to the point where economic returns are affected) will be low. This paper describes some current practices in southern pine nurseries and provides some economic injury levels for various pest control treatments.

Summary Gains in stand volume that result from competition control and fertilization are sometimes reported as ‘ percentage gains ’ . Because percentage gains arithmetically decline over time as stand volume increases, plantation managers have diffi culty in using percentage gains to project growth and revenues. The ‘ age-shift ’ method quantifi es the year advancements in stand growth due to silvicultural treatments and, for herbaceous vegetation management, it has been proposed that this metric is less likely to change after the juvenile growth phase. To test the sensitivity of the ‘ age-shift ’ method to time and hardwood competition, we used 20-year volume data from 11 loblolly pine ( Pinus taeda L.) studies that had early complete herbaceous and woody competition control. Volume growth gains were expressed in terms of percentages and ‘ age-shifts ’ . On all sites with no woody competition, percentage gains declined from age 8 years to age 20 years. In contrast, age-shift estimates on these plots either remained constant or increased over time. However, in four cases where woody basal areas were greater than 4 m 2 ha − 1 at age 15 years, age-shift gains due to herbaceous control decreased and eventually resulted in volume losses. When evaluating the response to early herbaceous competition control, age-shift calculations have promise as a useful predictive tool on sites with low levels of hardwood competition. Five methods for calculating age-shift are presented.

Four outplanting experiments in the North Island of New Zealand were examined to determine the effects of stock size on survival and early height growth of rooted fascicle cuttings of Pinus radiata D. Don. Survival and third-year tree height were examined in relation to (a) initial diameter, (b) initial height, (c) initial diameter squared, (d) bulk index (diameter squared × height), and (e) sturdiness index (height/diameter). Of the five attributes examined, initial diameter was correlated with survival on two sites, while height and sturdiness index were not correlated with survival. Cutting morphology was more consistently correlated with growth than with survival. On all sites, growth of cuttings after outplanting was positively related to size (e.g., diameter, height, bulk-index). Results from these trials suggest good performance of rooted fascicle cuttings can be expected when stem diameters (at the soil surface) range from 8 to 10 mm and heights range from 25 to 40 cm.

On some reforestation sites, the planting of large-diameter seedlings can lower establishment costs by reducing the need to apply extra chemicals to increase the performance of regular seedlings. On five sites, survival of large-diameter Pinus taeda L. or P. elliottii Englem. seedlings (average root-collar diameter 8.1 to 9.2 mm) was equal or greater than for regular seedlings (average root-collar diameter < 5.3 mm) treated with extra chemicals. On three sites, diameters and/or heights of large-diameter seedlings were not significantly different from those of regular seedlings treated with operational applications of herbicides, fertilizers and insecticides.

Hexazinone, premixed with controlled release carriers, was applied to charcoal root-dipped, sycamore seedlings in field studies conducted in 1997 and 1998. The objective was to determine the combined effects of the carriers and root dips on herbaceous weed control and seedling growth and survival. Two controlled release carriers, methylated seed oil and recycled newspaper fluff, were compared with the standard water carrier. The root dip consisted of activated charcoal combined with a synthetic water thickener. Weed control using the oil and newspaper carriers was less than or equal to weed control using the standard water carrier. Weed control increased with increasing hexazinone rate. Groundline diameter growth for root-dipped seedlings increased by four-fold in 1997, but had both negative and positive results in 1998. Survival for root-dipped seedlings increased by three-fold in 1997, but had mixed results in 1998, depending on the carrier. Accidental uptake of herbicides by sycamore foliage after bud break in 1998 may have lead to the inconsistent seedling responses to charcoal root dips.

Improving seedling performance by reducing seedling height can be an important aspect of nursery management. The plant growth regulator uniconazole was applied to regulate height growth of nursery-grown loblolly pine (Pinus taeda L.) seedlings. Tests involving a foliar spray (0,0.125, 0.25, 0.5 and 1.0 kg ai/ha) or a wick application (0, 125, 250, 500, and 1000 ppm) were conducted in Alabama, Georgia, and South Carolina. The wick applicator consisted of a perforated plastic pipe covered with a sponge cylinder supplied by a reservoir. With both application methods, as the rate of uniconazole increased, seedling height, root-collar diameter, and biomass decreased. Compared to the controls, uniconazole decreased the percentage of seedlings with root-collar diameters greater than 4.7 mm. At lifting there was no difference among rates for root/shoot ratio, but root/shoot ratios of uniconazole treated seedlings increased significantly after outplanting. Eighteen months after outplanting, there were no treatment effects on seedling height or survival. Wick applications of uniconazole merit further research because of soil persistence and costs associated with spray applications. South. J. Appl. For. 28(1):41–47.

Synopsis Three studies in the Coastal Plain of Georgia were remeasured 7 or 8 years after planting to determine the effects of planting depth on field performance of open-rooted seedlings [root-collar diameter (RCD) ≤ 5 mm]. Average planting depth (i.e, shoot height before planting minus shoot height above ground after planting) for machine planted P. elliottii was 14 cm while hand-planted P. taeda seedlings averaged 9-11 em deep. P. taeda showed no adverse effects on growth when planting seedlings up to 15 em deep. Data for machine planted P. elliottii indicated that seedlings were planted 9 mm deeper on double-beds than on single-beds. Small-diameter pine seedlings < 5mm RCD) were not planted as deeply as seedlings with large diameters (RCD ≥ 5 mm). For P. elliottii planted on double-beds, seedlings planted more than 15 em deep had slightly smaller diameters at breast height than seedlings planted 10 em deep. Although most tree planting guides recommend planting seedlings 7,5 em deep or less, many compa...

A loblolly pine (Pinus taeda L.) seedling grade study was established in January 1987 on a Coastal Plain site at Bellville, Georgia. The factorial study involved three seedling grades (Wakeley's Grade 1, 2, and 3) and three half-sib families (#5, 25, 56). Trees were measured at ages 8 and 13 yr. Both family and seedling grade affected survival, height, and diameter at age 8 yr. Survival among families varied by as much as 3 percentage points while there was a 10 percentage point difference between Grade 1 and Grade 2 seedlings. Only family was related to height and diameter at age 13. Volume gains from planting Grade 1 seedlings instead of Grade 3 seedlings varied by family but there were no significant interactions between family and seedling grade. Differences in height among families and among seedling grades decreased over time. At age 8, there was a 5.3 ft difference between the tallest and shortest family but by age 13, the difference declined to 3.7 ft.Overall, planting family 56 instead of family 25 resulted in an additional 645 ft3/ac by age 13. Planting Grade 1 seedlings instead of Grade 3 seedlings produced an additional 303 ft3/ac. Per acre volume differences among families were greater at age 13 than at age 8. In contrast, differences among seedling grades were about the same at age 8 and 13 yr. The overall mean annual increment (MAI) for this study was 207 ft3/ac/yr. In comparison, the MAI for Grade 1 seedlings of family 56 was 239 ft3/ac/yr. South. J. Appl. For. 26(3):153–158.

Four seedling conditioning treatments and four fall fertilization treatments were applied to loblolly pine (Pinus taeda L.) seedlings in a bare-root nursery in Alabama. Three conditioning treatments involved undercutting plus root wrenching (two, four, and six times), and a fourth treatment included top-pruning (three times) and no undercutting. Fertilizer treatments consisted of (i) control, (ii) 150 kg/ha of N, (iii) 150 kg/ha of N plus 150 kg/ha of P, and (iv) 150 kg/ha of K. On two sites, seedlings were planted in November, and an equal number were placed in cool storage and planted 6 weeks later in mid-December. Results 5 years after outplanting were generally similar for both sites; however, experimental error terms were higher on the sandy site. As a result, conditioning and fertilizer treatments had a statistically significant effect on volume per hectare at the loamy site but not at the sandy site. Volume per hectare was enhanced by undercutting in August followed by two root wrenchings and fall fertilization with N plus P. Storing seedlings reduced height, groundline diameter, and volume per hectare at both sites and reduced survival at the loamy site. Survival of both freshly planted and stored seedlings was greater than 71% at both sites.

Colorless, euhedral crystals were abundant on the roots of chlorotic pine seedlings from one nursery in Georgia and one in Alabama in 1998. Energy dispersive spectroscopy indicated these crystals were rich in calcium (Ca) and sulfur (S), and single crystal x-ray diffraction determined the crystals to be CaSO4·2H20 (gypsum). These crystals had formed on the roots where water moved from the soil into the seedlings to be transpired. No records were found of gypsum crystals on the roots of living plants. Drought conditions appear to be necessary for these crystals to form in humid regions and no economic impact beyond that of the drought was indicated.

When it comes to testing for differences in seedling survival, researchers sometimes make a Type II statistical error (i.e. failure to reject a false null hypothesis) due to the inherent variability associated with survival in tree planting studies. For example, in one trial (with five replications) first-year survival of seedlings planted in October (42%) was not significantly different (alpha = 0.05) from those planted in December (69%). Did planting in a dry October truly have no effect on survival? Authors who make a Type II error might not be aware that as seedling survival decreases (down to an overall average of 50% survival), statistical power declines. As a result, the ability to declare an 8% difference as “significant” is very difficult when survival averages 90% or less. We estimate that about half of regeneration trials (average survival of pines

Loblolly pine (Pinus taeda L.) seedlings were lifted from two nurseries in Georgia, and the roots were washed using equipment built for that purpose. Seedlings then received two levels of storage and were outplanted not far from the nursery of origin (one loam soil and one sandy soil). Immediately after washing, root weights and the length of fine roots did not differ among wash treatments from either nursery. Survival was excellent for all treatments on the loam soil, but a single wash reduced survival by 5 to 10% when seedlings were planted in sand. Washing slowed the rate of budbreak and early height growth. Bud growth of seedlings planted in a stress pit (containing sand) was correlated with both root growth 1 month after planting (r = 0.36,P = 0.0003) and survival 2 months after planting (r =0.62,P = 0.01). Among seedlings outplanted on a sandy site, initial height growth also correlated with survival (r = 0.49,P = 0.007). South. J. Appl. For. 25(1):25–30.

Researchers in the United States have generally taken a ``segregated'' approach to regeneration research. As a result, trials involving nurserytreatments are usually separated from trials involving site preparationtreatments. Researchers have concentrated on just the main treatmenteffects. Little effort has been placed on examining potential interactionsbetween nursery and site preparation treatments. Only a few nursery bysite preparation (NxSP) studies have been established. The profession hasgenerally assumed that gains from nursery and site preparation treatmentsare simply additive, or that the relative gains from nursery treatmentswould be insignificant when compared to intensive site preparationtreatments. Both of these assumptions may be incorrect. This review examines some of the NxSP interaction trials that have beenestablished in the United States during the last half of the 20thcentury. We predict that as rotation ages for plantations decrease, the needfor NxSP interaction trials will increase. NxSP interaction studies will berequired if researchers wish to include both nursery and site preparationtreatments in their early establishment models. To date, only a fewestablishment models have been developed in the United States.

A seedling size/intensive management study with Pinustaeda L. was established in 1993 on two sites in the CoastalPlain of Georgia and South Carolina. Each site contained a 2 × 2split-plot study involving two seedling sizes and two levels ofestablishment intensity. Ideotype ``B'' seedlings averaged 5.0 mmin diameter (at the root collar) and were 43 cm tall. Ideotype``A'' seedlings averaged 8.5 mm in diameter and were 50 cm tall. ``Standard'' establishment practices included herbicides(hexazinone and sulfometuron) and fertilizer (DAP) appliedduring the first year. The ``intensive'' management involved twoherbicide applications during the first year and two during thesecond year, fertilizer during the first and third years, andinsecticide applications during the first two years (for controlof tip moth, Rhyacionia frustrana Comstock).Intensive management did not affect survival but planting largerseedlings increased survival slightly on one site. However,treatments affected early growth at both sites. On both sites,fourth-year plot-volumes were increased with greaterestablishment intensity and larger seedlings but there was nointeraction between stock size and establishment intensity. Early growth gains were greatest when both intensive managementand larger seedlings were combined. Depending on site, thiscombination resulted in 21% to 51% more volume (at age 4) thanthe next best treatment (standard seedlings with intensivemanagement).

Early growth of two grades ofbare-root Pinus radiata D.Don seedlingswere studied in response to four soilcultivation treatments and two weed controltreatments.Soil cultivation treatments included (i) pitsmade by hand, (ii) pits made with an auger,(iii) ripping alone, and (iv) ripping plusdisking. Weed treatments included (i) manualrelease 1 year after planting or (ii) totalweed control for 1 year involving the use ofherbicides and additional hoeing. Bare-rootseedlings were separated into either medium(4.1-mm average root-collar diameter; height25–31 cm) or small (2.8-mm average root-collardiameter; height 14–20 cm) size classes. Growth on this site was excellent and 7 yearsafter treatment, trees in the least expensivetreatment averaged 12.8 m in height. Use ofmedium seedlings and extra weed controlincreased merchantable volume by20 m3 haminus 1 and 19 m3 haminus 1,respectively. When combined, the increase was39 m3 haminus 1. However, none of the soilcultivation treatments caused a significantincrease in merchantable volume. Disking onthis site proved to be of no benefit. Aboundary-line analysis was used to examine themarginal returns from investing in intensivesilviculture.

Tolerance of three pine species to postemergence applications of clopyralid was examined at ten southern nurseries over a 2 yr period. The herbicide was applied at various times during May, June, and July. At time of lifting, seedling morphology was evaluated (root-collar diameter, shoot height, root dry weight, and shoot dry weight). Loblolly pine (Pinus taeda L.), slash pine (P. elliottii Engelm. var. elliottii) and longleaf pine (P. palustdds Mill.) were tolerant to 210 to 840 g acid equivalent (ae)/ha. However, epinasty was occasionally observed on both loblolly pine and slash pine. The injury symptoms were ephemeral and seedlings appeared normal 3 months after treatment. Results from these tests suggest some pine species are tolerant to this herbicide at the seedling stage. As a result of this research, this herbicide can be legally used in many southern pine nurseries to control troublesome weeds such as sicklepod (Cassia obtusifolia L.), Florida beggerweed (Desmodium tortuosum [Sw.] DC.), horseweed (Erigeron canadensis L.) and other annual broadleaf weeds. South. J. Appl. For. 24(1):51-56.

A slash pine (Pinus elliottii Engelm. var elliottii) study was established to determine the "optimum" seedling size for use on a flatwoods site in the Coastal Plain physiographic province of Georgia, U.S.A. The optimum seedling is defined as the ideotype that will minimize overall reforestation costs while achieving established goals for initial survival and growth. Initial survival and fourth-year performance were examined in relation to (i) method of site preparation, (ii) herbicide application, and (iii) seedling class (based on root-collar diameter) and to associated establishment costs. Seedling class greatly influenced survival with large-diameter classes (8.5-11.5 mm) exhibiting the best survival (87-99%). Seedlings with 4.5-mm diameters averaged 75% survival. A second bedding pass (double bedding) reduced grasses and woody shrubs, and the herbicide imazapyr reduced grasses and herbaceous broadleaf weeds. Neither treatment improved pine survival. Use of 9.5 to 11.5-mm seedlings (without double bedding) produced larger trees 4 years after planting than 4.5-mm seedlings with double bedding. A simple cost analysis indicated the optimum seedling would be considerably larger (9.5-11.5 mm) in diameter than the "target" seedling (4.5 mm) typically produced at slash pine nurseries. For each dollar invested in establishment, planting the optimum pine seedling on this site resulted in greater gains in early survival and growth than either double bedding or use of imazapyr.

Studies have shown that clipping needles of longleaf pine before outplanting can increase average seedling survival by 13 percentage points. Under some situations, the increase in survival might be due to a reduction in transpiration. For loblolly pine, top-pruning in the nursery might increase average survival by 6 percentage points. Benefits of pruning appear greater when seedlings experience stress after planting and when nonpruned seedlings have low root weight ratios (root dry weight/total seedling dry weight). On some droughty sites, a seedling with a 0.3 root weight ratio might have an 80% chance of survival, while a seedling with a 0.2 root weight ratio might only have a 53% chance of survival. In most studies where heights were measured after 3 yr in the field, pruned seedlings were the same height as nonpruned seedlings (± 7 cm). South. J. Appl. For. 22(4):235-240.

Chloropicrin has been tested as a soil fumigant in forest nurseries throughout the world. From 1944 to the late 1960's, tests were conducted in Australia, Canada, Netherlands, New Zealand, the United Kingdom and the United States. Since 1985, studies have been conducted in Georgia, Mississippi, South Carolina, Texas, Virginia, Washington and Wisconsin. In Wisconsin, chloropicrin reduced soilborne pathogens as effectively as twice as much methyl bromide. Advantages of chloropicrin as a soil fumigant in southern pine nurseries include: efficacy similar to methyl bromide (in regards to reduction in fungi, nematodes and insects), an increase in Trichoderma populations, it is not a Class 1 ozone depleting substance, and no plastic tarp is required. Adding chloropicrin to other fumigants has increased the spectrum of biological activity. A disadvantage of chloropicrin is that it has less herbicidal activity than methyl bromide. Key words: fungicide, methyl bromide, disease, nursery management, seedbeds

This paper demonstrates a simple way of estimating the intensity and duration of planting check by examining height growth patterns. A “transplant stress index” is determined by the relationship between initial seedling height and subsequent height growth. This index is defined as the slope of a linear relationship between initial height and height increment. If the slope is negative, the plants (as a population) are said to be experiencing planting check. When the slope is approximately zero, the stock is said to be recovering from planting check. A steep positive slope suggests the stock has recovered from planting check. TSI values were determined for several conifers including Pinus elliottii Engelm. var. elliottii, Pinus taeda L., Pinus radiata D. Don, Picea sitchensis (Bongard) Carriere, and Larix× eurolepis Henry.

Relationships between root growth potential (RGP) and plantation survival were evaluated for 12 families of shortleaf pine (Pinus echinata Mill.) from Oklahoma and Arkansas in 2 consecutive years. Bare-root, 1+0 seedlings were either planted one day after lifting (nonstored) or were stored at 1° to 3°C for 4 weeks. Correlations were obtained using the traditional “research” method where seedlings are planted in the field prior to obtaining results from the RGP test. In addition, “operational” correlations were derived by planting seedlings after obtaining RGP test data. For nonstored seedlings, research correlations were generally higher (r values were larger in 18 of 24 cases) than operational correlations. The predictive ability of operational correlations may not be high enough with 28-day pot tests to warrant batch culling of freshly lifted shortleaf pine. However, results were mixed for stored seedlings. In one year, operational correlations were generally higher than research correlations.

Large-scale tree planting programs have placed a tremendous pressure on nursery managers to supply unprecedented numbers of seedlings. Inclusion of chemicals into seed production regimes have made it possible for southern pine nurseries to be the most productive in the world, in terms of both output per nursery and average cost per seedling. Nursery managers in the South rely on the use of fertilizers, fumigants, and pesticides to help keep production costs low. Judicious use of fertilizers can reduce the production of cull seedlings as well as increase field growth after outplanting. It has been our experience that investing in the use of pesticides and inorganic fertilizers provides a high rate of return for the nursery manager. South. J. Appl. For. 20(3):127-135.