Cone Production Research Articles

Postfire population dynamics of a fire-dependent cypress

Tecate cypress (Hesperocyparis forbesii) is a rare species restricted to four metapopulations in southern California, USA and a few isolated populations in northern Baja California, Mexico. It is a closed-cone, fire-dependent tree of conservation concern due to an increase in human-caused wildfires that have shortened the interval between fires in many of their populations. In 2003, the Mine/Otay Fire burned 70% of the Tecate cypress on Otay Mountain in San Diego County, California providing an opportunity to evaluate the immaturity risk of this species and to examine its recruitment, survivorship, and reproductive maturity over a 14-year period from 2004 to 2017. Sixteen sites were established in burned stands of Tecate cypress with prefire ages that ranged from 7 to 53 years old. After 14 years, the overall density of Tecate cypress was still higher than before the fire, however, the areal extent of the species decreased due to the loss of locations where either there was low cone production or fire intensity was too high. The immaturity risk for this species, while a function of prefire stand age, is confounded by other factors including the reproductive capacities of trees based on their density and size and the climatic variables affecting their growth over time. The future management of Tecate cypress and other fire-dependent species requires a knowledge of all factors impacting their immaturity risk, as well as an understanding of the potential fire–climate interactions that may impact their persistence in a future of climate change and altered fire regimes.

Climatic cues for secondary growth and cone production are sex-dependent in the long-lived dioecious conifer Araucaria araucana

Trees’ growth responses to climate may depend on tree age and site conditions. In dioecious species, sex adds an extra level of complexity due to differential reproductive effort between the sexes and potentially sex-related dimorphic growth. Araucaria araucana is a long-lived dioecious conifer with outstanding morphological and functional adaptations considered an excellent model to explore interactions between radial growth, climate variability and reproductive effort. We assessed the potential dimorphism of growth rates of the sexes, the effects of site, tree age and sex on the individual climatic responses, and the growth-climate-cone production relationships of A. araucana in two environmentally contrasted sites at the Andes of south-central Chile. We quantified tree-ring growth, its dependence on weather variability, and the relationships of cone production with growth and climate. We found site-dependent sexually-dimorphic growth rates, with females growing more in the warmer site while males growing more in the colder site. Resource allocation to growth was dependent on weather conditions prior to the growing season. Clear effects of site conditions, tree sex and age on the responses of individual tree growth to climate were identified. A more resilient response to drought stress occurred in the colder site and female trees’ growth showed tighter limitations by winter snow cover. Warm conditions in spring and summer exerted an age-dependent detrimental effect on growth, which is coherent with earlier xylogenesis resumption in younger trees. Cone production was strongly dependent on antecedent weather conditions up to seven years prior to seed dispersal that induced female cone primordia formation and favoured fertilization of female cones and soil nutrient uptake. The revealed lagged connections between vegetative growth, weather cues and cone production point towards a long-term life strategy for A. araucana.

Análisis espacial de las variables fenotípicas en un huerto clonal de Pinus arizonica Engelm. en el norte de México

Introduction: Seed orchards provide germplasm genetically suitable for use in forest restoration. Knowledge of the spatial distribution of attributes is crucial for their management. Objective: To model cone production and tree size variables in a clonal orchard of Pinus arizonica Engelm. from a geospatial perspective in order to determine their behavior and distribution. Materials and methods: The spatial pattern of tree size variables and cone production of 126 ramets were determined through a geospatial analysis, using the Getis-Ord G statistic. A Pearson correlation analysis (P ≤ 0.05) determined the variables best associated with cone production and these were examined with stepwise regression. In terms of cone production, the best combination was modeled through a geographically weighted regression. Results and discussion: Statistically significant (P Conclusion: Tree size variables and cone production presented a tendency towards clustering. The use of a geospatial perspective allowed a better understanding of the spatial dynamics of tree size variables.

Effect of fertilization on water use and yield of hops in mature hop plantation

The effect of decreasing nutrient availability on the ecophysiology and production of hop cones was studied in a plantation of cultivar 'Premiant', in Žatec hop growing region, Czech Republic. The plantation used to be fertilized by 60 t of manure ha(-1) year(-1) until November 2011 when it was discontinued as a part of the measures towards organic farming. Measurements of total evapotranspiration from the plantation using the Bowen ratio energy balance method, transpiration of hop bines by the means of sap flow, soil water and nutrient availability were conducted from 2011 to 2014. The yield of hop cones and the content of alpha acids were monitored in this period too. The concentration of total soil nitrogen (N) dropped from 19.4 mg kg(-1) in March 2012 to 8.2 mg kg(-1) in November 2014. Similarly, the content of N in leaves declined from 4.1% of dry mass in 2012 to 2.5% in 2014. The ratio between total evapotranspiration from the plantation to the potential evapotranspiration (PET) was not affected by the soil nutrient availability and did not vary among the years of study, ranging between average to 91 and 96% of PET. In the contrast to total evapotranspiration and PET, the proportion of hop transpiration on the total evapotranspiration steadily declined from 74 to 46% in 2011 and 2014, respectively. Plant regulation of stomatal conductance changed, bringing along lower stomatal aperture, especially upon the conditions of low vapor pressure deficit. In line with decline in transpiration and stomatal conductance, yield of alpha-acids declined from 204 kg ha(-1) in 2011 to 97 kg ha(-1) in 2014. To sum up, after the stop in fertilizing, total water use of the plantation remained similar as before, but the transpiration and production of alpha acids ha(-1) significantly decreased.

Climate Change Impacts on Pinus pinea L. Silvicultural System for Cone Production and Ways to Contour Those Impacts: A Review Complemented with Data from Permanent Plots

Umbrella pine (Pinus pinea L.) cones take three years to develop. With the increasing frequency of extreme droughts, water available for trees has decreased—climate change is a reality. The cone’s survival in its first two years of development and the average cone weight during its last year of maturation is affected, thus, reducing kernel quantity and quality. Climate change has resulted in forest fires becoming an inescapable issue in forest management planning. A literature review was carried out, focusing, on one hand, the predicted climatic changes for the Mediterranean basin and, on the other hand, the umbrella pine silvicultural mechanisms at tree, stand, and landscape levels that may help to face these constraints. Finally, the Portuguese case was focused, describing the management practices that are being adopted to achieve, even when the period of cone formation and growth include dry years, one to six tons of cones per hectare per year in adult stands.

Temperature and masting control Norway spruce growth, but with high individual tree variability

Tree growth and reproduction are subject to trade-offs in resource allocation. At the same time, they are both influenced by climate. In this study, we combined long records of reproductive effort at the individual- (29 years), population- (41 years) and regional (up to 53 years) scale, and tree ring chronologies, to investigate the effects of climate and reproductive allocation on radial growth in an Alpine Norway spruce forest.Seed and cone production was highly variable between years (mean individual CV = 1.39, population CV = 1.19), but showed high reproductive synchrony between individuals (mean inter-tree correlation = 0.72). No long-term trend in reproductive effort was detected over four decades of observations. At the stand scale, cone production was dominated by a small number of individuals (“super-producers”), who remained dominant over three decades.Individual tree growth responded positively to summer temperature, but the response to cone production varied between individual trees. Consequently, we found some evidence that mast years were associated with a divergence in growth between high and low cone producing individuals, and a decline in within-population growth synchrony.At the population level we found limited evidence of a relationship between growth and reproduction. Radial growth was lower than average in some mast years, but not in others. This was partly explained by summer temperature during the year of growth, with growth reductions restricted to mast years that coincided with colder than average summers. Regional mast records and tree ring chronologies provided some support to indicate that our results were consistent in other spruce stands, although the effect of mast years on growth appeared to vary between sites.Tree ring variation at the individual and population level, and between-tree growth synchrony are influenced by masting, and consequently dendrochronologists should consider both the occurrence of masting and the individual differences in reproductive effort when interpreting tree ring datasets. Our results also indicate that tree ring chronologies contain information to facilitate reconstruction of mast events, which will help address outstanding questions regarding the future response of masting to climate change.

An Efficient Numerical Method for the Symmetric Positive Definite Second-Order Cone Linear Complementarity Problem

An efficient numerical method for solving a symmetric positive definite second-order cone linear complementarity problem (SOCLCP) is proposed. The method is shown to be more efficient than recently developed iterative methods for small-to-medium sized and dense SOCLCP. Therefore it can serve as an excellent core computational engine in solutions of large scale symmetric positive definite SOCLCP solved by subspace projection methods, solutions of general SOCLCP and the quadratic programming over a Cartesian product of multiple second-order cones, in which small-to-medium sized SOCLCPs have to be solved repeatedly, efficiently, and robustly.

Whitebark and Foxtail Pine in Yosemite, Sequoia, and Kings Canyon National Parks: Initial Assessment of Stand Structure and Condition

The Inventory & Monitoring Division of the U.S. National Park Service conducts long-term monitoring to provide park managers information on the status and trends in biological and environmental attributes including white pines. White pines are foundational species in many subalpine ecosystems and are currently experiencing population declines. Here we present results on the status of whitebark and foxtail pine in the southern Sierra Nevada of California, an area understudied relative to other parts of their ranges. We selected random plot locations in Yosemite, Sequoia, and Kings Canyon national parks using an equal probability spatially-balanced approach. Tree- and plot-level data were collected on forest structure, composition, demography, cone production, crown mortality, and incidence of white pine blister rust and mountain pine beetle. We measured 7899 whitebark pine, 1112 foxtail pine, and 6085 other trees from 2012–2017. All factors for both species were spatially highly variable. Whitebark pine occurred in nearly-pure krummholz stands at or near treeline and as a minor component of mixed species forests. Ovulate cones were observed on 25% of whitebark pine and 69% of foxtail pine. Whitebark pine seedlings were recorded in 58% of plots, and foxtail pine seedlings in only 21% of plots. Crown mortality (8% in whitebark, 6% in foxtail) was low and significantly higher in 2017 compared to previous years. Less than 1% of whitebark and zero foxtail pine were infected with white pine blister rust and <1% of whitebark and foxtail pine displayed symptoms of mountain pine beetle attack. High elevation white pines in the southern Sierra Nevada are healthy compared to other portions of their range where population declines are significant and well documented. However, increasing white pine blister rust and mountain pine beetle occurrence, coupled with climate change projections, portend future declines for these species, underscoring the need for broad-scale collaborative monitoring.

Pine recolonization dynamics in Mediterranean human-disturbed treeline ecotones

Worldwide treelines seem to share a twofold condition: over 50% of them are advancing and 50% appear to be static. In this study we compared the encroachment patterns of four pine species across anthropogenic treelines in Southern Europe. Using a synchronic approach, we studied structure and recent spatio-temporal patterns of pine recruitment at upper treeline ecotones in Albania, Italy, Montenegro and Spain. Within altitudinal transects we mapped and sampled 964 living individuals of Pinus heldreichii, Pinus peuce, Pinus sylvestris and Pinus uncinata growing above the current forest line. We measured their basal diameter, total height, and counted the number of seed cones. We differentiated seedlings (height < 0.5 m) from saplings (0.5 m ≤ height < 2 m) and trees (height ≥ 2 m). From individuals with basal stem diameter >4 cm we extracted one increment core for cambial age determination and tree-ring width measurements. On smaller specimens, we estimated the age by counting annual internodes (terminal bud scars) along the whole stem. We compared the ground cover around each pine, applied point pattern analyses, modelled the probability of seed cone production and estimated the average distance of seed dispersal. The four pine species exhibited heterogeneous density values (87-1552 N° ha−1). The overall averaged means ranged 2–7 cm for basal diameter, 54–106 cm for total height and 9–20 years for cambial age, suggesting a recent encroachment process. None of these structural variables decreased with increasing relative altitude and distribution patterns exhibited a few higher density spots but not cohort spatial structure. Ground cover differed between species and more significantly between size classes. Grass was the most frequent type at all sites except for P. sylvestris where shrubs prevailed (>50%). Further differences appeared when discriminated by height thresholds, with larger share of saplings and trees neighboring shrubs and rocks. Basal area increments increased from 1990 and stabilized in recent years at all species except for P. peuce. Height and basal diameter predicted cones production better than cambial age. P. heldreichii and P. peuce dispersed seeds at longer distances than P. uncinata and P. sylvestris, suggesting different potential for further encroaching. Pine recruitment above the forest lines is quite synchronic at all sites (last 30 years), but in some cases it appeared as a high altitude tree densification process, whereas in others as a starting treeline advance. The use of permanent transects provides a detailed monitoring of tree survival and a more precise prediction of future treeline expansion.

Helical metals and insulators: Sheet singularity of the inflated Berry monopole

We study the new phases of interacting Dirac matter that host novel Berry signatures. We predict a topological Lifshitz phase transition caused by the changes of a Dirac cone intersection from a semimetalic phase to helical insulating or metallic phases. These helical phases provide the examples of gapless topological phase where spectral gap is not required for a topological protection. To realize nodal helical phases one would need to consider isotropic infinite-range inter-particle interaction. This interaction could emerge because of a momentum conserving scattering of electron from a bosonic mode. For repulsive/attractive interactions in density/pseudospin channel system undergoes a transition to helical insulator phase. For an attractive density-density interaction, a new metallic phase forms that hosts {\it nodal circle} and {\it nodal sphere} in two and three dimensions, respectively. A {\it sheet singularity} of Berry curvature is highlighted as a peculiar feature of the nodal sphere phase in 3D and represent the extension of the Berry monopole singularities into inflated monopole. To illustrate the properties of these helical phases we investigate Landau levels in both metallic and insulating phases. Our study provides an extension of the paradigm in the interacting Dirac matter and makes an interesting connection to inflated topological singularities in cosmology.

A Variant of the Affine-Scaling Method for a Second-Order Cone Program

A linear cone program in which the cone is the direct product of second-order cones (Lorentz cones) is considered. For its solution, we propose a primal affine-scaling type method generalizing the corresponding method used in linear programming. The method can be considered as a special way to solve a system of necessary and sufficient optimality conditions for a pair of mutually dual cone programs. These conditions are used to derive the dependence of the dual variables on the primal variables, and the dependence is substituted into the complementarity condition. The obtained system of equations is solved with respect to the primal variables by the fixed-point iteration method. The starting points in the method belong to the cone but do not necessarily satisfy the linear equality-type constraints. The local linear convergence of the method is proved under the assumption that the solutions of the primal and dual problems are nondegenerate and strictly complementary.

Linking climate, annual growth and competition in a Mediterranean forest: Pinus pinea in the Spanish Northern Plateau

Climate, competition and site conditions are the main drivers controlling annual secondary growth in tree species. These factors do no act independently on tree growth, but by means of interactions, resulting in mediated interactive effects. For example, the stress gradient hypothesis postulates alleviated interspecific competition under limiting spatial (site) or temporal (climate) resources. According to this, models predicting annual growth and yield for a given forest should consider these issues in their formulation. In this study, we present a modelling approach based on using data from permanent plots and dendrochronological analysis in order to describe annual tree growth in pure, even-aged stands of Pinus pinea L. in the Spanish Northern Plateau, a highly limiting environment due to its Mediterranean continental climate. Our method is based on identifying the different sources of variability by means of a multilevel linear mixed model, and thereby identifying the potential covariates explaining observed variability at the different spatiotemporal scales. Our results indicate that site related factors such as site index or dominant height exert a greater influence on annual secondary growth than size-symmetric competition. In addition, we found that the controlling influence of water stress is greater than that of temperatures on tree growth. Furthermore, our results allow evidence to be identified for the stress gradient hypothesis in temporal intraspecific interactions, since trees exposed to a higher degree of competition tend to grow more than expected in dry periods. In contrast, the effect of competition on growth, on average, tends to be aggravated at very poor sites. Finally, our modelling approach allows us to conduct growth and yield simulations under different climate scenarios at different spatial scales, providing results which point to significant decreases in timber and cone production under the more severe scenarios, which can be alleviated through more intensive silviculture.

Large-Neighborhood Infeasible Predictor–Corrector Algorithm for Horizontal Linear Complementarity Problems over Cartesian Product of Symmetric Cones

We present an infeasible interior-point predictor–corrector algorithm, based on a large neighborhood of the central path, for horizontal linear complementarity problem over the Cartesian product of symmetric cones. Throughout the paper, we assume that a certain property holds for the above-mentioned problem. This condition is equivalent to the property of sufficiency for the particular case of horizontal linear complementarity problem. The polynomial convergence is shown for the commutative class of search directions. We specialize our algorithm further by prescribing some scaling elements and also consider the case of feasible starting points. We believe this to be the first interior-point method based on large neighborhoods for the problem in consideration.

Is Leptoglossus occidentalis entirely responsible for the high damage observed on cones and seeds of Pinus pinea? Results from a fertirrigation trial in Portugal

The uncertainty surrounding the part played by an invasive North American seed bug, Leptoglossus occidentalis, in the observed decrease in seed production of the Mediterranean pine, Pinus pinea, is a limiting factor for its management. Furthermore, the possibility of increasing cone production through irrigation and fertilization regimes is gaining interest among landowners, but its effects on insect pests are still unknown.Using bagged branches in the field, we aimed at evaluating the impact of L. occidentalis on young and mature cones of stone pine trees submitted to fertirrigation (FR) compared to trees with no treatment (C). For two consecutive years (2015 and 2016), we carried out both an insect-exclusion trial and an insect-bagged trial. In the first one, polyester-covered branches, excluding insects, were compared to branches exposed to natural insect infestation. In the second trial, bags included either two adult bugs or 3–4 third-instar nymphs, placed there for one month during mid-summer, or were kept without insects. Branch protection resulted in a significant decrease in the mortality of second-year conelets which dropped to 6% compared to 30% in exposed branches. Seed damage also decreased from 60% on exposed branches to 10% on protected ones. The presence of nymphs in the bags resulted in a mortality of second-year conelets 63% higher than in exclusion bags, whereas adults had no effect. In contrast, bags with adults presented the highest seed damage. The partial damage of the kernel can be a signature of L. occidentalis feeding since such damage was not observed in exclusion bags. Additionally, another type of seed damage, showing a wholly shrunken and dry embryo without remaining endosperm, and a reduction in the number of extractable seeds may also be attributed to this seed bug. Overall, seed damage per mature cone reached up to 12% in bags with two adult bugs enclosed for a month, i.e., twice the seed damage in protected cones. Overall, FR trees were more susceptible to both conelet mortality and seed damage. In the particular case of L. occidentalis, FR regime influenced the consumption positively by the nymphs but not by adults.

Characterizing the dynamics of cone production for longleaf pine forests in the southeastern United States

Longleaf pine (Pinus palustris Mill.) forests are historically and ecologically important and also endangered ecosystems in the southeastern United States. In addition to extensive exploitation and land use conversion, one characteristic which contributed to their dramatic decline and presents a continuing challenge to their future recovery is the sporadic timing of their seed production. In this study, about 60 years of cone production data for longleaf pine forests at four different sites were quantitatively characterized from different perspectives. Results indicated that longleaf pine was different from masting species and there was no general trend of increasing coefficient of variation (CV) in cone production through time. On a decade scale, there was a significantly positive correlation between the CV of cone production and CV of average annual air temperature, but the CV of annual precipitation was negatively correlated with the CV of cone production at the Escambia (AL) and Blackwater (FL) sites. Phase coupling of cone production with a strength of approximately 0.4 existed only between the Escambia and Blackwater sites and no significant phase coupling was found between other sites. The implications of these results for forest management are discussed from a perspective of spatial and temporal complexity.

The effects of top pruning on growth and production of conelets and cones in Pinus brutia Ten seed orchards of different ages

In economic and biological terms (rapid growth, the ability to produce seeds at an early age, etc.) Pinus brutia Ten. is one the most important forest tree species in Turkey. Considerable progress has been made in Pinus brutia Ten. breeding program and both phenotypical and according to the results of progeny trials, totaling 615-hectare seed orchardshas been established. Pinus brutia Ten. seed orchardshas reached 43% of the total orchard area and covered the largest area. To acquire information on the management of seed orchards, top pruning has been carried out on three Pinus brutia Ten. seed orchards of different ages (old, middle-aged and young). Two top pruning regimes were applied in these three seed orchards, once in 2008 to the old orchard, while a single topping regime was applied in 2008 and 2012 to the middle-aged and young orchards.Each year, the height, diameter at breast height, and bi-directional crown diameter were measured, and all conelets and cones on ramets were counted beforeand after pruning. At the end of four years, control ramets in old and young seed orchards had higher values of height, diameter at breast height, and volume indexcompared to the middle-aged orchard. On the other hand, even though the control ramets in the middle-aged seed orchard reached a greater height, pruned ramets reached a greater volume index and diameter at breast height. While the height differences observed between control and pruned ramets in all seed orchards at the beginning eventually decreased, it was observed that the heights of pruned ramets grew proportionally larger. No difference was founded between the control and pruned ramets in terms of cone and conelet production. Pruning intervals and regimes varied in old, middle-aged and young seed orchards, and it was acknowledgedthat top pruning could be used for old, middle-aged and young seed orchard managements.

Longleaf pine cone–radial growth relationships in the southeastern U.S.A.

Longleaf pine (Pinus palustris Mill.) cones have been counted annually by the United States Forest Service (USFS) at eleven locations throughout the species’ range since 1958. These data have been useful for understanding spatiotemporal patterns in longleaf pine cone production, and are beneficial in timing regeneration efforts. Variations in annual mast (i.e. seed crop) are known to influence ring widths in numerous tree species, yet this relationship is poorly understood for longleaf pine. This research examines the relationship between longleaf pine cone data and tree-ring growth from trees sampled in the multi-decadal USFS cone-crop study. We examined cone–radial growth relationships using individual tree-ring data and proprietary cone data for each tree from six sites in four locations in the southeastern USA. We found that longleaf pine cones were correlated with basal area increment growth (BAI) over the three-year cone-development cycle. Low BAI years were more frequently associated with above-average cone crop and BAI during years that coincided with the largest cone-crop class (bumper, > 100 cones per tree) were statistically less than any other cone class. We prepared linear models that predicted radial growth using PDSI and cones as predictors, and found that including cones in the models did not improve adjusted R2 values. We conclude that while cone production is inversely related to radial growth, the combination of infrequent bumper years and the concentration of cone production by a few trees per stand, creates an environment where radial-growth chronologies assembled from longleaf pine for dendroclimatic purposes are unlikely to be significantly influenced by reproductive strain.

A path following interior-point method for linear complementarity problems over circular cones

Circular cones are a new class of regular cones that include the well-known second-order cones as a special case. In this paper, we study the algebraic structure of the circular cone and show that based on the standard inner product this cone is nonsymmetric while using the new-defined circular inner product this cone not only is symmetric but also the algebra associated with it, is a Euclidean Jordan algebra. Then, using the machinery of Euclidean Jordan algebras and the Nestrov–Todd search directions, we propose a primal-dual path-following interior-point algorithm for linear complementarity problems over the Cartesian product of the circular cones. The convergence analysis of the algorithm is shown and it is proved that this class of mathematical problems is polynomial-time solvable.

Effect of thinning intensity on tree growth and temporal variation of seed and cone production in a Pinus koraiensis plantation

Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands.

Post-Emergent Control of Nuisance Cones in Fraser Fir Christmas Tree Plantations

Heavy cone production by Fraser fir Christmas trees requires significant labor inputs to remove nuisance cones. We conducted two field trials in collaboration with operational Christmas tree farms to evaluate the effectiveness of post-emergent herbicides to stop the development of newly emergent cone buds. In the first trial (2016), we applied six products (two conventional herbicides and four herbicides labeled for organic production) to trees using back-pack sprayers in operational plantations at four farms in Michigan. Three products; Scythe, Axxe, and Avenger, provided better cone kill than the other products but resulted in phytotoxicity at two locations. In 2017, we applied the three most effective products from the earlier trial at three farms either as single applications or as two applications approximately one week apart. We also evaluated a hand-held mechanical de-coning device at two farms. For all the products and the mechanical device, cone control in the 2017 trial was high (&gt;80%). Phytotoxicity to foliage was low (mean rating, &lt;0.3; 0 = none, 2 = severe) for single applications of the herbicides. Repeated applications increased cone control slightly but also increased risk for phytotoxicity. The mechanical device caused significant damage to shoots and foliage. We attribute the increased product effectiveness and reduced phytotoxicity between the 2016 and 2017 studies to improved coverage and earlier spray timing. Based on the current retail product cost, chemical cone control can be cost-effective compared to handpicking cones if trees have high numbers of cones that can take several minutes to remove. The effect of using surfactants and reducing product rates should be investigated along with mechanized application.