Entire Crowns Research Articles

Analysis of patterns of light interception by the crowns of Cotoneaster lucidus Schlecht bushes in various ontogenetic states in the Kalinovsky Forest Park of Yekaterinburg

In the forest park area of Yekaterinburg Cotoneaster lucidus Schlecht. found as a naturalized introduced species in various forms of plantings. With increasing anthropogenic pressure on suburban forests, it is important to study the biological characteristics of invasive species and their intraspecific differentiation to preserve the gene pool, therefore, studying the patterns of manifestation of the size, ontogenetic and structural parameters of cotoneaster in coenopopulations makes it possible to identify the peculiarities of the dynamics of their development and give a complete picture of the processes of adaptation of this species to the conditions growth. The article studied the lighting parameters in different parts of the crowns of C. Lucidus bushes of various ontogenetic states, and analyzed their ability to intercept light. The parameters of lighting and its interception largely depend on the structural features and size of the crowns of bushes, their age and ontogenetic state. With age (transition to later ontogenetic states), the parameter of illumination received above the crown increases, the interception of illumination by entire crowns of bushes increases from 33.2% for j to 68.4% in the late generative state (at the same time, the interception of illumination by the lower parts of the crowns is relatively stable, varying from 10.7% to 16.7%), the correlation between the parameters of illumination and its interception in different parts of the crown becomes less pronounced. The latter is associated with the development of an increasingly complex and dense structure in the volume of the crowns of C. lucidus bushes.

Usefulness of powdered crown of mandibular first premolars in birth year estimation by radiocarbon dating

BackgroundRadiocarbon (14C), whose levels increased in the atmosphere between 1955 and 1963, accumulates in the enamel of human teeth only during the process of tooth formation and has been applied to estimate the birth year of unidentified corpses. However, enamel isolation from teeth is time-consuming and labor-intensive. Therefore, this study aimed to estimate the birth year using 14C in the crown of a single mandibular first premolar tooth. Materials and methodsFourteen mandibular first premolars collected from forensic autopsies were analyzed. For nine teeth, each tooth was cut longitudinally: half of the tooth was enamel, and the other half was crown (1). For the other five teeth, the entire crown was used (2). Thereafter, the 14C concentration in each tooth was measured using accelerator mass spectrometry. ResultsThe absolute error between the actual date of birth (DOB) and the estimated DOB was within the range of 1.0–8.8 years in the enamel of five teeth and 0.1–4.0 years in the crown halves of seven teeth (1). For the five teeth with entire crowns, the absolute errors ranged between 0.3 and 3.0 years (2). ConclusionThe absolute error of 14C-based year of birth estimation using the powdered crown of the mandibular first premolar teeth ranged between 0.1 and 4.0 years. Our method, which involves pulverizing an entire crown, eliminates the need for the equipment, time, and labor associated with enamel isolation. Therefore, 14C dating using powdered crowns of mandibular premolars can be useful for birth year estimation.

A probable genetic origin for pitting enamel hypoplasia on the molars of Paranthropus robustus

We report the frequencies of linear enamel hypoplasia (LEH) and, specifically, pitting enamel hypoplasia (PEH) defects in the teeth of Paranthropus robustus, for comparison with four other South African hominin species and three extant nonhuman primate species. Unlike LEH, the lesser known PEH is characterized by multiple circular depression defects across a tooth crown and is often difficult to interpret in terms of developmental timing and etiology. Teeth in all samples were examined macroscopically with type, position and number of defects recorded. Frequencies of teeth with LEH vary among hominin species, but the differences in PEH are considerable. That is, P. robustus has much higher rates of pitting defects, with 47% of deciduous teeth and 14% of permanent teeth affected, relative to 6.7% and 4.3%, respectively, for all other hominin teeth combined; none of the extant primate samples evidences comparable rates. The defects on P. robustus molars are unlike those in other species, with entire crowns often covered in small circular depressions. The PEH is most consistent with modern human examples of amelogenesis imperfecta. Additionally, the defects are: 1) not found on anterior teeth, 2) uniform in shape and size, and 3) similar in appearance/severity on all molars. Therefore, this form of PEH may have been a side effect of selection on another trait that shares the same coding gene(s), i.e., these defects have a genetic origin. We discuss a possible scenario that may explain how this form of PEH evolved to become so common in the Paranthropus genus.

Fusarium equiseti is associated with the wilt and dieback of Aquilaria malaccensis in Northeast India

AbstractAquilaria malaccensis, categorized by IUCN as globally vulnerable, is in high demand in the Middle East and Asian markets for its unique resinous agarwood. In August 2015, symptoms of dieback were observed on A. malaccensis trees planted in the Medicinal and Aromatic Plant Garden, Panbari, Golaghat of the Assam Forest Department. The entire crowns of 70 trees showed complete leaf loss and severe dieback. Rotting at the collar region and of roots was also observed. Isolation from the infected roots consistently yielded Fusarium equiseti identified following standard laboratory procedures and analysis of the internal transcribed spacer (ITS) sequence of the ribosomal DNA. Symptoms of wilt, dieback and root rot were observed on 5‐month‐old Aquilaria seedlings 25 days after inoculation with the isolated fungus. This paper is the first report of F. equiseti causing wilt and dieback of A. malaccensis.

Effects of Heterogeneity within Tree Crowns on Airborne-Quantified SIF and the CWSI as Indicators of Water Stress in the Context of Precision Agriculture

This research focused on understanding the effects of structural heterogeneity within tree crowns on the airborne retrieval of solar-induced chlorophyll fluorescence (SIF) and the Crop Water Stress Index (CWSI). We explored the SIF and CWSI variability observed within crowns of trees subjected to different water stress regimes and its effect on the relationships with leaf physiological measurements. High-resolution (20 cm) hyperspectral imagery was acquired to assess fluorescence retrieval from sunlit portions of the tree crowns using the Fraunhofer line depth method, and from entire crowns using automatic object-based tree crown detection methods. We also measured the canopy temperature distribution within tree crowns using segmentation algorithms based on temperature percentiles applied to high-resolution (25 cm) thermal imagery. The study was conducted in an almond orchard cultivated under three watering regimes in Cordoba, in southern Spain. Three airborne campaigns took place during the summer of 2015 using high-resolution hyperspectral and thermal cameras on board a manned aircraft. Relationships between SIF and the assimilation rate improved significantly when the sunlit tree crown pixels extracted through segmentation were used for all flight dates. By contrast, the SIF signal extracted from the entire tree crowns was highly degraded due to the canopy heterogeneity observed within tree crowns. The quartile crown segmentations applied to the thermal images showed that the CWSI values obtained were within the theoretically expected CWSI range only when the pixels were extracted from the 50th percentile class. However, the CWSI values were biased in the upper quartile (Q75) for all watering regimes due to the soil background effects on the calculated mean crown temperature. The relationship between the CWSI and Gs was heavily affected by the crown segmentation levels applied and improved remarkably when the CWSI values were calculated from the middle quartile crown segmentation (Q50), corresponding to the coldest and purest vegetation pixels (r2 = 0.78 in pure vegetation pixels vs. r2 = 0.52 with the warmer pixels included in the upper quartile). This study highlights the importance of using high-resolution hyperspectral and thermal imagery for pure-object segmentation extractions from tree crowns in the context of precision agriculture and water stress detection.

Light Intensity Affects Ozone-Induced Stomatal Sluggishness in Snapbean

Tropospheric ozone (O3) is the air pollutant of most concern to vegetation at present. Ozone impacts on stomata are still controversial, as both decreased stomatal conductance and slow stomatal responses to environmental stimuli (namely, stomatal sluggishness) have been shown. We postulated that the light environment affects stomatal sluggishness. To concurrently manipulate O3 and light conditions and measure gas exchange at leaf level, we developed an innovative O3 exposure system by modifying a commercially available gas exchange system. We exposed the first trifoliate leaf of the O3-sensitive genotype S156 of snapbean (Phaseolus vulgaris) to a 1-h O3 exposure (150 ppb) under 1000 μmol m−2 s−1 photosynthetic photon flux density, so that stomata were fully open and O3 uptake was maximized. Then, leaves were subjected to different light intensities (200, 1000, or 1500 μmol m−2 s−1) until a steady state was reached. As a metric of sluggishness, we quantified the stomatal responses to a sharp water stress generated by cutting the petiole at steady state. The results showed that O3 exposure induced stomatal sluggishness only under high light (stomata needed 53 % more time to half stomatal conductance relative to steady state) and did not when the plants were under lower light intensities. We conclude that O3-induced stomatal sluggishness may occur only in fully irradiated leaves, and suggest it is a minor response when entire crowns and canopies are assessed and a major reason of the higher O3 sensitivity of sun leaves than of shade leaves.

Canopy closure determines arthropod assemblages in microhabitats created by windstorms and salvage logging

Conifer-dominated forests of the Northern Hemisphere are prone to natural disturbances, such as windstorms, which create canopy openings by downing single trees to complete stands. The size of a windthrow determines how strongly microclimatic conditions are changed. After windstorms, damaged trees are commonly logged to ‘salvage’ economic returns, but effects on biodiversity are often negative. One cause of these negative effects on biodiversity might be the alteration of storm-created microhabitats, for example, as branches are cut off and root plates are flipped back into their pits when trunks are removed. The effect of these alterations of microhabitats on biodiversity under open and closed canopies, which represent extremes of microclimatic conditions, remains unclear. To investigate the relative importance of canopy closure and microhabitats for arthropod assemblages, we created six artificial windthrows located under an open canopy and six under a closed canopy by uprooting three spruce trees per plot. We used permutational analysis of variance to test whether cutting branches off uprooted trees and allowing them to rot on the forest floor affects branch-dwelling saproxylic beetles and whether repositioning upright root plates in their pits affects assemblages of carabids, epigeal spiders and harvestmen. Our final data set comprised 7657 arthropod individuals belonging to 28 species of saproxylic beetles, 28 species of carabids, 85 species of epigeal spiders, and 8 species of harvestmen. Carabid abundance was higher under a closed canopy and the number of epigeal spider species was higher under an open canopy. Canopy closure also significantly affected the assemblage composition of saproxylic beetles, carabids and epigeal spiders, with a higher mean moisture affinity of these assemblages on plots under a closed canopy. Arthropod assemblages of root plates and root plate pits did not differ, but the composition of branch-dwelling saproxylic beetle assemblages on cut and uncut branches significantly differed. Overall, assemblages of saproxylic beetles, carabids, epigeal spiders and harvestmen were pre-dominantly determined by canopy closure and not by alteration of storm-created microhabitats. Nevertheless, entire crowns of downed spruce trees should be retained in salvage-logged forests to provide this microhabitat for saproxylic beetle assemblages typical for naturally disturbed forests.

Reliability Analysis of Lithium Disilicate Crowns: Effectof Veneering and Milling Production Workflow.

Purpose To evaluate the reliability of lithium disilicate crowns produced using either CAD/CAM milling or thermopress workflow, for monolithic or veneered framework design for crowns. Materials and Methods Lithium disilicate crowns (N = 40) were produced using one of four different workflows, namely (a) MTP: monolithic thermopressed crowns, (b) MCM: monolithic CAD/CAM milled, (c) VTP: thermopressed frameworks veneered, or (d) VCM: CAD/CAM milled crowns veneered. The specimens were adhesively luted to resin composite abutments and then tested until fracture in a universal testing machine (1 mm/min). Failure types were classified and further evaluated under stereomicroscope and SEM. The data (N) were analyzed using one-way ANOVA. Weibull distribution values including the Weibull modulus (m), characteristic strength (0), and probability of failure at 5% (0.05) were calculated. Results Fabrication method did not significantly influence the mean fracture strength (N) of lithium disilicate crowns (MTP: 3626 ± 283; MCM: 3719 ± 483; VTP: 3754 ± 485; VCM: 3302 ± 604) (p = 0.154). Weibull distribution presented lower shape value (m) of VCM (m = 5.81) followed by VTP (m = 8.83), MCM (m = 8.84) compared to MTP (m = 12.9). Type V failures (severe fracture of the crown and/or tooth) were experienced explicitly in all groups. The monolithic specimens showed a homogeneous structure without porosities. Wake hackles were observed at the fracture surface, with a radial path directed to the cervical area. The veneered crowns presented twist and wake hackles propagated perpendicularly from the cement-ceramic interface. Conclusion Monolithic or veneered lithium disilicate crowns presented similar fracture strength when frameworks or entire crowns were milled or thermopressed but distribution with Weibull characteristics was more favorable for monolithic pressed crowns and the least reliable for the milled and veneered crowns. Clinical Significance Lithium disilicate ceramic crowns could be produced either by thermopressing or CAD/CAM milling workflow without sacrificing their reliability.

Dothistroma septosporum Identified in Greece on Pinus brutia and Pinus nigra Plantations.

Dothistroma needle blight (DNB) is caused by two ascomycete fungi, Dothistroma septosporum with a worldwide distribution and D. pini found in the United States, Russia, Ukraine, Hungary, and France (1). DNB has been known in Greece since the early 1980s (3) and the species responsible for the disease was reported as D. pini. In December 2011, needles were collected from three trees in Lagada, Thessaloniki regional unit of Central Macedonia (northern Greece), where the disease was first recorded. DNB infection seems to be limited to a valley in this area in Pinus nigra and P. brutia plantations established more than 50 years ago in an originally deciduous oak forest. Infections were observed over an area of 50 to 60 ha of pine plantations. Although the majority of pine trees were infected by the pathogen, the severity of the disease was relatively low and mortality of infected trees was not observed. Infections were limited to the lower branches in the 50-year-old trees, while on a limited number of younger trees of P. brutia (10 to 15 years old), infection was more severe, extending to the entire crowns of the trees. DNB does not appear to be very common in Greece. Infected needles had reddish-brown bands, usually with necrotic tips or entirely necrotic needles. Black sub-epidermal fruiting bodies (acervuli) were observed with the needle epidermis split and raised. Isolations were made from fruiting structures on needles of P. nigra and P. brutia (50-year-old trees) and P. brutia (10-year-old trees) after surface disinfection with 70% ethanol. Conidia from single fruiting bodies were transferred onto 3% malt extract agar (MEA) in petri dishes and incubated at 20°C. Colonies on MEA had a radial growth rate of 1.3 to 1.6 mm per week, were crustose, brown to grey-brown, and partly covered with slimy masses of conidia. The agar surrounding the colonies had a reddish color. Conidia from acervuli on the needles and the cultures were similar in shape and size, filiform, hyaline, 2 to 4 septate, and 1.8 to 2.5 (3.3) × 22 to 47 μm long. DNA was extracted from three cultures: one from P. nigra (CMW 37966) and two from P. brutia (CMW 37965, CMW 37967) using a standard phenol/chloroform method. The internal transcribed spacer (ITS) region was amplified and sequenced (1). Sequences were 100% identical to D. septosporum isolates in GenBank (e.g., AY808291). In addition, up to 12 randomly selected acervuli were excised directly from the needles of each of the three trees and DNA was extracted using PrepMan solution (Applied Biosystems). The mating types of these samples were determined using species-specific mating type primers for D. pini and D. septosporum (2). All acervuli were confirmed to be those of D. septosporum. Both mating types were found on needles from P. brutia and P. nigra. However, the teleomorph of D. septosporum was not detected on infected needles.

SEVERE DENTAL FLUOROSIS IN JUVENILE DEER LINKED TO A RECENT VOLCANIC ERUPTION IN PATAGONIA

The Puyehue-Cordon Caulle volcanic eruption deposited large amounts of tephra (ashes) on about 36 million ha of Argentina in June of 2011. Tephra was considered chemically innoxious based on water leachates, surface water fluoride levels were determined to be safe, and livestock losses were attributable to inanition and excessive tooth wear. To evaluate effects on wild ungulates, we sampled wild red deer (Cervus elaphus) at 100 km from the volcano in September-November 2012. We show that tephra caused severe dental fluorosis, with bone fluoride levels up to 5,175 ppm. Among subadults, tephra caused pathologic development of newly emerging teeth typical of fluorosis, including enamel hypoplasia, breakages, pitting, mottling, and extremely rapid ablation of entire crowns down to underlying pulp cavities. The loss of teeth functionality affected physical condition, and none of the subadults was able to conceive. Susceptibility to fluorosis among these herbivores likely resides in ruminant food processing: 1) mastication and tephra size reduction, 2) thorough and repeated mixing with alkaline saliva, 3) water-soluble extraction in the rumen, and 4) extraction in the acidic abomasum. Although initial analyses of water and tephra were interpreted not to present a concern, ruminants as a major component of this ecosystem are shown to be highly susceptible to fluorosis, with average bone level increasing over 38-fold during the first 15.5 mo of exposure to tephra. This is the first report of fluorosis in wild ungulates from a volcanic eruption. The described impact will reverberate through several aspects of the ecology of the deer, including effects on population dynamics, morbidity, predation susceptibility, and other components of the ecosystem such as scavenger and plant communities. We anticipate further impact on livestock production systems, yet until now, existence of fluorosis had not been recognized.

Paleoecology of echinoderm assemblages from the Upper Ordovician (Katian) Dunleith Formation of northern Iowa and southern Minnesota

The Dunleith Formation echinoderms lived on a shallow water carbonate platform (Benthic Assemblages outer 2 and 3 during the latter part of the Dunleith Regressive Cycle). The echinoderms were buried rapidly by storms or a volcanic ash bed in one example. The presence of complete specimens, entire crowns, attachment structures, and excellent preservation strongly suggests that these assemblages reflect in situ communities on the seafloor that have not been significantly mixed, transported, or concentrated in time. Most taxa are suspension feeders, namely 21 crinoids, one glyptocystitid rhombiferan, a paracrinoid, and two edrioasteroids, but a deposit feeding pleurocystitid rhombiferan is also common. Three assemblages are recognized and defined by their dominant taxa; in order of increasing depth, these are theCotylacrinna sandra,Pleurocystites strimplei, andCupulocrinus crossmaniassemblages. Substrates ranged from hard- or firm-ground carbonates to soft carbonate and siliciclastic muds. Diverse attachment structures are recognized: the recumbent stems of calceocrinids, lichenocrinids on shells, small distal stem tips, and round to lobate calcite pads cemented to shells or the substrate, open distal stem coils directly on the seabed or coiled around soft objects thereon, and large conical and highly modified cirrus holdfasts on hard- or firm-grounds. The echinoderms were located at levels ranging from the seafloor to almost a meter above, with maximum diversity at about 50 mm above the seafloor. The size frequency distributions of food particles and the ranges of ambient current velocities for successful feeding by the juveniles and adults of the common crinoids are modeled using filtration theory. The food particle size distributions and the current velocities for feeding are correlated with the arm or filtration fan morphology of the crinoids. Differences between these parameters tend to partially separate the feeding ecologies of species located at the same elevation. Nevertheless, considerable overlap remains between species for small sized food particles and the lower ranges of ambient current velocities for feeding. Except for theCotylacrinna sandraAssemblage, competition for space does not seem to have been important in regulating the ecological structure of the Dunleith crinoids. However, the deposit feeding pleurocystitids possibly competed for food and space in one example. The Dunleith assemblages are much more diverse with greater ecological complexity than seen in the relatively deep water fauna from the Upper Ordovician Trenton Group of the Walcott-Rust Quarry in New York (Benthic Assemblage 5).

The response of vertical foliage distribution to spacing and species composition in mixed conifer stands in central Oregon

The effects of initial spacing and species composition on vertical foliage distribution were tested in two mixed-species spacing trials in central Oregon. Relative and absolute foliage distributions on individual trees were estimated by building branch-level leaf area models for grand fir ( Abies grandis (Dougl. ex D. Don) Lindl.), lodgepole pine ( Pinus contorta Dougl. ex Loud.), and ponderosa pine ( Pinusponderosa Dougl. ex Laws.) and then estimating foliage distribution for entire crowns. Branch leaf area declined at the base of the live crown in all tree species, reinforcing the importance of accounting for branch position within the crown. Tree-level foliage distributions responded to differences in stand structure imposed by initial spacing and species composition. Foliage distribution also differed by tree social position within the stand. The effect of species composition and tree social position diminished with increasing spacing. Species with differing levels of shade tolerance can be quite plastic in the amount and vertical distribution of foliage in response to stand structure.

La sylviculture favorable au chêne, facteur majeur de la progression du Pic mar Dendrocopos medius en Suisse: Exemple du Bois du Devens (canton de Neuchâtel) | Silviculture that favours oak as a major factor in the expansion of the middle-spotted-woodpecker in Switzerland. Example of Bois du Devens (Canton Neuchâtel)

The middle-spotted-woodpecker Dendrocopos medius, which was deemed to have disappeared from the littoral of Neuchâtel,is a species in full expansion today, particularly in the Bois du Devens (MULHAUSER & BLANT en prép.). Without differentiated silvicultural interventions-i.e. differentiated according to area-today this region would be dominated largely by the beech. The article presents the evolution of the forest Bois du Devens, the development of silvicultural practice during the 20th century and its effect on the expansion of the middlespotted-woodpecker. The analysis of the silviculture practised in this forest since 1920, fleshed out with the numerical basis of the silvicultural inventories, provides confirmation of the dependence of the middle-spotted-woodpecker on oaks of major dimensions, with a preference for highly fertile habitats and underlines the importance of mature forest stands. Such heterogeneous stands are rich in microstructures, cavity trees,big trees, trees that accomplish their full life cycle, as well as entire crowns that are left on the ground after trees have been cut.

Ethanol in ponderosa pine as an indicator of physiological injury from fire and its relationship to secondary beetles

Sixteen days after a September wildfire, ethanol and water were measured in phloem and sapwood at breast height and the base of Pinus ponderosa Dougl. ex P. & C. Laws. with zero (control), moderate, heavy, and severe crown scorch. The quantity of ethanol increased with each level of injury, resulting in trees with severe scorch containing 15 and 53 times more phloem and sapwood ethanol, respectively, than controls. Ethanol concentrations in the sapwood and adjacent phloem were related, probably as a result of diffusion. Upward movement in xylem sap was most likely responsible for the relationship between sapwood ethanol concentrations at breast height and the stem base. As trees recovered from their heat injuries, the ethanol concentrations declined. In contrast, ethanol accumulated in dead trees that lost their entire crowns in the fire. Various bark and xylophagous beetles landed in greater numbers on fire-damaged trees than on controls the following spring and summer, suggesting that ethanol was being released to the atmosphere and influencing beetle behavior. Beetle landing was more strongly related to sapwood ethanol concentrations the previous September than in May. Sapwood ethanol measured 16 days after the fire was the best predictor of second-year mortality for trees with heavy and severe crown scorch.

Dieback of Acacia koa in Hawaii: ecological and pathological characteristics of affected stands

Koa ( Acacia koa) is an endemic Hawaiian tree that serves as a keystone species in the upper elevation forests of all the main islands. In the Mauna Loa Strip area of Hawaii Volcanoes National Park, mature koa stands are suffering from an unexplained dieback that has increased in severity since it was first noticed approximately 25 years ago. The dieback is often evident in patches, and generally spreads within stands in a radial fashion from a localized infection center. Entire crowns of affected trees become wilted, with foliage gradually progressing from an apparent healthy to a completely chlorotic condition. Although most trees die soon after the onset of symptoms, some trees are able to survive crown death by producing epicormic shoots on the lower portions of the trunk. Previously published studies reported that a vascular wilt fungus ( Fusarium oxysporum f. sp. koae) was associated with koa seeds and the rhizosphere of healthy and dieback-affected koa stands. The purpose of this study was to characterize the stand structure, soil conditions, and physiological condition of dieback-affected trees, and to assess the possible role of F. oxysporum f. sp. koae in the current dieback stands. This fungus was isolated from branches of symptomatic koa in dieback-affected stands and roots from healthy and dieback-affected stands. Possible differences in the pathogenicity and virulence of F. oxysporum f. sp. koae isolates obtained from the roots of healthy koa in unaffected stands and those from branches of dieback-affected koa were determined by greenhouse inoculations of koa seedlings. Healthy koa saplings in stands unaffected by dieback were also inoculated to determine if disease symptoms could be induced by inoculation of injured roots in the field. Both branch and root isolates were pathogenic; with the percent mortality of inoculated seedlings ranging from 30 to 60% for all isolates. Disease severity between branch and root isolates was not significantly different. Wilt symptoms were not observed in field inoculations of koa saplings after 8 months. Investigation of the dieback stand structure determined that the larger size classes (i.e., DBH>3 cm ) were all affected equally, with the smallest size class (i.e., 0–3 cm DBH) having the lowest percentage of dieback at each site. Soil from dieback stands had higher water content and was more acidic than that from neighboring unaffected stands. Phyllodes on epicormic shoots of dieback trees had a reduced area, mass, and mass to area ratio. Phyllodes on dieback trees also had reduced stomatal conductance and higher (less negative) leaf water potential. Results from the greenhouse inoculations demonstrated that F. oxysporum f. sp. koae is pathogenic to koa, but the pathogen’s activity in the field may be influenced by predisposing factors such as temperature fluctuations, water availability, soil type, and interactions with other soil organisms. F. oxysporum f. sp. koae appears to play an important role in regulating koa stand dynamics, growth, and physiology under environmental and edaphic conditions favorable for disease development.