bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Infection of Mother and Runner Plant Generations by Verticillium dahliae in a High Elevation Strawberry Nursery
Authors: Gordon Thomas R. , Kirkpatrick Sharon C. , Shaw Douglas V. , Larson Kirk D.
Published: February 2019

Strawberry cultivars Selva and Camarosa (Fragaria ×ananassa Duch.) were grown at a high elevation nursery in soil that was either naturally infested with Verticillium dahliae or was rendered pathogen-free through preplant fumigation with 2 methyl bromide: 1 chloropicrin (wt/wt) at 392 kg·ha-1. Plants grown in fumigated soil were inoculated with a conidial suspension of V. dahliae, prior to establishment. Just prior to harvest, plants were rated for disease based on symptoms of Verticillium wilt. At the same time, petiole samples were taken from mother plants and each of three generations of runner plants, along with the stolons subtending each of the sampled runner plants. Petioles and stolons were cultured to assay for the presence of V. dahliae, and scored as either infected or not infected. The experiment was conducted in each of two successive years, and the following conclusions were supported by results obtained in both years. First, symptoms of Verticillium wilt on mother plants of both cultivars were highly correlated with recovery of V. dahliae from petioles, but runner plants were consistently free of symptoms even though they were often infected. Second, runner plants sustained lower infection frequencies than mother plants, with the differences being significant in most cases. Lastly, infection of runner plants was due, at least in part, to transfer of inoculum from infected mother plants; in some cases this appears to have been the exclusive mode of infection.
Field Performance of Guardian™ Peach Rootstock Selections
Authors: Wilkins B.S. , Ebel R.C. , Dozier W.A. , Pitts J. , Eakes D.J. , Himelrick D.G. , Beckman T. , Nyczepir A.P.
Published: February 2019

Twelve peach [Prunus persica (L.) Batsch] seedling rootstocks [Lovell, Nemaguard, Flordaguard, 14DR51, five Guardian™ (BY520-9) selections, and three BY520-8 selections] budded with `Cresthaven' were planted in 1994 and evaluated through 2000 to determine performance under commercial management practices. Mesocriconema xenoplax population densities were above the South Carolina nematicide treatment threshold of 50 nematodes/100 cm3 of soil after 1996. However, symptoms of peach tree short life (PTSL) were not observed. Tree mortality was less than 14% through 1999, with most of the dead trees exhibiting symptoms consistent with Armillaria root rot. About 13% of the surviving trees in 1999 were removed in 2000 due to symptoms of phony peach. There were no differences in tree mortality among rootstocks. Tree growth, photosynthesis, and suckering varied among rootstocks, but leaf conductance, internal CO2, and leaf transpiration did not. Foliar calcium, magnesium, iron, and phosphorus varied among rootstocks, but all were within the range considered sufficient for peach trees. Fruit yield varied among rootstocks, but yield efficiency did not, indicating that higher yield corresponded with larger trees. Bloom date did not vary among rootstocks, but harvest date was advanced as much as 2 days for some rootstocks, compared to Lovell. Fruit weight varied among rootstocks but skin color, flesh firmness, and soluble solids content were similar. All rootstocks performed satisfactorily for commercial peach production.
Presidedress Soil Nitrate Testing Reduces Nitrogen Fertilizer Use and Nitrate Leaching Hazard in Lettuce Production
Authors: Breschini S.J. , Hartz T.K.
Published: February 2019

Trials were conducted in 15 commercial fields in the central coast region of California in 1999 and 2000 to evaluate the use of presidedress soil nitrate testing (PSNT) to determine sidedress N requirements for production of iceberg and romaine lettuce (Lactuca sativa L.). In each field a large plot (0.2-1.2 ha) was established in which sidedress N application was based on presidedress soil NO3-N concentration. Prior to each sidedress N application scheduled by the cooperating growers, a composite soil sample (top 30 cm) was collected and analyzed for NO3-N. No fertilizer was applied in the PSNT plot at that sidedressing if NO3-N was >20 mg·kg-1; if NO3-N was lower than that threshold, only enough N was applied to increase soil available N to ≈20 mg·kg-1. The productivity and N status of PSNT plots were compared to adjacent plots receiving the growers' standard N fertilization. Cooperating growers applied a seasonal average of 257 kg·ha-1 N, including one to three sidedressings containing 194 kg·ha-1 N. Sidedressing based on PSNT decreased total seasonal and sidedress N application by an average of 43% and 57%, respectively. The majority of the N savings achieved with PSNT occurred at the first sidedressing. There was no significant difference between PSNT and grower N management across fields in lettuce yield or postharvest quality, and only small differences in crop N uptake. At harvest, PSNT plots had on average 8 mg·kg-1 lower residual NO3-N in the top 90 cm of soil than the grower fertilization rate plots, indicating a substantial reduction in subsequent NO3-N leaching hazard. We conclude that PSNT is a reliable management tool that can substantially reduce unnecessary N fertilization in lettuce production.
Aminoethoxyvinylglycine Treatment of Peach Fruit Reduces Ethylene Production and Softening
Authors: Belding Robert D. , Lokaj Gail R.W.
Published: February 2019

`Biscoe' and `Encore' peach [Prunus persica (L.) Batsch] trees were treated in two years with AVG at 7, 14, or 21 days before first harvest (DBFH) or as a nontreated control (NTC). Fruit were harvested every 2 to 3 days based on observed initial yielding of fruit flesh and ground color. Fruit were further evaluated for maturity and quality based on the production of ethylene, ground color, diameter, flesh firmness, soluble sugars, and woolliness. Evaluations occurred 1 day after harvest and after 14 and 28 days in cold storage. AVG applications delayed early harvests of `Biscoe', but `Encore' harvests were not affected. Across all preharvest treatment timings, AVG reduced ethylene production by 64%. Ethylene production and fruit softening were most inhibited for fruit treated with AVG 7 DBFH. In this study, fruit treated with AVG demonstrated a significant negative correlation between fruit ethylene production and firmness. Average flesh firmness of fruit from AVG treatments were 11.8 Newtons greater than NTC fruit. Fruit treated 21 or 14 DBFH exhibited greener ground color than NTC fruit or fruit treated 7 DBFH. The NTC fruit had the highest ground color values, fruit treated 7 DBFH were intermediate, and fruit treated 21 or 14 DBFH had the lowest values for ground color. AVG has potential use as a management tool for controlling the timing of harvest and for allowing fruit to ripen more slowly and to hang longer on the tree, thus improving fruit size. In addition, AVG assists in maintaining the postharvest flesh firmness required to withstand handling during marketing. Chemical name used: aminoethoxyvinylglycine (AVG).
1-MCP Improves Storability of 'Queen Cox' and 'Bramley' Apple Fruit
Authors: Dauny Paul T. , Joyce Daryl C.
Published: February 2019

Better maintenance of firmness and suppression of ethylene production in 'Queen Cox' and 'Bramley' apple [Malus ×sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] fruit was achieved by prestorage applications of 1-MCP. 1-MCP concentration, exposure time and exposure temperature ranges of 0.1 to 10.0 μL·L-1 1-MCP, 6 to 48 h, and 0 to 20 °C, respectively, were effective on fruit subsequently stored for 2 ('Cox') and 3 ('Bramley') months in air at 3 to 4 °C. However, 1-MCP had little effect on either firmness or ethylene production after 4 ('Cox') or 6 ('Bramley') months storage. Nonetheless, 1-MCP treated 'Bramley' fruit had reduced rot and superficial scald incidences compared with untreated control fruit. Chemical name used: 1-methylcyclopropene (1-MCP).
How Application Times of 2,4-DP Influence the Ripening Capacity of `La France' Pears
Authors: Kondo Satoru , Settsu Kazuhiro , Jitratham Anan
Published: February 2019

The effective applications of synthetic auxin 2,4-DP on fruit ripening of `La France' pears (Pyrus communis L.) were examined. A solution of 90 μL·L-1 2, 4-DP was applied to fruit and leaves around the fruit as follows: Early 1 = 140 days after full bloom (DAFB); Early 2 = 140 and 150 DAFB; Late 1 = 150 DAFB; and Late 2 = 150 and 160 DAFB. The effects were compared with nontreated fruit. Internal ethylene concentrations increased earliest and rapidly in Early 2 followed by Early 1. Fruit firmness decreased earliest in Early 2 and Early 1. Water-soluble polyuronide (WSP) concentrations in Early 2 were higher than other treatments, but hexametaphosphate-soluble polyuronide (HMP) and cellulose concentrations were lower. At 200 DAFB, 40% of fruit in Early 2 reached edible condition on the tree. In addition, the fruit in Early 2 required shorter periods of time to reach edible condition in a controlled room at 20 °C after harvest of 170, 180, 190, and 200 DAFB. These results show that two 2,4-DP applications at 140 and 150 DAFB may be effective in inducing the ripening capacity of `La France' pears on the tree. Chemical name used: 2-(2,4-dichlorophenoxy)-propionic acid (2,4-DP).
Nondestructive Acoustic Firmness Tester Detects the Effect of Manure on Muskmelon Texture
Authors: Al-Haq Muhammad Imran , Sugiyama Junichi , Tomizawa Akiko , Sagara Yasuyuki
Published: February 2019

The effect of amount of manure (animal dung) on the texture of muskmelons (Cucumis melo L.) has been studied. Melons were grown in a greenhouse with 20 and 50 t·ha-1 of manure. Melons were harvested four times at 4-day intervals and kept at ambient conditions for about 8-12 days. Texture was determined by using “Firm Tester” that employs acoustic technology and to provide a firmness index expressed as transmission velocity [meters per second (m/s)]. At the time of the first, second, third and fourth harvest the fruit grown with 20 t·ha-1 manure gave mean transmission velocities of 54.5 ± 2.5, 55.2 ± 5.7, 49.6 ± 4.8, and 46.8 ± 9.4 m/s, respectively. Linear regression equations for fruit grown with 20 t·ha-1 manure showed that the fruit from the first harvest took 10 days to reach 40 m/s, while fruit from the second, third and fourth harvest took 11, 9.5, and 4 days, respectively, to reach this index. The corresponding values for fruit grown in 50 t·ha-1 of manure were 7.5, 10, 5.5 and 4.5 days, those from the second harvest gave the best keeping quality. The firmness index of melon grown in 20 t·ha-1 of manure was greater than that grown in 50 t·ha-1 manure. Higher soil NO3-N contents were associated with softer melons. The correlation between panelist scores for texture and the firmness index was 0.907. Both °Brix and panelist scores for sweetness indicated that manure did not affect the sweetness of melon. The digital firmness tester could detect the effect of manure on the texture of the melons, and could be used to determine the appropriate time of harvest for each and every individual melon.
Field and Detached-fruit Screening Tests for Resistance to Belly Rot in Cucumber
Authors: Wehner Todd C. , Shetty Nischit V. , Sloane Joseph T.
Published: February 2019

Field and detached-fruit screening tests were developed for evaluating cucumber (Cucumis sativus L.) plant introduction accessions, breeding lines, and cultivars (hereafter collectively referred to as cultigens) for resistance to fruit rot caused by Rhizoctonia solani Kuhn. The factors that were examined for developing a detached-fruit test were five inoculum levels of R. solani AG-4 and two cover treatments. The major influence on disease reaction was inoculum level. The best method used 50-mm-diameter fruit placed on sterile soil inoculated with 6400 oat grains/m2 colonized with R. solani and watered initially, then misted every 3 days for 1 minute, left uncovered, and rated after 10 days for the percentage of the fruit surface covered with lesions. Field and detached-fruit tests were conducted using two different inoculum levels of R. solani (3200 and 4800 oat grains/m2). The four most resistant cultigens, based on the results of field and detached-fruit tests, were PI 163216, PI 197088, PI 357852, and PI 280096. One field and detached-fruit test pair was not significantly correlated (detached-fruit screening test one vs. field screening test one), but the other (detached-fruit test two vs. field screening test two) was correlated (r = 0.50). The detached-fruit test could be used for general classification of resistance or susceptibility. Resistant cultigens could be identified with either method, but the field test had slightly lower coefficients of variation.
Cucumber Germplasm Resistant to Cladosporium cucumerinum
Authors: Park Young Hoon , Havey Michael. J.
Published: February 2019

Scab (caused by Cladosporium cucumerinum Ell. & Arth.) is an important disease of cucumber (Cucumis sativus L.), and the only source of resistance traces back to the cultivar Maine No. 2. We inoculated hypocotyls of 188 cucumber accessions with one strain of the scab fungus to identify other sources of scab resistance. Accessions NSL5731, 255933, 264666, 264667, 306785, 342951, 354952, 458845, and 535881 showed no symptoms. Plants in accession 525075 showed a continuous phenotypic distribution for reaction to scab; all other accessions were susceptible.
Simultaneous Isolation of Tonoplast and Plasmalemma from Citrus Juice Cells: Combination of Sucrose Gradient and Two Phase Partitioning
Authors: Etxeberria Ed , Gonzalez Pedro
Published: February 2019

By combining the principles of density gradient separation and two phase partitioning, we devised a system to obtain highly pure plasmalemma and tonoplast vesicles from citrus (Citrus limettioides Tan.) juice cells. Both tonoplast and plasmalemma fractions were virtually free from golgi, endoplasmic reticulum and mitochondria contamination. Plasmalemma and tonoplast samples were also clean from each other cross-contaminants. Immediately after isolation, 72% of the plasmalemma and 82% of the tonoplast vesicles were oriented rightside-out according to enzyme marker activities. After freezing and thawing, however, plasmalemma vesicles re-oriented evenly but orientation of tonoplast vesicles remained unchanged. Differential changes in marker activities before and after freezing and thawing indicated that the low levels of plasmalemma contamination within the tonoplast fractions were due to the presence of a separate population of plasmalemma vesicles and not to the existence of hybrid vesicles. The method described in this communication allows for future studies on photoassimilate accumulation in cells of important horticultural storage organs.
Mouse-ear of Pecan: I. Symptomatology and Occurrence
Authors: Wood Bruce W. , Reilly Charles C. , Nyczepir Andrew P.
Published: February 2019

Mouse-ear (ME) is a potentially severe anomalous growth disorder affecting young pecan [Carya illinoinensis (Wangenh.) K. Koch] trees in portions of the Gulf Coast Coastal Plain of the southeastern United States. A survey of its incidence and severity found it to be commonly exhibited by replants on second-generation orchard sites, or where mature pecan trees previously grew. While most frequently observed as a replant problem, it also occasionally occurs at sites where pecan has not previously grown. The disorder is not graft transmissible and is only temporarily mitigated by pruning. Degree of severity within the tree canopy typically increases with canopy height. Several morphological and physiological symptoms for mouse-ear are described. Important symptoms include dwarfing of tree organs, poorly developed root system, rosetting, delayed bud-break, loss of apical dominance, reduced photoassimilation, nutrient element imbalance in foliage, and increased water stress. The overall symptomatology is consistent with a physiological deficiency of a key micronutrient at budbreak, that is influenced by biotic (e.g., nematodes) and abiotic (e.g., water and fertility management strategies) factors. A comparison of orchard soil characteristics between ME and adjacent normal orchards indicated that severely affected orchards typically possessed high amounts of soil Zn, Ca, Mg, and P, but low Cu and Ni; and were acidic and sandy in texture. The Zn: Cu ratio of soils appears to be a major factor contributing to symptoms, especially since ME severity increases as the Zn: Cu ratio increases. However, Ni may also be a factor as the Zn: Ni ratio is also larger in soils of ME sites. It is postulated that the “severe” form of mouse-ear is primarily due to the physiological deficiency of copper at budbreak, but may also be influenced by Ni and nematodes.
Mouse-ear of Pecan: II. Influence of Nutrient Applications
Authors: Wood Bruce W. , Reilly Charles C. , Nyczepir Andrew P.
Published: February 2019

Mouse-ear (ME) is a severe growth disorder affecting pecan [Carya illinoinensis (Wangenh.) K. Koch] trees from southeastern U.S. Gulf Coast Coastal Plain orchards. Slight to moderate ME was substantially corrected by foliar sprays of either Cu or GA3 shortly after budbreak, but sprays were ineffective for severely mouse-eared trees. Applications of Cu, S, and P to the soil surface of moderately affected trees corrected deficiencies after three years. Incorporation of Cu or P in backfill soils of newly planted trees prevented ME, whereas incorporation of Zn or Ca induced ME and Mn was benign. The severe form of ME, commonly exhibited by young trees, appears to be linked to a physiological deficiency of Cu and/or Ni at the time of budbreak. It likely occurs as a replant problem in second-generation orchards due to accumulation of soil Zn from decades of foliar Zn applications to correct Zn deficiency.
Root and Shoot Growth Periodicity of Kalmia latifolia `Sarah' and Ilex crenata `Compacta'
Authors: Wright Amy N. , Warren Stuart L. , Blazich Frank A. , Blum Udo
Published: February 2019

The length of time between transplanting and subsequent new root initiation, root growth rates, and root growth periodicity influences the ability of woody ornamentals to survive transplanting and become established in the landscape. Research was conducted to compare root growth of a difficult-to-transplant species, Kalmia latifolia L. (mountain laurel), to that of an easy-to-transplant species, Ilex crenata Thunb. (Japanese holly), over the course of 1 year. Micropropagated liners of `Sarah' mountain laurel and rooted stem cuttings of `Compacta' holly were potted in 3-L containers. Plants were grown in a greenhouse from May to September, at which time they were moved outside to a gravel pad, where they remained until the following May. Destructive plant harvests were conducted every 2 to 4 weeks for 1 year. At each harvest, leaf area, shoot dry weight (stems and leaves), root length, root area, and root dry weight were determined. Throughout the experiment, shoot dry weight and leaf area were similar for the two species. New root growth of `Compacta' holly and `Sarah' mountain laurel was measurable 15 and 30 days after potting, respectively. Root length and root area of `Sarah' mountain laurel increased during May through December but decreased during January through May. Root length and root area of `Compacta' holly increased linearly throughout the course of the experiment. Final root: shoot ratio of `Sarah' mountain laurel was one-ninth that of `Compacta' holly. Results suggest that poor transplant performance of mountain laurel in the landscape may be related to its slow rate of root growth.
Effects of Media Porosity and Container Size on Overwintering and Growth of Ornamental Grasses
Authors: Meyer Mary Hockenberry , Cunliffe Bruce A.
Published: February 2019

Five ornamental grasses {little bluestem [Schizachyrium scoparium (Michx.) Nash], prairie dropseed [Sporobolus heterolepis (A. Gray) A. Gray], feather reedgrass [Calamagrostis ×acutiflora(Schrad.) DC. `Karl Foerster'], flamegrass (Miscanthus Anderss. `Purpurascens'), and variegated Japanese silvergrass (Miscanthus sinensisAnderss. `Variegatus')} were propagated by transplanting plugs or field divisions into 480-mL (10-cm round), 2.7-L (no. 1), and 6.2-L (no. 2) nursery containers with media ratios (v/v) of 0:1, 1:1, 2:1, 3:1, 1:0 rice hulls to sand, resulting in aeration porosities in 2.7-L containers of 5%, 12%, 22%, 28%, and 41%, respectively. Planting dates were between 28 Oct and 10 Nov. 1997; 30 Apr. and 7 May 1998; and 23-28 Oct. 1998 and 1-10 May 1999. Plants were covered with plastic and straw from the second week in November until the second week in April. Winter survival was evaluated 6 weeks after uncovering and for finished dates every 2 weeks thereafter. Species had a significant effect on overwintering survival, but container size and media did not. Sporobolus heterolepis and M. sinensis `Variegatus' had significantly lower overwintering survival than the other species. Container size significantly influenced growth; the 6.2-L containers had the highest values for all growth parameters. Growth response to media was a weak (nonsignificant) quadratic response, indicating for these species no clear trend for the best media aeration porosity.
Tolerance of Carrot to Low-rate Preemergent and Postemergent Herbicides
Authors: Ogbuchiekwe Edmund J. , McGiffen Milton E. , Nunez Joe , Fennimore Steven A.
Published: February 2019

Preemergent and postemergent herbicides were evaluated in the Mediterranean climate of the southern San Joaquin Valley and the desert climate of the Imperial Valley from 1998 through 2000. Sixteen herbicide treatments were applied both as preemergence (PRE) and postemergence (POST) applications to carrot (Daucus carota L.). Carrot was generally more tolerant to PRE herbicide applications than to POST applications. Carrot was tolerant to PRE and POST imazamox and triflusulfuron at both locations. Carrot root losses due to herbicide were consistent with visual ratings. Treatments that injured carrot tops early in the growing season did not always reduce yield at the end of the season. PRE applications of imazamox and triflusulfuron did not affect carrot tops or the number or weight of marketable carrots. Carrots grown in the Imperial Valley and in the San Joaquin Valley were tolerant to PRE applications of carfentrazone, sulfentrazone, and imazamox. Results were similar for POST applications, although carfentrazone slightly injured carrot roots. PRE application of herbicides increased forked roots more than POST. Chemical names used: α, 2-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1, 2,4-triazol-1-yl]-4-fluorobenzenepropanoic acid (carfentrazone); N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]me thanesulfonamide (sulfentrazone); N-(2 carbomethoxy-6-chlorophenyl)-5-ethoxy-7-fluoro (1,2,4) triazolo-[1, 5-c] pyrimidine-2-sulfonamide (cloransulam-methyl); 2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethyl-thein-3-yl)-acetamide (dimethenamid); (2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-(methoxymethyl)-3-pyridinecarboxylic acid) (imazamox); 3-chloro-5-[[[[(4,6-dimethoxy-2-pyrimidinyl) amino] carbonyl] amino] sulfonyl]-1-methyl-1H-pyrazole-4-carboxylic acid (halosulfuron); N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyridinesulfonamide (rimsulfuron); (methyl 2[[[[[4-(dimethylamino)-6-[2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl] amino] carbonyl] amino] sulfonyl]-3-methylbenzoate) (triflusulfuron).
Overcoming Dormancy of Mayapple Rhizome Segments with Low Temperature Exposure
Authors: Maqbool Muhammad , Cushman Kent E. , Moraes Rita M. , Gerard Patrick D.
Published: February 2019

American mayapple (Podophyllum peltatum L.) is a rhizomatous, herbaceous perennial found in wooded areas of eastern North America and is a source of the pharmaceutical compound podophyllotoxin. This research was conducted to determine the optimum duration of low temperature exposure in overcoming dormancy of fall-harvested rhizome segments for subsequent use as propagules in greenhouse plantings. Two types of rhizome segments were harvested from the wild and used in this study: two-node rhizome segments consisting of a terminal node and its adjacent one-year-old node and one-node rhizome segments consisting of a single node, other than a terminal node, of unknown age or rhizome position. For growth cycle I, rhizome segments were exposed to low temperature (≈4 °C) for 30, 45, 60, 75, or 90 days, planted in pots, and grown in a greenhouse set at 21 °C. Shoot emergence, shoots per pot, and plant height were recorded. Leaves were removed from plants when senescence first became evident, and leaf area was recorded. For growth cycle II, rhizome segments remained undisturbed in the original pots and were exposed to low temperatures (≈4 °C) for 90 days. Pots were again placed in the greenhouse and shoot emergence, shoots per pot, plant height, and leaf area were recorded. Increasing duration of low temperature exposure of rhizome segments up to 75 days appeared to increase percent emergence and plant height and decrease days to emergence, though changes in greenhouse conditions over the study period may have also influenced shoot emergence and plant growth. Two-node rhizome segments exhibited higher percent shoot emergence, shoot longevity, leaf area, and plant height than single-node segments during each growth cycle. Two-node rhizome segments also exhibited fewer days to emergence during growth cycle I. Rhizome segments produced no more than a single shoot in growth cycle I, whereas more than one shoot was produced in growth cycle II. Most of the effects of low temperature exposure during growth cycle I persisted throughout growth cycle II. These results indicate that dormancy of mayapple rhizomes can be overcome with low temperature exposure and shoots can be induced to grow at any time of year.
Improved Rooting of Peach Rootstock GF677 Hardwood Stem Cuttings Through Cultural Practices
Authors: Tsipouridis C. , Thomidis T.
Published: February 2019

The effect of cutting length, planting depth, irrigation of cuttings, soil compaction following frost, and prior blanching on rooting of `GF677' hardwood stem cuttings stuck directly into a nursery row was studied. The results showed that cuttings cut to 30 cm lengths rooted best of all length treatments tested. Cuttings planted so that the shoot tips were level with the soil surface (0-cm-deep treatment) rooted with significantly higher percentages than did the other planting depths. Irrigation, applied immediately after planting cuttings into a nursery row, had a negative effect on rooting. Cuttings that were loosened from the soil as a result of frost heaving rooted better when pushed back into the soil than did the controls. Finally, cuttings made from shoots that were treated by wrapping the base in red or black tape rooted better than the unwrapped controls.
Chromosome Karyotypes of Echinacea angustifolia var. angustifolia and E. purpurea
Authors: Qu Luping , Wang Xiping , Hood Eatherley , Wang Meihua , Scalzo Richard
Published: February 2019

Chromosome karyotypes of the most commonly cultivated and medicinally used Echinacea taxa, E. angustifolia DC. var. angustifolia and E. purpurea (L.) Moench., were analyzed. The chromosomes of both taxa are medium in length, ranging from 4.12 to 5.83 μm in E. angustifolia var. angustifolia and 3.99 to 6.08 μm in E. purpurea. No abrupt length changes in the chromosomes were noted. The karyotypes of the two species are generally similar, but a distinguishable feature exists in one pair of chromosomes. The centromere of chromosome pair 10 is subterminally located in E. purpurea, but terminally located in E. angustifolia var. angustifolia, which can be readily recognized in mitotic metaphase cell plates. This finding may provide useful information for Echinacea evolutionary, genetic, and breeding studies.
Soil Gas, Temperature, Matric Potential, and Creeping Bentgrass Growth Response to Subsurface Air Movement on a Sand-based Golf Green
Authors: Bunnell B. Todd , McCarty Lambert B. , Hill Hoke S.
Published: February 2019

Creeping bentgrass (Agrostis palustris Huds.) is used on putting greens for its fine-leaf texture, consistent speed, smooth ball roll, and year-round color. In recent years bentgrass use has extended into the warmer climates of the southern United States. Being a C3 plant, bentgrass is not well adapted to extended hot and humid environmental conditions. Subsurface air movement systems are now commercially available that can transport air through the root zone to alter soil conditions and potentially improve bentgrass survival. This research investigated the effects of subsurface air movement on the composition of soil gases, matric potential, temperature, and growth response of a sand-based creeping bentgrass golf green. Treatments included: air movement direction (evacuate, inject, and no air) and duration of air movement (0400-0600 hr, 1000-1800 hr, and 24 hours). Treatment combinations were imposed for 13 days. Subsurface air movement reduced CO2 at the 9-cm depth to values <0.0033 mol·mol-1 when evacuating or injecting air, depending upon duration. Soil matric potentials at a 9-cm depth were decreased by a maximum of 96% when evacuating air for 24-hour duration compared to no-air plots. Soil temperatures at 9 cm were decreased ≈1 to 1.5 °C when injecting air from 1000 to 1800 hr and 24-hour treatments and increased ≈0.75 °C when evacuating air from 1000 to 1800 hr. Subsurface air movement did not improve creeping bentgrass turf quality or rooting. Although not effective in improving the growth response of creeping bentgrass, subsurface air movement may be a useful tool to improve soil gas composition, reduce excess soil moisture, and potentially reduce soil temperature(s) of heat-stressed creeping bentgrass golf greens.
Effect of Salinity on Bermudagrass Cold Hardiness
Authors: Munshaw G.C. , Zhang X. , Ervin E.H.
Published: February 2019

Bermudagrass [Cynodon dactylon (L.) Pers.] is widely used along its northern limit of adaptation. However, cold hardiness and winter survival are common concerns facing turfgrass managers in these areas. The objective of this study was to determine the effects of moderate salinity applications on bermudagrass cold hardiness. Two trials were conducted in Summer 2002. The cultivar Princess was seeded into pots in a glasshouse at a rate of 24 kg·ha-1. Pots received a weekly solution of 20-20-20 at a rate of 4.9 kg·ha-1 N. Bi-weekly salinity treatments began ≈2 months after germination and consisted of 0, 5, 20, and 40 dS·m-1 in the form of NaCl. These treatments continued for ≈8 weeks. Weekly quality ratings and chlorophyll fluorescence measurements showed similar results, with the high salinity treatments having the poorest quality. Soil electrical conductivity measurements showed a significant increase for the high salinity rates over the lower rates at the end of the trials. Proline concentrations increased with increasing salinity treatments in Trial 1 and were highest with the 20 dS·m-1 rate in Trial 2. Plants were acclimated in a growth chamber, and artificial freezing tests revealed that the 5 and 20 dS·m-1 treatments had the highest percentage of regrowth after freezing. These results indicate that moderate applications of salt or the use of effluent water prior to hardening may be an important way to increase bermudagrass cold hardiness.
Variation in Reproductive Characteristics and Seed Production in the USDA Garlic Germplasm Collection
Authors: Jenderek Maria M. , Hannan Richard M.
Published: February 2019

Diverse garlic germplasm has proven to be essential for production of true seed. Yet, fertile accessions in garlic germplasm collections have not been characterized for breeders and researchers, and information on morphological characteristics associated with seed producing plants is very limited. The objective of this study was to evaluate reproductive characteristics and true seed production capacity in the USDA garlic germplasm collection. Most stable traits, such as flower stem appearance, opening ability of spathe, level of difficulty to remove bulbils, tepal color, umbel shape, and the number of flowers per umbel, were similar across populations evaluated. Other characteristics including position of stigma, tepal closure, pollen viability, time of flowering, scape senescence rate, and number of seeds produced by individual plants varied within accession evaluated. Of 47 accessions, 19 produced true seeds (from 48.5 to 1.5 seeds per plant) in the Central Valley of California. Seed production in the germplasm evaluated is adequate to initiate garlic breeding projects.
Effects of Calcium and Magnesium on Plant Growth, Biomass Partitioning, and Fruit Yield of Winter Greenhouse Tomato
Authors: Hao Xiuming , Papadopoulos Athanasios P.
Published: February 2019

Tomato (Lycopersicon esculentum Mill) `Trust' was grown on rockwool with nutrient solutions containing two levels of calcium (150 and 300 mg·L-1) in factorial combination with three levels of magnesium (20, 50, and 80 mg·L-1) in Winters 1997 and 1998, to investigate the effects of calcium and magnesium on growth, biomass partitioning, and fruit production. Plants grown at 20 mg·L-1 Mg started to show Mg deficiency symptoms (leaf chlorosis) at 8 weeks after planting. The chlorophyll content of middle and bottom leaves increased with increasing Mg concentration in the nutrient solution. At 300 mg·L-1 Ca, total fruit yield and fruit dry matter increased linearly with increasing Mg concentration; marketable fruit yield and total plant biomass showed similar response but to a lower degree. At 150 mg·L-1 Ca, total plant biomass, fruit dry matter and yield peaked at 50 mg·L-1 Mg. The biomass allocation to fruit increased while allocation to leaves decreased with increasing Mg concentration. The Mg effects on total and marketable fruit yield were mainly due to its influence on fruit yield in the late growth stage. Incidence of blossom-end rot (BER) at 150 mg·L-1 Ca increased linearly with increasing Mg concentration while it was not affected by Mg concentration at 300 mg·L-1 Ca. For a winter greenhouse tomato crop, the appropriate Ca and Mg concentrations for tomato production appear to be at 300 and 80 mg·L-1, respectively.
Both Traditional and Semi-bush Tropical Pumpkin Can Be Intercropped with Beans or Cowpeas
Authors: Chesney Patrick , Wessel-Beaver Linda , Maynard Donald N.
Published: February 2019

Most cultivars of tropical pumpkin (Cucurbita moschata Duchesne) are large, trailing plants. New semi-bush (SB) genotypes need to be tested against traditional long vine (LV) types. Both types of pumpkin have large amounts of interplant space during the early stages of growth that might allow for the planting of an intercrop. To test this hypothesis, as well as the performance of tropical pumpkins of varying growth habit, double rows of beans (Phaseolus vulgaris L.) or cowpeas [Vigna unguiculata (L.) Walp.] were intercropped between rows of SB or traditional LV tropical pumpkin in Spring and Fall 1993 in Lajas and Isabela, Puerto Rico. In general, interactions between intercrop treatment and pumpkin genotype were not significant. At its maximum percentage cover (MC) the LV genotype covered, or nearly covered, the entire plot while the SB genotype covered 50% of the plot or less. The SB pumpkin was harvested 5 to 27 days earlier than the LV type. Yield was two to 12 times greater, and average fruit size three to six times greater in the latter. Planting of an intercrop did not reduce pumpkin yield. Green-shelled yields of intercropped legumes averaged ≈700 kg·ha-1. Genotype of the pumpkin maincrop did not affect legume green-shelled yields in Lajas. In Isabela, legume green-shelled yields were 50% higher in SB than in LV pumpkin plots. Legume dry grain yields were greatly reduced in LV compared to SB plots. Intercropping of tropical pumpkin with a short season legume that can be harvested green-shelled is an efficient intercropping system that offers additional yield from the legume without sacrificing yield from the pumpkin maincrop. Both SB and LV pumpkins can be used in an intercrop system, but pumpkin yields were much greater with the LV genotype.
The Effect of Daily Light Integral on Floral Initiation of Pelargonium ×domesticum L.H. Bailey
Authors: Loehrlein Marietta M. , Craig Richard
Published: February 2019

Nine cultivars of Pelargonium ×domesticum L.H. Bailey were evaluated for the effect of daily light integral on floral initiation. Plants were grown at four daily light integrals: 5, 10, 15, or 20 mol·m-2·d-1 for a 16-hour photoperiod in environmental growth chambers at constant 15.5 °C. Meristems were examined at 50 mol·m-2 intervals for morphological changes associated with floral initiation. Two phenotypes were identified, cultivars with an association between floral initiation and cumulative irradiance and those with association between floral initiation and chronological time. Genotypic variation was observed among the irradiance-associated phenotypes.
Pathogenic Variation of Cladosporium caryigenum Isolates and Corresponding Differential Resistance in Pecan
Authors: Conner Patrick J. , Stevenson Katherine L.
Published: February 2019

To facilitate the breeding of scab-resistant pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars, more information is needed about the pathogenic variation of the causal organism, Cladosporium caryigenum (Ell. et Lang.) Gottwald (1982). This study examined the virulence patterns resulting from the field inoculations of 19 pecan cultivars with 12 monoconidial isolates from 8 pecan cultivars at 7 locations. The virulence pattern was different for each of the fungal isolates. Each isolate was virulent on some cultivars and avirulent on others. Most isolates were most virulent on the cultivar of their origin and one or a few other cultivars. Several cultivars were resistant to most of the tested isolates. The results indicate a large pool of differential and ephemeral resistance to scab resides in the pecan germplasm. Microscopic examination of developing lesions suggests that resistance is mediated by the speed of plant cell wall modifications that limit the growth of subcuticular hyphae. This information will be useful in the selection of cultivars with functionally different resistance genes for use in designing cultivar mixtures or in breeding programs.
Phytotoxicity of Several Iron Fertilizers and Their Effects on Fe, Mn, Zn, Cu, and P content of African Marigolds and Zonal Geraniums
Authors: Broschat Timothy K. , Moore Kimberly K.
Published: February 2019

Zonal geraniums (Pelargonium ×hortorum) from seed and african marigolds (Tagetes erecta), which are known to be highly susceptible to Fe toxicity problems, were grown with I, 2, 4, or 6 mm Fe from ferrous sulfate, ferric citrate, FeEDTA, FeDTPA, FeEDDHA, ferric glucoheptonate, or ferrous ammonium sulfate in the subirrigation solution. FeEDTA and FeDTPA were highly toxic to both species, even at the 1 mm rate. Ferrous sulfate and ferrous ammonium sulfate caused no visible toxicity symptoms on marigolds, but did reduce dry weights with increasing Fe concentrations. Both materials were slightly to moderately toxic on zonal geraniums. FeEDDHA was only mildly toxic at the 1 mm concentration on both species, but was moderately toxic at the 2 and 4 mm concentrations. Substrate pH was generally negatively correlated with geranium dry weight and visible phytotoxicity ratings, with the least toxic materials, ferrous sulfate and ferrous ammonium sulfate, resulting in the lowest substrate pHs and the chelates FeEDTA, FeDTPA, and FeEDDHA the highest pH. The ionic Fe sources, ferrous sulfate and ferrous ammonium sulfate, suppressed P uptake in both species, whereas the Fe chelates did not. Fe EDDHA should be considered as an effective and less toxic alternative for the widely used FeEDTA and FeDTPA in the production of these crops.
A Novel Intersectional Buddleja Hybrid
Authors: Lindstrom Jon T. , Bujarski Gregory T. , Burkett Brent M.
Published: February 2019

Buddleja indica Lam. is encountered frequently as a houseplant or a conservatory specimen and is attractive ornamentally for its oak-shaped foliage. Buddleja indica, a tetraploid African species, 2n = 76, was crossed to the Asiatic tetraploid species B. davidii Franch. The F1 generation was intermediate in foliage character between the two parents. Flowers of the F1 were either white or light lavender in color and the number of flowers per inflorescence was intermediate between the parents. The F1 plants were fertile. These hybrids might be suitable for greenhouse or container culture due to their attractive foliage and floral display.
Assessing How Cultural Practices Influence Long-term Productivity in Asparagus
Authors: Peterson* R. Seth , Drost Daniel
Published: February 2019

Asparagus producers have reported a decrease in plant longevity and plant productivity in asparagus fields. Eleven commercial sites (6 in California and 5 in Washington) were monitored starting in Spring 2003. The purpose in monitoring was to evaluate how long-term growth dynamics are affected by harvest pressure. Sites were planted as crowns in Spring 2002 and farm irrigation methods included furrow, sprinkler, and drip. Most sites were harvested starting in Spring 2003 at varying pressures. Harvest yields ranged from 0 to 1300 kg·ha-1. Carbohydrate (CHO) levels in the roots were sampled over the entire growing season and assessed with AspireUS (www.aspireus.com). At the last sampling in Oct. and Nov. 2003, CHO levels ranged from 438 mg·g-1 to 712 mg·g-1 (97% to 158% of the ideal). This resulted in a root CHO load of 2.6 to 6.3 megagrams/hectare. Root mass and distribution was sampled in Spring 2003 and again at the end of the growing season. Root biomass increased by 18% to 487% of the previous year's growth. Fern number, fern mass and plant population were also sampled. Fern number ranged from 3.2 to 6.4 stems per plant and total fern weight ranged from 8.9 to 36.2 megagrams/hectare. Plant populations were reduced by 3% to 19% when compared to the initial planted population. Findings suggest that excessive harvest pressure in the year after planting adversely affects storage CHO accumulation and root growth. Additional site monitoring will occur through 2005.
Expression of Anthocyanin Genes in Potato Periderm
Authors: Keifenheim Daniel , Tong* Cindy
Published: February 2019

Anthocyanins are a class of flavonoids that are responsible for pigments in flowers, fruit, and potato periderm. Developing `Norland' potatoes synthesize anthocyanins in periderm tissue when the tubers are mere swollen stolon tips. As the tubers enlarge, anthocyanin accumulation seems to stop, and anthocyanins synthesized early in development seem to be diluted as the tubers enlarge. Expression of dihydroflavonol reductase (DFR) limits anthocyanin synthesis in grape and maize fruit, and in petunia and snapdragon flowers. However, DFR expression in periderm tissue occurred throughout tuber development (Hung et al., 1999). To determine if expression of late anthocyanin pathway genes limit anthocyanin synthesis in developing potato tubers, we performed RNA gel blot analyses. Expression of leucoanthocyanidin dioxygenase and UDP glucose: flavonoid 3-O-glucosyl transferase was observed in swollen stolon tips but not in periderm of later tuber development stages. Surprisingly, expression was also observed in cortex tissue, although that tissue remained white throughout tuber growth.
Agrobacterium-mediated Transformation of Chokecherry (Prunus virginiana L.)
Authors: Dai* Wenhao , Johnson Christopher P. , Jacques Victoria A. , Walla James A.
Published: February 2019

An Agrobacterium-mediated transformation system was developed for chokecherry (Prunus virginiana L.), one of the most popular native small tree or large shrub species for resource conservation and wildlife habitat in North America. Leaf tissues from in vitro plants previously maintained in MS medium with 2.5 μm BA were co-cultivated on woody plant medium (WPM) containing 10 μm BA and 200 μm acetosyringone with Agrobacterium tumefaciens strain EHA105 harboring the binary Ti plasmid pBI121 carrying the uid A gene encoding for β-glucuronidase (GUS) and the npt II gene encoding neomycin phosphotransferase II. Infected leaf explants were disinfected in sterile water and antibiotics and then transferred to WPM containing 10 μM BA and the antibiotics cefotaxime, carbenicillin, and kanamycin (CCK) for shoot regeneration at 25 °C with a 16-hour photoperiod. Agrobacterium concentration, pre-conditioning of explants, application of acetosyringone, infection time, and kanamycin tolerance of leaf tissues were evaluated for effects on transformation efficiency. Regeneration of chokecherry shoots on kanamycin-containing medium and screening by GUS histochemical assays showed that both the npt II and the uid A genes were successfully transferred into chokecherry. The transformation will be further confirmed by polymerase chain reaction (PCR) and Southern blot analyses.
Effects of Osmotic Agents on Apple Pollen Grain Germination
Authors: Bajwa* Vikramjit S. , Rom Curt
Published: February 2019

Osmotic agents used to prevent apple pollen grain germination were studied in vitro by applying 10 μL of solutions to germinating apple pollen on germinating and growth media. Seven concentrations (0%, 0.25%, 0.5%, 1%, 2%, 5% and 10%) of the solution were prepared for each chemical and the characteristics of pH, EC, and osmotic potential were measured. Apple pollen was dispersed onto the media in petri dishes. Micro drops of solution were then applied to marked areas. Dishes were then placed in germination cabinets at 25 °C. Cumulative percentage pollen germination was calculated 4, 8, 12, and 24 h after treatment by microscopic observation. Generally, the cumulative percentage pollen germination decreased asymptotically with increasing chemical concentration. The most effective chemicals for restricting pollen germination and growth were CuSO4 (0.25%), CH3 COOH (0.25%), CaCl2 (10%), K2 S2 O5 (0.25%), Methyl Jasmonate (2%). The effect of these chemicals has also been tested on pistil viability both in vitro and on excised limbs.
Establishment of Seeded Bermudagrass Using Subsurface Drip Irrigation
Authors: Maurer* Michael , Weeaks Justin
Published: February 2019

Throughout much of the Southwestern United States, poor quality water and limited water resources require innovative methods to conserve water. No research to date has indicated whether seeded bermudagrass Cynodon dactylon can be established by using subsurface drip irrigation (SDI). In 2001 (Expt. I) and 2002 (Expt. II), seeded bermudagrass was evaluated for establishment using SDI. Treatments consisted of emitters and tubing spaced at 30, 46, and 61 cm. The control treatment consisted of pop-up sprinklers. Salinity accumulation is a concern when irrigating turfgrass in areas of poor water quality and low annual rainfall. Salinity accumulation was visible at the soil surface during establishment in 2001, but turfgrass showed no visible signs of stress due to salinity. In 2002, substantial rainfall reduced salinity accumulation during establishment as salinity was not present on the soil surface. Salinity accumulation was greater in most months at the 0-15 cm depth in both years compared to the 15-30 cm depth. Full turfgrass coverage (≥90%) for the control plots in 2001 was about 8.5 weeks and the SDI treatments had complete coverage in 10 weeks. Turfgrass coverage for all treatments in 2002 was 9 weeks. Expt. II had a slightly faster establishment rate due to greater rainfall and different soil characteristics than that of Expt. I. Root count and depth of roots for both years showed roots to 61 cm depth in all treatments. A general trend of higher salinity accumulation at the midpoint between tubing was seen in Expts. I and II. However, after significant rainfall salinity levels returned to concentrations comparable to initial soil salinity concentrations in both years. This research documents the ability to successfully establish seeded bermudagrass using SDI.