bluuebunny/crossref_metadata_2025 huggingface dataset:
517 Bloom Thinner Wilthin Decreased Fruit Set and Increased Fruit Yield and Quality of Three Apple Cultivars
Authors: Ansari Ejaz Mohammad , Matta Frank B. , Abbas Taqueer , Baquir Mohammad
Published: February 2019

The influence of bloom chemical thinner Wilthin on three apple cultivars (Royal Gala, Blushing Gold, and Ultra Gold) was investigated. Two experiments were conducted in 1995 and 1996 to determine the effect of Wilthin at 0%, 0.5%, 1.0%, and 1.5% on fruit length, fruit diameter, fruit weight, yield, juice pH, acidity, SSC, sucrose, glucose, fructose, fruit firmness, and fruit set. Wilthin reduced fruit set of `Royal Gala', `Ultra Gold', and `Blushing Golden' and increased yield of all cultivars. In general, Wilthin increased fruit weight of `Royal Gala', `Ultra Gold', and `Blushing Golden' both years. Wilthin increased fruit length and diameter of `Royal Gala' and `Ultra Gold', but it did not affect fruit length of `Blushing Golden'. Wilthin increased fruit juice pH of `Royal Gala', `Ultra Gold', and `Blushing Golden' during both years. Wilthin decreased fruit juice acidity of `Royal Gala', `Ultra Gold', and `Blushing Golden'. In 1995, Wilthin increased SSC of `Royal Gala' and `Ultra Gold'. In 1996, Wilthin did not effect SSC of `Royal Gala' and `Blushing Golden', but increased SSC of `Ultra Gold'. Wilthin increased sucrose concentration of `Royal Gala', `Ultra Gold', and `Blushing Golden'. Wilthin did not effect fruit juice glucose concentration of `Royal Gala' but increased fruit juice glucose concentration of `Ultra Gold' and `Blushing Golden'. Wilthin did not influenced fructose content of `Royal Gala' and `Blushing Golden' apples. Wilthin increased fructose contents of `Ultra Gold'. Accel increased fruit firmness of `Royal Gala', `Ultra Gold', and `Blushing Golden' and increased fruit firmness of `Royal Gala'.
525 Advanced Development of Split Trellis for Red Raspberry: Cultural Management and Machine Harvest Studies
Authors: Klauer Stephen F. , Chen Chuhe , Cameron J. Scott
Published: February 2019

In 1998, yield of the split (ST) vs. conventional trellis was again compared in `Meeker' red raspberry with work at Vancouver focusing on advanced trellis development and technology transfer. Field testing was expanded from two to five sites in northern (Lynden) and southwestern (Woodland, Ridgefield, WSUV REU) Washington, with a total of eight trials. These tested a variety of widths (28–51 cm), crossarm styles, and machine harvesters in fields with varied cultural practices. Four trials were machine-picked, and, in Vancouver, harvest efficiency was studied. For widths >43 cm, yields were 10% to 13% greater for ST in four trials, while widths less than 43 cm showed no increase. As in previous years, estimated yield potential was 20% to 59% higher for ST in three of four trials. Differences between actual/estimated yields were due to several factors, including damage to laterals, harvest inefficiency, and poor early fruit release. Yield potential was greater (28%) for ST in a second-year trial, suggesting sustainability. In various trials, numerous data were collected including canopy and primocane measurements, aboveground biomass, light interception and leaf: area, gas exchange, chlorophyll content, fourth derivative spectra, fluorescence, N content, and tissue for anatomical analysis. Results were similar to last year. Increased light within ST causes earlier and larger canopy growth and fruit development. There was a large increase in leaf number, leaf area and berry number. Increases in yield were again associated with higher number of lateral/cane. There was no difference in leaf physiological measurements/leaf area between treatments.
530 Fruitfulness of Evergreen vs. Deciduous Southern Highbush Blueberry after Cross-, Self-, and No Pollination
Authors: Martinez Ingrith D. , Lyrene P.M.
Published: February 2019

Fruit set, fruit size, and seed production after hand pollination in a greenhouse were compared for southern highbush blueberry managed in two ways: a) 69 clones were allowed to go dormant and lose their leaves in the field before being dug and subjected to 1000 hours at 5 °C and b) 26 clones were kept growing in a greenhouse through fall and winter without leaf loss and without chilling, to induce flowering on plants that had mature leaves. On each plant in both management systems, some flowers were self-pollinated, some were cross-pollinated, and others had the styles removed before anthesis to prevent pollination. For >1000 flowers per pollination treatment on the deciduous plants, fruit set averaged 1% for no pollination, 46% for self-pollination, and 76% for cross-pollination. The corresponding values for the evergreen plants were 23%, 59%, and 81%. Parthenocarpic berries averaged 0.37 g/berry for deciduous plants and 1.01 g for evergreen plants. Both crossed and selfed berry weights averaged slightly higher for the evergreen plants than for the deciduous plants, but seed number per berry was much lower for the evergreen plants (12 seeds in crossed berries and four seeds in selfed berries) compared to deciduous plants (37 and 8). Southern highbush blueberry plants that flower without going dormant appear to have much higher parthenocarpic capabilities than those that flower after a dormant period.
541 Floral Initiation of Regal Pelargonium Grown at Varying Daily Light Integrals
Authors: Loehrlein Marietta , Craig Richard
Published: February 2019

Nine cultivars of Pelargonium × domesticum representing three germplasm sources 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 mols/day for a 16-h photoperiod in environmental growth chambers at constant 15.5 °C. Meristems were examined at 50-mol intervals (0 to 350 mols) for morphological changes associated with floral initiation. Two phenotypes were identified, cultivars with an association between floral initiation and irradiance and those with association between floral initiation and chronological time. Genotypic variation was observed among the cultivars of each phenotype.
560 Molecular Analysis of the First Intron of the Chalcone Synthase A Gene in Petunia
Authors: Griesbach R.J. , Beck R.
Published: February 2019

A new method was developed to analyze genetic diversity among Petunia species. The first intron of the chalcone synthase A gene was cloned through the polymerase chain reaction (PCR) and partially sequenced. This sequence was used to dissect the intron into two halves (3' and 5' halves). The PCR primers for the 5' half amplified a single fragment that was the same length for all of the species that were studied. Restriction fragment length polymorphism (RFLP) analysis of the 5' half resulted in the same number and length of fragments for all the species that were evaluated. The PCR primers for the 3' half amplified a number of fragments that were characteristic for each species. This research provides a new tool for measuring genetic diversity. Genetic diversity measured with this tool should be closely related to evolutionary distance.
582 Off-season Carambola (Averrhoa carambola L. cv. Arkin) Production under Glass
Authors: Nuñez-Elisea Roberto , Crane Jonathan H.
Published: February 2019

Carambola (Averrhoa carambola L.) is native to the humid tropics of southeastern Asia, where it bears fruit year-round. In south Florida, winter conditions (strong winds and night temperatures below 15 °C) repress growth and flowering of the main commercial cultivar, Arkin, and fruit is produced from July to February. Off-season fruit would reach premium prices. We have previously demonstrated that selective pruning stimulates flowering of carambola at any time of the year. However, flowers produced during cool, windy weather have consistently failed to set fruit. This study was conducted in 1994–1995 to determine whether protected cultivation would help obtain off-season fruit. Four-year-old `Arkin' trees growing in 80-L containers were placed in a glasshouse or outdoors and pruned in November or December to force flowering during December–January. Glasshouse night temperatures during the winter were above 20 °C. All trees flowered in response to pruning. Outdoor trees produced less than one fruit per tree in late March to late April. Glasshouse trees produced 2.3 to 6.1 fruit per tree, 2 to 3 weeks earlier than trees outdoors. In the glasshouse, more than 98% of fruit were seedless, whereas all fruit produced outdoors were seeded. Production of seedless fruit indoors was achieved in the absence of insect pollinators, and yields were low compared to those of outdoor trees during the summer (at least 25 fruit per tree). We speculate that, under protected cultivation, the use of synthetic bioregulators during anthesis and insect pollinators may help increase production of off-season seedless and seeded fruit, respectively.
601 An Evaluation of Sulphosate and Four Glyphosate Formulations on Conifers
Authors: Kuhns Larry , Harpster Tracey
Published: February 2019

Though glyphosate is considered to be a nonselective herbicide, conifer growers have long known that under certain conditions, they could contact the lower branches of their trees with the herbicide Roundup without injuring them. Species, time of application, rate of application, surfactant, method of application, and pruning wounds are all factors affecting conifer tolerance to glyphosate. Because Roundup was widely used by conifer growers, they were very concerned when the formulation of Roundup was changed to contain a more active surfactant. The new product was marketed under the name Roundup Pro. This change increased its herbicidal activity and raised the possibility that it could damage trees if applied in the same way as Roundup. To determine the tolerance of conifers grown in the northeast to a variety of glyphosate formulations, and sulfosate, a set of studies was established. Roundup, Roundup Pro, Glyfos, Accord, and Sulfosate were all applied to field grown hemlock, white fir, Canaan fir, fraser fir, douglas fir, Colorado spruce, and eastern white pine. Rates of 1 to 3 lb active ingredient/A were applied in the fall after new growth was hardened off. In general, it was found that the risk of injuring trees with Roundup Pro is greater than with the old formulation of Roundup. However, in all cases in which Roundup Pro caused more injury than Roundup, the Roundup Pro was applied at 3 lb active ingredient/A. This rate is double the rate recommended for this use. In calibrated, directed spray applications at 1.5 lb active ingredient/A or less, Roundup Pro should be safe for use around the species tested after their growth has fully hardened in the fall.
614 Nitrogen Uptake Efficiency of Apple Rootstocks and Scions
Authors: Aguirre Paula B. , Roper Teryl R. , Krueger Armand R.
Published: February 2019

The uptake efficiency of apple scions and rootstocks has not been studied in the field. Using 15N (ammonium nitrate, 1 atom % 15N) we compared nitrogen uptake efficiency of 12 rootstocks grafted to one scion (Gala) and of 20 scions on the same clonal rootstock (M.9 EMLA) in orchards located in northeastern Wisconsin. Trees were treated in either Fall or Spring 1998 with 40 g actual N per tree applied as a liquid to the soil. N uptake was assessed by measuring 15N in leaf and wood tissue taken monthly from June to Oct. 1998. Tissues were oven-dried and analized using a ratio mass spectrometer. Treatment differences were greater among scions with the same rootstocks than among rootstocks with the same scion. Total N and 15N content differences were found between roostocks and these values were inversely related to tree size.
640 Sustainable Cropping Systems
Authors: Hutchinson Chad M. , McGiffen Milton E.
Published: February 2019

The goals of sustainable agriculture include decreased reliance on synthetic nutrients and pesticides and improved environmental quality for the long-term benefit of the land, livelihood of growers, and their communities. Cropping systems that maximize these goals use alternative fertility and pest control options to produce crops with minimal soil erosion and nutrient leaching. Cropping system elements that can help achieve these goals include: reduced tillage, cover crops, and organic soil amendments. Cover crops are grown before the cash crop and used to replenish the soil with nitrogen and organic matter. Cover crops often also influence pest populations and can be selected based on site-specific growing conditions. Cover crops can be mulched on the soil surface to prevent erosion and weed emergence or can be tilled directly into the soil to incorporate nitrogen and organic matter. Green waste mulch is an increasingly used soil amendment. Many municipalities are encouraging farmers to use green waste mulch in farming systems as an alternative to green waste disposal in landfills. Reduced tillage was once restricted to large-seeded field crops but recent technical advances have made it a feasible option for vegetables and other horticultural crops. Alternative farming practices; however, are still only used by a small minority of growers. Increases in price for organic produce and changes in laws governing farming operations may increase adoption of alternatives to conventional agriculture.
647 Aerial Mapping of Grapes for Analysis of Environmental Stress and Blackleaf Patterns
Authors: Lang N.S. , Smithyman R. , Mills L. , Wample R.L. , Silbernagel J. , Perry E.M.
Published: February 2019

Blackleaf (a.k.a. chocolate leaf) is of worldwide concern in Vitis due to its negative impact on fruit ripening, yield reduction and overall stress on grapevines. Research suggests blackleaf is induced by high levels of UV radiation and overall light intensity, which induce color changes (purple-brown-black) in exposed leaves, resulting in >50% reduction in photosynthesis. The ability to detect blackleaf symptoms before expression can provide insight into metabolic stresses and the possibility of the use and/or timing of management practices to reduce its impact. Remotely sensed imagery and spatial analysis may elucidate reflectance-related processes and symptoms not apparent to the un-aided eye. In this research we mapped canopy growth (leaves/shoot and shoots/vine), metabolic triggers (photosynthesis, leaf water potential, soil moisture), and percent blackleaf expression within vineyards using global positioning system (GPS), infrared gas analyzer, and digital remotely-sensed images. Each image and data record was stored as an attribute associated with specific vine location within a geographical information system (GIS). Spatial maps were created from the GIS coverages to graphically present the progression of blackleaf across vineyards throughout the season. Analysis included summary statistics such as minimum, maximum, and variation of green reflectance, within a vineyard by image capture date. Additionally, geostatistics were used to model the degree of similarity between blackleaf values as a function of their spatial location. Continuing research will be aimed at identifying spectral characteristics of early season stresses due to UV light, water stress, and reduced photosynthetic capacity. Spatial relationships between early season stress and later blackleaf expression will be assessed using joint spatial dependence measures. Overall, information obtained through digital image and spatial analysis will supplement site level information for growers.
654 Vegetable Transplant Biological Control Amendments
Authors: Vavrina Charles S. , Burrell N. Kokalis , Kloepper J.
Published: February 2019

Bell pepper (Capsicum annuum) seedlings treated with various biological preparations exhibited increased root and shoot growth both in the greenhouse and during subsequent field establishment. Early fruit set and pod development showed signs of possible yield improvement by the treatments, but treatment differences were not apparent at first harvest. Data from subsequent harvests did show yield increases with some preparations. Treatment organisms appeared to activate or induce systemic resistance to bacterial spot (Xanthomonas campestris) infestation though not to the level shown by Actigard (Novartis). Crop/treatment response under soil solarization, fumigation, and compost amended conditions will be discussed.
658 Processes Influencing Floral Initiation and Bloom: The Role of Phytohormones in a Conceptual Flowering Model
Authors: Davenport Thomas L.
Published: February 2019

The reproductive phenology of temperate tree fruit species, such as apple and peach, will be briefly introduced and compared to the reproductive phenologies of several tropical and subtropical tree fruit species. Conceptual models of citrus and mango flowering will be described which help to understand the physiological mechanisms of flowering and vegetative flushes in trees growing in subtropical and tropical environments. Possible roles for auxin and cytokinins in shoot initiation and for gibberellins and a putative florigenic promoter in induction will be discussed as they relate to the physiology of flowering and vegetative flushes of tropical species. Successful application of these conceptual flowering models in controlling flowering of citrus, mango, lychee, and longan through the use of growth regulators and other horticultural management techniques will be described.
661 Encouraging Flowering and Cropping in Slow-to-bear Tree Fruit with Bioregulators
Authors: Elfving D.C.
Published: February 2019

Some cultivars of deciduous tree fruit, especially in apple and pear, tend to come into bearing slowly. Bioregulators have been used to stimulate flowering and cropping in slow-to-crop cultivars, but success has been variable. Improved flowering may not necessarily lead to increased cropping. Reduction in vegetative vigor as a result of bioregulator treatment is often, but not always, associated with increased flowering. Bioregulators that act by interfering with gibberellin biosynthesis or that generate ethylene in plant tissues have proven effective for increasing flowering under a variety of conditions. Few studies have demonstrated that exogenous bioregulator applications to poorly cropping fruit trees can be used to produce sustained and economically significant improvement in fruiting while maintaining satisfactory fruit quality.
667 Apple Rootstocks for the Next Century
Authors: Robinson Terence L. , Johnson William C.
Published: February 2019

Rootstock breeding programs in the United States, the United Kingdom, Germany, Russia, Poland, the Czech Republic, and Japan have all released apple rootstocks in the recent past that are potentially important to the worldwide apple industry in the next century. Several of these programs are continuing to breed new rootstocks. Each program has focused on different breeding objectives, thus giving a wide range of horticultural characteristics among this new group of rootstocks. All programs have focused on the horticulturally important traits of productivity, dwarfing and precocity but certain programs have also emphasized other characteristics such as propagability, stress tolerance, disease resistance or insect resistance. Commercialization of this new group of rootstocks is proceeding at an extremely fast pace due to the worldwide networking of fruit tree nursery companies and the use of plant patents. This presents a large job for research and extension personnel to properly test rootstocks for adaptability to different growing areas before they are planted on a large scale. The national rootstock testing project (NC-140) composed of researchers from most apple growing states and provinces in the U.S. and Canada is collecting rootstocks from around the world and conducting uniform field trials that give performance data from a wide variety of climates and soils. This information becomes the basis for local rootstock recommendations in North America. This presentation reviews the most promising rootstocks from around the world and summarize the research information from North American and worldwide trials.
670 Long-term Impacts and Recovery of Perennial Tropical Fruit Crops from Hurricanes in South Florida
Authors: Crane Jonathan H. , Schaffer Bruce , Campbell Richard J.
Published: February 2019

Southern Florida has experienced numerous hurricanes, of which Hurricane Andrew was the most recent. Six years after this storm, nearly one-third of the 8093 ha of tropical fruit that existed in Miami–Dade County before the storm has never been replanted. The damage, reaction, and recovery from the storm varied among fruit species. The effect of heat stress and high light intensity was minimal on avocado, `Tahiti' lime, carambola, mamey sapote, guava, sapodilla, and longan. In contrast, mango trees experienced severe heat stress. Root damage caused by toppling and subsequent re-setting of sugar apple, atemoya, mango, and grafted `Tahiti' lime trees was severe; thus, trees not re-set were less likely to recover than trees left toppled or leaning. The extent and rate of recovery from hurricane-related wind stress also varied among species. Avocado, carambola, guava, and longan refoliated within 3 to 4 weeks after Hurricane Andrew. In contrast, mango, sugar apple, and atemoya trees went through two or more cycles of refoliating and dying back until tree death occurred. Iron and nitrogen deficiencies were common for mango, sugar apple, atemoya, and guava. Other consequences of hurricanes in south Florida include increased weed and vine growth and increased susceptibility to drought stress and insect infestations. Recovery to prehurricane crop production levels has varied among crops. For example, avocado and carambola production is near and exceeds pre-1992 levels, respectively. In contrast, `Tahiti' lime and mango production are about 20% pre-1992 levels. The long-term effect of the most recent hurricane on fruit production in south Florida has been a change in the crop species and/or cultivars planted.
674 The Impact of Tropical Cyclones on Perennial Species in the Mariana Islands
Authors: Marler Thomas E. , Lander Mark A.
Published: February 2019

The frequency of tropical cyclones is a major factor affecting the vegetation of the Mariana Islands, where these storms are called typhoons. An average of about one typhoon per year has passed within ≈100 km of Guam during the past 50 years. The physiognomy of Guam's natural and urban forests is largely determined by these typhoons. The impact of each typhoon is determined by a long list of interacting factors such as species characteristics; environmental and horticultural conditions preceding the typhoon; the intensity, direction, and duration of winds; the amount of rainfall associated with the typhoon; and the environmental and horticultural conditions following the disturbance. Many species survive typhoons by reducing aerodynamic drag of the canopy by abscising inexpensive leaves or breakage of small stems which results in an intact major structural framework. Speed of recovery for nonlethal damage following disturbance depends on nonlimiting conditions during recovery. Thus, the most destructive typhoons are those that occur in sequence with other environmental stresses. The most common of these may be heat and high-light stress, associated with subsequent high pressure systems, and severe drought conditions. For example, the 230–298 km·h–1 winds of Typhoon Paka in Dec. 1997 were followed by the driest year on record for Guam. Typhoon debris and drought generated 1400 forest and grassland fires from Jan. through May 1998. Sequential typhoons are also severely damaging. For example, Guam experienced three direct eye passages and two more typhoons within 113 km during the months Aug. to Nov. 1992. Damage susceptibility and recovery dynamics will be discussed in relation to these and other physical, chemical, biological, and human-induced factors.
Early Expression of Apical Control Regulates Length and Crotch Angle of Sylleptic Shoots in Peach and Nectarine
Authors: Cook Nigel C. , Rabe Etienne , Jacobs Gerard
Published: February 2019

Syllepsis is the predominant mode of branching in young peach and nectarine trees [Prunus persica (L.) Batsch]. Cultivars differ considerably in expression of apical control of sylleptic shoots. This has practical implications regarding tree training. Four cultivars were selected for increasing apical control by the central shoot axis, viz., `Zaigina', `Mayglo', `Fiesta Red' (all nectarines), and `Oom Sarel' (clingstone peach), respectively. Young, actively growing shoots were harvested when ≈300 mm in length, at a time when development of sylleptic shoots (laterals) had begun. Length, crotch angle, and position (as distance from the apex) of the laterals were recorded. When length of the laterals was plotted against their position, two zones were observed. The gradient of length vs. position was shallower in the distal than in the proximal zone. Autonomy in lateral shoots can be described as their ability to grow independently of apical control by the apex of the branch. Autonomy of laterals near the branch apex increased with their length. In `Zaigina' this was established via a more distal start of the second zone, and in `Mayglo' via an increased gradient in the second zone. The early loss or maintenance of apical control regulates architecture in sylleptically branched peach and nectarine shoots. Crotch angle widening of laterals appears to be largely dependent on position, but in some cultivars, such as `Mayglo', other factors are also involved. The data provide evidence of correlative phenomena between actively growing shoots.
Root and Cane Pruning Affect Vegetative Development, Fruiting, and Dry-matter Accumulation of Grapevines
Authors: McArtney S.J. , Ferree D.C.
Published: February 2019

Dormant, 2-year-old, own-rooted `Chambourcin' grapevines (Vitis sp.) were subjected to two levels of root pruning (none, two-thirds roots removed) and were subsequently trained with either one or two canes. Vines were destructively harvested at bloom and after harvest when dormant to determine the effect of stored reserves in the root and competition between shoots for these reserves on vine growth and berry development. Removing 78% of the root system reduced shoot elongation and leaf area more effectively than did increasing the number of shoots per vine from one to two. Root pruning reduced the elongation rate of shoots for 45 days after budbreak, whereas increasing the shoot number reduced the shoot elongation rate for only 20 days after budbreak. A positive linear relationship was observed between leaf area per shoot at bloom and the number of berries per single cluster. These results demonstrate the importance of 1) the roots as a source of reserves for the initial development of vegetative tissues in spring, and 2) the rapid development of leaf area on an individual shoot for high set of grape berries on that shoot.
Tomato Production under Mesh Reduces Crop Loss to Tomato Spotted Wilt Virus in Some Cultivars
Authors: Díez M.J. , Roselló S. , Nuez F. , Costa J. , Catalá M.S. , Lacasa A.
Published: February 2019

Seedlings of three tomato (Lycopersicon esculentum Mill.) cultivars [`RDD', carrier of the Sw5 gene, which confers resistance to tomato spotted wilt virus (TSWV); `Pitihué', tolerant to the virus; and the susceptible cultivar Rutgers] were placed at the four- to five-leaf stage in cages containing a population of viruliferous thrips (Frankliniella occidentalis Perg.), and remained there for 0, 7, or 15 days. Plants were subsequently transplanted either into the open field or in tunnels protected with a mesh of 14 × 10 threads/cm. Systemic symptoms and number of dead plants were recorded and enzymelinked immunosorbent assays (ELISA) were performed. `Rutgers' exhibited severe systemic symptoms regardless of treatment and a high number of plants died. The level of infected plants remained low when protective measures were applied to seedlings of `Pitihué' and acceptable yields were obtained. In open air cultivation, where seedling infection was severe, <20% of `RDD' plants became infected and high yields were obtained; protected cultivation did not reduce yield. Although the percentage of infected plants was higher when cultivated under mesh, the yield of all three cultivars was greater than in the open field. The environment created under mesh stimulated growth, neutralizing the effect of the infection.
Calcium Fertilizers Fail to Affect Pod Calcium Concentration and Yield of Four Snap Bean Cultivars
Authors: Quintana J.M. , Harrison H.C. , Palta J.P. , Nienhuis J. , Kmiecik K.
Published: February 2019

To measure the effect of added Ca fertilizer on the Ca concentration of snap bean pods, four snap bean cultivars were grown during Summer 1996 and 1997 at Hancock, Wis. Fertilizer treatments consisted of 80 kg of Ca per hectare applied as Ca sulfate (CaSO4·2H2O) or Ca nitrate [Ca(NO3)2], and the control (no Ca applied. The experimental design was a randomized complete block with a factorial set of treatments (4 × 3). Calcium sulfate was applied at planting, whereas Ca nitrate was split applied four times at weekly intervals starting 1 week before flowering. Yield and Ca concentration in pods were determined. The statistical analysis showed no significant effect of Ca fertilizers on pod Ca concentration or yield. A strong cultivar effect was detected for both parameters measured. `Evergreen' (5.47 mg Ca per gram dry weight) had the highest pod Ca concentration and `Labrador' (4.10 mg Ca per gram dry weight) the lowest. No significant fertilizer × cultivar interactions were observed. Results for pod Ca concentration remained consistent, even when significant year effects were found for both parameters.
A Naturally Occurring Compound for Controlling Powdery Mildew of Greenhouse Roses
Authors: Newman Steven E. , Roll Michael J. , Harkrader Ronald J.
Published: February 2019

Quaternary benzophenanthridine alkaloids (QBAs) isolated from plants in the family Papaveraceae are effective for the control of some fungal diseases. Extracts from Macleaya cordata, a species rich in QBAs, were formulated at 150 mg·L–1 QBA for spray application to greenhouse roses (Rosa sp.) infected with Sphaerotheca pannosa var. rosae (powdery mildew). The QBA formulation was applied at 10-day intervals. For comparison, copper sulfate pentahydrate, piperalin, and fenarimol also were applied to mildewinfected plants within the same greenhouse at their respective labeled rates. One day after treatment, visible symptoms of mildew infection were reduced 60% by QBA, whereas fenarimol, copper sulfate pentahydrate, and piperalin reduced the symptoms of infection 50%, 75%, and 85%, respectively. Subsequent studies demonstrated that a tank mix of QBA and piperalin provided enhanced control of powdery mildew on rose. Results from this study indicate that QBAs have the potential to be developed as a biorational fungicide for greenhouse use with both fungicidal and fungistatic activity.
Resistance of Petunia Phenotypes to Botrytis cinerea
Authors: Krahl Kimberly H. , Randle William M.
Published: February 2019

Although Petunia hybrida Vilm., a major bedding plant, is susceptible to many diseases, no formal disease resistance studies have been conducted. Botrytis cinerea Pers. ex Fr. is a ubiquitous pathogen, causing great damage to greenhouse-grown ornamental crops, including petunia. In this study, a screening procedure for B. cinerea resistance in petunia was developed and 48 diverse petunia phenotypes were screened for resistance to B. cinerea in two seasons, spring and fall. The range of variability for resistance to B. cinerea in petunia was wide and continuous. Spearman's rank correlation coefficients between seasons were significant and moderate. While the majority of phenotypes displayed less than a 10% difference in mean percent infection in spring vs. fall seasons, several phenotypes displayed large differences that require further testing. One cultivar, `Pink Sensation Improved', exhibited low and consistent mean percent infection in both spring and fall and, therefore, may be a useful source of resistance to B. cinerea in petunia.
Phytophthora Root Rot of Blueberry Increases with Frequency of Flooding
Authors: de Silva Amal , Patterson Keith , Rothrock Craig , McNew Ron
Published: February 2019

Phytophthora root rot is a severe disease on blueberry (Vaccinium corymbosum L.) in poorly drained soils. Little is known about how mulching and frequent waterlogging affect disease severity in blueberries. Phytophthora cinnamomi Rands was grown on rice hulls, which were incorporated into the soil at the rate of 10% (v:v). Waterlogging conditions were imposed for 48 hours 1 week after planting on mulched and nonmulched blueberry plants at weekly, biweekly, and monthly intervals for a total of 3 months. Control plants were not subjected to flooding. The severity of Phytophthora root rot increased with time. Significant linear relationships were found between flooding interval and disease severity rating of shoot, percentage of root infection, and shoot and root dry weights of plants. Disease symptoms were minimal in control plants, but shoot disease rating and percentage of root infection were high in mulched and nonmulched plants that were flooded every week. Shoot and root dry weights were higher in 1997 than in 1996. In 1996, mulched plants had higher shoot dry weights than did nonmulched plants. Disease incidence was higher with weekly and biweekly flooding than with monthly or no flooding. However, mulching did not affect root infection.
Anaerobic Production of Methanethiol and Other Compounds by Brassica Vegetables
Authors: Forney Charles F. , Jordan Michael A.
Published: February 2019

Methanethiol (MT) is a volatile compound responsible for the unpleasant odor evolved when fresh broccoli (Brassica oleracea L., Italica group) is held under anaerobic conditions. Inductive atmospheres can develop in storage, transportation containers, or modified atmosphere packages, resulting in reduced quality. To determine if related vegetables are capable of producing MT, 12 different vegetables from the genus Brassica were cut into ready-to-eat forms. Fifty-gram samples were sealed in 500-mL glass jars and flushed with N2. After 24 h in the dark at 20 °C, headspace samples from the jars were analyzed for MT and other volatiles. Headspace concentration of MT was greatest in broccoli florets, followed by pak choi (Brassica rapa L., Chinensis group) leaf blades, savoy cabbage (Brassica oleracea L., Capitata group), broccoflower (Brassica oleracea L., Botrytis group), and green and red cabbage (Brassica oleracea L., Capitata group). Broccoli stems, kale (Brassica oleracea L., Acephala group), Brussels sprouts (Brassica oleracea L., Gemmifera group), pak choi petioles, rutabaga (Brassica napus L., Napobrassica group) root, cauliflower (Brassica oleracea L., Botrytis group) florets, Chinese cabbage (Brassica rapa L., Pekinensis group), and kohlrabi (Brassica oleracea L., Gongylodes group) tubers produced <3% of the MT produced by broccoli florets. Green tissues appeared to have a greater capacity to produce MT than nongreen tissues. Anaerobic production of CO2 and ethanol did not relate to the vegetable's ability to produce MT. The production of dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) were also induced by the anaerobic conditions. Green cabbage produced the greatest concentration of DMDS, followed by savoy cabbage and broccoli florets. Production of DMTS was similar to the pattern observed for MT, but DMDS production was not highly correlated with MT production.
Resistance Levels of Pot Anthurium Cultivars to Xanthomonas campestris pv. dieffenbachiae
Authors: Norman D.J. , Yuen J.M.F. , Henny R.J.
Published: February 2019

One cut-flower and 14 pot anthurium cultivars were screened for resistance to anthurium blight by spraying four isolates of Xanthomonas campestris pv. dieffenbachiae (McCulloch and Pirone) Dye onto leaf surfaces in replicated experiments. Varying degrees of resistance were observed among the 15 cultivars tested. The pot cultivars Julia and Gemini were the most resistant, while the cut-flower cultivar Hearts Desire was the most susceptible. Each cultivar displayed different degrees of resistance to individual isolates of the pathogen. The results of this research permit the selection of clones with greater resistance for use in breeding and also create a baseline for comparing resistance of newly developed cultivars.
A Meta-analysis of Strawberry Yield Response to Preplant Soil Fumigation with Combinations of Methyl Bromide–chloropicrin and Four Alternative Systems
Authors: Shaw Douglas V. , Larson Kirk D.
Published: February 2019

Yield for annual California strawberry (Fragaria ×ananassa Duch.) production systems in soils treated with combinations of methyl bromide–chloropicrin (MB:CP) were compared with four alternative soil treatment systems using meta-analysis. Studies represent 11 production seasons, and were conducted at three distinct locations in California. Fumigation with mixtures of methyl bromide (MB) and chloropicrin (CP) increased yield significantly compared with any and all alternatives lacking MB. In a combined analysis of 45 studies, fumigation with MB:CP compounds increased yield an average of 94.4% (d+ = 2.874 ± 0.098) compared with yields for plants in nonfumigated (NF) soils. Further, the effect of MB:CP fumigation increased over the first three strawberry cultivation cycles: MB:CP–fumigated soils provided a 59.2% (d+ = 2.166 ± 0.146) yield advantage when one cycle of fumigation was omitted, a 100.2% (d+ = 3.000 ± 0.143) advantage when two cycles were omitted, and a 148.4% (d+ = 6.201 ± 0.348) yield advantage when three or more cycles of MB:CP were omitted. In a combined analysis that included 34 studies, soil fumigation with MB:CP conferred a 9.6% (d+ = 0.751 ± 0.087) yield advantage over fumigation with CP alone. Soils treated with MB:CP yielded 6.8% (d+ = 0.437 ± 0.114) more fruit than those treated with very high rates of CP (336–396 kg·ha–1), and 15.4% (d+ = 1.190 ± 0.134) more than soils treated with commercially realistic rates (168–224 kg·ha–1). Similar to the comparison using NF soils, the efficacy of very high rates of CP appeared to diminish over cycles of strawberry cultivation; MB:CP increased yield 2.2% (d+ = 0.043 ± 0.162) in the first CP production cycle, 10.6% (d+ = 0.588 ± 0.174) and 13.7% (d+ = 2.054 ± 0.401) in the following two cycles. Combinations of dichloropropene (DP) and CP were no more effective than were lower rates of CP alone, and MB:CP conferred a 14.4% (d+ = 0.962 ± 0.162) yield advantage over mixtures of DP:CP. Mixtures of MB:CP increased yield 29.8% (d+ = 3.199 ± 0.287) compared with metam sodium (MS). The standardized effect was similar when comparing MB:CP combinations with either MS or NF soils, suggesting little effect of MS on the yield response. Chemical names used: trichloronitromethane (chloropicrin); 1,3-dichloropropene (dichloropropene); sodium N-methyldithiocarbamate (metam sodium).
Acetolactate Synthase Inhibitors Increase Ethylene Production and Cause Fruit Drop in Citrus
Authors: Burns Jacqueline K. , Hartmond Ulrich , Kender Walter J.
Published: February 2019

The abscission action of two sulfonylureas and one imidazolinone was evaluated in laboratory studies with harvested orange (Citrus sinensis L. cv. Valencia) fruit and greenhouse studies with orange (cv. Hamlin) and grapefruit (Citrus paradisi Macf. cv. Marsh) trees. Dipping harvested fruit in 90 mg·L–1 imazameth, 2 mg·L–1 metsulfuronmethyl, or 30 mg·L–1 prosulfuron solutions increased levels of internal ethylene. Internal ethylene concentration was higher when fruit were dipped in 2 mg·L–1 metsulfuron-methyl solutions at low pH. Fruit retained on trees and dipped in 2 mg·L–1 metsulfuron-methyl solutions produced more ethylene than control fruit. Drop of treated fruit began when ethylene production was at a maximum. High temperatures (average 33 °C) suppressed ethylene production and fruit drop of metsulfuron-methyl–treated fruit. The results indicate the importance of environmental conditions in evaluating the potential of sulfonylureas and imidazolinones as abscission agents for citrus. Chemical names used: ±-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid (imazameth); methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2yl) amino] carbonyl] amino] sulfonyl] benzoate (metsulfuron-methyl); 1-(4-methoxy-6-methyl-triazin-2-yl)-3-[2-(3,3,3-trifluoropropyl) phenylsulfonyl] urea (prosulfuron); N-(phosphonomethyl) glycine (glyphosate); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1 H-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin).
Yield and Dry Weight of Dehydrator Onions after Uprooting at Maturity and Delaying Harvest
Authors: Wall Arthur D. , Corgan Joe N.
Published: February 2019

In dry climates, onions usually have the roots undercut at maturity before harvest. In a 2-year study, dehydrator onions were uprooted at maturity to simulate undercutting, and harvest was delayed for several time intervals. Treatment effects on fresh and dry yield, the number of bulbs per plot, bulb fresh and dry weights, and percent dry weight of bulbs were measured. Plots were considered mature when 80% of the tops had fallen. Delaying harvest 15 days after maturity without uprooting did not reduce yield significantly. Yield and both bulb weight and percent dry weight tended to decline when harvest was delayed >15 days after maturity, especially if plants were uprooted. This suggests that undercutting of onions should not be performed until just prior to harvest and that harvest should not be delayed >15 days past maturity. Yield losses in delayed harvest treatments were attributed primarily to Fusarium basal rot.
Inhibiting Growth of Flowering Crops with Ancymidol and Paclobutrazol in Subirrigation Water
Authors: Million J.B. , Barrett J.E. , Nell T.A. , Clark D.G.
Published: February 2019

Contamination of recirculated subirrigation water with growth retardants poses a potential problem for growers. Eight concentrations of ancymidol or paclobutrazol ranging from 0 to 100 μg·L-1 (0 to 1000 μg·L-1 for petunia) were supplied constantly in subirrigation water to potted plants to identify critical levels at which plant growth is affected. Concentrations of ancymidol resulting in 20% reduction in plant size relative to untreated controls were 3, 10, 98, 80, and 58 μg·L-1 for Begonia ×semperflorens-cultorum Hort. `Gin', chrysanthemum (Dendranthema ×grandiflora Kitam.) `Nob Hill', Impatiens walleriana Hook f. `Super Elfin Coral', Petunia ×hybrida Hort. Vilm.-Andr. `Madness Pink', and Salvia splendens Sell ex Roem. & Schult. `Red Hot Sally', respectively. Respective values for paclobutrazol were 5, 24, 17, 390, and >100 μg·L-1. The results provide useful information for managing potential growth retardant contamination problems or for applying growth retardants in subirrigation water. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); (±)-(R*,R*)-β-[(4-chlorophenyl)methyl]-α-(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Nucleic Acid Scanning Techniques Distinguish Closely Related Cultivars of Poinsettia
Authors: Starman Terri Woods , Duan Xiangrong , Abbitt Shane
Published: February 2019

DNA amplification fingerprinting (DAF) was used to evaluate the genetic relationships among 11 cultivars of poinsettia (Euphorbia pulcherrima Willd.). Amplification was with 10 octamer oligonucleotide primers that generated 336 DNA bands. Thirty-one percent of the bands were polymorphic and distinguished among cultivars. Genetic relationships were evaluated by cluster analysis, and the resulting dendrogram closely agreed with published cultivar relationships. Arbitrary signatures from amplification profiles (ASAP) were further used to characterize two cultivars, `Nutcracker Red' and `Peterstar Red', that were previously found to be genetically and morphologically similar, as well as five cultivars in the “Freedom” series. The DAF products generated with arbitrary octamer primers were reamplified with mini-hairpin decamer primers in these experiments. The ASAP profiles were complex and yielded a total of 231 bands, 38% of which were polymorphic and capable of distinguishing each Freedom cultivar. Five of the eight primer combinations distinguished `Nutcracker Red' from `Peterstar Red'. Thus, closely related cultivars of poinsettia can be separated using new and improved molecular fingerprinting protocols.
Using Random Amplification of Polymorphic DNA for a Taxonomic Reevaluation of Pfitzer Junipers
Authors: Le Duc Alice , Adams Robert P. , Zhong Ming
Published: February 2019

Van Melle (1947) proposed that juniper cultivars of the Pfitzer Group were of hybrid origin and ascribed the name Juniperus ×media Melle. This purported hybrid of J. chinensis L. × J. sabina L. has not been accepted unanimously by the horticultural community. Random amplified polymorphic DNAs (RAPDs) were used to analyze and establish new evidence for the hybrid origin of the Pfitzer Group, using both parents and seven cultivars of the Pfitzer Group. Principal coordinate analysis (PCO) of 122 RAPD bands demonstrated that samples of J. chinensis cluster tightly together, as do the J. sabina samples. Cultivars of the Pfitzer Group lacked affinity with either species, but stood apart as a distinct cluster. The data support Van Melle's conclusion that the Pfitzer Group is separate from J. chinensis and indicate hybrid origin from parents J. chinensis and J. sabina. We recognize Juniperus ×pfitzeriana (Späth) Schmidt [Pfitzer Group] as the correct name for cultivars of Pfitzer junipers. Juniperus ×media, proposed by Van Melle, was rendered illegitimate because of the earlier name J. media V.D. Dmitriev.
Salinity Duration and Concentration Affect Fruit Yield and Quality, and Growth and Mineral Composition of Melon Plants Grown in Perlite
Authors: del Amor F.M. , Martinez V. , Cerdá A.
Published: February 2019

The shortage of good quality water in semiarid zones necessitates the use of saline water for irrigation. In order to simulate the usage of brackish irrigation water in greenhouse melon (Cucumis melo L. cv. Galia) culture in perlite, plants were supplied with nutrient solutions containing 0 (control), 20, 40, and 60 mm NaCl applied at four different times. Treatments were applied during early vegetative growth [14 days after transplanting (DAT)], beginning of flowering (37 DAT), beginning of fruit set (56 DAT), and beginning of fruit ripening (71 DAT). All vegetative and fruit yield parameters were significantly reduced when salinization was started 14 DAT. This inhibitory effect of salinity was progressively lessened when salinity was imposed at later dates. This suggests that the response of melons to salinity depends on the duration of exposure to saline water. Salinity treatments increased fruit reducing sugars, acidity, and total soluble solids. Fruit yield reduction at each salinization time was correlated with salinity levels, but there was some evidence of a nutrient imbalance, since leaf concentrations of N-NO3, and especially K, were low at higher salinities. These results indicate that brackish waters can be used for growing melon with minimum yield losses if concentration and duration of exposure are carefully monitored.