Euphorbia Pulcherrima Willd Research Articles

Preconditioning of the generalist herbivore Trialeurodes vaporariorum to greenhouse monocultures and its subsequent performance on wild polycultures

AbstractGeneralist herbivores can face many challenges when choosing their host plant. This can be particularly difficult if their choice and performance are affected by host experience. Greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), is an invasive generalist herbivore, which has established in year‐round greenhouses at northern latitudes where it cannot overwinter outdoors. It mainly uses crops such as cucumber (Cucumis sativus L.), tomato (Solanum lycopersicum L.), and ornamentals as host plants. However, every summer the insect escapes greenhouses and is exposed to natural vegetation. We evaluated the performance of T. vaporariorum on diverse vegetation outside greenhouses after prolonged experience of greenhouse crops. First, we surveyed the vegetation near infested greenhouses. Development success of the insect differed among wild hosts. We identified five new hosts among 12 plant species that bore pupae and were thus considered suitable as the insect's host plants. Members of the Urticaceae and Onagraceae were the most preferred and frequently inhabited by all insect life stages. The highest abundance of insects occurred in plots with low plant species richness, independent of plant family in these habitats. We then studied experimentally the impact of 1 year of preconditioning to one of three common greenhouse crops, cucumber, tomato, or poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch), on the performance of the preconditioned adults and their progeny on four wild plants. Adults from tomato and poinsettia preferred the novel host species over the species to which they were preconditioned. The whitefly population preconditioned to cucumber was the most fecund on all offered hosts. We conclude that generalist herbivores can have large variation in performance, despite polyphagy, on novel hosts as shown by the variable abundance of T. vaporariorum pupae among outdoor hosts. Furthermore, performance of whiteflies on natural vegetation was affected by experience on greenhouse crops. Based on our observations, we provide insights and recommendations for pest management.

1-Methylcyclopropene Improves Ethylene Tolerance of Unrooted Herbaceous Cuttings but Delays Adventitious Root Development in Angelonia, Calibrachoa, Impatiens, Portulaca, Sutera, and Verbena Cultivars

Knowing which herbaceous taxa are ethylene sensitive and managing exposure of unrooted terminal stem cuttings to ethylene in those taxa are critical for maintaining high-quality propagules that root readily. Of 59 taxa surveyed, freshly harvested terminal cuttings of Begonia hybrid ‘Snowcap’, Lantana camara L. ‘Patriot Sunbeam’, and Portulaca oleracea L. ‘Fairytales Sleeping Beauty’ were sensitive to exogenous application of 1 μL·L−1 ethylene, as demonstrated by leaf abscission within 24 hours of treatment. Exposure to 1-methylcyclopropene (1-MCP) at 700 μL·L−1 for 4 hours before ethylene treatment prevented ethylene injury in these species/cultivars. Exposing unrooted cuttings to 700 μL·L−1 1-MCP induced significant endogenous ethylene biosynthesis in terminal cuttings of the five taxa tested: Euphorbia pulcherrima Willd. ex Klotzsch ‘Visions of Grandeur’, Impatiens hawkeri W. Bull ‘Sonic Red’, Pelargonium peltatum (L.) L’Hérit. ‘Mandarin’, Pelargonium ×hortorum Bailey (pro sp.) [inquinans × zonale] ‘Rocky Mountain White’, and Petunia ×hybrida Vilm. ‘Suncatcher Coral Prism’. Exogenous 1 μL·L−1 ethylene improved adventitious rooting in two cultivars: Begonia hybrid Anita Louise and Fuchsia triphylla L. Honeysuckle. Other trials showed that 1-MCP exposure reduced root number and length of P. ×hortorum ‘Kardino’ and delayed adventitious rooting in all six cultivars tested: Angelonia angustifolia Benth. ‘Carita Lavender’, Calibrachoa ×hybrida Llave & Lex. ‘Terra Cotta’, I. hawkeri ‘Sonic Red’, P. oleracea ‘Fairytales Sleeping Beauty’, Sutera cordata Kuntze ‘Abunda Blue Improved’, and Verbena ×hybrida Groenl. & Ruempl. ‘Aztec Wild Rose’. Subsequent exposure to 1 μL·L−1 ethylene partially mitigated the negative effects on rooting from exposing cuttings to 1-MCP.

The Effect fo Iron Nano-Chelate Fertilizer and Cycocel (CCC) on Some Quantity and Quality Characters of Euphorbia Pulcherrima Willd

The Effect fo Iron Nano-Chelate Fertilizer and Cycocel (CCC) on Some Quantity and Quality Characters of Euphorbia Pulcherrima Willd

Silicon Supply through Subirrigation System Alleviates High Temperature Stress in Poinsettia by Enhancing Photosynthetic Rate

본 연구는 고온 스트레스에서 규소가 분화용 포인세티아(Euphorbia pulcherrima Willd. 'Ichiban')의 내고온성과 생장에 미치는 영향을 조사하였다. 포인세티아를 삽목하여 발근된 삽목묘 중 균일한 개체를 선발하여 상토가 담긴 10cm 화분에 정식하였다. 세 가지 규산염(<TEX>$K_2SiO_3$</TEX>, <TEX>$Na_2SiO_3$</TEX>, <TEX>$CaSiO_3$</TEX>)을 0(-Si), 또는 <TEX>$50(+Si)mg{\cdot}L</TEX><TEX>^{-1}$</TEX> Si농도로 순환식 저면베드에서 저면관수 또는 엽면살포 방식으로 약 2개월간 재배하였다. 포인세티아의 고온 스트레스에 대한 저항성을 알아보기 위하여 규소 처리 8주째에 식물생장상의 온도를 <TEX>$35^{\circ}C$</TEX>로 조절하여 18일동안 재배하였다. 모든 규산염처리에서 효소적 항산화 효소인 APX의 활성이 증가하였고, 비효소적 항산화 효소인 ELP의 활성은 감소하였다. 저면으로 공급한 <TEX>$K_2SiO_3$</TEX>와 <TEX>$Na_2SiO_3$</TEX>처리에서 대조구에 비해 Fv/Fm, 광합성율, 규소함량이 증가하였다. 따라서 규산염 처리가 대조구보다 고온 스트레스에 의해 발생하는 생장의 저해가 적었으며, 특히 저면으로 <TEX>$K_2SiO_3$</TEX>와 <TEX>$Na_2SiO_3$</TEX>를 공급하였을 때 가장 효과적이었다. The effect of Si supplied during plant cultivation on tolerance to high temperature stress in Euphorbia pulcherrima Willd. 'Ichiban' was investigated. Rooted cuttings were transplanted into 10-cm pots and a complete nutrient solution, containing 0 or <TEX>$50mg{\cdot}L^{-1}$</TEX> Si as either <TEX>$K_2SiO_3$</TEX>, <TEX>$Na_2SiO_3$</TEX>, or <TEX>$CaSiO_3$</TEX>, was supplied through subirrigation or weekly foliar applications. After two months of cultivation, plants were placed in an environment-controlled chamber and subjected to <TEX>$35{\pm}1^{\circ}C$</TEX> (high temperature) conditions for 18 days. Enhanced specific activities of enzymatic antioxidants (APX) and suppressed specific activities of non-enzymatic antioxidants (ELP) were observed in the high temperature-stressed plants with Si application. The Fv/Fm (maximum quantum yield of photosystem II), photosynthetic rate, and Si contents in the shoot increased in the treatments of <TEX>$K_2SiO_3$</TEX> and <TEX>$Na_2SiO_3$</TEX> supplied through subirrigation. The Si-treated plants had more tolerance of high temperature stress than the control plants. Of the Si sources and application methods tested, <TEX>$K_2SiO_3$</TEX> and <TEX>$Na_2SiO_3$</TEX> supplied through subirrigation were found to be the most effective in enhancing tolerance to high temperature stress.

Biodegradable pots for Poinsettia cultivation: Agronomic and technical traits

A large quantity of plastics is utilized by floriculture and especially for the production of flowering potted plants, where the pot is a very important component of the whole marketable product. Among these, poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) is a typical example of ornamental potted-plant characterized to have a relatively long crop cycle, a strong demand, especially in Europe and North America, concentrated in the Christmas period and a short shield life. Its cultivation produces a huge quantity of plastic pots to be managed in the right way to avoid environmental risks. A solution of this problem could be the use of biodegradable pots instead of traditional ones. Nevertheless, it is necessary to verify if these materials, although having biodegradability properties, are able to ensure comparative levels of technical use as traditional plastic materials.In this paper, three different kinds of biodegradable pots (biodegradable polyester, plain or added with plant fibers) plus a traditional one (polypropylene, PP) were tested in two cultivation cycles of poinsettia (E. pulcherrima cv Premium red). The trial was carried out in a heated greenhouse located in Southern Italy (40° 38′N; 14° 55′E; 50m a.s.l.). Agronomical response of plants as well as the mechanical and colorimetric behavior of pots over time were studied.Result have shown that poinsettias growth in pots charged with plant fiber have had good values of some agronomical qualitative and quantitative indexes. Mechanical tests have pointed out that pots made by 100% biodegradable polyesters have a good mechanical resistance, with a decrease of the maximum tensile strength (σmax) of just 32.2% during the trial, and a fixed color over time. Pots made of biodegradable polyesters variously added with plant fibers do not seem appropriate for poinsettia cultivation especially for the fast falling of the σmax that, in the case of the biodegradable pot added with 20% of plant fibers, that decreased of 81.3% during the trial.

Effect of applying calcium chloride and three milk supplements to poinsettia ‘Prestige Red’

ABSTRACTSome poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cultivars are susceptible to bract calcium (Ca) deficiency in developing bracts. In this study, we evaluated the efficacy of foliar uptake of Ca from milk-based products plus calcium chloride (CaCl2) as a potential Ca source. Weekly foliar applications of 237 mL L−1 whole milk, 80 mL L−1 powdered milk, 30 mL L−1 condensed milk, 0.94 g L−1 CaCl2, or distilled water (used as a control) were applied to runoff of ‘Prestige Red’ for four weeks. The four largest bracts with petioles on three different inflorescences and three leaves with petioles below the transitional leaf per inflorescence were collected per pot. None of the treatments affected bract or leaf Ca concentration. Powdered milk treatments resulted in a higher concentration of zinc (Zn) in bracts and aluminum (Al) in bracts and leaves. White residue remained on the bracts and leaves after treatment with powdered milk, which would reduce marketability.

Poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch).

Genetic engineering is an important tool for introducing desired genes into poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch). We describe in this chapter an Agrobacterium tumefaciens-mediated transformation protocol for poinsettia. A detailed description of genetic transformation, antibiotic selection, subsequent regeneration via somatic embryogenesis, and rooting as well as molecular and morphological analyses is included. The methodology described here could facilitate the future engineering of poinsettia for research purpose as well as commercial production of poinsettia plants with improved resistance or novel traits.

Effects of Daily Light Integral and Canopy Density on Shoot Growth and Development in a Poinsettia (Euphorbia pulcherrima Willd. ex. Klotsch) Stock Plant Canopy

Poinsettia stock plants consist of a dense canopy of competing shoots, and the growth and development of these individual shoots have not been previously quantified. The effects of air temperature, daily light integral (DLI), and canopy density (CD) were investigated on poinsettia (Euphorbia pulcherrima Willd. ex. Klotsch) ‘Freedom Red’ shoot development in a stock plant canopy. Plants were grown at two constant temperatures (20.3 or 25.7 °C), five CD (43, 86, 129, 172, or 215 shoots/m2), and three DLI treatments (2.6, 4.4, or 7.7 mol·m−2.d−1 for the September planting and 4.0, 6.0, or 10.6 mol·m−2.d−1 for the January planting). Shoot position at the final data collection was used to assign shoots to different levels within the canopy; Level 1 = the four highest shoots, Level 2 = the next four highest shoots, and so forth for Levels 3, 4, and 5. Temperature did not significantly affect leaf unfolding rate (LUR), shoot fresh mass (FM), or shoot caliper, whereas DLI and CD affected shoot growth and development. LUR and FM increased as DLI increased from 2.6 to 10.6 mol·m−2.d−1, whereas LUR and FM decreased on the uppermost shoots in the canopy, e.g., Level 1 shoots, as CD increased from 43 to 129 shoots/m2. Therefore, higher CD required higher DLI to achieve similar LUR and FM. Shoot caliper on Level 1 shoots increased from 6.3 to 7.4 mm as CD decreased from 129 to 43 shoots/m2; and shoot caliper increased from 5.8 to 7.6 mm as DLI increased from 4.0 to 10.6 mol·m−2.d−1. The DLI environment needs to be managed to accommodate greater CD, to sustain growth and development of individual shoots within the canopy of poinsettia stock plants.

Influence of growth retardant on growth and development of Euphorbia pulcherrima Willd. ex Klotzsch

This study was undertaken to evaluate the influence of single foliar flurprimidol treatment on morphology and transpiration of ‘Roman’ and ‘Freedom Red’ poinsettias. The growth retardant flurprimidol (Topflor 015 SL) was applied once as a foliar spray at concentrations of 5, 10 or 15 mg × dm&lt;sup&gt;-3 &lt;/sup&gt;when lateral shoots were about 5 cm in length. Single foliar flurprimidol treatment was sufficient to inhibit stem elongation of both poinsettia cultivars. The degree of growth inhibition depended on cultivar and growth retardant concentration. As compared to the control, the shoots of flurprimidol treated ‘Roman’ and ‘Freedom Red’ plants were up to 44% and 37% shorter, respectively. The desirable plant heights for ‘Roman’ and ‘Freedom Red’ poinsettias were obtained with flurprimidol at concentrations of 5 and 10 mg × dm&lt;sup&gt;-3&lt;/sup&gt;, respectively. The shoots of flurprimidol sprayed poinsettia were also more rigid and aligned relative to each other and thus the bracts on the plant were placed on the same level. The diameters of growth retardant treated poinsettias were up to 13% narrower. The leaf areas, petiole lengths, fresh and dry weights of ‘Roman’ and ‘Freedom Red’ poinsettias treated with flurprimidol were substantially smaller as compared to the control. The bract diameters of both poinsettia cultivars were only slightly affected by growth retardant application. Plants exposed to flurprimidol had also intensified green leaf pigmentation. There was almost no abscission of the oldest leaves in the low portions of growth retardant treated plants, compared to those of the control ones. Flurprimidol had no effect on transpiration rate per unit leaf area and stomatal conductance in both poinsettia cultivars. No phytotoxicity was observed in flurprimidol treated plants. Chemical name used: α-(1-methylethyl)-α-[4-(trifluromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol).

Identification and characterization of the black fly, Bradysia difformis (Diptera: Sciaridae) on poinsettia crops (Euphorbia pulcherrima) of central Mexico

The aim of this study was to identify and characterize the developmental stages of the most abundant black fly species associated with poinsettia crops (Euphorbia pulcherrima Willd. ex Klotzsch) in the producing area of Central Mexico. Collecting samples were conducted in greenhouses of the locations of Atlacomulco (Mexico), Tenango de las Flores (Puebla), Xochimilco (Mexico City), and Zacatepec and Tetela del Monte (Morelos). A total of 2,141 adult specimens of Diptera were obtained, being Bradysia difformis Frey (Diptera: Sciaridae) the most abundant species (99.5%). Life cycle of this species was completed between 26-28 days under controlled conditions of temperature and humidity (25°C and 70% RH). The differentiation of larval instars by morphometrics of the head capsule between instars I vs II, showed very low error probabilities (1:10,000); while differentiation between instars II vs III, and III vs IV resulted with higher error probabilities, between 17:100 and 36:100 individuals, respectively. For this reason it is recommended to explore other features in addition to measurements of width of the cephalic capsules for discriminating different larval stages. This is the first record of B. difformis for Mexico, although this genus was previously reported affecting poinsettia crops.

규산칼륨 첨가 양액으로부터 6가지 분식물의 규소 흡수도

본 실험은 인공배지가 담긴 용기에서 재배되는 6가지 분식물의 지상부와 지하부에 흡수된 규소의 양과 각 양액에 첨가된 규소의 농도에 따른 흡수 경향을 구명하고자 수행되었다. 화훼농가에서 주로 재배되고 있는 분식물 중에서 국화, 스파티필럼, 칼랑코에, 아이비, 카네이션, 그리고 포인세티아를 선정하고 균일한 묘를 선별하여 350mL 마젠타 박스에서 재배하면서 <TEX>$K_2SiO_3$</TEX>를 이용하여 Si를 0, 2.7 또는 5.4mM 농도로 첨가하였다. 각 마젠타 박스에 에어펌프에 1m 길이의 polyethylene 튜브를 연결하여 전체 실험기간 동안 <TEX>$2L{\cdot}h^{-1}$</TEX>(노즐당 <TEX>$143mL{\cdot}h^{-1}$</TEX>)로 양액에 통기하면서 재배하였다. 양액의 EC는 <TEX>$1.5mS{\cdot}cm^{-1}$</TEX>로, pH는 5.6으로 실험 시작 전에 조정하였다. 모든 환경 조건이 동일한 조건에서 재배한 작물을 15일째에 수확하여 지하부와 지상부의 규소 함량을 몰리브덴청법을 이용하여 측정하였다. 이를 바탕으로 규소 흡수 정도와 농도에 따른 규소 함량 변화를 알아보기 위해 단순회귀분석을 통해 검정하였으며, 양액 내에 남아 있는 규소 함량은 ICP-AES을 이용하여 측정하였다. 6가지 분식물 중 지하부의 규소 함량은 카네이션에서 가장 높고 포인세티아에서 가장 낮았다. 그리고 지상부의 규소 함량은 카네이션에서 가장 높았고 칼랑코에에서 가장 낮았다. 지상부와 지하부를 합친 식물체의 총규소 함량은 포인세티아, 칼랑코에 및 국화 는 규소 흡수 정도가 낮았고, 스파티필름은 중간 그리고 아이비와 카네이션은 높게 나타났다. 본 연구의 결과에서 규소 흡수 정도는 식물마다 달랐고 회귀분석이 식물에 따라 다양하게 나타났다. This research was carried out to investigate silicon (Si) uptake levels by six potted plant species from a nutrient solution supplemented with <TEX>$K_2SiO_3$</TEX>. Uniform rooted plants of Dendranthema grandiflorum Ramat., Spathiphyllum patinii N.E. BR., Kalanchoe blossfeldiana, Hedera helix L., Dianthus caryophyllus L., and Euphorbia pulcherrima Willd. were grown in 350 mL boxes, one plant per box, containing a nutrient solution supplemented with either 0, 2.7, or 5.4 mM Si as <TEX>$K_2SiO_3$</TEX>. The nutrient solution in each container was adjusted to EC <TEX>$1.5mS{\cdot}cm^{-1}$</TEX> and pH 5.6. The solution in each container was aerated by an 1 m-long polyethylene tube, all connected to a vacuum pump. After 15 days of cultivation in a glasshouse Si contents in the roots and shoots were measured using the colorimetric molybdate method and amount of remaining Si in the nutrient solution was measured using the ICP-AES to calculate the amount of absorption. A simple regression analysis was performed to observe the changes in Si contents in the roots and shoots as affected by concentration of Si supplied to the solution. Among the six species tested, carnation had the greatest and poinsettia the lowest tissue levels of Si concentration in the root, whereas carnation had the greatest and kalanchoe the lowest tissue levels of Si concentration in the shoot. Based on the Si content in the whole plant, Si uptake levels by poinsettia, kalanchoe, and chrysanthemum were low, whereas those by spathiphyllum were intermediate, and those of English ivy and carnation were high. These results indicated that the uptake level of Si by the plant vary depending on plant species.

First report of Tobacco mosaic virus (TMV) and Poinsettia mosaic virus (PnMV) in poinsettia (Euphorbia pulcherrima Willd. Ex Klotzch) in Mexico

Cite This Article T, O. O., Martínez, D. O., Rojas, S. R., Ponce, G. V., Díaz, C. N. (2013). First report of Tobacco mosaic virus (TMV) and Poinsettia mosaic virus (PnMV) in poinsettia (Euphorbia pulcherrima Willd. Ex Klotzch) in Mexico. Phyton-International Journal of Experimental Botany, 82(all), 235–241.

Anthocyanin and chlorophyll content during poinsettia bract development

The concentration of anthocyanins, chlorophyll a and b were quantified during bract development of three differently colored Euphorbia pulcherrima Willd. cultivars (‘Mars White’, ‘Mars Pink’, and ‘Mira Red’) and bract color was colorimetrically determined. Color parameter a* increased from the first analyzed stage of bract development to the subsequent stages in all poinsettia cultivars. Chlorophyll a predominated over chlorophyll b in partially pigmented bracts and a sharp decrease in chlorophyll a content was detected in fully pigmented bracts. Eleven different anthocyanic pigments were identified with the use of high-performance liquid chromatography/mass spectrometry (HPLC/MS). The predominant cyanidin-3-galactoside, cyanidin-3-glucoside, cyanidin-3-rutinoside, pelargonidin-3-glucoside and pelargonidin-3-rutinoside were also detected in white and pink poinsettia bracts. Anthocyanin content levels increased significantly with the transition from partially to fully pigmented bracts in all analyzed cultivars and their accumulation coincided with the arrest of photosynthetic pigments synthesis.

Ethno-Medico-Botanical Study in Lawachara National Park, Bangladesh

Use of medicinal plants for primary health care by the local people in and around the Lawachara National Park, Bangladesh was recorded. A total of 56 plant species under 30 families with 70 formularies (treatment mode) have been documented. Among the medicinal species, Citrus limon (L.) Burm. f., C. maxima (Burm.) Merr., Cucurbita pepo L., Lepisanthes rubiginosa (Roxb.) Leenh., Euphorbia pulcherrima Willd. ex Klotz., Mimosa diplotricha C. Wright ex Sauv. have been reported as new medicinal species from Bangladesh. Out of these plant species, 39.29% belonged to herbs, 19.64% shrubs, 3.71% trees and 5.36% climbers. In majority cases, leaves of the medicinal plants were found leading in terms of their use followed by fruit, bark, stem, seed, whole plant, latex, rhizome and inflorescence. DOI: http://dx.doi.org/10.3329/bjb.v41i1.11087 Bangladesh J. Bot. 41(1): 97-104, 2012 (June)

Development of Euphorbia pulcherrima under Reduced Finish Temperatures

The holiday poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch.) is the number two potted flowering crop sold in the United States with a reported wholesale value of $146 million in 2010. Profitability is increasingly threatened as the cost to heat greenhouses has increased by over 90% in the last 10 years. As energy costs continue to increase and poinsettia prices remain relatively constant, growers are seeking cultivars that can be finished under reduced temperatures. Our objectives were to quantify how reduced temperature finishing (RTF) 2 weeks after the start of short days influences height, bract area index, and time to anthesis of poinsettia. Eight red poinsettia cultivars were selected based on their early response attributes (initiate and finish within 6 to 8 weeks), moderate to high vigor, and naturally large bracts. Rooted cuttings were grown at day/night temperature set points (12 h/12 h) of 24/19 °C until 15 Oct. and under a 16-h photoperiod consisting of natural daylengths with day-extension lighting until 1 Oct. On 15 Oct., plants were transferred to day/night temperatures (12 h/12 h) of 20/14, 21/17, or 24/19 °C. Time to anthesis from the start of short days was 60 and 55 days at 24/19 °C and 76 and 68 days at a reduced finishing temperature of 20/14 °C for ‘Prestige Early Red’ and ‘Early Orion Red’, respectively. Final height was not significantly influenced by RTF in either cultivar. Our results indicate that RTF is a viable option that greenhouse growers can use to help reduce energy costs of carefully selected poinsettia cultivars.

Interactions of Light Intensity, Insecticide Concentration, and Time on the Efficacy of Systemic Insecticides in Suppressing Populations of the Sweetpotato Whitefly (Hemiptera: Aleyrodidae) and the Citrus Mealybug (Hemiptera: Pseudococcidae)

The impact of light intensity on the uptake and persistence of the systemic neonicotinoid insecticides, imidacloprid and dinotefuran, were evaluated in poinsettia (Euphorbia pulcherrima Willd.) and yellow sage (Lantana camara L.). Insecticide residues were measured in leaves sampled from the treated plants at four time intervals after treatment to determine the relationship between insecticide concentration and efficacy against two insect pests: sweetpotato whitefly, Bemisia tabaci Gennadius, and the citrus mealybug, Planococcus citri Risso. The insecticides were evaluated at their respective label rate and at the comparable label rate of the other insecticide under two different light environments: ambient and shade. The uptake of dinotefuran into yellow sage was more rapid at both treatment rates than both rates of imidacloprid, resulting in higher percent mortality of whitefly nymphs (89.8-100) compared with imidacloprid (14.1-89.2) across all 4 wk. Additionally, plants that received both rates of dinotefuran had fewer whitefly pupae (< 1.0) at week 4 compared with imidacloprid-treated plants (23.7-25.3). The uptake of dinotefuran into poinsettia plants was also more rapid and resulted in quicker and higher percent mortality of whitefly nymphs (89.5-99.6) compared with imidacloprid (14.1-89.2) across all 4 wk. However, despite efficient uptake, the efficacy of both systemic insecticides was less for citrus mealybug where percent mortality values were <50% among all the treatments across the 4 wk. The use of the two systemic insecticides evaluated in regards to pest management in horticultural cropping systems is discussed.

Development of Botrytis cinerea Pers. ex Fr. on leaves of common poinsettia (Euphorbia pulcherrima Willd.)

The development of &lt;i&gt;Botrytis cinerea&lt;/i&gt; was assessed on six cultivars of common poinsettia, differing in the colour of bracts, and being in great demand among buyers of these ornamental plants. Resistance to this pathogen differed in the investigated poinsettias. Cultivar 'Malibu Red' (red bracts) turned out to be most susceptible, while cv. 'Marblestar' (cream-pink) and cv. 'Coco White' (white) - relatively resistant to this fungus. After application of various inoculation methods (leaf discs, cut off leaves, whole plants) the differences in resistance to &lt;i&gt;B. cinerea&lt;/i&gt; were confirmed for two extreme cultivars - susceptible ('Malibu Red') and resistant ('Coco White'), which indicated genetic background of this polymorphism. The rate of disease development on poinsettia leaves was affected by the amount of spores used for inoculation (optimum density of 3.5·10&lt;sup&gt;5&lt;/sup&gt; &lt;i&gt;B. cinerea&lt;/i&gt; conidia / ml suspension) and the addition of stimulants (0.1 M glucose with 0.05 M KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;), which facilitated germination and infection of the host tissue. The inoculated poinsettia leaves showed high stability of plasma membranes. In the susceptible cultivar, in spite of the development of necrotic spots, a significant increase in the membrane damage index (by 13%) was found only on day 7 of the disease development.

Effects of Pinching, Cycocel and B-nine Treatments on Branching Habit of Pot Poinsettia (&lt;i&gt;Euphobia pulcherrima&lt;/i&gt; Willd)

Poinsettia ( Euphorbia pulcherrima Willd ) is a popular pot plant in many countries and there is a high potential to introduce it to the Sri Lankan floriculture markets. Naturally, poinsettia becomes colourful under short day conditions. However, artificial induction of flowers is necessary for it to produce marketable plants throughout the year. In the natural condition, plants show a vigorous growth and the height is undesirable to accept as a pot plant. Hence, pinching and application of growth retardants were practiced in this study to obtain short bushy plants. Potted rooted cuttings of Euphobia pulcherrima Willd were subjected to single and double pinching and to cycocel and B-nine applications, in 12 combinations. Significantly greater height reduction of shoots (20 cm) and highest number of shoots per plant (36) were obtained when the plants were exposed to double pinching followed by 1500 ppm cycocel application at 14 day intervals. Application of plant growth regulator, B-nine (5000 ppm) did not exert much effect on reducing the shoot height. However, it had some effect on increased shoot production in combination with double pinch. Double pinch gave significantly greater height reduction and increased shoot number when growth regulators were applied. DOI: http://dx.doi.org/10.4038/tar.v21i3.3303 TAR 2010; 21(3): 284-292

Control growth of Euphorbia pulcherrima Willd. ex Klotzsch ‘Sonora Jingle’ and ‘Sonora White’ using ethephon

Ethephon was sprayed on Euphorbia pulcherrima Willd. ex Klotzsch (poinsettia) ‘Sonora Jingle’ and ‘Sonora White’ to control their height and produce more compact potted plants. The results showed that Ethephon could effectively control the growth of ‘Sonora Jingle’ and ‘Sonora White’ poinsettia. Height was reduced by was 33.4 ± 0.8% for ‘Sonora Jingle’ and 30.8 ± 1.3% for ‘Sonora White’ poinsettia, when 700 mg L−1 Ethephon was sprayed three times on 29 August, 20 September, and 13 October 2005, respectively. Similar to other plant growth retardants, side effects including phytotoxicity and delays to first bract color were also observed on Ethephon treated poinsettia. However, all plants produced were still of a marketable quality.

Population genetic structure of the newly invasive Q biotype of Bemisia tabaci in Taiwan

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is among the top 100 invasive pests in the world, and it causes serious agricultural damage and economic losses in many countries. More than 24 biotypes of the sweetpotato whitefly have been detected worldwide, of which the Q biotype has recently been reported to be a new invasive pest spreading throughout the world via trade in poinsettias, Euphorbia pulcherrima Willd. ex Klotzsch (Euphorbiaceae). In 2006, the Q biotype was first recorded in Taiwan in greenhouses, but not in the field, suggesting that the invasion of this biotype might be at an early stage in that country. The mitochondrial cytochrome oxidase I (COI) gene and 12 microsatellite loci were used to investigate the genetic structure of multiple B. tabaci Q biotype populations. The presence of only a few COI haplotypes and a low number of nucleotide differences suggest high genetic similarity among these populations. Microsatellite analyses also revealed low genetic differentiation and frequent gene flow among greenhouses. The molecular evidence supports the occurrence of a recent genetic bottleneck in the B. tabaci Q biotype. Bayesian cluster analyses indicated that at least two invasion events have occurred in Taiwan. Phylogenetic analyses of microsatellites support Q biotype migration among greenhouses, which was likely facilitated by the frequent movement of poinsettias between greenhouses. Future management strategies should focus on developing plantlet trade regulations to avoid further anthropogenic dispersal of the B. tabaci Q biotype among greenhouses in Taiwan.