Irrigation in pine nurseries

This review provides information and opinions about irrigation practices in pine nurseries. Even when nurseries receive more than 15 mm of rainfall week-1, managers irrigate seedbeds to increase germination, increase seed efficiency, and increase root growth. In the southern United States, a 7-month old pine seedling in an outdoor nursery typically receives 2 to 6 kg of water supplied from either sprinklers (39 nurseries) or center-pivot irrigation (12 nurseries). Most nursery managers do not intentionally subject the crop to moisture stress, since most reforestation sites receive adequate rainfall, and many studies show that reducing root mass does not increase seedling performance. In fact, nursery profits can be reduced by more than $13,000 ha-1 when deficit irrigation reduces average seedling diameter by 1 mm. Although some researchers believe that failure to properly drought stress pine seedlings might increase outplanting mortality by up to 75%, research over the past 40 years does not support that myth. When pine seedlings average 5 mm (at the root-collar), water stress is not a reliable method of increasing tolerance to an October freeze event. In several greenhouse trials, researchers grew and tested seedlings that nursery managers would classify as culls (i.e., dry root mass < 0.5 g). Unfortunately, it is common for researchers to make irrigation recommendations without first developing a water-production function curve.

Nature Connection in Early Childhood: A Quantitative Cross-Sectional Study

There have been calls to reconnect children with nature, both for their own wellbeing, as well as for ecological sustainability. This has driven the growth of outdoor and nature-schools for all ages, but especially in the early childhood education sector. However, to date, there has not been a quantitative study that looks at whether these settings actually promote nature connection. This paper aims to examine the role of nature nurseries in the promotion of connection to nature, when compared to traditional nurseries. Data were collected on the nature connection, using the Connection to Nature Index for Parents of Preschool Children, of 216 children aged 1–8 years, 132 of whom attended nature nurseries while the rest attended traditional nurseries. Duration and frequency of attendance, sex, and parental nature connection were also reported. Statistical analyses were conducted for overall nature connection scores, individual dimension sub-scores and, for the children who attended nature nursery, against predictors. Results indicate that attending a nature nursery is associated with higher nature connection. Predictors for children’s connection to nature were parental nature connection, and total time spent in attendance of an outdoor nursery. This suggests a dose-response style relationship between attendance and nature connection. Implications for real-life applications are put forward and further research directions are explored.

Effect of Topdressed Controlled-release Fertilizer Rates on Nursery Crop Quality and Growth and Growing Substrate Nutrient Status in the Niagara Region, Ontario, Canada

The objectives of the current study were to 1) determine the best topdressed controlled-release fertilizer (CRF) application rates for quality and growth of two nursery crops under temperate climate outdoor nursery production conditions in the Niagara region, Ontario, Canada, and 2) evaluate the nutrient status of the growing substrate following topdressing of two CRF types during the growing season. Fall-transplanted Goldmound spirea (Spiraea ×bumalda ‘Goldmound’) and Wine & Roses® weigela [Weigela florida (Bunge) A. DC. ‘Alexandra’] were grown in 2-gal (7.56 L) containers and topdressed on 7 May 2015 with Osmocote Plus 15N–3.9P–9.9K, 5–6 month CRF or Plantacote 14N–3.9P–12.5K, 6 month Homogeneous NPK with Micros. CRF was applied at rates of 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 g nitrogen (N)/pot for both species. The best plants at the end of the growing season (i.e., 23 Sept. 2015) were spirea at 3.0–4.5 and 3.0–6.0 g N/pot, and weigela at 3.0–4.5 and 6.0 g N/pot, with Osmocote and Plantacote, respectively. At CRF rates above these rates, the majority of plants showed no increase in growth or quality attributes. All weigela plants, despite CRF application rate, showed K deficiency symptoms during the study. Using marketable-size criteria and plant growth data over time, estimates of production timing are presented for fall-transplanted, spring-topdressed weigela and spirea. These estimates may assist growers in choosing CRF application rates to meet time-sensitive production goals. Early in the growing season, NO3-N and P concentrations in the growing substrate were highest at CRF rates ≥4.5 and ≥6.0 g N/pot, respectively, and P continued to be high in August and September at 9.0 g N/pot. NH3-N and K concentrations at all CRF application rates were greater early in the growing season and decreased over time. At high CRF rates toward the end of the growing season, concentrations of NO3-N, NH3-N, and P once again increased. Considering crop-specific CRF application rates and understanding changes in growing substrate nutrient status during the growing season may help nursery growers prevent negative environmental impacts from over-fertilizing.

First Report of Mango Malformation Disease Caused by Fusarium pseudocircinatum in Mexico

Mango (Mangifera indica L.) malformation disease (MMD) is one of the most important diseases affecting this crop worldwide, causing severe economic loss due to reduction of yield. After the first report in India in 1891 (3), MMD has spread worldwide to most mango-growing regions. Several species of Fusarium cause the disease, including F. mangiferae in India, Israel, the USA (Florida), Egypt, South Africa, Oman, and elsewhere; F. sterilihyphosum in South Africa and Brazil; F. proliferatum in China; F. mexicanum in Mexico; and recently, F. tupiense in Brazil (1,2,3,4). Besides F. mexicanum, F. pseudocircinatum, not yet reported as a causal agent of MMD, was isolated in Mexico from affected inflorescences and vegetative malformed tissues (4). Symptoms of vegetative malformation caused by F. pseudocircinatum included hypertrophied, tightly bunched young shoots, with swollen apical and lateral buds producing misshapen terminals with shortened internodes and dwarfed leaves. Infected inflorescences of primary or secondary axes on affected panicles were shortened, thickened, and highly branched, while the peduncles became thick, remained green and fleshy, and branches profusely resembled a cauliflower in shape and size (3). Ten isolates of F. pseudocircinatum were recovered from cultivars Ataulfo, Criollo, Haden, and Tommy Atkins in Guerrero, Campeche, and Chiapas states and characterized. Isolates produced mostly 0-septate but occasionally 1- to 3-septate oval, obovoid, or elliptical aerial conidia (0-septate: 4 to 19 [avg. 8.7] × 1.5 to 4 [avg. 2.6] μm) in false heads in the dark and in short false chains under black light, unbranched or sympodially branched prostrate aerial conidiophores producing mono- and polyphialides, and sporodochia with straight or falcate conidia that were mostly 3- to 5-septate, but sometimes up to 7-septate (3-septate: 25 to 58 [avg. 41] × 2 to 3.3 [avg. 2.9] μm; 5-septate: 33.5 to 76.5 [avg. 56.7] × 2.5 to 6 [avg. 3.5] μm). Circinate sterile hyphae were rarely formed. Two representative isolates, NRRL 53570 and 53573, were subjected to multilocus molecular phylogenetic analyses of portions of five genes: nuclear large subunit 28S ribosomal RNA, β-tubulin, calmodulin, histone H3, and translation elongation factor (TEF)-1α (GenBank GU737456, GU737457, GU737290, GU737291, GU737371, GU737372, GU737425, GU737426, GU737398, and GU737399). Two pathogenicity tests were conducted with NRRL 53570 and 53573 on healthy 2-year-old nucellar seedlings of polyembryonic Criollo; 20 μl conidial suspensions (5 × 106 conidia/ml) of each isolate and water controls were inoculated separately on 15 buds on 3 different trees, as described previously (1). The following conditions were used in experiment 1: 24 to 27°C with light intensity of 16.2 to 19.8 •Mol m−2s−1 in the range of 400 to 700 nm, and photoperiods of 14 h light and 10 h dark. Typical vegetative disease symptoms were discernible in plants inoculated with NRRL 53570 (20%) and 53573 (7%) after 8 months. In experiment 2, after 3 months growth under the above conditions, seedlings were transferred to an outdoor nursery in Iguala, Guerrero. Typical vegetative symptoms of MMD were observed in 86.7 and 13.3% of the buds inoculated with F. pseudocircinatum NRRL 53570 and 53573, respectively, after 9 months. Isolates from typical symptomatic vegetative buds were confirmed as F. pseudocircinatum by sequencing a portion of their TEF-1α gene, thus fulfilling Koch's postulates. This is the first report of F. pseudocircinatum as a causal agent of MMD. References: (1) S. Freeman et al. Phytopathology 89:456, 1999. (2) C. S. Lima et al. Mycologia 104:1408, 2012. (3) W. F. O. Marasas et al. Phytopathology 96:667, 2006. (4) G. Otero-Colina et al. Phytopathology 100:1176, 2010.

Infrared Camera Measurements Reveal Diurnal Variation in the Effect of Mechanically Induced Internal Voids on Stem Temperatures of Small Trees Passively Heated by the Sun

The relationship between stem temperature measured by an infrared (IR) camera and a tree’s internal condition was proposed as a basis for diagnosing potentially hazardous defects in the landscape. Before practical application, this diagnostic technique needs clarification to guide expectations of its resolution and precision. In this study, cylindrical voids of varying size were created in 5 cm diameter stems of Dracaena fragrans and Syzygium grande by mechanically removing tissue from specimens in an outdoor nursery, and the surface temperature of these plants was measured twice daily at 0830h and 1830h using an IR camera. The collected IR images were analyzed using a concurrent mixed methods approach with qualitative image evaluation and quantitative temperature analysis where the temperature distributions of stems containing internal voids were compared to those without defects. For both species, there was no difference in stem temperatures, as observed in IR images, among any experimental plants at 0830h, but an anomalous temperature reduction was exclusively apparent at 1830h near the 3.8 cm void, occupying 76% stem cross-sectional area. There was also a larger decrease in the linear temperature trend (0.34°C–0.51°C) near this void margin compared with other treatments, although this was more pronounced in the monocot species than eudicot. The remaining treatments did not exhibit stem temperatures visibly different from the control. Under experimental conditions, the technique identified relatively large internal defects, but the reduced heat capacity of stems containing such defects is only apparent in the evening after being passively heated by the sun.

Pine Bark Substrates Amended with Parboiled Rice Hulls: Physical Properties and Growth of Container-grown Spirea during Long-term Nursery Production

The decline in the availability of pine (Pinus taeda L.) bark (PB) supplies and increasing prices have caused concerns in the nursery industry. Research was conducted to evaluate the effect of parboiled rice (Oryza sativa L.) hulls (PBH) as a substrate amendment to PB-based container substrates on the growth of Spiraea ×bumalda L. ‘Anthony Waterer’ and to examine the changes in physical properties of the substrates during long-term production cycles under outdoor nursery conditions. Six substrates were formulated by blending PB with 0%, 20%, 40%, 60%, 80%, or 100% PBH (by volume). Substrate composition affected plant growth components evaluated, generally decreasing growth as the amount of PBH increased. However, amending PB with up to 40% PBH did not result in a significant decrease in plant growth or increase the volume or frequency of irrigation for container-grown spirea. Physical properties of substrates amended with PBH improved over time. Based on these results, PB-based substrates amended with up to 40% PBH retained physical properties that were generally within current guidelines for nursery container substrates after one (25 weeks) and two (70 weeks) growing seasons.

Growth Control of ‘Taylortown Red’ and ‘Homestead Purple’ Verbena with Pistill in Nursery Production

Verbena canadensis ‘Homestead Purple’ and ‘Taylortown Red’ were treated with one or two spray applications of the plant growth regulator (PGR) Pistill (ethephon) at 0, 250, 500, 750, or 1000 ppm. Plants were in 3.8 liter (1 gal) containers under outdoor nursery conditions. Plant widths of ‘Homestead Purple’ verbena were suppressed linearly with increasing Pistill concentrations up to 24% at 2 weeks after initial treatment (WAT) and up to 18% at 4 WAT. Widths of ‘Taylortown Red’ verbena were suppressed 22% at 2 WAT with a single application at 500 to 1000 ppm, and linearly up to 33% at 4 WAT with 2 applications. Two applications of Pistill suppressed heights and widths of both cultivars at 7 WAT compared to one application.