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- Author or Editor: Cheryl R. Boyer x
Euonymus fortunei (Turcz.) Hand.-Mazz. is susceptible to anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Fungicides have provided little control of anthracnose on E. fortunei in past studies. Identification of cultural practices that reduce disease incidence would be beneficial to the nursery industry. Containerized E. fortunei `Emerald'N Gold' plants were placed either on gravel beds or black plastic-covered gravel beds. Half of the beds in each bed treatment were sprayed with a 10% bleach solution monthly to attempt to reduce the presence of C. gloeosporioides inoculum. Plants were rated monthly from May (initial rating) through October for disease severity. A covariate analysis was performed using initial ratings as the covariate for ratings from all other months. Bleach did not affect disease ratings at any time. Disease ratings of plants on plastic-covered beds were lower than those of plants on gravel beds. Disease ratings decreased linearly as the growing season progressed.
A survey of commercial nursery growers was conducted to identify cultural practices used in wintercreeper euonymus (Euonymus fortunei) production. Growers that have or have not experienced anthracnose incited by Colletotrichum gloeosporioides on wintercreeper euonymus participated in the survey. Nurseries reported using a variety of practices to produce quality plants for sale. Plant culture appeared similar between nurseries with anthracnose problems on wintercreeper euonymus and those without anthracnose problems.
Dahlia (Dahlia ×hybrida) is an important floriculture crop that has gained popularity in recent years. Greenhouse growers have recently reported a phenomenon known as “dahlia decline,” that can affect potted dahlias in greenhouse production. The crop exhibits graying foliage, root decline, and plant death, and the phenomenon has reportedly caused partial or total crop loss and has no known initiating factor. We hypothesized that plant exposure to supraoptimal root-zone temperatures (RZTs) during production may decrease dahlia root quality, especially above 40 °C and could initiate dahlia decline. Because there is a lack of understanding on how supraoptimal RZT may impact dahlia growth and development, experiments were conducted to evaluate the effects of supraoptimal RZTs on seven dahlia cultivars in Spring 2019 and 2020. Dahlias were grown for 4 to 5 weeks in the greenhouse and then root zones were exposed to ≈22 (control), 35, 40, 45, or 50 °C using a water bath. Root quality was rated before treatment and rated weekly after the hot water bath treatment, along with vegetative growth parameters for 4 weeks. In both years, significant decline in root ratings were observed. ‘XXL Veracruz’ and ‘XXL Sunset’ average root ratings decreased after a 45 and 50 °C treatments in year 2 and both cultivars demonstrated increased root rating averages by 3 weeks after treatment. Cultivars exhibited a significant increase in root rating in the final observations when compared with root ratings taken 1 week posttreatment even if the initial decline after treatment was not significant. Overall plant height was significantly impacted, resulting in shorter heights in both years for all cultivars as treatment temperatures increased to 50 °C in comparison with the control and 35 °C, and a few cultivars exhibited significantly shorter height at 40 and 45 °C. Ultimately, our research did not show typical plant responses that were consistent with reported dahlia decline, but we were better able to characterize dahlia response to supraoptimal RZT.
Plants of Euonymus fortunei `Emerald Gaiety', `Emerald 'n Gold' and `Canadale Gold' were sprayed to runoff weekly at two sites with one of three fungicide treatments or water (control) to determine fungicide effectiveness in controlling anthracnose caused by Colletotrichum gloeosporioides. Copper sulfate pentahydrate was applied at 0.4 or 0.6 g·L-1 a.i. or mancozeb was applied at 1.8 g·L-1 a.i.. Plants were rated for disease incidence approximately monthly. No interaction occurred between fungicide and cultivar. Differences among fungicide treatments were not apparent until weeks 18 or 20 depending on the site, when plants treated with mancozeb had lower disease ratings than plants receiving any other treatment. Cultivars differed at almost every rating date at both sites. Poison agar experiments were conducted to determine mycelial inhibition by copper sulfate pentahydrate or mancozeb.
Heat stress is problematic to root growth in the production of containerized nursery plants. Container color may moderate effects of solar radiation on substrate temperatures. Studies were conducted near Manhattan, KS, to evaluate effects of container color on growth of roots and shoots in bush beans (Phaseolus vulgaris L.), red maple (Acer rubrum L.), and eastern redbud (Cercis canadensis L.). Four treatments among studies included containers colored flat and gloss white, silver, and black; a green container color treatment was added to the tree studies. Plants were grown in bark-based soil-less substrate and temperatures were measured at 5-cm depths in the south sides and centers. After 4 months, plant variables were measured. Roots were separated into three sections: core, north, and south. In the bean study, substrate temperatures at the south side of the container averaged lowest in flat and gloss white (≈36 °C) and greatest in black containers (50.3 °C). Root density at the south side was reduced in beans by 63% to 71% in black compared with flat and gloss white. In heat-sensitive maples, substrate temperatures at the south side of containers averaged up to 7.7 °C greater in black and green than in other treatments. Substrate temperatures in the center averaged 3.5 to 3.8 °C greater in black than in flat and gloss white, resulting in up to 2.5 times greater root density in flat and gloss white than in black containers. In heat-tolerant redbuds, the effects of container color on whole-plant growth were less evident. Data suggest that heat-sensitive plants benefit from being grown in white containers or painting outer surfaces of green and black containers white.
A substrate component (WholeTree) made from loblolly pine (Pinus taeda L.) was evaluated along with starter fertilizer rate in the production of greenhouse-grown petunia (Petunia ×hybrida Vilm. ‘Dreams Purple’) and marigold (Tagetes patula L. ‘Hero Spry’). Loblolly pine from a 12-year-old plantation were harvested at ground level, chipped, and further processed through a hammer mill to pass a 0.64-cm screen. The resulting WholeTree (WT) substrate was used alone or combined with 20% (WTP2) or 50% (WTP5) (by volume) Canadian sphagnum peatmoss and compared with an industry standard peat-lite (PL) mix of 8 peatmoss : 1 vermiculite : 1 perlite (by volume). Substrates were amended with 1.78 kg·m−3 dolomitic lime, 0.59 kg·m−3 gypsum [CaSO4-2(H2O)], 0.44 kg·m−3 Micromax, 1.78 kg·m−3 16N–2.6P–9.9K (3- to 4-month release), and 1.78 kg·m−3 16N–2.6P–10.8K (5- to 6-month release). A 7N–1.3P–8.3K starter fertilizer (SF) was added to each substrate at 0.0, 1.19, 2.37, or 3.56 kg·m−3. Container capacity (CC) was greatest for PL and decreased as the percentage of peatmoss in the substrate decreased with WT having 35% less CC than PL. Conversely, air space (AS) was greatest for the WT and decreased as percentage of peatmoss increased with PL containing 33% less AS than WT. In general, petunia dry weight was greatest for any substrate containing peatmoss with a SF rate of 2.37 kg·m−3 or greater. The exception was that petunia grown in WT at 3.56 kg·m−3 SF had similar dry weight as all other treatments. Marigold dry weight was similar for all substrates where at least 2.37 kg·m−3 SF was used.
The objective of this study was to evaluate the potential for use of container substrates composed of processed whole pine trees (WholeTree). Three species [loblolly pine (Pinus taeda), slash pine (Pinus elliottii), and longleaf pine (Pinus palustris)] of 8- to 10-year-old pine trees were harvested at ground level and the entire tree was chipped with a tree chipper. Chips from each tree species were processed with a hammer mill to pass through a 0.374-inch screen. On 29 June 2005 1-gal containers were filled with substrates, placed into full sun under overhead irrigation, and planted with a single liner (63.4 cm3) of ‘Little Blanche’ annual vinca (Catharanthus roseus). The test was repeated on 27 Aug. 2005 with ‘Raspberry Red Cooler’ annual vinca. Pine bark substrate had about 50% less air space and 32% greater water holding capacity than the other substrates. At 54 days after potting (DAP), shoot dry weights were 15% greater for plants grown in 100% pine bark substrate compared with plants grown in the three WholeTree substrates. However, there were no differences in plant growth indices for any substrate at 54 DAP. Plant tissue macronutrient content was similar among all substrates. Tissue micronutrient content was similar and within sufficiency ranges with the exception of manganese. Manganese was highest for substrates made from slash pine and loblolly pine. Root growth was similar among all treatments. Results from the second study were similar. Based on these results, WholeTree substrates derived from loblolly pine, slash pine, or longleaf pine have potential as an alternative, sustainable source for producing short-term horticultural crops.
Online, direct selling (ODS) has become the leading way that people acquire goods, with Amazon (Seattle, WA) being the largest online vendor in the United States. This study sought to determine if horticultural businesses were engaging in ODS with Amazon, ebay, and other websites. Researchers examined the ODS activity of 498 businesses using quantitative content analysis methods, and found that 93 horticultural industry businesses were conducting some form of ODS through their websites, but only four offered products on Amazon. Results indicate that ODS remains an untapped marketplace for the horticultural industry, particularly for small, rural businesses.
A study was conducted at Auburn University to evaluate freshly chipped pine trees as an alternative substrate in container nursery crops. Two substrates were tested alone and in combination with aged pine bark (PB), peat (P), and composted poultry litter (PL). A 6:1 (v:v) PB: sand control treatment was also included. The two substrates were both composed of small caliper (2 to 10 cm) Pinus taeda processed in a chipper (including needles) (AUC); however, one substrate was additionally processed through a hammermill with a 0.95-cm screen (AUHM). Treatments included were 100% AUC, 3:1 (v/v) AUC:PB, 3:1 (v/v) AUC:P, 3:1 (v/v) AUC:PL, 1:1 (v/v) AUC:PB, 1:1 (v/v) AUC: P, 1:1 (v/v) AUC:PL, and the same treatments for the AUHM substrate. There were a total of 15 treatments with six replications per treatment. Each substrate was amended with 0.45 kg·m-3 gypsum, 6.35 kg·m-3 Polyon 17–6–12 (17N–2.6P–10K) and 0.68 kg·m-3 MicroMax. Trade gallon (2.8-L) containers were filled with respective substrates and planted with Lantana camera `New Gold' on 20 July 2005. AUC and AUHM treatments amended with either PL or P resulted in Lantana with growth indices similar to PB:sand (6:1). In general, plants tended to be larger when amended on a 1:1 basis with either PL or P, but were similar statistically to those amended 3:1. For example, plants grown with AUHM:P 1:1 or AUHM:PL 1:1 were 7.3% and 8.8% larger, respectively, than plants grown in the same medium at 3:1. The lowest growth indices tended to occur with AUC and AUHM alone or amended with pine bark. Lantana root growth followed a similar trend to growth indices in that greatest coverage of the rootball surface occurred with AUC or AUHM treatments amended with PL or P.
A study was conducted at Auburn University in Auburn, AL, and the U.S. Department of Agriculture–Agricultural Research Service, Southern Horticultural Laboratory in Poplarville, MS, to evaluate clean chip residual (CCR) as an alternative substrate component for annual bedding plant production. Clean chip residual used in this study was processed through a horizontal grinder with 4-inch screens at the site and was then processed again through a swinging hammer mill to pass a 3/4- or 1/2-inch screen. Two CCR particle sizes were used alone or blended with 10% (9:1) or 20% (4:1) peatmoss (PM) (by volume) and were compared with control treatments, pine bark (PB), and PB blends (10% and 20% PM). Three annual species, ‘Blue Hawaii’ ageratum (Ageratum houstonianum), ‘Vista Purple’ salvia (Salvia ×superba), and ‘Coral’ or ‘White’ impatiens (Impatiens walleriana), were transplanted from 36-cell (12.0-inch3) flats into 1-gal containers, placed on elevated benches in a greenhouse, and hand watered as needed. Ageratum plants grown at Auburn had leaf chlorophyll content similar or greater than that of plants grown in PB. There were no differences in salvia; however, impatiens plants grown in PB substrates at Auburn had less leaf chlorophyll content than those grown in CCR. There were no differences in ageratum, salvia, or impatiens leaf chlorophyll content at Poplarville. There were no differences in growth indices (GI) or shoot dry weight (SDW) of ageratum, while the largest salvia was in PB:PM and the largest impatiens were in PB-based substrates at Auburn. The GI of ageratum at Poplarville was similar among treatments, but plants grown in 4:1 1/2-inch CCR:PM were the largest. Salvia was largest in 4:1 CCR:PM and PB:PM, and although there were no differences in GI for impatiens at Poplarville, the greatest SDW occurred with PB:PM. Foliar nutrient content analysis indicated elevated levels of manganese and zinc in treatments containing CCR at Auburn and PB at Poplarville. At the study termination, two of three annual species tested at both locations had very similar growth when compared with standard PB substrates. This study demonstrates that CCR is a viable alternative substrate in greenhouse production of ageratum, salvia, and impatiens in large containers.