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Open access

Shital Poudyal and Bert M. Cregg

Interest in capturing and reusing runoff from irrigation and rainfall in container nurseries is increasing due to water scarcity and water use regulations. However, grower concerns related to contaminants in runoff water and other issues related to water safety are potential barriers to the adoption of water capture and reuse technologies. In this review, we discuss some of the key concerns associated with potential phytotoxicity from irrigating container nursery crops with recycled runoff. The concentration of pesticides in runoff water and retention ponds is orders of magnitude lower than that of typical crop application rates; therefore, the risk of pesticide phytotoxicity from irrigation with runoff water is relatively low. Nonetheless, some pesticides, particularly certain herbicides and insecticides, can potentially affect crops due to prolonged chronic exposure. Pesticides with high solubility, low organic adsorption coefficients, and long persistence have the greatest potential for crop impact because they are the most likely to be transported with runoff from container pads. The potential impact on plant growth or disruption of physiological processes differs among pesticides and sensitivity of individual crop plants. Growers can reduce risks associated with residual pesticides in recycled irrigation water by adopting best management practices (e.g., managing irrigation to reduce pesticide runoff, reducing pots spacing during pesticide application, use of vegetative filter strips) that reduce the contaminant load reaching containment basins as well as adopting remediation strategies that can reduce pesticide concentrations in recycled water.

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David A. Baumbauer, Colleen B. Schmidt and Macdonald H. Burgess

Kale, leaf lettuce, and spinach were grown for 28 days in growth chambers under daily light integrals (DLI) of 8, 10, 12, and 14 mol·m−2·d−1. Fresh weight (FW), dry weight (DW), leaf area, and chlorophyll concentration were measured. Increasing DLI positively influenced lettuce FW; an increase from 1.27 g/plant to 4.33 g/plant was measured. DW for all species increased in a linear fashion under increasing DLI, with lettuce increasing 203%, kale 47%, and spinach 42% as DLI increased from 8 to 14 mol·m−2·d−1. Leaf area response was species-dependent, with lettuce leaf area increasing under increasing DLI while kale leaf area decreased under higher DLI. Chlorophyll levels in kale leaves decreased from DLI of 8 to 12 mol·m−2·d−1, and then increased to 14 mol·m−2·d−1 DLI. Chlorophyll content in kale leaves had a nonlinear response to DLI and the best fit was with a quadratic model. Growers wanting to add supplemental lighting can expect the greatest gains in lettuce yield compared with those of kale and spinach.

Open access

Kaitlyn M. Orde and Rebecca Grube Sideman

Day-neutral strawberry (Fragaria ×ananassa) cultivars show promise for extending the fruiting season and increasing production in the northeastern United States, but published research on cultivar yield in the region is lacking. Furthermore, few studies have investigated the effects of low tunnels on yield, fruit, and plant characteristics. We evaluated eight day-neutral cultivars (Albion, Aromas, Cabrillo, Monterey, Portola, San Andreas, Seascape, and Sweet Ann) on open beds and under low tunnels in two separate experiments conducted in 2017 and 2018. Cultivars began producing ripe fruit within 10 weeks of planting in both years, and continued producing fruit without interruption for 20 weeks (2017) and 18 weeks (2018). Annual total yield ranged from 234.9 to 497.8 g/plant and marketable yield ranged 126.4 to 389.1 g/plant, depending on cultivar and year. Cultivar significantly affected the percent marketable yield, late season yield, fruit size, soluble solids content (SSC), runner emergence, and plant size. Except for the cultivar Sweet Ann, low tunnels did not increase season-long marketable or total yield, but did increase the percent marketable yield for all cultivars in 2017, and most cultivars in 2018. Furthermore, marketable yield was significantly greater under low tunnels than open beds during 6 late-season weeks in 2018. Fruit SSC was greater under low tunnels in 2018, and low tunnels reduced runner emergence for certain cultivars. Season-long average air temperatures were higher under low tunnels, but the greatest temperature differences occurred when low tunnels were closed. We demonstrate that day-neutral cultivars can produce high annual yields in New England, but that cultivar selection is paramount.

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Tongyin Li, Guihong Bi, Richard L. Harkess and Eugene K. Blythe

Mineral nutrient uptake of Encore® azalea ‘Chiffon’ (Rhododendron sp.) affected by nitrogen (N) rate, container type, and irrigation frequency was investigated. One-year-old azalea plants were planted in two types of 1-gallon containers: a black plastic container or a biodegradable container (also referred to as a biocontainer) made from recycled paper. Azalea plants were fertilized with 250 mL of N-free fertilizer twice weekly plus N rates of 0, 5, 10, 15, or 20 mm from ammonium nitrate (NH4NO3). All plants were irrigated daily with the same amount of water through one or two irrigations. Plants fertilized without N had the lowest concentrations of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) averaged in the entire plant, which were at deficient levels for azalea species. High N rates of 15 or 20 mm resulted in the highest plant average concentrations of P, K, Ca, and Mg. Concentrations of micronutrients including iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) showed varied trends affected by different treatments. With high N rates of 15 and 20 mm, paper biocontainers increased uptake of both macro- and micronutrients in terms of total nutrient content (mg or μg per plant) compared with plastic containers. One irrigation per day increased root concentrations of Cu and Zn and root contents of Fe, Zn, Cu, and B, but decreased leaf K concentration compared with two irrigations per day. The beneficial effects of high N rates and biocontainers on mineral nutrient uptake of Encore® azalea ‘Chiffon’ likely indirectly occurred through increasing plant growth.

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Rayane Barcelos Bisi, Rafael Pio, Daniela da Hora Farias, Guilherme Locatelli, Caio Morais de Alcântara Barbosa and Welison Andrade Pereira

Pear (Pyrus spp.) is a temperate-climate fruit species that has gametophytic self-incompatibility. Cross-pollination among intercompatible cultivars can be useful in selecting for breeding programs. The objective of the present study was to evaluate effective fruiting from cross-pollination between hybrid pear cultivars and to characterize pear tree S-alleles. Seven cultivars were evaluated: Cascatense, Centenária, D’água, Primorosa, Seleta, Tenra, and Triunfo. Controlled crosses were carried out in two seasons and consisted of spontaneous self-pollination, parthenocarpy, and cross-pollination between cultivars. During the 2 years of research, the overlap of the entire flowering periods of all cultivars was higher than 50%. Phenology was evaluated from the beginning of pruning, and the time elapsed from pruning to the flowering phenophase was computed. Finally, the flowering-period overlap of the cultivars was analyzed. S-alleles were characterized by polymerase chain reaction (PCR) using primers specific to previously known alleles. Under field conditions, the Primorosa cultivar has high potential as a pollinizer for D’água, Seleta, Tenra, and Triunfo. Pear tree hybrid cultivars have a high frequency of the S1 and S5 alleles. The S5S8 and S1S4 alleles are amplified in the D’água and Seleta cultivars, respectively, conferring compatibility between these cultivars. The S1 and S5 alleles are amplified in ‘Primorosa’, ‘Cascatense’, and ‘Triunfo’, conferring interincompatibility.

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Carlee Steppe, Sandra B. Wilson, Zhanao Deng, Keri Druffel and Gary W. Knox

Trailing lantana (Lantana montevidensis) is a popular low-growing ornamental plant valued for its heat and drought tolerance and continuous purple or white flowering throughout much of the year. Recently, trailing lantana was predicted to be invasive by the University of Florida/Institute of Food and Agricultural Sciences (UF-IFAS) Assessment of Non-Native Plants in Florida, and therefore not recommended for use. All cultivars fall under this designation unless proven otherwise. Eight trailing lantana varieties were obtained from wholesale growers and naturalized populations found in Texas and Australia. Plants were propagated vegetatively, finished in 4-inch pots, and planted under field conditions to determine morphological and cytological differences among varieties. Australian trailing lantana differed morphologically from the other varieties in its smaller habit, leaves (which had serrate-crenate leaf margins, and fewer appressed hairs), heavy fruiting, and cold sensitivity (observational reduced growth and flowering during winter months). Nuclear DNA content analysis suggests that Australian trailing lantana is likely a tetraploid and all other varieties evaluated were likely triploids with high levels of sterility. Pollen stainability of Australian trailing lantana was moderately high (58.83%), whereas pollen production was rarely observed in all other varieties. Results support that there are two forms of trailing lantana, the U.S. varieties distinguished by their leaf and flower morphology, ploidy level, and the absence of fruit and viable pollen.

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Chia-Hui Tang, Ching-Shan Kuan, Su-Feng Roan, Chin-Lung Lee, Jer-Way Chang and Iou-Zen Chen

Open access

Derek W. Barchenger, Sopana Yule, Nakarin Jeeatid, Shih-wen Lin, Yen-wei Wang, Tsung-han Lin, Yuan-li Chan and Lawrence Kenyon

Chile pepper (Capsicum annuum L.) is an increasingly important vegetable and spice crop. Among the most devastating chile pepper–infecting viruses, especially in tropical and subtropical regions, are members of the whitefly transmitted Begomovirus, which cause pepper yellow leaf curl (PYLC). An effective PYLC management strategy is the development of resistant cultivars. However, genetic recombination, acquisition of extra DNA components, and synergistic interactions among different begomoviruses have resulted in the rapid emergence of new viruses that can infect new hosts, cause new disease symptoms, and overcome host resistance. In this project, 98 Capsicum entries comprising breeding lines, open pollinated varieties, genebank accessions, and wild species were screened for resistance to strains of Pepper yellow leaf curl Thailand virus (PepYLCThV). We used a randomized complete block design with three replications and 10 plants per replication in field net-houses at two locations (Khon Kaen and Kamphaeng Saen, Thailand) using augmented inoculation by viruliferous whiteflies. Scoring was done at ≈60, 90, and 120 days after inoculation using a standardized 6-point scale (1 = no symptoms to 6 = very severe symptoms), and the average of the scores of 10 plants within each replication was used for analysis. Although no entry was immune to the disease, the breeding line 9852-123 was highly resistant. Several accessions and lines were moderately resistant at both locations, although a high level of variability within these entries was observed. Overall, the disease severity at the Khon Kaen location was greater compared with Kamphaeng Saen, highlighting the importance of multilocation testing for disease resistance. The resistant entry identified here can be used to study gene action and to move resistance genes into well-adapted germplasm.

Open access

S. Christopher Marble, Shawn T. Steed, Debalina Saha and Yuvraj Khamare

Mulches have been evaluated extensively as a weed management tool in container plant production, but most research has focused on loose-fill wood-derived mulch materials, such as pine bark or wood chips. In this experiment, pine (mixed Pinus sp.) bark (PB), shredded hardwood (HW), and pine sawdust were evaluated for weed control and crop response both alone and in combination with a guar gum tackifier alongside a plastic film mulch, a paper slurry mulch, and the paper slurry mulch + PB and compared with a nonmulched, nontreated control and a single application of preemergence herbicide (oxyfluorfen + pendimethalin). Mulch materials were applied to nursery containers ranging from 7 to 25 gal at two different nurseries and at two research centers in central Florida in 2017 and 2018. Results showed that the plastic mulch provided more than a 90% reduction in hand weeding time and weed weight over a 6-month period, and similar control was achieved with PB, paper slurry + PB, and the HW treatment (64% to 91% reduction in weeding time and weed weight). No growth differences were observed with any mulch treatment in any species evaluated including ligustrum (Ligustrum japonicum), Chinese elm (Ulmus parvifolia), or podocarpus (Podocarpus macrophyllum).