Variation and Correlation between the Physical Properties of Dogwood Seeds

Information about the physical properties of berries of selected dogwood species is available in the literature, but the basic physical traits of berry seeds have not been investigated to date. In this study, the terminal velocity, thickness, width, length, angle of external friction and mass of seeds of 11 dogwood species were measured. The measured parameters were used to calculate the geometric mean diameter, aspect ratio and sphericity index of each seed. The average values of the evaluated parameters were determined in the following range: terminal velocity - from 9.95 to 13.15 m s-1, thickness - from 3.31 to 5.02 mm, width - from 4.14 to 5.38 mm, length - from 4.33 to 11.55 mm, angle of external friction - from 9.97 to 29.85 ºC, mass - from 33.06 to 175.51 mg. The analyzed dogwood species were arranged in the following ascending order based on the geometric mean diameter of their seeds: Cornus macrophylla, Cornus alba, Cornus amonum, Cornus kousa, Cornus obliqua, Cornus controversa, Cornus walteri, Cornus sanguinea, Cornus florida, Cornus officinalis and Cornus mas. The seeds of Cornus alba, Cornus controversa, Cornus florida, Cornus kousa, Cornus macrophylla, Cornus mas and Cornus officinalis could be sorted with the use of mesh sieves with longitudinal openings, the seeds of Cornus macrophylla, Cornus sanguinea and Cornus walteri - with the use of mesh sieves with round openings, and the seeds of Cornus alba, Cornus macrophylla and Cornus obliqua - with the use of cylindrical graders.

Inhibition of Digestive Enzymes and Antioxidant Activity of Extracts from Fruits of Cornus alba, Cornus sanguinea subsp. hungarica and Cornus florida–A Comparative Study

The fruits of some Cornus species (dogwoods) are used in traditional medicine and considered potential anti-diabetic and hypolipemic agents. The aim of the study was to determine the ability of extracts from Cornus alba (CA), Cornus florida (CF), and Cornus sanguinea (CS) to inhibit digestive enzymes namely α-amylase, pancreatic lipase, and α-glucosidase, as well as isolation of compounds from plant material with the strongest effect. In addition, the phytochemical profile and antioxidant activity of extracts from three dogwoods were compared with HPLC-DAD-MS/MS and DPPH scavenging assay, respectively. Among the aqueous-ethanolic extracts, the activity of α-amylase was the most strongly inhibited by the fruit extract of CA (IC50 = 115.20 ± 14.31 μg/mL) and the activity of α-glucosidase by the fruit of CF (IC50 = 38.87 ± 2.65 μg/mL). Some constituents of CA fruit extract, such as coumaroylquinic acid, kaempferol, and hydroxytyrosol derivatives, were isolated. Among the three species of dogwood studied, the greatest biological potential was demonstrated by CA extracts, which are sources of phenolic acids and flavonoid compounds. In contrast, iridoid compounds or flavonoid glycosides found in fruits of CF or CS extracts do not play a significant role in inhibiting digestive enzymes but exert antioxidant activity.

Control of Insects and Diseases with Intelligent Variable-rate Sprayers in Ornamental Nurseries1

Intelligent spray technology can reduce pesticide use and safeguard the environment; however, its ability to effectively control insects and disease must be validated before its adoption by growers. Comparative tests for two different laser-guided variable-rate intelligent sprayers and the same sprayers with conventional constant-rate mode were conducted to control pests at two ornamental nurseries in two growing seasons in Ohio. Crabapple [Malus ‘Sutyzam’ (Sugar Tyme®), M. sargentii], apple (Malus pumila), maple [Acer ×freemanii ‘Jeffersred' (Autumn Blaze®), A. rubrum ‘Franksred' (Red Sunset®) and A. rubrum], birch (Betula nigra and Betula populifolia ‘Whitespire'), London planetree (Platanus ×acerifolia ‘Bloodgood') and dogwood (Cornus florida) were used as the test plants. Intelligent spray technology reduced pesticide use by 56.1% and 51.8% on average at the two nurseries, respectively. Compared to conventional air-assisted sprayers, severity of scab on apple trees and powdery mildew in dogwood was reduced on intelligent spray-treated plants at one nursery, and there were equal or fewer leafhoppers in maple trees and aphids in birch trees when sprayed using intelligent spray technology at both nurseries. These results suggest that intelligent, variable-rate sprayers achieve equivalent or greater insect and disease control in ornamental tree nurseries compared to conventional, constant-rate sprayers. Index words: aphid, apple scab, environmental protection, leafhopper, precision spray, powdery mildew, sustainable. Species used in this study: apple (Malus pumila Mill), birches (Betula nigra L, Betula populifolia Marsh. ‘Whitespire'), crabapples [Malus ‘Sutyzam' (Sugar Tyme®), M. sargentii Rehder], dogwood (Cornus florida L.), maples [Acer ×freemanii E. Murray ‘Jeffersred' (Autumn Blaze®), A. rubrum L. ‘Franksred'(Red Sunset®) and A. rubrum L.], London planetree [Platanus ×acerifolia (Ait.) Willd. ‘Bloodgood'].

Evaluation of Biological Agents for Control of Macrophomina Root Rot and Powdery Mildew in Flowering Dogwood (Cornus florida L.)

Six biological control agents (BCAs) (two bacteria, two fungi, and two yeasts) that were previously shown to be effective against powdery mildew (Erysiphe pulchra) were tested for efficacy against Macrophomina phaseolina root rot on flowering dogwood (Cornus florida) in the greenhouse. Two of the bacterial isolates, Stenotrophomonas sp. (B17A) and Serratia sp. (B17B), were effective in controlling both macrophomina root rot and powdery mildew, similar to fungicide control thiophanate methyl, when roots were drenched with the six BCAs individually. In addition, the two bacterial BCAs improved plant growth with respect to stem diameter, stem length, dry weight, and green foliage compared with fungicide-treated plants or nontreated controls grown in sterile soil. These results confirm previous results in which B17A and B17B suppressed powdery mildew and also promoted plant growth in flowering dogwood. Although macrophomina root rot has been previously reported as a potential problem in flowering dogwood, especially in field conditions, simultaneous infection with macrophomina root rot and powdery mildew has not been previously reported. This study confirmed that M. phaseolina infection was characterized by stubby roots and black root lesions, and plants infected with both powdery mildew and macrophomina root rot had smaller root mass compared with fungicide-treated plants. Neither of the two pathogens killed their host plants, but compounded infections significantly reduced the plant root system and plant growth. The efficacy of the two bacterial isolates in controlling both powdery mildew and macrophomina root rot suggests their potential utilization in controlling both diseases in dogwood nursery production and in other plants that are hosts to both powdery mildew and macrophomina root rot. Plant growth promoted by the two BCAs may be attributed to powdery mildew and macrophomina root rot control, but comparisons between fungicide-treated plants and control plants not inoculated with BCAs or root rot pathogen suggested that the two BCAs may play a role as bio-stimulants in growth enhancement. These results also suggest that the two biocontrol agents are not phytotoxic to dogwood.