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  • Author or Editor: J. T. Davis x
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Abstract

Phytotoxicity of burlap treated with 6 concentrations of CuSO4 or copper naphthenate (Cu Nap) was determined by enclosing the root balls of Cotoneaster divaricata in the treated burlaps, observing their growth for 40 weeks, and analyzing root, stem and leaf tissue for Cu, Fe, and Mn. Burlap treated with up to 4.0% Cu Nap or levels of CuSO4 less than 0.2% was not phytotoxic. Burlap treated with solutions of CuSO4 ≥0.2% was phytotoxic. Tissue analyses indicate that the injury from CuSO4 treated burlap was the result of high Cu concentrations in the roots of enclosed plants.

Open Access

Abstract

Photographs of five fully foliaged shade tree canopies (Acer. rubrum, Gleditsia triacanthos inermis, Gymnocladus dioicus, Pyrus calleryana, and Zelkova serrata) were taken using four film types, 50- and 28-mm lenses, and a range of three f-stops. Photographs of four leafless shade tree canopies (Gleditsia, Gymnocladus, Pyrus, and Zelkova) were taken using three film types and two lenses, at two f-stops. Film densities were determined with a light source and quantum sensor system for negatives of fully foliaged and leafless canopies and correlated with mean percentage of shade measured with a pyranometer. Pan-X film, at the correct f-stop setting, gave the highest correlation to mean percentage of the fully foliaged canopies. The 50-mm lens gave a higher correlation than the 28-mm lenses. Plus-X film, at an f-stop one above the proper setting, gave the highest correlation to mean percentage of shade of the leafless canopy. Plus-X film produced the most consistent results when photographs of the leafless canopy were taken during different days and times of the day. Using a densitometer to measure film density of the negatives gave high correlations to mean percentage of shade of the leafless canopy.

Open Access

Abstract

Treatment of burlap with copper sulfate (CuSO4) or copper naphthenate (Cu Nap) retarded its deterioration in soil. Deterioration of CuSC4-treated burlap was independent of treatment concentration while deterioration of Cu Nap-treated burlap was directly related to treatment concentration. Burlap treated with CuSC4 had a higher Cu content and lower initial break strength than burlap treated with Cu Nap. At 24°C, burlap treated with CuSC4 retained effective strength an average of 27 weeks, with Cu Nap, between 8 and 72 weeks. The rate of deterioration was significantly lower at 2°.

Open Access

Abstract

Five species of ornamental trees were examined with an Eppley pyranometer for interception of total solar radiation between 380 nm and 1100 nm. Measurements were made at the northern dripline and expressed as percentage of shade. Trees were selected for varying forms, branch, and canopy densities. Mean percentage of shade for the fully foliaged and leafless canopies, respectively, were Pyrus calleryana ‘Chanticleer’ 75% and 43%, Acer rubrum ‘Red Sunset’ 69% and 25%, Zelkova serrata ‘Village Green’ 61% and 24%, Gymnocladus dioicus 60% and 15%, Gleditsia triacanthos inermis ‘Moraine’ 56% and 21%. No statistically significant (PSO.05) correlation was observed among solar radiation intercepted and photosynthetically active radiation (PAR) intercepted, pathlength, silhouette area, and canopy volume. Growth habit did not affect shading capacities significantly.

Open Access

Abstract

The influence of leaching and water quality on the service life of Cu-treated burlap was investigated. Copper ammonium carbonate (CAC) and copper naphthenate (Cu Nap) treated burlap were more resistant to leaching with distilled H2O than CuSO4-treated burlap. When evaluating water quality, burlap treated with CuSO4 was found to be susceptible to ionic exchange of the Cu by Fe, Ca, Mg, Na or K. Soil burial tests of burlap treated with Cl or SO4 salts of Cu, Fe, Ca, Mg, Na and K resulted in the replacement of Cu and burlap deterioated within 1 month which was similar to untreated burlap. Water quality of leachates from 12 organic holding media such as pine bark, contained Ca and Mg in concentrations high enough to replace Cu in CuSO4-treated burlap. An inert holding media such as river sand would be preferred to reduce ion replacement and thus extend the service life of Cu-treated burlap.

Open Access

Abstract

7-Oxabicyclo (2.2.1) heptane, 2-3-dicarboxylic acid (endothall) alone was not an effective chemical abscissor of bean leaves (Phaseolus vulgaris L. cv. Red Kidney) until a concn of 30 to 40 mg/liter was attained, but in the presence of 800 mg/liter (2-chloroethyl)phosphonic acid (ethephon) abscission began at 5 mg/liter endothall. Low pH (1.5) significantly lowered the break strength of abscission zone explants of leaves sprayed with ethephon and endothall compared to pH 6.0, and endogenous ethylene production from endothall alone was higher at pH 1.5 than pH 6.0.

Open Access

Abstract

Minnesota 101 is a monoecious, short intemode breeding line of muskmelon, Cucumis melo L. Its primary use is envisaged as that of a breeding line useful as a parent in the production of F1 hybrid cultivars, and as germplasm in the long term improvement of muskmelon.

Open Access

Relative water usage of four species of container-grown woody ornamental shrubs (Buxus japonica (Japenese boxwood), Leucophyllum frutescens (Texas sage), Ligustrum japonica (ligustrum) and Pittosporum tobira wheeleri (dwarf) pittosporurm)), normally used for home landscaping in south Texas, were evaluated by comparing water consumption and frequency of watering with growth rates and horticultural quality after six months growth in containers. Growth rates were determined by the difference in plant height and leaf area from the control unwatered plants and were used to characterize the suitability of ornamental shrubs for xeric landscapes. While frequency of watering had no significant effects on plant height, only ligustrum and dwarf pittosporum plants watered on weekly basis showed positive change in leaf area. There was considerable leaf regrowth in Texas sage plants after initial leaf loss. Of all the shrubs tested, dwarf pittosporum plants watered biweekly used less water to maintain their horticultural quality.

Free access

Abstract

The Arkansas Agricultural Experiment Station announces the release of ‘Encore’ southernpea [Vigna unguiculata (L.) Walp], ‘Encore’ has potential as both a commercial and home garden cultivar because of its high yield (Table 1), concentrated set, and bush plant habit (Fig. 1).

Open Access

Mentha longifolia, a wild relative of the polyploid, cultivated Mentha (mint) species, was evaluated as a potential model system for genetic research relevant to the cultivated mints. Fourteen Mentha longifolia accessions maintained by the US Department of Agriculture (USDA), Agricultural Research Service, National Clonal Germplasm Repository (NCGR), were highly diverse with respect to geographic origin, oil composition, verticillium wilt resistance, aspects of morphology, and molecular marker polymorphism. Accession CMEN 584 was the only carvone chemotype, while CMEN 682 was the only accession with high menthol content. Trans-piperitone oxide was the primary oil component of accessions CMEN 17 and CMEN 18, while pulegone was most abundant in CMEN 20, CMEN 500, CMEN 501, and CMEN 585. Four accessions—CMEN 585, CMEN 17, CMEN 501, and CMEN 81—were consistently resistant to verticillium wilt, while CMEN 584 and CMEN 516 were highly susceptible. Pairwise similarity coefficients were calculated and a UPGMA (unweighted pair-group analysis) tree was constructed on the basis of 63 informative randomly amplified polymorphic DNA (RAPD) marker bands. CMEN 585 and CMEN 584 shared the greatest number of bands (16), and formed a distinct cluster in the UPGMA tree. Seven pairs of accessions had no bands in common, emphasizing the high degree of molecular diversity represented by these accessions. The favorable features of diploid (2n = 2x = 24) genome constitution, comparatively small genome size (400 to 500 Mb), self-fertility, fecundity, and diversity with respect to economically relevant traits, contribute to M. longifolia's potential usefulness as a model system for the cultivated mints. As a perennial species amenable to vegetative propagation, M. longifolia's spectrum of susceptibility/resistance to an important vascular wilt disease encourages its further evaluation as a system for broader studies of plant–microbe interactions and disease resistance mechanisms.

Free access