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  • Author or Editor: R. D. Wright x
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This study evaluated the effects of nine alternative substrates on herbicide efficacy in container-grown nursery crops: 1) VT (pine wood chips hammer-milled to pass a 0.4-cm screen); 2) USDA (pine wood chips hammer-milled to pass a 0.64-cm screen; 3) AUC (Pinus taeda chipped including needles); 4) AUHM (AUC hammer-milled to pass a 0.48-cm screen; 5) 1 VT: 1 commercial grade pinebark (v/v); 6) 1 USDA: 1 pinebark (v/v); 7) 1 AUC: 1 pinebark (v/v); 8) 1 AUHM: 1 pinebark (v/v); and 9) 6 pinebark: 1 sand (v/v). Each substrate was amended with 6.35 kg of 17–6–12 (17N–2.6P–10K) control-release fertilizer, 2.27 kg of lime, and 0.89 kg micromax per cubic meter. Containers (8.3 cm) were filled on 15 June and three herbicides applied the next day: Rout (oxyfluorfen + oryzalin at 2.24 + 1.12 kg·ha-1), Ronstar (oxadiazon at 4.48 kg·ha-1) and a nontreated control. The next day, containers were overseeded with 25 prostrate spurge seed. Data collected included weed counts 30 and 60 days after treatment (DAT) and weed fresh weights at 60 DAT. Spurge occurred less in the two treatments of 100% pine wood chips followed by the AUC treatment. With spurge, the least weed fresh weight occurred with the USDA and AUC treatments. For example, at 30 DAT, spurge count was reduced by 33%, 40%, and 70%, respectively, when comparing VT, USDA, and AUC to pinebark: sand. Spurge fresh weight at 60 DAT followed a similar trend. With all of the substrates except AUHM, the addition of commercially used pine bark resulted in less weed control. Rout provided superior control followed by Ronstar and the nontreated control. These data show that control of prostrate spurge with commonly used preemergent applied herbicides may actually be improved with some of the alternative substrates currently being tested.

Free access

Scale insects are some of the most abundant and damaging pests of urban forests in North America. Despite their prevalence, scale insect emergence during the winter dormant season, which could contribute to their population growth and spread and thereby inform management, has not been thoroughly investigated. Crapemyrtle bark scale (CMBS), Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae), is a nonnative pest of a widely grown landscape tree, crapemyrtle (Lagerstroemia spp.). Now present throughout the Southeast and Mid-Atlantic regions of the United States, CMBS has spread rapidly since its initial detection in Plano, TX, USA, in 2004. The contributions of year-round activity to the insect’s widespread abundance and economic importance are unclear. Here, after infesting crapemyrtles with known numbers of CMBS in Summer 2021, we recorded the presence or absence of CMBS immatures on infested trees from Autumn 2021 to late Winter 2022. We found that active nymphs occurred throughout the entirety of these colder seasons. Additionally, average CMBS density drastically increased from October to March, growing from 28 ± 10 SE insects per plant to 554 ± 133 SE, respectively. Our results highlight previously unknown aspects of year-round crawler emergence by CMBS, which could provide opportunities for landscape managers to use targeted winter applications of less harmful pesticides such as horticultural oils.

Open Access

Abstract

Rooted stem cuttings of Ilex crenata Thunb. ‘Helleri’ were grown in a series of experiments for 3 or 6 weeks at day/night temperatures ranging from 6°/2° to 26°/22°C. Percentage of tissue N increased over time at all temperatures but at progressively slower rates as temperature decreased. Temperatures of 18°/14° or less prevented visible shoot elongation, although plant dry weights increased at all temperatures. Percentage of dry weight K increased and P, Ca, Mg, Mn, and Zn decreased with time for plants grown at 10°/6°, 14°/10° and 18°/14°, whereas the total amounts of each nutrient per plant increased. Nutrient content increased at greater rates as temperature increased. Nitrogen accumulation data were used to develop a method of timing fertilizer application in the fall. The proposed procedure ensures adequate nutrient accumulation to support vigorous spring growth without jeopardizing proper cold acclimation in the fall

Open Access

Abstract

Pine bark was shown to adsorb 1.5 mg of N/g of bark when NH4 solutions were leached through the bark. Increasing pH of bark increased adsorbed NH4. At pH 3.3, only NH4 was adsorbed to bark particles when a fertilizer solution containing NH4, Ca, K, and Mg was applied. However, adsorption of NH4 and other cations increased as pH was increased from 3.8 to 5.8. These data indicate that 2 types of sites exist for the adsorption of NH4 to pine bark. One site is effective at lower pH; the other is active as pH increases. Daily application of 2.5 cm of water containing 50 ppm NH4 required 20 days for equilibration to occur so as to satisfy all binding sites. Thus, incorporation of NH4 into a pine-bark medium prior to planting may be advisable to prevent low N levels from occurring in the container solution due to NH4 binding when plants are first planted and fertilized.

Open Access