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  • Author or Editor: Wheeler Foshee x
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Orchard floor treatments of total weed control with herbicides, disking, mowing, grass control only with herbicides, and no control of vegetation were maintained in a 3 × 3-m area underneath young pecan [Carya illinoinensis (Wangehn.) K. Koch] trees. Soil compaction in treated areas was compared to heavily trafficked row middles. Mean cone index (CI) readings obtained from a cone penetrometer for the heavily trafficked areas were higher, indicating greater compaction than all other treatments in the 4.7- to 11.8-cm soil depth range. Heavily trafficked areas had severe compaction (>2.0 MPa) at the 9.5- to 22.9-cm soil depths. Mowed plots had similar CI readings at 14.2- to 54.3-cm depth as those heavily trafficked. The mowed areas had severe compaction at the 14.2- to 22.9-cm depth range. Grass control only with herbicides and plots with no control of vegetation had low CI throughout the soil profile. Disking, grass control, and no control treatments had similar effects, except at the 4.7-cm depth, where disking reduced compaction. An orchard floor management practice that minimized traffic near young trees, but also reduced weed competition, appears to be the best choice.

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Kiwifruit (Actinidia deliciosa A. Chev. and Actinidia chinensis Planch) require winter chilling to complete rest and growing degree hours to grow. This study was conducted to compare the chilling requirement and growing degree hours for budbreak and floral development of two female cultivars of A. chinensis, ‘Golden Sunshine’ and ‘Golden Dragon', two female cultivars of A. deliciosa, ‘AU Fitzgerald’ and ‘Hayward', and two male cultivars of A. deliciosa, ‘AU Authur’ and ‘Matua'. In 2005 and 2006, shoot cuttings were made from dormant 1-year canes at nodes 6 to 20, starting from the basal end of canes and held in cold storage at 4 °C. Cuttings were removed from storage and flowering was forced in a greenhouse maintained at 25 °C. Maximum budbreak was determined to be 700 h for ‘Golden Sunshine’, 800 h for ‘Golden Dragon’ and ‘AU Fitzgerald’, and 900 h for ‘Hayward’, ‘Matua’, and ‘AU Authur’. Growing degree hour to first budbreak were 9,500 h for ‘Golden Dragon’ and 15,000 h for ‘Golden Sunshine’, with the correlation of determination too low for the other cultivars. The high heat requirement for ‘Gold Sunshine’ would reduce the risk of injury by late spring frosts. Bloom period of both male cultivars overlapped with bloom periods for all cultivars except ‘Golden Dragon’ for fully mature vines in the field.

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Hairy vetch (Vicia villosa Roth), common vetch (V. sativa L. `Cahaba White'), arrowleaf clover (Trifolium vesiculosum Savi `Yuchi'), crimson clover (T. incarnatum L. `Tibbee'), red clover (T. pratense L. `Redland II'), yellow nutsedge (Cyperus esculentus L.), buckwheat (Fagopyrum sagittatum Gilbert), hairy indigo (Indigofera hirsuta L.), bahiagrass (Paspalum notatum Flugge `Pensacola'), common bermudagrass [Cynodon dactylon (L.) Pers.], and centipedegrass [Eremochloa ophiuroides (Munro) Hack] were grown for 3 years in a 3 × 3-m spacing around young pecan [Carya illinoinensis (Wangenh.) K. Koch] trees. Compared to weed-free plots, all cover crops suppressed tree growth substantially, and there were no differences among cover crops in the degree of suppression. Mean trunk cross-sectional area of weed-free trees increased 26-fold by the end of the third growing season but increased only 13-fold for trees grown with any cover crop. These results suggest that cover crops, if grown in young pecan orchards to promote beneficial insects, should be excluded from the immediate area around the young trees.

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Effects of combining labeled rates of halosulfuron (Sandea) and s-metolachlor (Dual Magnum) were evaluated as a preemergence (PRE) application in a randomized complete block designed experiment at the Wiregrass Experiment Station in southeastern Alabama. Treatments were assigned in a factorial arrangement of four levels of halosulfuron (0.0, 0.009, 0.018, and 0.036 lbs. a.i./acre) and six levels of s-metolachlor (0.0, 0.25, 0.50, 0.75, 1.0, and 1.25 lbs. a.i/acre). The purpose of the study was to ascertain possible synergistic effects from combining these two herbicides to control nutsedge at a possible lower cost. Two repetitions were completed in 2005 with data pooled in analysis. Results found no interaction between the halosulfuron and the s-metolachlor and therefore no synergistic affects. Analysis of the main effects revealed that the highest labeled rate of either herbicide gave the highest percent control relative to the nontreated control. Soil activity of halosulfuron in controlling nutsedge has been shown to be less effective than foliar applications. Our own LD90 greenhouse studies confirmed this to be true. We examined four application techniques of halosulfuron (POST both soil and foliar, POST foliar only, POST soil only, and PRE soil only) to determine the LD90. Results revealed that halosulfuron had the lowest LD90 from the treatments with a foliar application. However, some soil activity was observed. Results from field studies indicated that PRE applications of halosulfuron must be at the highest labeled rate to provide effective control. S-metolachlor was equal to halosulfuron on percent control and is lower in cost on a per acre basis.

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American skullcap (Scutellaria lateriflora L.), a medicinal plant species valued for its sedative properties associated with flavonoids, is generally harvested from the wild. Scientific information on how field cultivation practices affect dry matter yield is lacking in this species. A 2 × 2 × 3 split plot factorial experiment within a randomized complete block design was conducted on a Marvyn loamy sand (fine-loamy, kaolinitic, Thermic Typic Kanhapludults) in Central Alabama to explore effects of light, irrigation, and nutrient application on dry matter yield of American skullcap. Treatment factors were shade (40% shade vs. no shade), irrigation (applied at 30 kPa vs. no irrigation), and nutrients [no added nutrients vs. nutrients added as chemical fertilizer (100 kg nitrogen, 68 kg phosphorus, 42 kg potassium/ha) or chicken litter (100 kg nitrogen, 50 kg phosphorus, and 123 kg potassium/ha)]. Shade formed the main plot units, whereas irrigation × nutrient factorial combinations were subplots. Skullcap shoots in experimental plots were harvested four times during the course of the two-year experiment (2007, 2008). All growth variables measured, except percent dry matter, performed better under shade than in full sun. Dry matter yield was increased 45% by shade, 61% by irrigation, and 22% by addition of nutrients. A significant irrigation × nutrients interaction was observed at the first and second harvests. Highest yields were obtained with the irrigation + manure and irrigation + fertilizer treatments under shade and the lowest with fertilizer and the control treatments in full sun.

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A field experiment was conducted from 1995 to 1999 in central Alabama to determine the effect of repeated applications of glyphosate herbicide on young ‘Sumner’ pecan trees. Herbicide treatments were applied on ‘Sumner’ pecan trees varying in age from newly established (first growing season) to established fourth-year growing season trees. Measurements taken included tree mortality, trunk cross-sectional area, nut yield, and nut quality in the third and fourth years of the study. Glyphosate applications were targeted at the lowest 5 to 8 cm of the tree trunk (“standard” treatment), a percentage (lowest 33%, 67%, or 100%) of the tree trunk below the first scaffold limb, or a percentage (lowest 25%, 50%, 75%, or 100%) of tree foliage to simulate situations ranging from minor spray drift to major misapplication. No adverse effects were detected when glyphosate was applied to trunks, regardless of tree age. However, repeated application of glyphosate to 75% to 100% of tree foliage resulted in a significant reduction of growth and, in some cases, tree death. Results indicate that limited contact of glyphosate with the lowest 5 to 8 cm of the trunk of the young pecan tree, which usually occurs during conventional orchard weed management, is unlikely to result in adverse effects on young pecan trees.

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Okra (Abelmoschus esculentus ‘Clemson Spineless’) was grown on an Orangeburg sandy loam soil in Shorter, AL. Okra was direct-seeded in single rows. Treatments consisted of five mulch colors: black, white, red, silver, and blue installed either with or without spun-bonded row cover. Soil temperatures were 4 to 7 °C lower than air temperatures in all treatments. The use of darker (black, blue, red) -colored plastic mulches increased early and total yield of okra compared with bare soil with and without row cover. Increased soil and air temperatures did not always correlate to an increase in yield. It can be concluded that the use of dark plastic mulch is advantageous to growers of okra in climates that do not have cool springs, but the added use of row covers to plastic mulch has no effect on growth and yield. The profit of marketable okra produced using a row cover was $1.37 versus $1.35 per pound without a cover in 2003 and $1.28 versus $1.29 per pound in 2004. Blue plastic mulch is ≈$0.08 per foot more expensive than black plastic. Our data do not show an economic advantage for blue over black mulch for okra, but the positive effect cited by other authors may be more pronounced with leafy vegetables.

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An experiment was conducted to determine the effects of banded phosphorus (P) applications at differing rates in irrigated and nonirrigated pecan (Carya illinoinensis) plots on P movement within the soil, P uptake and movement within pecan trees, and the yield and quality of nuts. On 20 Mar. 2015, P applications of 0 kg·ha−1 (0×), 19.6 kg·ha−1 (1×), 39.2 kg·ha−1 (2×), and 78.5 kg·ha−1 (4×) were administered to bands of triple superphosphate to randomly selected trees in nonirrigated and irrigated plots of a ‘Desirable’ orchard bordered by ‘Elliot’ trees. When P was applied at the 2× and 4× rates, the total soil test P decreased linearly by 35% and 54%, respectively, in nonirrigated plots and by 41% and 59%, respectively, in irrigated plots over the course of the experiment. There was no change in soil test P over time at the 0× rate for either irrigation regimen; however, at the 1× rate, soil test P decreased 44% in the irrigated plot but did not change in the nonirrigated plot. The largest linear decrease of the soil test P from the start of the experiment to the end of the experiment occurred in the top 0 to 7.6 cm. In contrast, soil test P at a depth of 15.2 to 22.9 cm decreased linearly by 23% in the nonirrigated plot, but it did not decrease over time in the irrigated plot. Increasing the P application rate increased foliar P quadratically in the nonirrigated plot, but only the 4× application rate increased foliar P compared with the 0× control. In the irrigated plot, foliar P concentrations decreased linearly from 2015 to 2017, and foliar P concentrations were not influenced by the P application rate. No differences in pecan yield or quality were observed in either irrigated or nonirrigated plots. Overall, P banding may not be the most sustainable way to increase foliar concentrations of P quickly or to maintain concentrations of the nutrient in the long term.

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Field studies were conducted in 2016 and 2017 in Tallassee, AL, to evaluate the effect of preemergence (PRE) herbicide applications pre- and postcrimp in a cereal rye (Secale cereale) cover crop for control of escape weeds in watermelon (Citrullus lanatus). Treatments were arranged in a randomized complete block design with an augmented factorial treatment arrangement with four replications. The augmented factorial arrangement included three levels of PRE herbicides, two levels of application timing, and a nontreated control. PRE herbicide treatments included ethalfluralin (18 oz/acre), fomesafen (2.5 oz/acre), and halosulfuron (0.56 oz/acre). Application timings were precrimp (herbicide applied before crimping and rolling of the cover crop) and postcrimp (herbicide applied after crimping and rolling of the cover crop). A nontreated cover crop only treatment was also included. There were no interactions among application timing and herbicide. Results indicated application timing influenced total weed coverage but not watermelon yield. Total weed coverage was lowest in precrimp applied treatments at 2, 4, and 6 weeks after treatment (WAT). Comparing individual treatments revealed no significant differences among herbicides with respect to watermelon yield; however, all herbicides increased yield compared with the nontreated.

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Parsley seeds are known for nonuniform and long germination; consequently, vegetable nurseries commonly use priming techniques to improve the production of parsley seedlings. The objectives of this study were 1) to characterize the imbibition curve of parsley seeds, 2) to evaluate the effect of different priming agents on parsley seedling production, and ultimately 3) to compare priming techniques for emergence and vigor of parsley’s seedlings, thus providing an optimal priming strategy for parsley seedling production. Using three priming agents—water (seeds imbibed for 24, 48, 72, and 96 hours), polyethylene glycol 6000 (PEG6000) (seeds imbibed at –0.5, –1.0, –1.5, and –2.0 MPa for 29, 58, 87, and 116 hours), and gibberellic acid (GA) (seeds imbibed at 0.5, 1.0, 1.5, and 2.0 g·L−1 a.i. of solution for 15, 30, 45, and 60 minutes), and two parsley cultivars (Krausa and Titan), three experiments evaluated parsley seedling parameters, including emergence speed index (ESI) and total emergence (TE) in a complete randomized block design (n = 4) each. In Expt. 1 (hydropriming), increasing water imbibition time (IT) reduced ESI on both parsley cultivars. In addition, the TE quadratically reduced with the increase of water IT. In Expt. 2 (osmopriming), there was no significant main effect or interaction of treatments on ESI. Regardless of PEG6000 concentration, the TE had a linear increase with the increase of IT for cultivar Krausa but not for cultivar Titan. In Expt. 3 (hormonal priming), there was a significant increase in ESI and TE with the increase in GA rate. Ultimately, strategies for analysis of best priming were water at 24 hours of IT, PEG6000 at –2.0 MPa for 116 hours of IT, and GA at 2.0 g·L−1 a.i. of solution for 15 minutes of IT. Once compared with an untreated seeds treatment, priming strategies of water imbibition for 24 hours and PEG6000 at –2.0 MPa for 116 hours had the highest ESI and TE.

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