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  • Author or Editor: A.R. Harmon x
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Abstract

Many pecan groves throughout the south are grazed for pasture. Simazine at 3 lb/A is recommended for pastures, but the amount of residue accumulating in pecan nuts grown in pastures treated with this herbicide is not known. In this study rates of 0, 1, 2, 4, and 8 lb/A of active Simazine was applied as a spray underneath the canopy of approximately 40-year old Stuart pecan trees on March 16, 1963 while trees were dormant. Two replications were used. On November 14, a 10 lb nut sample was collected from each tree and analyzed by the Geigy Research laboratories. All samples contained less than 0.04 ppm of Simazine in both shells and kernels, which is considered essentially no residue. No damage to the trees was noticed.

Open Access

Abstract

‘Coastal Red’ sweet potato [Ipomoea batatas (L.) Lam.] was developed by the Univ. of Georgia at the UGA Coastal Plain Experiment Station. This cultivar combines high yield with high resistance to fusarium wilt and root-knot nematodes, resistance to soil insects, excellent storage quality, profuse plant production from bedded roots, and good baking and canning quality in a red-skinned cultivar.

Open Access

`Crimson Sweet' watermelon plants grown under various mulches and rowcovers were harvested weekly and analyzed for absolute growth rate (AGR), relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), specific leaf area (SLA), specific leaf weight (SLW), leaf weight ratio (LWR), leaf area duration (LAD), biomass duration (BMD), and runner growth. Hourly air and soil temperatures were monitored inside the rowcovers. Vispore and Reemay rowcovers generally showed greater mean AGR, LAR, SLA, LAD, and BMD than Agronet black-clear and black mulches. No significant differences in LWR were found between mulched and rowcovered plants. Plants under mulches and rowcovers showed significant increases in AGR, RGR, NAR, LAR, SLA, LAD, and BMD over noncovered (bare ground) plants. Longest runner length was highly correlated with total runner length. Growth analyses depicted decreased growth rate inside the rowcovers during the hottest weeks of the summer, and generally correlated well with the earliness and total yield of the crop.

Free access

Abstract

Concentration of pecan roots in the 15-45 cm layer of soil and lower soil pH, P, and K in the 15-30 cm layer than in adjacent layers indicate that pecan trees are feeding primarily in this zone. Fertilization with N-containing complete fertilizers or NH4NO3 reduced soil pH gradually, and continued annual application gradually affected deeper soil layers. Phosphorus and K applications affected soil pH very little.

Continued annual applications of P gradually built up residual soil P (measured one year later) to high levels at all layers sampled for old trees over a 10-year period. When P applications were based on topsoil P levels, subsoil P level was not affected over a 5-year period.

Applications of K usually increased residual soil K, but rate effects were slow to appear in old trees and were often erratic. Rates of K were readily reflected in residual soil K levels at depths to 70 cm when rates were based on topsoil K level.

Open Access

Abstract

Zinc uptake by pecan leaves as affected by Zn sources and methods of application was compared for young and old pecan trees. Sources of Zn used were ZnSO4, ZnO, ZnHEDTA, and ZnEDTA. Methods of application were broadcast, in holes, and foliar sprays. Chelates were applied at 1/5 - 1/10 the rate of Zn used for ZnSO4 or ZnO. Leaf Zn from trees treated with ZnO broadcast was either equal to or greater than that from trees treated with ZnSO4 broadcast when both were applied every year. On young Zn deficient trees, ZnEDTA entered the tree earlier than the other sources when broadcast. Zinc deficiency symptoms appeared when leaf Zn was 40 ppm or less. Foliar sprays of ZnSO4 caused erratic and temporary increases in leaf Zn.

Open Access

Six processing squash and pumpkin cultivars (Marrow, Howden, Butternut, Buttercup, Golden Delicious, and Turk's Turban) were direct-seeded into replicated plots treated with selected pre-emergence herbicides. Treatments included application of varying rates of clomazone, an inhibitor of carotenoid biosynthesis. Problems associated with bleaching and whitening of fruit, and storability have been reported in squash and pumpkins treated with labelled rates of clomazone. Therefore, this study was initiated with FMC to evaluate herbicide treatment effects on cultivars during 6 wk postharvest storage. Replicated samples were stored at 18°C and quality was evaluated at each storage interval (0, 2, 4, 6 wk). Quality was assessed by total carotenoid and reduced ascorbic acid contents, color retention, peroxidase and lipoxygenase activities, % soluble solids, and fatty acid composition. Results indicated differences in levels of tissue bleaching, carotenoid contents, enzyme activities among cultivars over time. Treatment with high rates of clomazone resulted in reduced tissue carotenoid content, with certain cultivars more affected than others.

Free access

‘Flicker’ is a southern highbush blueberry (SHB, Vaccinium corymbosum) cultivar frequently selected by growers in Central and South Florida. In 2014, several growers in Central Florida experienced issues with anthracnose stem lesions and twig dieback on ‘Flicker’, resulting in a reduction in new plantings and the removal of many existing plantings. The objective of this study was to determine the level of anthracnose susceptibility of certain commercially available SHB cultivars, which information can be used to limit further use of susceptible cultivars in the University of Florida blueberry breeding program. The screening was performed using a spray inoculation of a virulent Colletotrichum gloeosporioides isolate onto whole V. corymbosum plants, followed by measurement of incidence and severity of disease over time. In repeated experiments, ‘Flicker’ and two other cultivars had a significantly higher mean number of lesions and area under the disease progress curve (AUDPC) than any other tested cultivar, and in both experiments, the observed lesions were similar in many respects to those previously reported on northern highbush blueberry (also V. corymbosum). Although the results of these experiments may ultimately indicate that Flicker has a unique genetic susceptibility to this form of anthracnose among SHB cultivars commercially grown in Florida, screening of additional cultivars must be performed for confirmation.

Open Access

Abstract

A pot study using Tifton loamy sand and quartz sand determined the effect of Attapulgus Clay (AC) on the growth of turnips as a soil amendment.

Applications of AC increased the growth of all parts of the turnip plant. Yield of edible roots and leaves was significantly higher than the check when the soil and sand medium contained 1% AC. A concentration of 5% AC was required for significant increases in fibrous root yield. Leaf growth and dry matter percentage in the edible root was .87 g/pot and 1.46 percentage points higher, respectively, in the soil than in the sand media. Conversely, fibrous root growth was .47 g/pot higher in the sand than in the soil media. In the spring edible root and leaf growth were 6.97 and 6.48 g/pot, respectively, higher than in the fall for a 60-day growth period.

Open Access

The objective was to analyze the physical, chemical, and biological water quality in horticulture irrigation systems in 24 ornamental plant greenhouses and nurseries in the United States. At each greenhouse or nursery, water was collected from up to five points (“Sample Types”) which included 1) “Source” from municipal or private well supplies, 2) “Tank” from enclosed storage containers, 3) “Subirrigation” from water applied to crops in ebb-and-flood systems, 4) “Furthest Outlet” that were irrigation emitters most distant from the Source, and 5) “Catchment Basin” from open outdoor retention areas. On average, Source water had the highest physical and microbial quality of Sample Types including the highest ultraviolet (UV) light transmission at 86%, lowest total suspended solids (TSS) at 3.1 mg·L−1, and lowest density of aerobic bacteria with 1108 cfu/mL of water. Average quality of recycled water from Subirrigation or Catchment Basins did not meet recommended levels for horticultural irrigation water for UV transmission (68% to 72% compared with recommended 75%), microbial counts (>100,000 cfu/mL compared with recommended <10,000 cfu/mL), and chemical oxygen demand (COD) (48.2 to 61.3 mg·L−1 compared with recommended <30 mg·L−1). Irrigation water stored in Tanks or applied at Furthest Outlets had lower physical and biological water quality compared with Source water. Level of aerobic bacteria counts highlighted a risk of clogged microirrigation emitters from microbial contaminants, with highest bacteria levels in recirculated irrigation water. The physical, chemical, and microbial water quality results indicate a need for more effective water treatment to improve biological water quality, particularly with recirculated irrigation.

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