Search Results

You are looking at 1 - 10 of 13 items for

  • Author or Editor: H. Wilson x
Clear All Modify Search

The genus Rosa consists of more than 100 species classified into four subgenera, Eurosa, Platyrhodon, Hesperhodos, and Hulthemia, and distributed widely throughout the northern hemisphere. The subgenus Eurosa includes 11 sections. The other subgenera are monotypic. One hundred and nineteen accessions and 213 markers of 36 rose species that include eight sections of the subgenus Eurosa and one species each from the subgenera Hesperhodos and Platyrhodon were used to calculate a similarity matrix, which was clustered with the unweighted pair group method using arithmetic means (UPGMA). The RAPD markers distinguished between all the rose accessions, and species grouped into their respective sections. Therefore, classification of Rosa using RAPD data generally supports traditional classification. The Asian rose sections (Laevigatae, Banksianae, Bracteatae, Pimpinellifoliae, Chinenses, and Synstylae) were consistently separated from the primarily North American sections (Cassiorhodon and Carolinae). The Cassiorhodon and Carolinae sections were grouped together with the subgenera Hesperhodos and Platyrhodon. Both subgenera separated out at the same level as sections within the subgenus Eurosa, suggesting that they are more appropriately classified as sections within the subgenus Eurosa. Sections Cassiorhodon and Carolinae overlapped, and are probably best grouped as one section as previously suggested.

Free access

During 1989, clomazone (Command) was applied pretransplant or preemergence to transplanted and seeded watermelon (Citrullus lanatus, cv. Charleston Gray), respectively. Rates of 280, 414, and 560 g ai·ha-1 (0.50, 0.75, 1.0 pt/A) clomazone were applied to a Bojac sandy loam. Plots were rated for percentage weed control 21 DAT. Control of common lambsquarters [Chenopodium album (L.)], large crabgrass [Digitaria sanguinalis (L.) Scop.], and smooth pigweed (Amaranthus hybridus L.) increased with rate although smooth pigweed control was low. A significant phytotoxic injury characterized by bleaching and reduced growth occurred at all rates on melon transplants. No significant phytotoxicity occurred in seeded plots 35 DAT. Vine length (cm) was recorded 42 DAT. Vine length was reduced significantly at the 560 g·ha-1 rate in transplants. Vine length of seeded watermelons was not significantly affected.

Free access

Abstract

Xylem fluid and cotyledon, stem, and leaf tissue of eight watermelon [Citrullus lanatus Thunb. (Matsum. and Nakai)] cultivars differentially suspectible to races 0, 1, and 2 of Fusarium oxysporum f. sp. niveum, (E.F. Sm.) Synd. and Hans., causal agent of fusarium wilt, were assayed for general proteins and specific enzymes using SDS and IEF-PAGE and starch gel electrophoresis (SGE). SGE detected no variant isozymes among the watermelon cultivars in the six enzyme systems examined (GOT, MDH, PGI, IDH, PGM, PER); however, electrophoretic variants between tissue types were observed. Cotyledon tissue expressed an additional peroxidase band not seen in stem tissue. When xylem fluid samples were applied to IEF and SDS-PAGE and silver-stained, variant protein banding patterns were observed between the cultivars. The fusarium wilt-susceptible cultivar Black Diamond lacked the protein bands at pI = 5.1, 5.2, and 5.6 that were present in other cultivars. In addition, wilt-resistant ‘Dixielee’ possessed a differential band at pI = 6.0. We believe this to be the first report of electrophoretic differences among commercial watermelon cultivars.

Open Access

Changes in fructose, sucrose, and glucose were investigated in cured roots of `Beauregard', `Jewel' and `Travis' sweet potatoes stored at 15°C and 1.5°C for 8 wk. Samples of 6 roots each in triplicate were analyzed at 2 wk intervals. At each interval, samples were also heated for 5, 10, 20 or 40 min. at 100°C to determine changes in rate of maltose conversion. Roots stored at 15°C displayed gradual or no increase in sugars over the 8 wk. Roots stored at 1.5°C increased more rapidly in sugars, especially fructose, over the same time. `Jewel' had the greatest increase in the sugars when stored at 1.5°C. There was no consistent pattern of maltose conversion in roots stored at 15°C over the 8 wk storage time. Roots stored at 1.5°C displayed a reduction in ability to convert starch to maltose upon heating. Less maltose was produced with increasing time of storag at 1.5°C. `Beauregard' and `Jewel' changed the most, while `Travis' changed only slightly.

Free access

Abstract

Incorporation of S-propyl dipropythiocarbamate (vernolate) to a depth of 5.0 cm in soil resulted in more vigor reduction of sweet potatoes [Ipomoea batatas (L.) Lam.] than incorporation to a depth of 10.0 to 12.5 cm. The initial plant response to vernolate by ‘Nemagold’ was greater than by either ‘Julian’ or ‘Centennial’. Yields of all 3 cultivars were not affected by vernolate at the rate of 2.2 kg/ha, but yields were reduced at rates of 4.5 and 6.7 kg/ha. Activated carbon applied as a suspension in the transplant water protected sweet potatoes from vigor reductions at rates of vernolate up to 6.7 kg/ha. Dipping roots in a suspension of activated carbon prior to transplanting failed to protect sweet potatoes from vernolate injury.

Open Access

Pest management is of primary importance to the vegetable industry in our nation. In recent years producers have undergone much scrutiny concerning their pest control strategies, which often include the use of chemical pesticides. Due to the detrimental effects of many fumigants, growers are being forced to incorporate more environmentally sound agricultural practices while still producing a healthy, marketable commodity. The effects of three different fumigants and reflective mulches on plant growth and development were studied in field-grown, staked tomatoes. Methyl bromide, Telone II, or Telone C-17 were used in fumigation of plots. The establishment of mulch color was done via applications of exterior enamel paint, white or red in color, to the surface of black polyethylene mulch. With the exception of total marketable yields, no interactions existed between mulch color and fumigant. Red mulch and Telone II treatments resulted in the highest total marketable yield. Telone II application increased early marketable yield. White mulch color increased preharvest yield and black mulch color decreased early marketable yield. Low initial populations of nematodes may be the cause for lack of response due to fumigation.

Free access

System requirements for organic strawberry (Fragaria × ananassa) runner production under cover were determined during the 2001-02 and 2002-03 seasons. In the field, yield and fruit quality were assessed for organically produced runners (plug and bare-rooted transplant) in comparison with barerooted conventionally produced runners under organic, BioGro certified production conditions. The preferred organic production system was the enhanced suspended system, where mother plants grew on benches in the tunnel house and the first two runners were potted into growth substrate. This system produced approximately 50 plug transplants/mother plant or 200 plug transplants/m2. The least preferred system was the nursery bed, where mother plants were allowed to produce runners that yielded approximately 100 bare-rooted runners or 100 transplants/m2. Tunnel house production of runners (plug transplants and bare-rooted) allowed earlier planting (March vs. May) compared to field-produced bare-rooted runner plants. The earlier planting date increased yield by approximately 181 g/plant. Under organic production conditions, organically produced runners (plug and bare-rooted transplants) performed at least as well as bare-rooted conventionally produced runners. Our results show that indoor production of organic strawberry runners is possible. We also showed that organically produced runners (bare-rooted and plug transplants) perform similarly in the field compared to bare-rooted conventionally produced runners. Generally, there were no differences in yield or fruit quality among runner sources.

Full access

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.

Free access

Abstract

‘Beauregard’ sweet potato [Ipomoea batatas [L.] Lam.] was developed by the Louisiana Agricultural Experiment Station to combine resistance to diseases and insects of local importance with good horticultural and culinary characteristics. This cultivar, first designated L82-508, is named after Louisiana's renowned civil engineer and “Napo-lean in Grey,” Gen. P.G.T. Beauregard.

Open Access