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  • Author or Editor: L. Brandenberger x
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Melon growers in the Lower Rio Grande Valley of Texas have observed in the past that particular sizes of melons and the earliness of melons had a direct effect upon economic returns. A replicated study was carried out during two seasons to determine what specific effects plant density, row arrangement, and cultivar would have on fruit size and yield. The study combined six spacing treatments with three cultivars in a randomized design utilizing five replications on top of raised beds on 80-inch centers. Work was initiated by direct seeding and then thinning to the desired spacing interval in plots located in a commercial field. Plots were harvested by commercial harvesting crews. Results indicate that different plant spacings and honeydew cultivars can result in differences in fruit size, earliness, and returns/acre over different seasons and environments although spacing and cultivar acted independent of one another. Lower plant populations resulted in the production of larger fruit and higher plant populations resulted in the production of smaller fruit. Cultivar did affect the size of fruit produced, with some cultivars resulting in larger melons and others producing more small melons. In both seasons, the double-row 24-inch spacing resulted in an earlier harvest and exhibited a higher percent harvest for the first harvest in both years. Cultivar Sure 7050 was significantly later than either `Honeybrew' or `Morning Ice'. Returns/acre were significantly different between spacing treatments for a majority of harvests. The double-row 24-inch spacing resulted in the highest returns/acre. Both `Morning Ice' and `Sure7050' had significantly higher returns when compared to `Honeybrew'.

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The squash leaf curl virus (SLCV), transmitted by the sweet potato whitefly (Bemesia tabaci biotype B), is widespread on fall-planted watermelon in the Rio Grande Valley and Coastal Bend areas of south Texas. The objective of the study was to evaluate colored mulches for their effects on whitefly populations, virus incidence, and watermelon yield. Eleven polyethylene films were included as treatments in both a spring and fall study and were replicated five times in a randomized block design. Plastic mulches caused substantial improvement in melon yields (40%) in the spring crop, similar to responses obtained in other studies on cantaloupes. Fall yield increases due to the use of mulches did not occur. Whitefly populations were much lower in 1996 than they have been in previous years, therefore this was not an adequate test of its effects on whitefly behavior. Even so, there were indications in the fall crop that the use of plastic mulch tended to result in lower whitefly numbers. No evidence was found of any difference between the various mulch materials regarding whitefly counts.

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Bare soil, 13 different polyethylene mulching films, and K-Mulch kenaf paper film were compared to one another for use in early spring production of cantaloupe melons. The mulching treatments were applied to the top of raised beds spaced 200 cm apart in late January and seed of the cantaloupe variety Cruiser were planted in early February. Treatments were replicated five times in a complete randomized block design. Plots were irrigated throughout the season utilizing a drip irrigation system. Crop responses to mulches throughout the growing season were determined by measuring vine growth, fruit yield, Fruit quality and earliness. Mulch tensile strength was determined throughout the season, and ease of cleanup and disposal were evaluated after the growing season. Differences were recorded for treatments particularly regarding ease of cleanup.

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Because of the limited number of herbicides in spinach, beet, and swiss chard, a screening study was initiated to identify new preemergence herbicides. Field soil at the study was a fine sandy loam. The study was initiated on 8 Apr. 2004 at Bixby, Okla. Each plot had four direct seeded rows of spinach, beet and chard. 22 treatments were replicated four times in a RBD that included a nontreated check. Treatments used 12 preemergence herbicides. Herbicides were applied PRE with a research sprayer at 20 GPA in a 6-ft swath perpendicular to crop rows. The experimental area received 0.5 inch of irrigation after application. Callisto (mesotrione) and V10146 (Valent exp. compound) both resulted in 100% death of beet, chard and spinach seedlings. Herbicides that had injury at or below Dual Magnum included Pyramin (pyrazon), Nortron (ethofumesate), Lorox (linuron), and Bolero (thiobencarb) tank-mixed with Bio-Power. Yields were zero for the nontreated check and several treatments due to weed competition and the lack of crop plants in some plots. Treatments with the highest beet yields included Dual Magnum at 0.5 lbs/acre, Pyramin at 3.6 lbs/acre, and Outlook (dimethenamid-P) at 0.25 lbs/acre (11,822, 8,034, 8,010 lbs/acre respectively). Highest chard yields were from Dual Magnum at 0.5 lbs/acre, Pyramin at 3.6 lbs/acre, Outlook at 0.5 lbs/acre + Bio-Power, and Outlook at 0.5 lbs (12,753, 12,596, 11,495, and 10,563 lbs/acre, respectively). Spinach yields were highest for Dual Magnum at 0.5 lbs/acre, Define (flufenacet) at 0.3 lbs/acre, and Outlook at 0.5 lbs/acre + Bio-Power (4,465, 4,259, and 3,207 lbs/acre, respectively).

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Trials were conducted to determine southern pea performance in two different production environments in Oklahoma. Plots consisted of one row 20 feet long with 30 or 36 inches between rows. Seed were spaced 10 seed per foot and were inoculated with Rhizobium at planting. The trials were seeded on 15 June 2004 at Bixby, Okla. (elevation836), and on 16 June 2004 at Goodwell, Okla. (elevation 3293). Trials included at least three replications in a RBD for the 15 cultivar/breeding lines. Plots received a PRE application of Dual Magnum at 1.0 lb ai/acre tank-mixed with Pursuit at 0.063 lb a.i./acre. Supplemental water was applied with overhead irrigation. Maturity before harvest was rated as percentage of dry pods. TX158BEgc, LA 96-4, and US-1076 had the highest percentage of dry pods at both Bixby and Goodwell for blackeye, cream, and pinkeye types, respectively. Yields are given as imbibed lb/acre. Peas with consistent yields at both Bixby and Goodwell included blackeye types AR 00-178 with yields of 2,558 and 4,738 lb/acre, respectively, and ARK Blackeye #1, which had yields of 2,605 and 4,406 lb/acre, respectively. The highest yielding cream type at Bixby was LA 96-4, at Goodwell it was Early Acre, these had yields of 2,346, and 3,983 lb/acre, respectively. The highest yielding pinkeye types included AR 96-854 at Bixby and AR 01-1293 at Goodwell which yielded 3,593 and 4,366 lb/acre, respectively. LA 96-18 had yields of 2,886 and 2,853 lb/acre at Bixby and Goodwell, respectively, and was the most consistent yielding pinkeye for both sites.

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Southern peas for the processing market are an important crop for producers in South Texas, but little testing of new varieties or breeding lines has been carried out. Grower field trials during three different years and an on station trial provided an opportunity to evaluate >30 different pea cultivars or breeding lines. Cultivars and breeding lines were evaluated for earliness, maturity, yield, and performance in high-pH soils. Yields varied significantly each season, with Arkansas Blackeye # 1 providing consistently high yields in the three grower trials. Both Arkansas 87-435-68 and Texas Pinkeye produced significantly higher yields in the high soil pH trial at Weslaco. Yields for Arkansas 87-435-68 and Texas Pinkeye in the Weslaco trial were 1428 and 1231 lb of dry peas per acre, respectively.

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Evaluation of new southernpea cultivars and advanced breeding lines for spring and fall cropping is important for both producers and processors of this crop in South Texas. The spring trial included three commercially available cultivars and 17 advanced breeding lines from the Univ. of Arkansas breeding program. Foliage color ratings taken in the spring correlate with similar ratings taken in 1995 and indicate that Arkansas 435-87-68 may be tolerant to high pH soils that caused yellowing in several other cultivars. The highest producing varieties, Arkansas 87-435-68 and Arkansas 92-552, produced net yields > 1000 lb/acre. The fall trial included the same material as the spring trial plus four more commercially available cultivars. Maturity ratings taken in early October varied widely between cultivars and breeding lines. Recorded ratings represented growth stages ranging from cultivars with no flowering to those that had set pods that were filling. The most mature types included Arkansas breeding lines 96-593, 95-368, 96-556, and 95-301, which had maturity ratings of 3.8, 3.5, 3.5, and 3.3, respectively. Net yields varied widely among cultivars in the fall trial. Yields ranged from 23.8 to 522.8 lb/acre. Those with the highest net yields included 'Early Scarlet', Arkansas 91-285, Arkansas Blackeye #1, and Arkansas 95-368, with yields of 522.8,402.2, 401.2 and 400.5 pounds per acre, respectively. Although yields in the trial were considerably lower than expected, several cultivars produced 400 or more pounds of peas per acre compared to many commercial fields that were not harvested.

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Spinach germplasm (707 accessions) from collections from six countries were screened for resistance to race 4 of the downy mildew pathogen Peronospora farinosa f. sp. spinaciae; these collections contained germplasm that originated from 41 countries. The predominant species examined was Spinacia oleracea L., however, eight accessions of S. turkestanica Iljin and two accessions of S. tetrandra Stev. were also tested. About 40 seedlings of each accession were inoculated. The cultivar St. Helens was included as a susceptible control in each test. The majority of accessions tested (>98%) were susceptible to race 4. Nine accessions exhibited some resistance to race 4 (9% to 38% of the seedlings within an accession were resistant), and two accessions, CGNO 9546 and SPI 82/87, exhibited a high level of resistance (60% and 80% resistant, respectively). Resistance identified in several of the accessions in this study may be useful for breeding for race 4 resistance.

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Fertilization programs used commercially for bell peppers (Capsicum annuum) in the subtropical Lower Rio Grande Valley of Texas may vary substantially from recommendations based on research. Therefore, a commercial fertilization program used on a significant fraction of the pepper production in this area was evaluated at two locations. Preplant soil tests showed NO3-N levels were low at one location and very high at the other. Nitrogen application where preplant soil NO3-N was low resulted in a six-fold yield increase (from 197 to 1203 kg·ha–1), and improvements in fruit weight, fruit volume, fruit density, wall thickness, wall strength, and carotenoid and chlorophyll a and b contents. No other nutrient application at either location or N application at the site where preplant soil NO3-N levels were high significantly affected yield by size class, fruit quality characteristics, storage properties, or mineral and organic components. Nitrogen application had the greatest effect on dry-weight accumulation and N uptake during fruit set and maturation when N demand was high. Where N responses were observed, N application increased total dry weight in plant and fruit by 150% and total N uptake by 186%, yet this increase amounted to a N fertilizer uptake efficiency of only 12%. Thus, N should be used judiciously to prevent pollution of drainage and ground waters.

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Uniconazole is approved for use as a chemical option on tomato (Solanum lycopersicum) for height control, but research is limited. In this study, 12 tomato cultivars were chosen with three cultivars each of indeterminate, determinate, heirloom, and container types. Plants were sprayed with a one-time application of 0, 2.5, 5, 7.5, or 10 mg⋅L–1 of uniconazole during the two- to four-leaf stage to evaluate height control. Results indicated no significant difference between concentrations for plant height, stem caliper, and plant dry weight. The greatest soil plant analysis development (SPAD) values were observed with the 10-mg⋅L–1 treatment. Flower response in ‘Brandywine’ to a single application of 0, 2.5, or 5 mg⋅L–1 of uniconazole demonstrated a greater number of flowers per plant at 5 mg⋅L–1, whereas no significant difference was shown for the number of flower clusters or the number of flowers per cluster at other treatment levels. Using 2.5 mg⋅L–1 uniconazole was effective for reducing plant height across all cultivars of greenhouse-grown tomato seedlings compared with the control, whereas addition of 5 mg⋅L–1 was shown to increase the number of flowers in the heirloom cultivar Brandywine.

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