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  • Author or Editor: David A. Bender x
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Two cultivars of onions, `New Mexico Yellow Grano' and `Midstar' were seeded in single bed plots in mid-October 1985 and 1987 for overwinter transplant production. Plots were covered with spunbonded polyester (POL) or tunnels of clear polyethylene (CLR) or microperforated polyethylene (PER) (1985 only) in early November and compared to uncovered controls. Temperatures were monitored 5 cm above the soil surface under the covers in each plot with three parallel-wired thermocouples. Heat unit (HU) accumulation (number of degrees by which the daily mean temp exceeded 0°C) was recorded for each plot and compared with onion plant size. HU accumulation by mid-February 1986 under CLR, POL and PER was 139%, 131% and 113%, respectively, of that over bare ground. In mid-March 1988 cumulative HU under CLR and POL were 192% and 125% of those over bare ground. Plant diameter varied with variety but increased linearly with cumulative HU for all varieties. `New Mexico Yellow Grano' reached the minimum 4 mm size for transplanting at about 1800 HU while `Midstar' required only 1500 HU. CLR produced useable transplants by early March and the other covers by late March. Numbers of useable transplants per meter of bed in mid-March ranged from 3-6 in uncovered plots to 102-153 under PER tunnels, 185-203 under POL and 263-301 under CLR tunnels. CLR tunnels appear to provide sufficient HU accumulation to produce onion plants for transplanting in early March in West Texas.

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Two cultivars of onions, `New Mexico Yellow Grano' and `Midstar' were seeded in single bed plots in mid-October 1985 and 1987 for overwinter transplant production. Plots were covered with spunbonded polyester (POL) or tunnels of clear polyethylene (CLR) or microperforated polyethylene (PER) (1985 only) in early November and compared to uncovered controls. Temperatures were monitored 5 cm above the soil surface under the covers in each plot with three parallel-wired thermocouples. Heat unit (HU) accumulation (number of degrees by which the daily mean temp exceeded 0°C) was recorded for each plot and compared with onion plant size. HU accumulation by mid-February 1986 under CLR, POL and PER was 139%, 131% and 113%, respectively, of that over bare ground. In mid-March 1988 cumulative HU under CLR and POL were 192% and 125% of those over bare ground. Plant diameter varied with variety but increased linearly with cumulative HU for all varieties. `New Mexico Yellow Grano' reached the minimum 4 mm size for transplanting at about 1800 HU while `Midstar' required only 1500 HU. CLR produced useable transplants by early March and the other covers by late March. Numbers of useable transplants per meter of bed in mid-March ranged from 3-6 in uncovered plots to 102-153 under PER tunnels, 185-203 under POL and 263-301 under CLR tunnels. CLR tunnels appear to provide sufficient HU accumulation to produce onion plants for transplanting in early March in West Texas.

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Field production of adapted transplants could allow West Texas growers to meet the strong demand for `Texas Grano 1015Y' onions in June. A trial was conducted to determine optimal timing for seeding and covering field beds with row covers to produce transplants for planting in early March. Onions were seeded in drip-irrigated field beds at 10-day intervals from mid-October to mid-November and covered with 4-mil polyethylene tunnels at 10-day intervals from mid-November to mid-December. Plants were evaluated on 11 March and transplanted into field plots with greenhouse-grown plants. Seeding in October or covering in mid-November produced acceptable 4-leaf transplants by early March. Plant height, dry weight, number of leaves and survival decreased as seeding or covering was delayed. In field trials, row cover plants produced equal yields and only slightly smaller bulbs than greenhouse plants. Despite the large size of some of the field-grown transplants, no bolting was observed.

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Indian mustard trap crops have successfully reduced pesticide use on commercial cabbage in India. Diamondback moth has been a serious pest of cabbage in Texas and has demonstrated resistance to most classes of insecticides. Use of a trap crop could fit well in an integrated management program for cabbage insects, Three-row plots of spring and fall cabbage were surrounded by successive single-row plantings of Indian mustard in trials at Lubbock, Texas to determine the efficacy of interplanting for reducing insecticide applications. Insects in the cabbage and Indian mustard were counted twice weekly, and insecticides were applied selectively when economic thresholds were reached. Indian mustard was highly attractive to harlequin bugs, and protected intercropped spring cabbage. Cabbage plots without mustard required two insecticide applications to control the infestation. False chinch bugs were also highly attracted to Indian mustard. Lepidopterous larvae, including diamondback moth, did not appear to be attracted to the trap crop. Indian mustard trap crops reduced insecticide applications to spring cabbage but had no positive effect on fail cabbage.

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A system for collecting winter rainfall and storing it for crop use during the growing season was developed and tested for three seasons for non-irrigated cantaloupe production. In early fall raised beds on 2-m centers were shaped with two trenches ca. 30 cm wide and 10 cm deep spaced 50 cm apart. Black plastic mulch was applied over the beds, with small mounds of soil placed on the plastic over the trenches to conform the mulch to the shape of the beds. Slits 15 cm long were made in the bottom of the trenches at 1 m intervals. Fifty kg/ha of a polyacrylamide gel was incorporated into the top 10 cm of some beds prior to shaping. Precipitation falling prior to spring planting was channelled into the beds through the trenches and prevented from evaporating by the mulch. Cantaloupes were seeded through the plastic in the spring and grown without irrigation. The rainfall capture system increased soil moisture in the surface 15 cm by 50% and in the top 60 cm by over 20%. Plant stands were increased from <10% in uncovered plots to nearly 70% under the system. Under drought conditions in two of the three seasons, yields were significantly higher in the rainfall capture plots than in uncovered plots, although not commercially acceptable. In a wet season, similar differences were noted and good commercial yields were obtained with the system. The rainfall capture system in conjunction with supplemental irrigation has the potential to allow excellent cucurbit production with limited water.

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Indian mustard (Brassica juncea) has been reported to be a preferred host for diamondhack moth (Plutella xylostellu) and other insect pests when interplanted with cabbage (Brasssica oleracea var. capitata). A cabbage-Indian mustard companion planting study was conducted to determine the seasonal occurrence of cabbage insects and the potential for using a trap-crop system to reduce insecticide applications to cabbage in West Texas. Three-row plots of cabbage 9 m long were transplanted with and without sequentially seeded borders of Indian mustard in three seasons. Harmful and beneficial insects were counted at roughly weekly intervals. Insecticides were applied when insect populations in individual plots reached predetermined thresholds. Indian mustard did not appear to be more attractive than cabbage to lepidopterous pests, but did preferentially attract hemipterans, particularly harlequin bugs (Margantia histrionica). The mustard trap crop eliminated two insecticide` applications in one trial by reducing harlequin bug pressure on the cabbage.

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Trenched beds covered with plastic mulch was used to capture and retain precipitation for dryland cantaloupe production. Two trenches were formed in the fall in raised beds. Plastic mulch was laid over the beds and slitted at ca. 1 meter intervals over the trenches. Soil was placed over the slits, conforming the plastic to the shape of the trenches and channeling precipitation into the beds. Cantaloupes were seeded in the spring and grown with no supplemental irrigation. Planting moisture was significantly greater under the capture system than in unmulched beds. Seedling emergence time was reduced from 18 to 6 days and vine growth in the first 6 weeks was almost doubled. Total and marketable yields were doubled and fruit size significantly increased when water was limiting. Elevated soil temperatures under the mulch enhanced plant growth and yield even when moisture was not limiting. Combining a moisture capture system with supplemental irrigation could allow commercial production of cucurbit crops under limited water conditions in semi-arid areas.

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A system of intercropping cabbage (Brassica oleracea var. capitata L.) with Indian mustard [Brassica juncea (L.) Czern.] to reduce pesticide applications was evaluated over three cropping seasons. Insects were monitored in nonintercropped cabbage, cabbage plots surrounded by Indian mustard, and the Indian mustard intercrop. Insecticide applications were made to individual plots based on specific treatment thresholds for lepidopterous insects and accepted pest management practices for other insects. Intercropping had no significant effect on the number of lepidopterous larvae in cabbage. Indian mustard did not appear to preferentially attract lepidopterous insects, but was highly attractive to hemipterans, especially harlequin bugs [Murgantia histrionica (Hahn)]. In one season with heavy harlequin bug pressure, intercropping with Indian mustard eliminated two insecticide applications to cabbage. Intercropping cabbage with Indian mustard does not appear to be an economical pest management practice under normal pest pressures in West Texas.

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Watermelon is grown under a range of moisture regimes from rainfed to heavily irrigated, but water requirement patterns are not well documented. Drip irrigation and plastic mulch provide the opportunity to control water applications to optimize yield and quality. Water applied through subsurface drip irrigation was measured in two watermelon trials in 1998 (25 seeded and 20 seedless cultivars) and 1999 (26 seeded and 14 seedless cultivars) at Lubbock, Texas. Melons were transplanted in plastic-covered raised beds 13.6 m long spaced 2 m apart. Irrigation was applied when morning soil moisture tension measured by tensiometers exceeded 20 kPa. Watermelon yields ranged from 50 to 100 t·ha-1 with excellent quality. Weekly water use averaged 14 mm during the first 3 weeks of establishment then increased to 28 mm during the next 3 weeks as plants were running and blooming. During the 5-week fruit-enlargement period, water uptake averaged 57 mm, then decreased as full fruit size was attained. Similar uptake patterns in both years suggest that meaningful crop coefficients for scheduling watermelon irrigation could be based on phenological growth stages.

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