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  • Author or Editor: David A. Bender x
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Large weeds, particularly amaranths, are a serious impediment to mechanical harvesting of jalapeno peppers. Several herbicides were applied in 1998 and 1999 postemergence topical (PT) to commercial fields when peppers had four to six leaves, or postdirected (PD) with a shielded sprayer ≈1 month later, and evaluated for crop injury, weed control, and effects on yield. Treatments were applied to four-row plots 9 m long with a CO<subscript>2 backpack sprayer. PT treatments included pyrithiobac sodium at 0.036, 0.053, or 0.071 kg·ha–1 a.i. with nonionic surfactant or crop oil concentrate, metolachlor at 1.68 kg·ha–1 a.i., and oxyfluorfen at 0.14 or 0.28 kg·ha–1 a.i.. PD treatments consisted of the same rates of pyrithiobac sodium with nonionic surfactant only, and the same rates of oxyfluorfen. Pyrithiobac sodium PT caused significant chlorosis (reduction in SPAD chlorophyll) in new foliage and reduction in plant height after 1 week, but plants recovered with no effect on final plant height, chlorophyll, or yield. No significant difference was observed between the two adjuvants. Metolachlor had no measurable effect on pepper growth or yield. Oxyfluorfen PT killed young apical tissue and caused chlorosis of immature leaves. Plants recovered, but plant height was reduced by 14% to 28% and yield by 11% to 43%. PD treatments had no effect on pepper growth or yield. All herbicides provided adequate weed control under light pressure. Pyrithiobac sodium appears to have potential as a postemergence herbicide for control of amaranth in jalapeno peppers.

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A market window for onion occurs when f.o.b. prices are above grower break-even price for a period of 4 to 6 weeks. Market windows were calculated to occur from late June to early August and from early October through December for northwest Texas onions. Five-year average prices ranged from $6.25 to $7.40 (1990–94), and a breakeven price of $5.38/50-lb sack was calculated from an analysis of total costs of production and marketing and historic yields. Ongoing research and grower demonstrations with advanced breeding lines, commercial cultivars, and selections from yellow, white, and red cultivars have defined certain cultivars that display superior attributes and mature within the market window. Superior cultivars adapted to the first market window include XPH-87N60, `Sunre 1445', `Sunre 1462', `Yula', `Spano', `Cimarron', `Riviera', `Utopia', and `Alabaster'. Superior cultivars adapted to the second market window include `Sweet Perfection', `Sterling', `Vega', `Bravo', `Capri', `Vaquero', `El Charro', `Quest', `Shasta', and `Vision'. `Vaquero', `Sunre 1462', `Sunre 1445', `El Charro', and `Viceroy' have potential for short-term storage for October to December markets.

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Thrips are the major insect pest of onions grown in South Texas. Four cultivars, `IPA-3', `TG1015Y', `1664' (glossy control), and `1900B' (waxy control), were grown in a split-plot design with insecticide sprayed or nonsprayed treatments as the main plots and cultivar as the subplots. The experiment was conducted at the Texas Agricultural Experiment Station, Weslaco, Texas, in the 1995-96 season. The objectives of the study were to compare `IPA-3' and `TG1015Y' for thrips resistance and evaluate possible resistance mechanisms that may be present in `IPA-3'. The average number of thrips per plant and leaf damage rating were significantly higher for `TG1015Y', indicating that some resistance is present in `IPA-3'. However, there were no significant differences in yield between the two cultivars. A comparison of leaf wax characteristics indicated no significant difference between `TG1015Y' and `IPA-3' using gravimetric or gas chromatography techniques. However, scanning electron micrographs of `TG1015Y' leaves appeared more similar to `1900B' and `IPA-3' appeared more similar to `1664'. The insecticide spray treatment had significantly fewer thrips, less damage, and higher yield than the nonsprayed treatment.

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