There is the need to develop potato (Solanum tuberosum) cropping systems with higher yields and crop quality. Field studies were conducted with cover crops grown under limited irrigation (<8 inches) to assess the effects of certain types of cover crops on potato tuber yield and quality. On a commercial farm operation before the 2006 and 2007 potato season, mustard (Brassica sp.), canola (Brassica napus), and two cultivars of sorghum-sudangrass (Sorghum bicolor × S. sudanense) were planted. A wet fallow ground treatment where no cover crop was planted was used as a control. Before the 2008 season, barley (Hordeum vulgare), barley plus applied compost, sunflower (Helianthus annus), pea (Pisum sativum), and annual ryegrass (Lolium multiflorum) cover crops were added. The results of these 2006–08 studies showed that cover crops have the potential to increase potato tuber yield and quality, as measured by tuber size (larger tubers) and appearance (e.g., tubers with reduced defects such as cracks, knobs, and misshapes). In 2 of the 3 years, most of the cover crops, especially sorghum-sudangrass, increased yields and tuber quality. Positive results from sorghum-sudangrass suggest there is potential to harvest hay from cover crops and still obtain tuber benefits.
Samuel Y.C. Essah, Jorge A. Delgado, Merlin Dillon, and Richard Sparks
Brian K. Hamilton, Leonard M. Pike, Alton N. Sparks, David A. Bender, and Richard W. Jones
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.