Search Results
Sweet corn (Zea mays L.var. rugosa or saccharata) is sown across a wide range of dates to provide a steady supply of marketable ears for fresh market and processing. There is a perception in the sweet corn industry that plant density tolerance declines in late-season plantings in the midwestern United States; however, publicly available data to support this perception cannot be found. Using field experiments, the objectives of this research were to quantify the effect of the sowing date on growth responses to plant density and determine the extent to which the sowing date influences the optimum plant density and maximum yield/profit. There were few main effects or interactions of the sowing date on crop growth. More importantly, there was no effect of the sowing date on the economically optimum plant density or plant density that optimized yield. Although variations exist in sweet corn optimum plant densities in the midwestern United States, these variations are likely driven by several factors other than the sowing date that have not yet been fully characterized.
Abstract
“No choice” procedures were established to complement “free choice” procedures for determining resistance of apple fruit to 4 insect pests. ‘Starking Delicious’ was more resistant to damage by apple maggot, Rhagoletis pomonella (Walsh) than ‘Jonathan’ or ‘Golden Delicious’. There were no differences in damage to ‘Jonathan.’ ‘Golden Delicious’ and ‘Starking Delicious’ by plum curculio, Conotrachelus nenuphar (Herbst) or redbanded leafroller, Argyrotaenia velutinana (Walker). The resistance of some apple scab resistant selections to these insects and codling moth, Laspeyresia pomonella (L.) previously determined in a “free choice” test was confirmed in this “no choice” test.
Abstract
Wisconsin 1983 cucumber (Cucumis sativus L.) was released in Feb. 1984 by the USDA and the Univ. of Wisconsin-Madison to provide breeders with a line having high fruit quality and multiple-disease resistance to produce hybrid cultivars and germplasm for breeding purposes. (Resistance identified in green house evaluation for anthracnose and downy mildew was confirmed in field tests conducted by E.V. Wann, U.S. Vegetable Laboratory, ARS/USDA, Charleston, S.C.)
Abstract
Methods of evaluating resistance of apple fruit to 4 insect pests were established by modifying existing rearing procedures. When ‘Jonathan’ was used as the check cultivar and an adjustment was made for variation between trays among checks, it was possible to separate selections that were significantly more resistant from randomly selected samples of apple genotypes. We found 9.7 22.9, 32.3, and 17.0% of the selections tested against the codling moth, Laspeyresia pomonella (L.), plum curculio, Conotrachelus nenuphar (Herbst), apple maggot, Rhagoletis pomonella (Walsh), and redbanded leafroller, Argyrotaenia velutinana (Walker), respectively, had significantly less damage than the check.
Fertilizer costs and increased awareness of non-point source pollution run-off amplify the pressures on farm economics. Intensive farming operations provided the impetus for our study using effluent from anaerobic thermophilically digested poultry litter as a potential fertilizer. Five fertilizer treatments were used: unfertilized control, pelletized municipal sludge, commercial crop specific products, 1x digested solids and 2x digested solids. All four applications of fertilizer were equalized for nitrogen based on commercial product recommendations. Beds treated with 2x solids accumulated higher percentage of organic matter over the 5-year period. A statistically significant increase in phosphorus was found in the solids beds in 2003. Beds with 2x solids showed statistical significance for Mg, Zn and Cu. Fertilizer trials included blueberries, tomatoes, potatoes, and sweet corn. Potato fresh weight was not significantly different in 2002 or 2003, but was in 2001. Tomato fruit number was not significantly different in 2001 or 2003, but was in 2002. Tomato fresh weight for 2x solids was not significantly different from the commercial or pelletized sludge treatments in 2002 and 2003 suggesting that tomato may discriminate between treatments. Commercial and pelletized sludge fertilizers were statistically better for sweet corn fresh ear weight and number of ears in 2002 and 2003. Blueberry yields were not significantly different between treatments for any year. As this is a perennial crop, it may be several years before a significant difference is observed. While not a total solution, our research shows the effectiveness of digested poultry litter as part of a nutrient management program; making livestock residuals a nutrient resource which offers the potential for organic use.
A survey of 78 commercial iceberg and romaine lettuce (Lactuca sativa L.) fields in the coastal valleys of central California was conducted in 2004–2005. Whole leaf samples were collected at early heading and again within 1 week of harvest. Diagnosis and Recommendation Integrated System (DRIS) leaf concentration norms were calculated for N, P, K, Ca, Mg, S, B, Zn, Mn, Fe, and Cu. Iceberg and romaine lettuce had sufficiently similar leaf nutrient concentrations that the data were combined in the DRIS calculations. Optimum leaf nutrient ranges were developed using data from high-yield fields in which all nutrients were in balance according to the DRIS approach. The DRIS-derived optimum ranges for K and Ca were substantially lower than previously published leaf sufficiency ranges, whereas for the other nutrients, the DRIS optimum ranges were in close agreement. Cu was the nutrient most frequently below the optimum range in low-yield fields. Comparison of leaf nutrient concentrations with soil nutrient availability and grower fertilization practices suggested that significant improvement in fertilizer management was possible.
A fresh-market tomato trial was conducted in 2003 at two locations in Arkansas (Fayetteville and Kibler) to evaluate new and old tomato varieties of interest to home gardeners and farmers' markets. The observational trial consisted of 43 varieties, indeterminates and determinates. Heirloom tomatoes comprised a large portion of the trial due to increasing popularity. Heirlooms are unique and can be very eye-catching. There is immense variety in shape, size, and color. They can be large or small, many times the shape is irregular, and the fruits flawed (cracking, cat-facing, green shoulders). The fruit may not store or ship well; most are grown and sold locally. Some heirlooms are better than others. A few of the varieties that stood out in the trial were Costoluto Genovese, Abraham Lincoln, Dona, and Persimmon. Costoluto Genovese, a uniquely ruffled red tomato, was the highest yielding variety at the Kibler location. Fruit quality remained high even in the highest temperatures. One of the most promising was a orange variety called Persimmon, it produced large fruit and the plants provided excellent cover. Dona and Abraham Lincoln, both reds, yielded well and had good flavor. San Marzano and Arkansas 7985 were the best paste types. Arkansas varieties such as Bradley, Ozark Pink, and Arkansas Traveler 76 also did well. Brandywine varieties had low yields and lesser quality fruit. Green zebra, a green striped fruit with good flavor, yielded less due to Blossom End Rot. Cherokee Purple and Carbon were two from the purple/black category that did not do well; yields were low and the fruit cracked.
Japanese plum (Prunus salicina Lindel. `Casselman') trees exposed to three atmospheric ozone partial pressure treatments were sprayed with a summer application of Volck Supreme oil (1% aqueous solution) to control an outbreak of spider mites (Tetranychus spp.). Phytotoxic effects were observed on the foliage of trees in the plots exposed to ambient or higher atmospheric ozone partial pressures 5 days following spray application. Foliage on trees exposed to 0.044 and 0.081 μPa·Pa-1 ozone [12-h mean (8 Apr. to 12 June 1992)] partial pressures developed water spotting and more foliage abscission than trees exposed to charcoal-filtered air (0.024 μPa·Pa-1 ozone). Thus, ozone air-pollution stress may predispose plants to increased phytotoxicity from summer oils.
This study was undertaken to determine if endogenous IAA content and axillary bud development correlate with phenylalanine ammonia-lyase (PAL) induction and russet spotting (RS) susceptibility among RS susceptible and resistant cultivars of Iceberg lettuce (Lactuca sativa L.). Final levels of ethylene-induced PAL activity and RS development were highly correlated among cultivars, field conditions, and harvest dates. Harvested Iceberg lettuce midribs contained relatively low amounts of free IAA (maximum of 5.2 ng·g-1 fresh weight). There was poor correlation between free IAA content in lettuce leaf midribs and final RS development among all cultivars, growing conditions, and harvest dates. Axillary bud development, as measured by the number of visible buds per head, bud weight, or bud length, were not significantly correlated with final RS development or midrib IAA content. Cultivars with higher initial free IAA content lost much of their IAA after 8 days storage at 5C in air ± ethylene.