Browsing by Subject "Insecticides"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
Item Effects of the stages of bloom and selected insecticides on the control of the sorghum midge (Contarinia sorghicola)(Texas Tech University, 1969-05) Stanford, Robert LelandThe sorghum midge, Contarinia sorghicola (Coquillet), has established itself as a yearly threat to the success of grain sorghum production in West Texas. Significant losses in sorghum yield from the midge and the lack of efficient control measures have forced early planting of most sorghum varieties. When weather conditions do not permit early planting, the farmer will usually choose a shorter-season variety rather than attempt to control the sorghum midge on a longer-season variety with a much higher yield potential. The higher yield from varieties in which the heads emerge later in the summer months is due in part to cooler nights, less extreme day temperatures, and more rainfall at critical stress periods. Better use can be made of the irrigation water supply by delaying or alternating, some of the sorghum plantings on a farm. Without effective and economical midge control a farmer must plant early or use varieties which bloom before August. Several tests have shown that any sorghum blooming after July most likely will be attacked by the midge.Item Influence of plant spacing on arthropod population density and yield loss potential in cotton produced under different insecticide routines(Texas Tech University, 1988-05) Faye, DouDou DianeNOT AVAILABLEItem Insecticide screening and methods of application of insecticides for white grub control in grain sorghum.(Texas Tech University, 1974-08) Holt, Thomas JosephNot availableItem Integrating prescribed burning and insecticide to reduce Fire ant impacts on Bobwhite chicks(Texas Tech University, 2003-12) Norton, Amy AllieneThe red imported fire ant (RIFA) has caused extensive damage to wildlife populations in Texas since its infestation. Northern bobwhite quail in particular have felt the negative impacts of RIFA. RIFA can cause severe injury to bobwhite chicks, rendering them unable to forage for food or escape predators. Observational and experimental evidence has shown that hatching bobwhite chicks experience a low survival rate when exposed to a significant number of foraging RIFA. Control and management of RIFA in Texas is important in protecting bobwhite habitat and potentially increasing bobwhite chick survival and nest success. We initiated a study in Victoria and Goliad counties to examine integrated control methods for RIFA in bobwhite quail habitat. Our research objective was to determine if a reduced rate of insecticide and/or prescribed burning could decrease the foraging activity of RIFA below the threshold that causes mortality of northern bobwhite chicks. Eight research sites were established in early 2002. Each site was divided into a burned and unburned plot. Individual burned and unburned plots randomly received one of four rates of insecticide treatment: 0, 50, 75 or 100% of the recommended label rate of Amdro®. Bait cup sampling of RIFA was conducted immediately prior to, four weeks, eight weeks, and twelve weeks after insecticide treatment. Treatments and sampling were repeated on six plots in 2003 on previously untreated sites in Calhoun County, Texas. Differences in RIFA foraging activity were analyzed among treatments. Differences were assessed using a two-factor repeated measures analysis of variance. RIFA foraging activity was responsive to Amdro® insecticide treatments. As the rate of Amdro® applied increased, foraging activity of RIFA declined. Data from 2002 and 2003 revealed a difference in mean number of foraging RIFA in insecticide treated plots versus control plots (P<0.05) when testing for the main effect of insecticide treatment. In both years, the mean number of foraging RIFA collected in bait cups in burned plots was not different from nonburned plots (P>0.05).Item Pesticide impact on non-target wildlife in irrigated crops: simulated impact of cholinesterase-inhibiting pesticides on white-winged doves in the Lower Rio Grande Valley of Texas(Texas A&M University, 2007-09-17) Pisani, Jorge MarceloI present a simulation model that should be a useful tool for risk assessment of the impact of insecticide inhibitors of cholinesterase (ChE) applied in irrigated agricultural fields on non-target wildlife. I developed the model as a compartment model based on difference equations (????t = 1 hour) and programmed with Stella???? VII software. Conceptually the model is compartmentalized into six submodels describing the dynamics of (1) insecticide application, (2) insecticide movement into floodable soil, (3) irrigation and rain, (4) insecticide dissolution in water, (5) foraging and insecticide intake from water, and (6) ChE inhibition and recovery. To demonstrate application of the model, I simulate historical, current, and ??????worst-case?????? scenarios, that examined the impact of ChE-inhibiting insecticides on white-winged doves (WWDO - Zenaida asiatica) in the Lower Rio Grande Valley of Texas (LRGV), USA. To my knowledge, there are no field data verifying that the cause of ChE deprivation in WWDO is due to the ingestion of ChE-inhibiting insecticide residues dissolved in drinking water. I parameterized the model to represent a system composed of fields of cotton, sorghum, corn, citrus, and brushland that encompasses the activity range of a WWDO in the LRGV. I simulated situations representing the typical scenario of WWDO using irrigated crop fields in the absence and in the presence of rain. I also simulated ??????worst case?????? scenarios in which methyl parathion was applied at high rates and high frequency. Based on results of the simulations, I conclude that it is unlikely that WWDO are seriously exposed to ChE-inhibiting insecticides by drinking contaminated water. Only in rare cases, for example, when a rain event occurs just after the application of insecticides, are levels of ChE inhibition likely to approach diagnostic levels (20 %). The present simulation model should be a useful tool to predict the effect of ChE-inhibiting insecticides on the ChE activity of different species that drink contaminated water from irrigated agricultural fields. It should be particularly useful in identifying specific situations in which the juxtaposition of environmental conditions and management schemes could result in a high risk to non-target wildlife.Item Some effects of insects on a mixed prairie(Texas Tech University, 1974-12) Shaw, Richard ArchieNot availableItem The evaluation of reduced rates of insecticide application for a grain sorghum pest management program(Texas Tech University, 1973-05) Brothers, Garry WayneNot available