Northwest Iowa On-farm Research Soybean Yield Response to Headline Fungicide

Six years ago the Northwest Iowa On-Farm Research Project was started to cooperate with local farmers to compare crop production methods on a field scale size. Through this project, over 300 replicated comparisons have been done. Beginning in 2012, the Northwest Iowa On-Farm Research project will be recognized as a part of Iowa State University Farmer Assisted Research and Management (FARM) program. This program will also expand to southwest Iowa, north central Iowa, and central Iowa.

On-farm Cooperator Trials 2011: Effect of Extended-duration Row Covers on Muskmelon and Winter Squash on Bacterial Wilt and Yield

Susceptible cucurbit crops are difficult to grow in Iowa because of bacterial wilt, caused by Erwinia tracheiphila. Striped and spotted cucumber beetles transmit bacterial wilt. Other insect pests such as squash vine borer and squash bugs may also have an economic impact on yield, particularly in squash.

The New ISU Farm Network

Since its inception in 1946, Iowa State University’s (ISU) Western Research Farm (WRF) has fulfilled its original stated objective of “careful research giving definite answers to specific problems.” In continuing with that tradition, the WRF joined the Onfarm Research Network of the ISU Corn and Soybean Initiative (CSI) and started conducting on-farm trials with participating local producers during the 2010 growing season.

Controlling Bacterial Wilt in Muskmelon with Perimeter Trap Cropping

Perimeter trap cropping (PTC) involves planting one or more rows of a cucurbit crop that is highly attractive to cucumber beetles around the border of a main cucurbit cash crop that is less attractive to the beetles. Cucumber beetles attempting to migrate into the field are concentrated in the relatively more attractive border crop, where they can be controlled by insecticides. In New England, perimeter trap cropping using Blue Hubbard squash as the border crop around pumpkin, cucumber, or butternut squash controlled cucumber beetle/bacterial wilt with as few as one border spray of insecticide. This strategy reduced insecticide use on the main crop by up to 94 percent, nearly eliminating sprays on the main cash crop. In on-farm trials, 8 of 10 Massachusetts growers found that using perimeter trap cropping saved them money. The same tactic also effectively managed cucumber beetles on muskmelon and squash in Oklahoma.

Effects of Novel Growth Hormone Secretagogues on Growth Hormone Secretion in Farm Animals

The requirement for growth hormone (GH) secretion by the anterior pituitary gland in beef calves is demonstrated by a complete lack of long bone-growth and muscle accretion after hypophysectomy (surgical removal of the pituitary gland). When the connecting link (hypophyseal stalk) to the basal region (hypothalamus) of the brain is surgically severed, long bone growth and body weight gain are greatly limited compared with sham-operated controls. This limited growth results from obliteration of episodic GH secretion and reduced basal blood concentration of the hormone compared with sham-operated controls. Thus, the hypophyseal stalk-transected (HST) calf provides an appropriate model to determine mechanisms by which hypothalamic neuropeptides from the brain regulate GH secretion, and thereby growth in the young calf. Neuropeptides have been isolated and characterized in bovine hypothalamus that stimulate GH secretion (GH-releasing hormone [GHRH]) or factor [GHRF] and inhibit GH secretion (GH release-inhibiting hormone [GHRIH] or somatostatin [SRIH]). A dose of .067 micrograms of GHRF per kilogram of body weight injected intravenously in HST calves abruptly increased plasma GH concentration to 55 nanograms per milliliter from the control period mean of 5 nanograms per milliliter. HST calves then were infused intravenously with .033 and .067 microgram somatostatin per kilogram of body weight, during which a pulse injection of .067 microgram of GHRF was administered. GH increase was limited to 9 and 5 micrograms per kilogram body weight during the .033- and .067 microgram SRIH infusions after GHRF; no GH rebound was observed after the SRIH was discontinued. GHRF from humans contains 40 to 44 amino acids. Rat hypothalamic GHRF analogs containing 29 to 32 amino acids elicited dose-dependent GH peak release in these HST calves. In 1977, Bowers and Monomy isolated novel GH releasing peptides consisting of only six amino acids; they caused GH release by isolated pituitary cells in culture and acute GH release when administered intravenously. We recently have utilized a novel nonpeptidyl GH secretagogue of low molecular weight in the pig to determine its mechanisms of action within the central nervous system.

Effect of Relaxin on Parturition in Ruminants

The biology of relaxin differs in many respects between ruminants and nonruminants. Immunoreactive blood concentration of circulating relaxin is much less in ruminant (cattle and sheep) than in nonruminant (pigs) farm animals. The ovaries of the pig produce abundant quantities of the hormone in late pregnancy, whereas tissue sources of relaxin are not clearly defined in sheep and cattle. Relaxin facilitates parturition by cervical dilation and pelvic canal expansion in several mammalian species. Relaxin injected intramuscularly during late pregnancy can cause earlier parturition in cattle, but in sheep limited evidence indicates it does not induce earlier delivery than seen in diluent-treated controls. Intravenous infusion of increasing dosages of relaxin in beef heifers the last days of pregnancy decreased plasma progesterone concentration compared with phosphate buffer controls, but oxytocin plasma concentrations remained similar throughout the posttreatment period. Although continuous intravenous infusion of relaxin depressed blood levels of progesterone, it did not result in earlier parturition than seen in the diluent treated controls. Thus, the timing and method of relaxin administration during late pregnancy in ruminants affect remodelling of collagen and pelvic canal relaxation and can result in earlier parturition.

Intensive Rotational Grazing of Steers at the Andrew Jackson Demonstration Farm

Fifty head of crossbred steers started grazing 51 acres of pasture on May 1 in a rotational grazing system using a variable density paddock system. Twenty-two head grazed 92 days, 27 grazed 140 days, and one steer died. A total of 11,922 pounds was produced on 5,804 animal-days of grazing. The average daily gain was 2.02 pounds for group 1 and 2.07 for group 2. The stocking rate for the first 92 days was .98 steers per acre and .53 for the final 48 days. The animal days of grazing per acre was 113 and the pounds of gain per acre was 233. Total return for land, labor and management for the demonstration was $2,829.76 or $55.49/acre.

Management Intensive Grazing of Stockers at the Andrew Jackson Demonstration Farm (1996 – 1998)

The Andrew Jackson Demonstration Farm (AJDF) is located in central Jackson County in east central Iowa. A board of directors operates the farm for the purpose of demonstrating different production practices and management strategies. From 1996 to 1998 management intensive grazing practices and the grazing of stockers on a combination of permanent and tillable pasture have been demonstrated. Grazing strategies or practices demonstrated during these years included establishment of Eastern Gamagrass and Big Bluestem, variable density grazing, measuring forage on-offer, estimating dry matter intake, grazing corn, pasture renovation, and fencing and water systems. Production performance data were gathered for the three years stockers that were grazed. During this time the stockers averaged 121 animal days of grazing, a 1.1 head per acre stocking rate, a 1.85 pound average daily gain, and 228 pounds of gain per acre. The financial measures evaluated the value of gain on pasture and the pasture cost of the gain. The value of gain per pound was positive for 1996 and 1997 at $.58 and $.52 whereas in 1998 it was a -$.04. Pasture costs per pound of gain ranged from $.12 to $.16. Production performance is only one part of the profit picture when evaluating a stocker operation. Buysell margins are the other significant part that can greatly impact the profit potential of a summer grazing program.

Effect of MGA on Performance, Sexual Behavior, Carcass Quality and Tenderness in Mixed-Sex Pens of Cattle

The effect of MGA in mixed pens of steers and heifers was evaluated over a three-year period at the ISU Armstrong Research Farm near Lewis, Iowa. Two pens of approximately 40 head were fed diets with or without MGA in each of three replications. Estrus and riding activity was monitored using the Heat Watchâ system. At slaughter, in addition to routine carcass data collection, a rib sample was collected from each carcass for tenderness evaluation. There was no effect on dry matter intake due to MGA treatment. Mixed-sex pens that were fed MGA were 4% more efficient than controls. MGA-fed steers gained similarly to control steers. MGA fed heifers gained 8% faster than control heifers. MGA highly reduced measures of estrus and riding activity throughout the feeding period. MGA feeding improved marbling and tenderness measured in both steers and heifers. These data suggest that MGA has potential to improve performance, quality grade and tenderness in mixed pens of steers and heifers.

Effect of Yeast Supplement on Performance of Steer Calves

The effect of Prosponse® yeast supplement fed to newly arrived steers was evaluated at the ISU Armstrong Research Farm near Lewis, Iowa. Four pens of approximately 32 head were fed similar diets with 2 pens receiving yeast supplement and 2 pens not. Calves were weighed on delivery to the feedlot and allocated on weight and sire. Calves were on test 34 days. There was no effect on daily gain or feed to gain. Dry matter intake trended higher for the yeast supplemented calves (P=.10). These data suggest that yeast supplement may improve dry matter intake in newly arrived feedlot calves.

Pasture Weaning at the McNay Memorial Research and Demonstration Farm: A Progress Report

In September 1995, 225 spring-born calves were weaned on pasture at the McNay Memorial Research and Demonstration Farm to explore procedures necessary to conduct a successful pasture-weaning program. In the two to three week post-weaning period, average daily gains (ADG) for the two groups weaned that year were 1.06 and 3.06 pounds; there were no health problems. In 1996, a research trial utilizing 242 spring-born calves was conducted to compare pastureweaned and feedlot-weaned calves. Half of the calves were weaned on pasture for three weeks and then placed in a feedlot for three more weeks. The other half of the calves were weaned directly into the feedlot for the six week post-weaning period. ADGs during the three week post-weaning period were 1.24 and 2.42 for the pastureweaned and feedlot-weaned calves. For the entire six week trial, ADGs were 1.83 and 2.40 for the pastureweaned and feedlot-weaned calves. There was no sickness in either weaning treatment during the six week trial. Initial experience indicates pasture-weaning is a feasible method of getting calves through a stressful procedure.

Effects of Pasture Conditions in Spring on Seasonal Forage Productivity

Fifteen beef cow-calf producers in southern Iowa were selected based on locality, management level, historical date of grazing initiation and desire to participate in the project. In 1997 and 1998, all producers kept records of production and economic data using the Integrated Resource Management-Standardized Performance Analysis (IRM-SPA) records program. At the initiation of grazing on each farm in 1997 and 1998, Julian date, degree-days, cumulative precipitation, and soil moisture, phosphorus, and potassium concentrations were determined. Also determined were pH, temperature, and load-bearing capacity; and forage mass, sward height, morphology and dry matter concentration. Over the grazing season, forage production, measured both by cumulative mass and sward height, forage in vitro digestible dry matter concentration, and crude protein concentration were determined monthly. In the fall of 1996 the primary species in pastures on farms used in this project were cool-season grasses, which composed 76% of the live forage whereas legumes and weeds composed 8.3 and 15.3%, respectively. The average number of paddocks was 4.1, reflecting a low intensity rotational stocking system on most farms. The average dates of grazing initiation were May 5 and April 29 in 1997 and 1998, respectively, with standard deviations of 14.8 and 14.1 days. Because the average soil moisture of 23% was dry and did not differ between years, it seems that most producers delayed the initiation of grazing to avoid muddy conditions by initiating grazing at a nearly equal soil moisture. However, Julian date, degree-days, soil temperature and morphology index at grazing initiation were negatively related to seasonal forage production, measured as mass or sward height, in 1998. And forage mass and height at grazing initiation were negatively related to seasonal forage production, measured as sward height, in 1997. Moreover, the concentrations of digestible dry matter at the initiation of and during the grazing season and the concentrations of crude protein during the grazing season were lower than desired for optimal animal performance. Because the mean seasonal digestible dry matter concentration was negatively related to initial forage mass in 1997 and mean seasonal crude proteins concentrations were negatively related to the Julian date, degree-days, and morphology indeces in both years, it seems that delaying the initiation of grazing until pasture soils are not muddy, is limiting the quality as well as the quantity of pasture forage. In 1997, forage production and digestibility were positively related to the soil phosphorus concentration. Soil potassium concentration was positively related to forage digestibility in 1997 and forage production and crude protein concentration in 1998. Increasing the number of paddocks increased forage production, measured as sward height, in 1997, and forage digestible dry matter concentration in 1998. Increasing yields or the concentrations of digestible dry matter or crude protein of pasture forage reduced the costs of purchased feed per cow.

Intensive Rotational Grazing of Steers on Highly Erodible Land at the Adams County CRP Project, 2001

A steer grazing demonstration was conducted in 2001 at the CRP Research and Demonstration Project farm near Corning, Iowa. Ninety-five steers were delivered to the Adams County CRP farm on April 27, 2001. The steer pasture at the CRP farm was 76 acres, divided into 33 paddocks with electric fence. Cattle were moved 101 times to a fresh paddock during the grazing season. Most of the moves (79.2%) followed 1 day of grazing in a paddock. No paddock was grazed for more than 3 days in succession. Rate of gain on pasture (2.12 lbs./animal/day) was higher in 2001 than in any previous year in the 8-year steer grazing project at the CRP farm. The 95 steers gained a total of 21,056 pounds on pasture, and the cost of the gain on pasture was $51.30/cwt. The 2001 steer grazing project showed a small profit above all costs. The net profit was $4.12/steer or $5.15/acre. Large profits and large losses are possible, primarily depending on the difference between the buying and selling prices.

Effects of Seed Treatments and a Soil-applied Nematicide on Corn Yields and Nematode Population Densities

Plant-parasitic nematodes are microscopic worms that feed on plants. Almost every nematode that feeds on corn is capable of feeding on many other plants. These nematode parasites are thought to be native to most Iowa soils and to have fed upon native plants before corn was grown as a cultivated crop. Population densities (numbers) of most species of plant-parasitic nematodes that feed on corn have to increase to damaging levels (called damage thresholds) before yield loss occurs.

Effect of Fungicides and Plant Populations on Soybean Disease and Yield

Applications of foliar fungicides on soybeans have been shown to reduce disease pressure and protect yield under the right conditions, especially in environments that have very wet or humid conditions. In the past decade, fungicide use in Iowa has increased. Initially, growers were concerned with the potential threat of soybean rust, which is controlled effectively by foliar fungicides. In Iowa, however, there has not been any case of yield reduction due to soybean rust. New potential purposes for foliar fungicides include “plant health” benefits and the reduction of foliar diseases endemic in Iowa such as Septoria brown spot, Cercospora leaf blight, and frogeye leaf spot. Currently what is not known is how the efficacy of fungicides is affected when agricultural practices change. Our question: How does plant population affect the efficacy of fungicides?