Corn Leaf Diseases and Their Control

The 1993 growing season was another unusual year for leaf diseases of corn. Some diseases went rampant and other diseases, which were expected because of the wet weather, did not develop on corn leaves. The various diseases will be discussed

Common Corn Diseases

The causes of root and stalk rots of com commonly observed in Iowa are primarily fungal pathogens. In some instances the pathogen causes both root rot and stalk rot and some pathogens are associated with only one or the other

Control of Corn Leaf Diseases

Leaf diseases of corn in Iowa in 1990 were probably the most severe since the 1970 epidemic of Southern corn leaf blight. The leaf diseases resulted in an early maturing of the corn in many fields which was attributed erroneously to a late season heat stress in many popular reports. These leaf diseases combined with heavy corn borer infestations in some areas contributed greatly to the smaller kernels, poor kernel fill, and lower yields than expected. The leaf diseases will be discussed individually

Controlling Corn Diseases

Root and Stalk Rots, Leaf Diseases, and Leaf Disease Contro

Inheritance of Gray Leaf Spot Resistance in Corn

Gray leaf spot disease, caused by Cercospora zeae-maydis Tehon and Daniels, has become a significant disease in Iowa corn (Zea mays L.) production. Incidence of gray leaf spot has increased with the increased use of conservation tillage practices. The inheritance of resistance to gray leaf spot was studied via use of generation mean analyses for five crosses and via use of 100 S1 progenies developed from an F2 population. Experiments were conducted at two locations that included either natural or artificial inoculation with C. zeae-maydis spores. Additive and dominance effects were significant in nearly all instances. Heritability for gray leaf spot resistance among S1 progenies was 0.78. Because resistance seemed to be determined by additive genetic variation, it seems selection for greater resistance to gray leaf spot can be effective. In all instances, the level of gray leaf spot resistance in single-cross hybrids was improved, whether the single-cross hybrid was produced with either one or both parents having resistance. It seems single-cross hybrids will have adequate levels of resistance to gray leaf spot if at least one of the parents has resistance

Foliar Fungicides in Seed Corn Production

Since 1982, we have conducted a program to determine the fungicides that may be effective for controlling foliar diseases in inbred and hybrid com. For the past seven years we have limited our research to only inbreds or sister line hybrids. In 1990, we started a cooperative program with seed companies and have conducted our research in commercial seed production fields in five greatly different years in terms of weather patterns. Thirty experiments have been established in seed production fields and 25 fields have been harvested for yield. Five experiments were abandoned because of herbicide injury interactions (2,4-D) with the fungicides, excessive Stewarts disease (a bacterial disease that can not be controlled with fungicides and was devastating), or drought

A Diamond Thin Film Flow Sensor

We present the results of theoretical modeling and experimental testing of a diamond thin film sensor for flow studies. It is shown that the high thermal conductivity of a diamond film can enhance the frequency response of the flow sensor. One-dimensional heat diffusion equation was solved using the finite difference method for determining the frequency response. Two different sensor structures were analyzed: a Ni film on a quartz substrate (Ni/Q) and an intermediate layer of diamond film between the Ni film and quartz substrate (Ni/D/Q). The theoretical model predicts a frequency response for the Ni/D/Q sensor higher than that of the Ni/Q sensor. Diamond films for the Ni/D/Q sensor were deposited onto the quartz substrate by microwave plasma-enhanced chemical vapor deposition (MPECVD). The conditions for a high nucleation density were established for obtaining a continuous diamond thin film. A subsequent nickel film patterned and deposited serves as the sensing arm in the bridge circuit of an anemometer. The measured frequency response of the Ni/D/Q sensor combination is greater than 220 kHz, as compared to the Ni/Quartz sensor response of 120 kHz

The Use of Telehealth Technology in Assessing the Accuracy of Self-Reported Weight and the Impact of a Daily Immediate-Feedback Intervention among Obese Employees

Objective. To determine the accuracy of self-reported body weight prior to and following a weight loss intervention including daily self-weighing among obese employees. Methods. As part of a 6-month randomized controlled trial including a no-treatment control group, an intervention group received a series of coaching calls, daily self-weighing, and interactive telemonitoring. The primary outcome variable was the absolute discrepancy between self-reported and measured body weight at baseline and at 6 months. We used general linear mixed model regression to estimate changes and differences between study groups over time. Results. At baseline, study participants underreported their weight by an average of 2.06 (se = 0.33) lbs. The intervention group self-reported a smaller absolute body weight discrepancy at followup than the control group. Conclusions. The discrepancy between self-reported and measured body weight appears to be relatively small, may be improved through daily self-monitoring using immediate-feedback telehealth technology, and negligibly impacts change in body weight

A new approach to physical activity maintenance: Rationale, design, and baseline data from the Keep Active Minnesota trial

<p>Abstract</p> <p>Background</p> <p>Since many individuals who initiate physical activity programs are highly likely to return to a sedentary lifestyle, innovative strategies to efforts to increase the number of physically active older adults who successfully <it>maintain </it>beneficial levels of PA for a substantial length of time are needed.</p> <p>Methods/Design</p> <p>The Keep Active Minnesota Trial is a randomized controlled trial of an interactive phone- and mail-based intervention to help 50–70 year old adults who have recently increased their physical activity level, maintain that activity level over a 24-month period in comparison to usual care. Baseline, 6, 12, and 24 month measurement occurred via phone surveys with kilocalories expended per week in total and moderate-to-vigorous physical activity (CHAMPS Questionnaire) as the primary outcome measures. Secondary outcomes include hypothesized mediators of physical activity change (e.g., physical activity enjoyment, self-efficacy, physical activity self-concept), body mass index, and depression. Seven day accelerometry data were collected on a sub-sample of participants at baseline and 24-month follow-up.</p> <p>Discussion</p> <p>The Keep Active Minnesota study offers an innovative approach to the perennial problem of physical activity relapse; by focusing explicitly on physical activity maintenance, the intervention holds considerable promise for modifying the typical relapse curve. Moreover, if shown to be efficacious, the use of phone- and mail-based intervention delivery offers potential for widespread dissemination.</p> <p>Trial registration</p> <p>ClinicalTrials.gov Identifier: NCT00283452.</p