Gregory W. Roth

Predicting weed emergence for eight annual species in the northeastern United States

Abstract A 2-yr experiment assessed the potential for using soil degree days (DD) to predict cumulative weed emergence. Emerged weeds, by species, were monitored every 2 wk in undisturbed plots. Soil DD were calculated at each location using a base temperature of 9 C. Weed emergence was fit with logistic regression for common ragweed, common lambsquarters, velvetleaf, giant foxtail, yellow foxtail, large crabgrass, smooth pigweed, and eastern black nightshade. Coefficients of determination for the logistic models fit to the field data ranged between 0.90 and 0.95 for the eight weed species. Common ragweed and common lambsquarters were among the earliest species to emerge, reaching 10% emergence before 150 DD. Velvetleaf, giant foxtail, and yellow foxtail were next, completing 10% emergence by 180 DD. The last weeds to emerge were large crabgrass, smooth pigweed, and eastern black nightshade, which emerged after 280 DD. The developed models were verified by predicting cumulative weed emergence in adjacent plots. The coefficients of determination for the model verification plots ranged from 0.66 to 0.99 and averaged 0.90 across all eight weed species. These results suggest that soil DD are good predictors for weed emergence. Forecasting weed emergence will help growers make better crop and weed management decisions. Nomenclature: Common lambsquarters, Chenopodium album L. CHEAL; common ragweed, Ambrosia artemisiifolia L. AMBEL; eastern black nightshade, Solanum ptycanthum Dun. SOLPT; giant foxtail, Setaria faberi Herrm. SETFA; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; smooth pigweed, Amaranthus hybridus L. AMACH; velvetleaf, Abutilon theophrasti Medikus ABUTH; yellow foxtail, Setaria glauca (L.) Beauv. SETLU.

Economic and Environmental Implications of Small Grain Production and Use on Pennsylvania Dairy Farms

Two challenges facing dairy producers are low profit and environmental issues related to nutrient management. Whole–farm simulation was used to determine if adding small grain crops to traditional corn and alfalfa rotations provided long–term environmental and economic benefits. Small grain cropping strategies included 1) corn double cropped with barley harvested as cash crop grain and straw bedding, 2) corn double cropped with barley harvested as feed grain and straw, 3) corn double cropped with barley harvested as silage, 4) corn double cropped with rye harvested as silage, and 5) corn replaced with cash crop wheat and straw bedding. Nitrogen leaching loss over the farm was reduced by 10 kg/ha (8.9 lb/acre) when 40% of the corn was double cropped with a small grain, and soil P accumulation was reduced by 2 kg/ha (1.8 lb/acre) per year. Annual farm net return or profit was increased by up to

Corn yield loss estimates due to diseases in the United States and Ontario, Canada from 2012 to 2015.

93/cow when double–cropped barley or single–cropped wheat was harvested as grain and straw, by about

The Effect of Weed Density and Application Timing on Weed Control and Corn Grain Yield1

30/cow for double–cropped barley silage, and

Development of a quicktest kit method to measure soil nitrate

50/cow for double–cropped rye silage. Use of small grains generally reduced the risk or year–to–year variation in net return. The economic benefit of using small grains was not sensitive to farm size, herd milk production level, the amount of forage used in animal rations, or grain prices, but there was less benefit when the farm was moved to a more northern climate. If straw was not harvested and used for bedding, the economic benefit for producing grain as a cash crop or feed was eliminated. Use of small grain crops on Pennsylvania dairy farms should be encouraged, particularly when double cropped with corn, to reduce N leaching loss, reduce soil P accumulation, and improve farm profit.

Effect of Soil Disturbance on Annual Weed Emergence in the Northeastern United States

Annual decreases in corn yield caused by diseases were estimated by surveying members of the Corn Disease Working Group in 22 corn-producing states in the United States and in Ontario, Canada, from 2012 through 2015. Estimated loss from each disease varied greatly by state and year. In general, foliar diseases such as northern corn leaf blight, gray leaf spot, and Goss’s wilt commonly caused the largest estimated yield loss in the northern United States and Ontario during nondrought years. Fusarium stalk rot and plant-parasitic nematodes caused the most estimated loss in the southernmost United States. The estimated mean economic loss due to yield loss by corn diseases in the United States and Ontario from 2012 to 2015 was

Effect of Row Spacing and Herbicides on Burcucumber (Sicyos angulatus) Control in Herbicide-Resistant Corn (Zea mays)'

76.51 USD per acre. The cost of disease-mitigating strategies is another potential source of profit loss. Results from this survey will provide scientists, breeders, government, and educators with data to help inform and prioritize research, policy, and educational efforts in corn pathology and disease management. M U E L L E R E T A L . , P L A N T H E A L T H P R O G R E S S 1 7 (2 0 1 6 )

Current European corn borer, Ostrinia nubilalis, injury levels in the northeastern United States and the value of Bt field corn†

A 2-yr experiment repeated at five locations across the northeastern United States evaluated the effect of weed density and time of glyphosate application on weed control and corn grain yield using a single postemergence (POST) application. Three weed densities, designed to reduce corn yields by 10, 25, and 50%, were established across the locations, using forage sorghum as a surrogate weed. At each weed density, a single application of glyphosate at 1.12 kg ai/ha was applied to glyphosate-resistant corn at the V2, V4, V6, and V8 growth stages. At low and medium weed densities, the V4 through V8 applications provided nearly complete weed control and yields equivalent to the weed-free treatment. Weed biomass and the potential for weed seed production from subsequent weed emergence made the V2 timing less effective. At high weed densities, the V4 followed by the V6 timing provided the most effective weed control, while maintaining corn yield. Weed competition from subsequent weed emergence in the V2 application and the duration of weed competition in the V8 timing reduced yield on average by 12 and 15%, respectively. This research shows that single POST applications can be successful but weed density and herbicide timing are key elements. Nomenclature: Glyphosate; corn, Zea mays L.; forage sorghum, Sorghum bicolor (L.) Moench. Additional index words: Glyphosate-resistant corn, herbicide application timing, postemergence weed control, weed competition, weed density. Abbreviations: POST, postemergence; WAP, weeks after planting.

Corn Earworm (Lepidoptera: Noctuidae) in Northeastern Field Corn: Infestation Levels and the Value of Transgenic Hybrids

Abstract A soil nitrate test taken about 4 weeks after emergence has been proposed to predict the corn (Zea mays L.) yield reponse to sidedress N fertilizer applications. Use of this test would be increased if the soil analysis and interpretation could be done rapidly, since the fertilizer must be applied within one to two weeks after sampling. Because of this time constraint, mailing samples to a centralized laboratory is unattractive to many farmers. One potential solution to this problem would be to have the analysis done locally using a quicktest kit. A proposed method for analyzing soil samples for nitrate was adapted for use under field conditions. The method is based on the analysis of soil extracts using nitrate sensitive test strips and a hand held reflectometer. Two soil measuring methods, a conventional scooping method and a weighing procedure using an inexpensive balance, were evaluated for inclusion in the test kit. Evaluation was based on the ability of the methods to measure 20 g of soil. F...

HAART Adherence Strategies for Methadone Clients Who Are HIV-Positive A Treatment Manual for Implementing Contingency Management and Medication Coaching

A 2-yr experiment evaluated the effect of spring soil disturbance on the periodicity of weed emergence. At four locations across the northeastern United States, emerged weeds, by species, were monitored every 2 wk in both undisturbed plots and plots tilled in the spring with a rotary cultivator. Eight weed species including large crabgrass, giant and yellow foxtail, common lambsquarters, smooth pigweed, eastern black nightshade, common ragweed, and velvetleaf occurred at three or more site-years. Spring soil disturbance either had no effect or reduced total seedling emergence compared with undisturbed soils. Total seedling emergence for large crabgrass, giant foxtail, smooth pigweed, and common ragweed were on average, 1.4 to 2.6 times less with spring soil disturbance, whereas eastern black nightshade and velvetleaf were mostly unaffected by the soil disturbance. The influence of soil disturbance on yellow foxtail and common lambsquarters emergence varied between seasons and locations. Although the total number of emerged seedlings was often affected by the soil disturbance, with the exception of yellow foxtail and common ragweed, the periodicity of emergence was similar across disturbed and undisturbed treatments. Nomenclature: Common lambsquarters, Chenopodium album L. #3 CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; eastern black nightshade, Solanum ptycanthum Dun. # SOLPT; giant foxtail, Setaria faberi Herrm. # SETFA; large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA; smooth pigweed, Amaranthus hybridus L. # AMACH; velvetleaf, Abutilon theophrasti Medicus # ABUTH; yellow foxtail, Setaria glauca (L.) Beauv. # SETLU. Additional index words: Integrated pest management, periodicity of weed emergence, spring soil disturbance.