Dr. York received his B.S. degree in Agronomy in 1974 and M.S. degree in Crop Science in 1976 from North Carolina State University. After receiving his Ph.D. in Agronomy with a weed science specialization from the University of Illinois in 1979, he then joined the Crop Science faculty at N. C. State. He served as the cotton extension specialist from 1979 to 1983 and then assumed his current position as weed science extension specialist. In 2001 he was named as a William Neal Reynolds Professor of Agriculture. His current responsibilities include weed management research and extension in corn, cotton, small grains, and soybeans. He advises graduate students and previously taught the weed management course in the Agricultural Institute for 14 years.

RESEARCH

Dr. York maintains an extensive applied research program on weed management in agronomic crops. In addition to evaluation of new herbicides, he focuses on efficacy and economics of management systems in conventional and herbicide-resistant crops, development of systems for specific problem weeds, weed management in conservation tillage cotton, pesticide interactions, effects of herbicides on rotational crops, and alternatives for herbicides presenting environmental problems or in danger of greater regulation. More information on his research activities is available at his Research Homepage.

A major effort is devoted to cotton. Cotton acreage has increased 24-fold since eradication of the boll weevil, with over 1 million acres planted in 2001. About 75% of the acreage is planted to Roundup Ready varieties, hence much of the research is focused on management systems in this transgenic cotton. Research is being conducted in the following areas: efficacy, yield, fiber quality, and net returns in Roundup Ready vs. conventional varieties; role of residual preemergence, postemergence, and post-directed herbicides; tank mixes to broaden the control spectrum; effect of timing of early season applications on weed competition and cotton yield; timing of preharvest applications; and evaluation of new transformation events. Research also is being conducted in conventional varieties and on management systems for organic soils.

Conservation tillage is being rapidly adopted by North Carolina cotton growers. This has created some new issues in weed management. Of particular concern has been control of cutleaf eveningprimrose, a winter annual that becomes troublesome in the absence of tillage. Research has demonstrated that 2,4-D as a component of the burndown program is highly effective on this weed. Work also has been conducted to determine the necessary waiting interval between application and planting. Many growers are reluctant to put 2,4-D in their sprayers, hence work is continuing to find other acceptable programs.

The increase in cotton acreage has led to substantial changes in crop rotations. Specifically, most of the state's peanuts and greater than half of the tobacco is now rotated with cotton. Research has previously been conducted to determine the potential for fluometuron applied to cotton to carry over to tobacco and for imazapic and imazethapyr applied to peanuts to carry over to cotton. Work is currently in progress to determine the potential for residual lay-by herbicides applied to cotton to carry over to tobacco and peanuts.

The major focus in wheat currently is on finding alternatives to diclofop to control diclofop-resistant Italian ryegrass. Ryegrass is the most serious weed problem in wheat in North Carolina, with heavy infestations reducing yield up to 75%. Greater than half of the ryegrass in North Carolina is resistant to diclofop, and there are currently no good alternatives. Research is in progress to evaluate several promising experimental compounds in development for both ryegrass control and wheat tolerance. The work is focused on efficacy and crop tolerance as affected by time of application, carriers, adjuvants, and tank mixes. Work also is in progress to evaluate ryegrass management systems in a non-transgenic, herbicide-resistant line of wheat.

In most of North Carolina, atrazine-based programs are the main stay for weed control in corn. Atrazine has been detected in some municipal water impoundments, and research is currently underway to evaluate alternatives to atrazine in both conventional and transgenic corn. Work also is being conducted to compare economic returns of management systems in herbicide-resistant and conventional hybrids. Total postemergence programs are used extensively in corn in the Blacklands. One of the primary concerns there is corn injury from the interaction of organophosphate insecticides used for billbugs and sulfonylurea herbicides. Research is currently being conducted on alternatives to sulfonylureas and on potential for interactions between herbicides and some new chemistry for billbugs.

About 75% of the soybeans in North Carolina are Roundup Ready. Extensive work was conducted in mid- to late 90's to compare efficacy and economics of glyphosate-based and conventional management systems. Most of the current work is focused on control of species, such as Commelina, Murdannia, and Ipomoea, which are not adequately controlled by glyphosate.

Dr. York has worked extensively with plant growth regulators for cotton and peanuts. He published the first research in the United States on use of mepiquat chloride in cotton, and more recently, on use of prohexadione calcium in peanuts.

Selected Research Publications

Culpepper, A. S. and A. C. York. 2000. Weed management in glufosinate- and glyphosate-resistant soybean (Glycine max). Weed Technol. 14:77-88.

Culpepper, A. S., A. C. York, and C. Brownie. 1999. Influence of bromoxynil on annual grass control by graminicides. Weed Sci. 47:123-128.

Mitchem, W. E., A. C. York, and R. B. Batts. 1996. Peanut response to prohexadione calcium, a new plant growth regulator. Peanut Sci. 23:1-9.

Wade, H. F., A. C. York, A. E. Morey, J. M. Padmore, and K. M. Rudo. 1998. The impact of pesticide use on groundwater in North Carolina. J. Environ. Qual. 27:1018-1026.

York, A. C., D. L. Jordan, R. B. Batts, and A. S. Culpepper. 2000. Cotton response to imazapic and imazethapyr applied to a preceding peanut crop. J. Cotton Sci. 4:210-216. 

EXTENSION

Dr. York, in cooperation with specialists in Crop Science and other departments, is actively involved in training programs for extension agents, consultants, dealers, and agrichemical industry personnel. He also regularly participates in various county and state field days and grower meetings.

He is responsible for North Carolina's weed management recommendations for corn, cotton, small grains, and soybeans. These recommendations are found in the North Carolina Agricultural Chemicals Manual, Cotton Information, the North Carolina Corn Production Guide, and the Small Grain Production Guide.

Dr. York's extension program has been recognized with receipt of the Weed Science Society of America's Outstanding Extension Award, the Cotton Foundation's Cotton Extension Education Award, North Carolina State University's Outstanding Extension Service Award, Epsilon Sigma Phi's State Distinguished Service Award, and the Crop Protection Association of North Carolina's Walton Dennis Award for Environmental Stewardship. He also has received two certificates of excellence for extension publications from the American Society of Agronomy and was elected to Ag Consultant magazine's Hall of Fame.

Extension Publications

Jordan, D. L. and A. C. York. 2001. Weed management in peanuts. p. 30-68 in 2001 Peanut Information. N. C. Coop. Ext. Serv. Bull. AG-331 (Revised).

York, A. C. and A. S. Culpepper. 2001. Weed management in cotton. p. 73-119 in 2001 Cotton Information. N. C. Coop. Ext. Serv. Bull. AG-417 (Revised). 

York, A. C. and A. S. Culpepper. 2000. Weed management. p. 86-126 in 2000 North Carolina Corn Production Guide. N. C. Coop. Ext. Bull. AG-594 (Revised).

York, A., R. Weisz, L. Crooks, and B. Tarleton. 2000. Small grain weed control. p. 57-63 in Small Grain Production Guide 2000-01. N. C. Coop. Ext. Serv. Bull. AG-580.

GRADUATE EDUCATION

Dr. York is a full member of the graduate faculty and is actively involved in graduate student education. He has directed three M.A., 16 M.S. and four Ph.D. students and has served on numerous graduate committees. One of his former students received both the Southern Weed Science Society's and the Weed Science Society of America's outstanding Ph.D. student awards, and several students have won the Southern Weed Science Society's graduate student contest. Four former students are now extension specialists in Georgia, Mississippi, and North Carolina, one is in academia in Uruguay, one is the IR-4 program coordinator for N. C. State University, three are county extension agents, and one is in state regulatory affairs. The remainder of the students are in research and marketing with private industry, including BASF, DuPont, Monsanto, Pioneer Hi-Bred International, Stoneville Pedigreed Seed, and Syngenta.