White Mold
continued from page 1Given the effects of the fungus on yield, Pennypacker was at first puzzled by finding no significant difference in the number of plants infected in plots with different row spacing. She discovered, however, that there was a significant difference in the place that infection occurred on the plant. The infection was on the main stem in 57% of the infected plants in the 14" rows, 39% in 21" rows, and 28% in 28" rows. A main stem lesion is often more deadly to the plant than a lesion located on a petiole or side branch. So Pennypacker speculates that the increased yield in widely spaced rows may be caused by the tendency of the white mold lesions to occur on a non-lethal site in those plants.
Pennypacker has conducted one year of field tests of the herbicide COBRA® , which has shown promise in controlling soybean white mold in the Midwest. She found no significant increase in yield in fields sprayed with COBRA®, although there was a significant decrease in the amount of white mold present and in the number of sclerotia produced. This should be beneficial for the health of future crops planted in a field with a history of white mold.
In cooperation with Dr. Marvin Hall, associate professor of agronomy, Pennypacker has examined the possibility that alfalfa planted in the spring in a soybean field where white mold was a problem could be threatened by the white mold fungus. They found that if alfalfa planting was delayed until mid- to late-May, there was no significant reduction in the first year's yield, but there was a significant reduction in winter survival. However, if planting occurred in April, alfalfa winter survival was not reduced. All of these field studies are being repeated this summer.
Pennypacker found through greenhouse experiments that there appear to be two types of soybean response to white mold infection. One is light sensitive and the other isn't. Most cultivars show more resistance to white mold when light levels are high, but become susceptible when light levels are reduced. A few cultivars don't seem to vary their response with light level.
Light is essential for photosynthesis and soybean plants appear to use the sugar produced by photosynthesis to make compounds that protect them
against white mold fungus. If light levels are too low, the plants may not be able to produce these defense compounds. Pennypacker hopes in the future to investigate the physiological and genetic basis for these two types of response. This line of research could help plant breeders develop soybean cultivars with more effective resistance to white mold.
Pennypacker's research has been supported by the Pennsylvania Soybean Promotion Board and the Valent, U.S.A. Corp., manufacturers of COBRA® herbicide. Penn State Agronomy Department personnel who collaborated in this research include Dr. Marvin Risius, professor of plant breeding, Dr. Elwood Hatley, professor of agronomy, Ed Werner, technical/administrative specialist, Robert Dickerson, research support technician, Buck Fetzer, technician, and Mark Antle, research support technologist. Pennypacker gratefully acknowledges the cooperation of Kenneth Eck, in Muncy and William Wheler in Jersey Shore, on whose farms the field experiments were conducted.
Pennypacker can be reached at (814) 863-7625; e-mail p1q@psu.edu.
· NEWS BRIEF · NEWS BRIEF · NEWS BRIEF · Dr. Barbara Pennypacker recently presented an invited lecture at the 7th International Congress of Plant Pathology, Edinburgh, Scotland. Her lecture was titled "Impact of light and CO2 on resistance to vascular wilt fungi in alfalfa."
Astronaut and Penn State professor James Pawelczyk presented the keynote address at the 1998 Penn State Golf Turf Conference in November at University Park. Pawelczyk flew on the Space Shuttle Columbia in spring 1998 and took Penn State turfgrass seeds into space. Other Penn Staters who spoke at the conference were Dr. Thomas Watschke, Dr. Charles Mancino, Mr. George Hamilton, Dr. Andrew McNitt, and Mr. Steven Josimovich. Six hundred fifty people attended.
The 1999 Eastern Pennsylvania Turf Conference and Trade Show was held in early January. It was sponsored jointly by Penn State and the Pennsylvania Turfgrass Council. Several members of the Penn State turfgrass program spoke at the
conference, including Dr. Thomas Watschke, Dr. Peter Landschoot, Dr. Andrew McNitt, Mr. George Hamilton, Dr. Charles Mancino, and Dr. David Huff. More than 1,600 people attended. The 1999 Western Pennsylvania Turf Conference will take place in February. More than 1,800 people are expected to attend.
Dr. Les Lanyon, professor of soil fertility, recently published the following referred papers:
Dou, Z., L.E. Lanyon, J.D. Ferguson, R.A. Kohn, R.C. Boston, and W. Chalupa. 1998. An integrated approach to managing nitrogen on dairy farms: Evaluating farm performance using the Dairy Nitrogen Planner. Agron. J. 90:573-581.
Saporito, L.S. and L.E. Lanyon. 1998. Evaluating management and soil and weather contributions to potential nitrate leaching from a Pennsylvania dairy farm using NLEAP. J. Environ. Qual. 27:1367-1375.Dr. Nathan Hartwig presented a paper on "Competitive control of annual weeds with a crownvetch living mulch and companion seeding of soybean in no-tillage corn," at the Northeastern Weed Science Society meeting in January in Cambridge, MA. The paper citation is: Northeastern Weed Sci. Soc. 53:29, 30.
Charles Krueger, professor of agronomy, and Harry Pionke, research leader with the USDA Pasture Systems and Watershed Management Research Laboratory, recently edited a publication called Priority Pasture Research and Education Needs. This is a supplement to the proceedings for the conference, "Grazing in the Northeast: Assessing Current Technologies, Research Directions, and Education Needs." This publication was developed and adopted by the Northeast Pasture Research and Extension Consortium membership, a private-public partnership of graziers, agri-business suppliers, land-grant universities, USDA/Agricultural Research Service, and USDA/Natural Resources Conservation Service representatives located primarily in the Northeast Region. NRAES-113S.