Evaluation of nematode thresholds and turf damage
Summary:
A study conducted in 2007 at La Jolla Country, with cooperator and golf course superintendent John Pollok, investigated the relationship between nematode counts and turf damage. After surveying samples from all 18 bentgrass greens for nematodes, we found that there were three different species present —ring nematode Criconemella, root knot nematode Meloidogyne and spiral nematode Helicotylenchus. However, none of these nematodes, even when occurring in high numbers, was associated with turf damage.
The full print version of the report, "Evaluation of nematode populations and nematode damage" is now available.
The bottom line? Don't treat for nematodes unless you are really sure that they are the source of your turf damage. Consult this PACE Update on nematodes and turf for information on how to identify nematode damage at your location.
Principal investigators: John Pollok, La Jolla Country Club, and Larry Stowell, Ph.D. and Wendy Gelernter, Ph.D., PACE Turf
Posted 9/15/08
Leaching evaluation conducted at Mission Viejo Country Club
Summary:
Kevin Hutchins, CGCS, superintendent at Mission Viejo Country Club (Mission Viejo, CA) evaluated the impact of leaching poorly draining fairways that have low saturated hydraulic conductivity. The fairway soils run as high as 20% clay and 30% silt. Estimated saturated hydraulic conductivity is less than 0.4 inches per hour (1 cm/hr). Irrigation was applied slowly in attempt to match soil infiltration rates. Fifteen minute irrigation cycles were followed by two hour soaks over the course of three consecutive days. A total of 5 inches (13 cm) of water was applied. The results showed that leaching reduced soil salinity and nitrogen by about 20%, while chloride was reduced by 40%. Sulfur and sodium levels were slightly reduced, but not significantly. This study illustrates the difficulty encountered when attempting to leach soil salts from soils that have low saturated hydraulic conductivity.
Principal investigators: Kevin Hutchins, CGCS, Mission Viejo Country Club, Larry Stowell, Ph.D. and Wendy Gelernter, Ph.D., PACE Turf
Posted 9/1/08
Using virtual irrigation to forecast disease
Poster presentation at the 2008 American Phytopathological Society meetings, July 26 - 30, Minneapolis, MN.
Authors: Larry Stowell and Wendy Gelernter (PACE Turfgrass Research Institute) and Frank Wong and Chi-Men Chen, University of California Riverside
Click here to view the poster (130 KB)
Summary: Recent research suggests that soil moisture impacts the severity of turf diseases such as anthracnose caused by Colletotrichum cereale, Pythium root dysfunction caused by Pythium volutum, gray leaf spot (GLS) caused by Magnaporthe grisea and brown ring patch (BRP) caused by Waitea circinata var. circinata. The virtual irrigation audit, a simple computer model that predicts the size and location of both wet and dry areas on golf course turf, was designed to provide diagnosticians and turf managers with a precision turfgrass management tool for disease and soil moisture management. In this study, the virtual audit was successfully used to describe the occurrence of GLS and BRP on golf course turf.
