Weed Control 77

Objective

Develop more efficient, environmentally safe systems for control of weeds, disease and insect pests

Increasingly cumbersome Environmental Protection Agency procedures and regulations have made registration of promising new chemical compounds difficult - discouraging our researcher;, chemical companies and growers. However, we are sponsoring very productive research at the UCD Environmental Toxicology Laboratory which is helping speed registration by providing needed information to regulatory agencies. We must continue a strong program in this area if we are to retain the use of chemicals essential for pest control.

Weed control

Weed control advances have been hampered by governmental restrictions. Even so, Hydrothol 191 has been registered for American pondweed control, and UC scientists have screened several hundred other new compounds. One, bentazon (Basagran), is likely to receive registration for label specified use on rice. In tests over a 4-year period by UCD weed scientists, bentazon controlled river bulrush, seedling cattails, sedges and some broadleaved weeds. Of great importance, an amended label has been secured permitting increased amounts of molinate (Ordram) for 1978 use on rice.

The light areas which received no molinate are overrun with watergrass; the dark areas received molinate and are free of grass. Cooperative field experiments like this at the Rice Experiment Station, at UCD, and in farmer fields helped the Stauffer Chemical Company secure an amended registration for granular molinate (Ordram). In 1978, following label guidelines, up to 9 pounds of active ingredient molinate per acre can be used for grass control in rice.

New short-statured rice varieties such as Calrose 76, M7 and M9 will require close attention to weed control; otherwise, sedges and bulrushes will overtake them, reducing yield and slowing harvest operations.

Research by UCD agricultural engineers Drs. Norman B. Akesson and Wesley E Yates has resulted in improved plane and helicopter equipment and application methods. This has saved propanil from being banned south of Interstate 80 and has returned the use of MCPA on rice in parts of the San Joaquin Valley where it was once banned.

Dr. David E. Bayer, UCD weed researcher, discusses results of his weed control trials at the 1977 UCD Rice Field Day. Bayer and Dr. Donald E. Seaman, UCD agronomist, have screened more than 200 new chemicals to determine their usefulness for weed control in rice.

Studies by Dr. Donald G. Crosby on the fate of pesticides in the environment saved MCPA for use on rice and provided essential basic information about molinate.

Sowing unsoaked coated seed into shallow water or onto a muddy field may be the next major advance in rice production. Tests beginning in 1975 proved that aerial sowing of drycoated rice has several economic advantages, including less seedling drift and more uniform stands. The seed coating will probably include a fungicide, a herbicide and a growth stimulant.

UCD's Dr. Don E. Seaman is testing rice seed coated with herbicides. Note the weedy control blocks in the third tier back. Dr. D. S. Mikkelsen is testing other coating substances.