W. Thomas Lanini

Extension Weed Ecologist
216 Robbins Hall
FAX: 530-752-4604


B.A.-California State University, Sacramento, Biology/Chemistry, 1977
M.S.-University of California, Davis, Ecology, 1981
Ph.D.-University of California, Davis, Ecology, 1983

Professional Experience

Assistant Professor, Agronomy Department, The Pennsylvania State University, 1983-86
Associate Specialist, Botany Dept, UC Davis, 1986-90
Specialist, Botany Dept, UC Davis, 1990-94
Sabbatical, Everglades Research Station, University of Florida, 1993
Specialist, Department of Vegetable Crops, UC Davis, 1994-present


My applied research program focuses on low input weed management and weed biology and ecology. Low input weed management studies have included the use of biological control agents, crop competition through intercropping or cover crops, cultural control through rotation or planting date manipulation, water management, and reduced rates of herbicides. Weed biology and ecology studies have focused on weed/crop competition and methods to predict weed emergence. Early biological control studies examined the broad spectrum affects of phytotoxins produced by the fungus, Gliocladium virens, on weeds and crops (Jones et al. 1988), finding differential responses among the various plant species. More recent studies have examined control of yellow starthistle with a combination of seed feeding insects and competition from planted grasses. This study is the first in California to utilize multiple insect species for biological control. Combining the competitive effect of the planted grasses and the seedhead predation by the biological control insects has resulted in more rapid decline of yellow starthistle populations than either method alone. Oat nurse crops have been used extensively for alfalfa establishment in nonirrigated systems. We determined that reducing the oat seeding rate and method of planting would allow this method to work in irrigated systems (Lanini et al. 1991). These studies also helped to determine that a fairly large market existed for alfalfa-oat or alfalfa-grass hay. This has led to more recent studies examining the interplanting of oats or grasses into an established alfalfa stands, as a method of increasing yield and decreasing weeds without the use of herbicides. Studies are examining grass species, fertility requirements, timing and method of grass seeding, and forage composition and quality. Interseeding grasses has resulted in 10 to 15% increases in forage yields and decreases in weed biomass by 50 to 95%. Increases in yields and decreases in weeds have more than offset the cost of interplanting. The use of subsurface, drip irrigation reduces the water requirements/costs in irrigated crops. During the dry summer months, subsurface, drip irrigation does not wet the soil surface, which reduces or prevents weed germination and growth (Grattan et al. 1988). These studies have shown that germination of small seeded weeds is reduced to a greater extent than large seeded weeds in subsurface irrigated systems compared to sprinkler or furrow irrigation. The cost/benefits of weed control by a combination of reduced rate herbicide treatments and hand weeding were found to be equal to or better than weeds controlled by herbicides alone in several vegetable crops (Lanini and LeStrange 1991, 1994). It was found that reducing the rate of standard preemergence herbicide treatments by 50% resulted in little or no change in control for most weed species, while some species required the full rate for control. This has led to a current project, examining methods for predicting weed species and density prior to preemergence herbicide application. Soil samples are taken prior to crop planting and several soil/seed separation methods are being evaluated for their ability to extract weed seeds and they ease/practicality of use. Another study is examining variable rate, banded layby applications in processing tomatoes. Herbicide rates close to the crop row are reduced or eliminated, assuming that competition from the crop will prevent or suppress weed germination and growth. Further from the crop, higher rates are used as these areas either do not develop crop canopy cover or develop only partial cover late in the growing season. Herbicides are reduced 40 to 60% when variable rate applications are made relative to constant rate treatments. Several studies have bee conducted to examine the growth and yield relationships of the crops and weeds. In one instance, dodder (Cuscuta camprestris) was found to germinate during a very specific time period, which has allowed growers to alter their planting date to avoid this parasitic weed. Further studies are examining alternate hosts of this parasitic weed which will lead to rotation recommendations in order to avoid this pest.

Selected References

Grattan, S.R., L.J. Schwankl, and W.T. Lanini. 1988. Weed Control by Subsurface Drip Irrigation. Calif. Agric. 42:22-24.

Jones, R.W., W.T. Lanini, and J.G. Hancock. 1988. Plant Growth Response to the Phytoxin Viridiol Produced by the Fungus Gliocladium virens. Weed Sci. 36:683-687.

Lanini, W.T. and M. LeStrange. 1991. Low-input Management of Weeds in Vegetable Fields. Calif. Agric. 45:11-13.

Lanini, W.T., S.B. Orloff, R.N. Vargas, J.P. Orr, V.L. Marble, and S.R. Grattan. 1991. Oat Companion Crop Seeding Rate Effect on Alfalfa Establishment, Yield and Weed Control. Agron. J. 83:330-333.

Lanini, W.T. and M. Le Strange. 1994. Weed Control Economics in Bell Peppers (Capsicum annuum) with Napropamide and Hand Weeding. Weed Tech. 8:530-535.

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