||Extension Weed Ecologist
216 Robbins Hall
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
Assistant Professor, Agronomy Department, The Pennsylvania State University,
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
applied research program focuses on low input weed management and weed
biology and ecology.
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.
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
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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