Methyl bromide alternatives

14 Pages·2002·3.6 MB·English

Historic, Archive Document
Do not assume content reflects current
scientific knowledge, policies, or practices.

Sh
B7SMY7 |
Inside This Issue Methyl bromide’s reign as the gold While quarantine use is »
standard of soil fumigants currently exempted from the
became tarnished as its ozone upcoming ban, the Montreal
The Status of Methyl Bromide
depleting properties surfaced. In Protocol Technology and
TATION Sic od, Sena tee asc eweetCaane s 1
2005, methyl bromide will be Economic Assessment Panel
Plantpro 45 as a Control of Soil-Borne lost to growers as a soil treat- may reconsider the exemption.
Pathogens, Weeds, Nematodes, and ment option, and other practices In 1998, the latest year for
Seed-Borne Pathogens...............::006 6
and compounds must fill the which statistics are available,
void. ARS and others have put the United States used
TeChIGAl FEPONE isc cet ctc snes cadens nterapeanesncese 8
significant efforts into research- approximately 570,015 pounds
ing various ways to fill the gap for quarantine purposes. In
that will be left when methyl exporting U.S. goods to other
bromide is completely unavail- countries, fumigation with
able. This report is a compila- methyl bromide may be
tion, or a status of sorts, of the required. Methyl bromide is
leading options available to also used at U.S. ports-of-entry
growers in the United States. to disinfest commodities found,
on inspection, to be infested
Before the methyl! bromide with nonindigenous pests, the
mandatory reductions began in introduction of which may
1999, U.S. agriculture used irreparably harm U.S.
This issue and all back issues of the
about 60 million pounds of the agriculture.
Methyl Bromide Alternatives newsletter are now
available on the Internet at fumigant. Soil fumigation
<http://www.ars.usda.gov/is/np/mba/ accounted for 75 percent of the The primary focus for the U.S.
mebrhp.htm>.
Visit the ARS methyl bromide research methyl bromide used, with Department of Agriculture in
homepage at about 11 percent used to facing the loss of methyl bro-
<http:/www.ars.usda.gov/ismbmebrweb.htm>.
fumigate harvested commo- mide is research, although
dities during storage and import technology transfer and educa-
This newsletter provides information on research
or export. Another 6 percent of tion activities with the private
for methyl bromide alternatives from USDA,
universities, and industry. methyl bromide was used to sector are also included. Addi-
fumigate structures such as food tional funding has been given to
Address technical questions to Kenneth W. Vick,
USDA, ARS, National Program Staff, 5601 processing plants, museums, assist in the registration of
Sunnyside Ave., Beltsville, MD 20705-5139. transport vehicles, and potential alternative fumigants.
Phone [phone], fax [phone].
warehouses. The last 8 percent The Agricultural Research
Address suggestions and requests to be added to was used to produce other Service (ARS), which serves as
the mailing list to Sharon Durham, USDA, ARS,
chemicals. the lead agency in these activi-
Information Staff, 5601 Sunnyside Ave., Beltsville,
MD 20705-5129. Phone [phone], fax (301) ties, has established a national
504-1641.
Vol. 8, No. 1 Methyl bromide alternatives
program called Methyl Bromide
this time, however, neither university scientists, extension
Alternatives which includes all
iodomethane nor propargyl personnel, and grower represen-
ARS research on this topic.
bromide are registered as tatives meet periodically to
Information about the program
pesticides and will have to go evaluate research results and
and the research being con-
through the process of plan future trials.
ducted can be found at the web
registration, which is costly and
site:
time-consuming, before they are Vegetable Crops
http://www.nps.ars.usdgao.v .
available to producers. Also,
In the United States, tomato
restrictions on use may be
crop production uses 24 percent
ARS Research on Alternatives implemented due to concerns
of preplant methyl bromide,
about its environmental fate
Preplant Soil Fumigation more than any other crop.
since many of the growing
Peppers account for 12 percent.
Research on preplant soil regions are close to schools and
Methyl bromide is used for
fumigation consists of residences.
preplant fumigation of soil in
investigations of alternatives
both nurseries and fields before
that use other chemicals, Because the bulk of preplant
transplanting. Target pests
biological controls, disease/pest methyl bromide, nearly 80
include soil-borne pathogens,
resistant plants, modified percent, is used on strawberries,
particularly Fusarium oxy-
cultural practices, and tomatoes, ornamentals, peppers,
sporum, Phythium spp., and
integrated pest management and nursery crops, ARS’ pri-
Phytophthora spp.; nematodes,
practices to control weeds, mary research focus has been
especially root knot nematodes
pathogens, nematodes, and on these crops with special
(Meloidogyne spp.); and weeds
damaging insects. Viable emphasis on tomatoes in Florida
such as purslanes, spurges, and
methyl bromide alternatives are and strawberries in California as
nutsedges.
difficult to identify compared to model crops. Additional re-
replacements for other ozone search has addressed replant
The most promising fumigant
depleters because many factors difficulties often associated
alternatives for control of
affect the efficacy: crop and soil with perennial crops such as
nematodes, pathogens, and
type, climate, and target pests. grapes, apples, and peaches.
weeds are a combination of
These factors change from one
metam-sodium plus chloropi-
geographical location to ARS’ strategy for evaluating
crin, Telone (1,3-dichloro-
another; therefore, it is potential alternatives is to first
propene, or 1,3-D) C-17 (83
important to be aware that test the approaches in controlled
percent 1,3-D and 17 percent
technology developed in one experiments to determine
chloropicrin), Telone C-35 (65
location is most successfully efficacy and follow up with
percent 1,3-D and 35 percent
used in the areas in which the field tests of those determined
chloropicrin), propargyl bro-
research was conducted. Two to be effective. The impact of
mide, pebulate (Tillam) plus
the variables that affect efficacy
chemicals, iodomethane
Telone C-17, and iodomethane
(methyl iodide) and propargyl is addressed by conducting field
(methyl iodide), according to
bromide, have shown promise trials at multiple locations with
research results in 2000 from
in field studies. lodomethane different crops and against
Dr. Joseph Noling, an extension
has an advantage over the various diseases and pests.
nematologist with the Univer-
chemically similar methyl Those alternatives that are
sity of Florida’s Institute of
bromide—it photodegrades effective in field trials are
Food and Agricultural Sciences
before reaching the further tested in field-scale
at Lake Alfred, Florida.
stratosphere, so it is not an validations, often by growers in
ozone-depleting substance. At their own fields. Research
teams that include ARS and
2
U.S. Department of Agriculture
Vol. 8, No. 1 Methyl bromide alternatives
According to a 1997 U.S. EPA growth of tomato and pepper sive year. Bell and chili peppers
study, metam-sodium and transplants and increased that demonstrate high levels of
plastic mulch controlled all tomato yields. Incidence of resistance to root-knot nema-
weeds tested in the southeastern Fusarium was decreased in this todes have been developed and
United States except nutsedge, study in some PGPR plots. commercially released. Crop
the most bothersome weed in Studies conducted by C. Dou- rotation has reduced nematode
horticultural crops. Noling glas Boyette at USDA’s South- populations in pepper fields,
reports that metam-sodium ern Weed Science Research resulting in increased yield. Soil
displays erratic control, with Unit at Stoneville, Mississippi, solarization, though it works
excellent control in some indicate that a fungal pathogen, well on occasion, has performed
studies and very little in others. Myurothecium verrucaria, inconsistently. Water quality
Although this variability is shows promise for controlling issues have limited the practice
attributed to differences in weeds in pepper and tomato of flooding fields to kill pests in
application, it still presents a plots without affecting the regions that have a high water
major shortcoming. The use of transplants. Additional biologi- table, such as some parts of
paper mulch, a cultural ap- cal control agents that are under Florida.
proach, is also being studied for development include Dactylaria
nutsedge control. Preliminary higginsii, which, after having Strawberries
small-scale tests have demon- been shown to be extremely
Producers of strawberries are
strated good nutsedge suppres- effective in controlling purple
the second largest preplant users
sion, and this approach also nutsedge in small-scale field
of methyl bromide in the United
eliminates the need for polyeth- trials, is now under evaluation
States, targeting pests such as
ylene mulch. Although this by Erin Rosskopf in large-scale
soil-borne pathogens, nema-
research has just been started, it plots through a cooperative
todes, and weeds. Soil-borne
reflects that long-term, more research project between USDA
pathogens of particular note are
sustainable approaches are and the University of Florida.
Phytophthora, Phythium,
being studied in addition to Rosskopf, a research microbi-
Rhizoctonia, and Verticillium
short-term, chemical alterna- ologist at USDA’s U.S. Horti-
dahliae. Methy! bromide is used
tives. cultural Research Laboratory in
for preplant treatment of soil in
Fort Pierce, Florida, is also
nurseries and in production
While biological controls show developing a biological control
fields before transplanting
promise for control of patho- agent, Phomopsis amaran-
strawberries. In the nursery
gens and weeds in vegetable thicola, for use in vegetables
industry, the use of methyl]
nurseries and production fields, and ornamentals. This fungal
bromide is critical because
effective control may require plant pathogen significantly
healthy, vigorous plants provide
several years of continuous affects the growth of pigweeds
growers with a fighting chance
treatment. Another possible (Amaranthus spp.) and has been
to control disease problems in
biological control is competitive field-tested in small-scale trials
the field.
displacement of pathogenic over several seasons.
organisms in soil through the
In the field of nonchemical
use of nonpathogenic organisms Cultural controls, another
approaches, several PGPR
and soil amendments. In an- nonchemical approach, show
strains seem to enhance the
other approach, Nancy Kokalis- promise and are under continual
growth of strawberries and are
Burrelle at USDA’s U.S. Horti- testing. A period of several
being further tested in field
cultural Research Laboratory at years is necessary for this
studies. While resistance to
Fort Pierce, Florida, uses plant approach to work at an optimal
fungal pathogens is under
growth promoting rhizobacteria level since pest population
(PGPR) that have enhanced the levels are reduced each succes-
5
U.S. Department of Agriculture
Vol. 8, No. 1 Methyl bromide alternatives
evaluation, only low levels of research plots in 2000, seem to plant pathogens. Viruses,
resistance have been identified. give good response with slightly bacteria, and other microorgan-
Soil solarization, in limited field smaller yields (5 to 15 percent) isms, like fungi, will remain in
trials in Florida, has shown compared to those with methyl the soil for as long as the food
yields that are comparable to bromide. These chemical source 1s available.
those of methyl bromide treated alternatives have disadvantages
plots, although unpredictable that include greater weed Developing alternatives to
weather events will limit its problems, especially with methyl bromide for replant of
usefulness. In California, where chloropicrin alone; longer vineyards, as well as fruit and
most commercial strawberries waiting times before planting; nut trees, is particularly chal-
are grown, soil solarization 1s and regulatory limitations on lenging because the results of
not an option due to a lack of use. Drip application, according these studies can only be ascer-
solar radiation and low tempera- to current studies, may reduce tained over a period of years.
tures. emissions and worker risk. Scientists have not been able to
Although fungicides, such as isolate pathogens that consis-
Thomas Trout of ARS’ Water metalazyl (Ridomil) and tently cause replant disorder.
Management Research Labora- fosetyl-aluminum (Aliette), Various species of nematodes
tory in Parlier, California, and slowly reduce a portion of the are present in the soils, such as
Hussein Ajwa (formerly of the fungal spectrum encountered in ring nematodes in sandy soils
Water Management Research fields over a period of years, the and pin nematodes in sandy-
Laboratory, now with Univer- lack of control of other patho- loam soils. In some instances of
sity of California-Davis) found gens does not support this replant disorder, small roots are
that various mixtures of 1,3-D/ approach. It appears that in the evident but no obvious patho-
chloropicrin resulted in yields near future, alternative chemical gens are present.
comparable to methyl bromide fumigants are the only technol-
fumigation. Continuing studies ogy likely to replace methyl A number of nonchemical
are being conducted to deter- bromide for control of soil- approaches are being explored,
mine minimum effective rates, borne pathogens in strawberry including biocontrol and growth
optimum application conditions, nurseries and production fields. enhancement agents. Results of
and the impact of virtually these studies are several years
impermeable film on efficacy Grapes, Fruit Trees, and Nut away. A number of cultural
and rate of application. Ajwa Trees control methods appear promis-
and Trout, in conjunction with ing. Some field studies have
Methyl bromide has been used
the California Strawberry been set up to determine
for fumigating soil before
Commission, conducted 4 years whether fallowing for several
planting or replanting to kill
of field trials in growers’ fields months to several years and the
pathogens and plant parasitic
to test and demonstrate the most use of cover crops may alleviate
nematodes in the soil. Methyl
likely effective alternatives to replant disorder. The use of
bromide is capable of destroy-
methyl bromide fumigation for some wheat cultivars as a cover
ing most life stages of soil-
preplant soil treatment for crop seems to reduce levels of
dwelling organisms as well as
strawberries. Nearly all Califor- pathogenic microbes in apple
the roots of old trees and vines.
nia strawberries are grown with orchards, according to Mark
Without fumigation, roots are
preplant fumigation with methyl Mazzola, a plant pathologist in
likely to remain present for at
bromide/chloropicrin mixtures, ARS’ Tree Fruit Research
least 3 years after tree removal.
which typically doubles market- Laboratory in Wenatchee,
These woody roots provide a
able yield. Mixtures of 1,3-D Washington, and Yu Huan Gu,
food source for a variety of soil-
and chloropicrin and chloropi- formerly of the Tree Fruit
borne nematodes, insects, and
crin alone, in Ajwa and Trout’s Research Laboratory, in studies
4
U.S. Department of Agriculture
Vol. 8, No. 1 Methyl! bromide alternatives
conducted in 2000. Under replant disorder. Fungicides to Dried Fruits and Nuts
certain conditions, preplant soil control soil-borne pathogens
Low-temperature (10 °C)
solarization also appears to be a have been used unsuccessfully.
storage and controlled-atmo-
viable alternative for control of
sphere (5 percent O,) storage
the ring nematode (Criconella Sally Schneider, also of ARS’
were found to effectively
xenoplax) in orchards. Alter- Water Management Research
control pests of dried fruits and
ations in cultural practices, such Laboratory, treated a 65-year-
nuts.
as soil excavation in the fall old vineyard that was infested
prior to planting and subsequent with significant plant parasitic
Fresh Fruits
exposure of this soil to freeze/ nematode populations with
thaw cycling during the winter, drip-applied Telone II EC and
In a number of crops, including
or establishing new plants in the shank-applied 1odomethane. citrus and papaya exported from
old aisle rather than the old row, The field was then replanted Hawaii and other places and
appear effective in reducing with three grape rootstocks that limes imported into Florida, the
replant problems. demonstrated broad resistance use of forced hot air for quaran-
to most nematodes in grape
tine treatment of fresh fruits has
Another viable alternative to production areas. Three years been commercialized. Hot water
methyl bromide for some trees after planting, the Harmony immersion for quarantine
seems to be host-plant resis- rootstock supports minimal treatment has been commercial-
tance; for example, “Deep populations of the root knot
ized for litchi exported from
Purple” rootstock for fruit and nematode, even in untreated Hawaii and guavas exported
nut trees appears resistant to plots, but supports higher from Florida. Conversely, cold
pathogens in orchards. How- populations of the citrus nema- treatments are used commer-
ever, graft compatibility deter- todes than either Thompson cially for avocado and starfruit
minations require waiting for Seedless or Teleki 5C. Iodo- exported from Hawaii. Large-
symptoms to appear, which can methane and Telone/Vapam scale tests have shown irradia-
take years. “Guardian” root- combinations appeared to act as tion to be effective for disinfes-
stock demonstrates exceptional adequate replacements during tation of sweetpotato weevils in
resistance to peach tree short the 3-year evaluation. sweetpotatoes exported from
life induced, in part, by the ring Florida, Malaysian and other
nematode and may prove to be a Postharvest Research fruit flies in fruits exported
viable alternative to preplant from Hawaii, and maggots in
Developing alternatives for
methyl bromide fumigation for blueberries exported from
controlling pests of stored and
nematode control. Florida. Field-study results are
exported commodities is the
used to establish and maintain
realm of postharvest research.
At ARS’ Water Management pest-free zones in lieu of
Many commodities cannot be
Research Laboratory in Parlier, postharvest treatments for fruit
exported legally without methyl
California, Cynthia Eayre is flies in citrus exported from
bromide treatment to eradicate
investigating chemical controls. Texas. Approximately two-
quarantine pests and certify the
Preliminary results from 2 years
thirds of the fruit, in most years,
commodities pest free. Alterna-
of data, reported in 2000, show can be harvested under the
tive fumigants, heat and cold
that iodomethane effectively requirements of a pest-free zone
treatments, modified atmo-
controls peach replant disorder. so that methyl bromide treat-
spheres, and combinations of
Combinations of resistant ment is not required.
treatments are various research
rootstock and either 1,3-D or
approaches being explored.
metam-sodium also appear to be
possible alternatives for methyl
bromide for control of peach
U.S. Department of Agriculture
Vol. 8, No. 1 Methyl! bromide alternatives
Processing Facilities and effectiveness in some cases in utilize any alternative technolo-
Warehouses the future. Much of the research gies that become available.
on these approaches is still to be
Methyl bromide is used by Plantpro 45 as a
conducted, and it is unlikely that
many food companies to fumi-
economic use of these alterna- Control of Soil-Borne
gate processing facilities and
tives will be available for many
Pathogens, Weeds,
storage areas to rid these areas
uses before the 2005 phase-out
of insect pests. A proven alter- Nematodes, and
has occurred. Due to the mul-
native treatment is raising the Seed-Borne Pathogens
tiple combinations of crop, pest
temperature of the facilities to
or pathogen, environmental
near 50 °C for 2 to 3 days. Also,
conditions, weed species, soil Plantpro 45, a low-risk iodine-
a combination of heat and
type, etc., combinations of based compound, was studied
diatomaceous earth seems
approaches will be necessary to by Nancy Kokalis-Burelle to
particularly effective in areas
effectively manage diseases and ascertain its usefulness for soil-
that may be difficult to heat. pests. borne pathogen and weed
control. The results are some-
Emissions Reductions For postharvest and export uses, what mixed. Two years of
several nonchemical ap- greenhouse and field trials have
A methyl bromide recapture
proaches, such as heat/cold shown that Plantpro 45 has
and recycling system was
designed by ARS and commer- treatments and modified atmo- some potential for control of
cialized, and is now in opera- spheres, demonstrate some root-knot and sting nematodes,
possibilities as methyl bromide some soil-borne fungal and
tion at the Dallas-Fort Worth
International Airport. The pilot alternatives. A methyl bromide bacterial pathogens, seed-borne
recapture system vastly reduced recapture system has been fungal pathogens, and economi-
the amount of methyl bromide developed and is in use at one cally important weed species.
released to the atmosphere—93 airport in Texas.
“Plantpro 45 works by disrupt-
to 96 percent of recoverable
Research is only one cog in the ing membranes in organisms.
methyl bromide is captured by
machinery to bring reliable, When compounds are in contact
the carbon in field tests.
effective, and economical with nematodes and eggs in the
methyl bromide alternatives to lab you get good toxicity, but in
Conclusions
farmers and other users of the soil the effect is lessened,”
Currently registered alternative methyl bromide. A critical role says Burelle. “Soil is a very
fumigants such as metam- must be filled by the chemical complex medium and water
sodium, chloropicrin, and 1,3-D industry: registering and mar- doesn’t move through the soil
seem likely to be the most keting any promising unregis- as expected, and results vary
reliable replacements. However, tered alternatives. It is currently from trial to trial.”
it is probable that the replace- uncertain if there is adequate
ments will not be as reliable as financial incentive for the Nematode Control
methyl bromide in all cases. chemical industry to bring new
Plantpro 45 showed some
These alternatives were once products to market in light of
reduction of root-knot nema-
the standard chemicals used but the minor-use nature of methyl
tode damage on tomato at
in many cases were replaced by bromide. Users of methyl
multiple field locations in
methyl bromide. bromide will ultimately make
Florida. However, Burelle
decisions, based on several
found it didn’t perform as well
For preplant purposes, biologi- factors including economic
cal control and host-plant as methyl bromide.
considerations, as to whether to
resistance may demonstrate
U.S. Department of Agriculture
Vol. 8, No. 1 Methyl! bromide alternatives
In field trials conducted in Fungal and Bacterial Control the best looking fruit and best
cooperation with the IR-4 yield in tomatoes.” At the
In several locations in Florida,
methyl bromide alternatives
Oceanside, California, site
Plantpro 45 demonstrated
research program on strawber-
during 2001 trials, Plantpro 45
fungicidal and bactericidal
ries in Florida, Plantpro 45
(3/4X) + metam (applied as a
effects by providing significant
seemed to control soil popula- bed-top broadcast spray strictly
control of Fusarium crown rot
tions of sting nematode. In two for weed control) outperformed
and bacterial wilt of tomato in
locations, nematodes were all alternatives in yield, produc-
naturally infested fields. Under
reduced from about 175 nema- ing 5,069 25-pound cartons/acre
greenhouse conditions, a soil
todes per 250 cc of soil in the compared to 5,059 25-pound
drenching with Plantpro 45 of
untreated plots to approximately cartons/acre produced by a
80 ppm followed by a planting
50 in the Plantpro 45 (plus combination of methyl bromide
21 days later and a foliar appli-
Devrinol) plot and about 25
and chloropicrin (50/50) and
cation at 80 ppm | week after
nematodes per 250 cc of soil in 4,518 25-pound cartons/acre in
planting increased root and
the methyl bromide treated plot. the untreated control.
shoot weight and improved root
In another IR-4 trial at Duke
condition of tomato when
Farm, Dover, Florida, a combi- Strawberry trials in Oxnard and
grown in field soil naturally
nation of Plantpro 45 + Salinas, California, produced
infested with Fusarium crown
Fosthiazate + Devrinol brought mixed results. During first-year
rot.
sting nematode levels to 0.8 per trials (2000 fall planting/2001
100 cc of soil compared to 29.3 harvesting), plants were sub-
In an IR-4 tomato trial carried
per 100 cc of soil in the un- stantially less vigorous in
out in southern California
treated control plot. When a Plantpro 45 treated plots,
(Tustin, Orange County), by
combination of only Plantpro 45 relative to the methyl bromide/
Nelson, a preplant application
+ Devrinol was used, the sting chloropicrin treated plots.
of Plantpro 45 (1X rate of 142
nematode population was However, Nelson notes that the
gallons per treated acre, applied
reduced to 6.8 per 100 cc soil. compound was applied both as
in 1.5 inches of water), gave
preplant treatment and as
control of Rhizoctonia solani
Efficacy for nematode control postplant treatment applications
comparable to that of the me-
was not tested in the IR-4 and that the postplant applica-
thyl bromide/chloropicrin
California strawberry trials, tions in particular appeared to
standard at the 6-inch soil
since plant parasitic nematodes inhibit growth of the strawberry
depth. However, a postplant
are not widely prevalent in plants. In the second-year trials
application at a reduced rate of
California soils cropped to (2001 fall planting/2002 har-
(63 gallons per treated acre, also
strawberries due to a lack of vesting), the postplant applica-
applied in 1.5 inches of water),
sandy soil, the nematode’s tion was eliminated and vigor
did not provide similar control
preferred environment, ex- improved. Plants will continue
of this soil-borne pathogen.
plained Mike Nelson of Plant fruiting until June 2002 in the
Sciences, Inc. (Watsonville, southern California (Oxnard)
Crop Performance
California). In addition, Nelson trial and until late October 2002
found that Plantpro 45 seems to In IR-4 tomato trials conducted in the northern California
confer some fungicidal benefits; over a 2-year period in Califor- (Salinas) trial, at which times
for instance, it controls Rhizoc- nia, Plantpro 45 treatments the season-total fruit yields will
tonia at upper soil depths and be assessed.
produced marketable fruit
meets industry standards. yields comparable to the indus-
try standard, according to Burelle notes that Plantpro 45
Nelson. “Plantpro 45 produced can negatively impact crop
growth. “Postplant applications
U.S. Department of Agriculture
Vol. 8, No. 1 Methyl! bromide alternatives
should not be attempted on were observed in the 2000 not at this time. Telone prod-
peppers or strawberries since Florida tomato trials. At the ucts, including Telone II (1,3-
they are especially sensitive to Lake Jem trial site, the combi- dichloropropene) and Telone C-
the chemical and should be nations of Plantpro 45 + metam 17 and Telone C-35 (mixtures
closely monitored on all other (applied as a bed-top broadcast of 1,3-dichloropropene and
crops.” spray strictly for weed control) chloropicrin), constitute the
did not significantly control most likely replacements for
Weed Control yellow nutsedge. However, at methyl bromide in many crops
the Live Oak trial site, the in Florida, including vegetables
Plantpro 45 does provide some
Plantpro 45 (1X) + metam and ornamentals.
weed control, according to
(metam again used strictly for
Burelle’s study. Multiple green-
weed control) combinations Large-scale trials have demon-
house experiments on weed
reduced the incidence of this strated these products on grower
infestation levels in naturally
weed species to a level compa- farms, especially tomato farms.
weed-infested soil showed that
rable to that of the methyl One of the main obstacles for
Plantpro 45 has potential to
bromide/chloropicrin standard. adoption of alternatives is
control one of Florida’s major
nutsedge control, and most of
herbaceous weed species in
Seed Treatment the currently available alterna-
vegetable crops: purslane
tives either provide no control
(Portulaca oleracea). Further In a different application,
or erratic performance in
studies on the herbicidal effects Plantpro 45 seems to also
Florida soils. Tillam has been
of Plantpro 45 confirm signifi- provide some efficacy as a seed
identified as a herbicide which
cant reductions in populations treatment. Burelle worked with
can be used in conjunction with
of nightshade, purple and an oriental-vegetable grower
Telone to provide nutsedge
yellow nutsedge, and crabgrass. who had a problem with
control; however, it is only
High-foliar applications of Fusarium. “Plantpro 45 has
labeled in tomato and has
Plantpro 45 on emerged weeds, good potential as a seed treat-
produced crop damage in some
followed by rototilling prior to ment,” says Burelle. Further
cases. In general, it is felt that
planting, provided effective studies are needed.
these instances of phytotoxicity
control of weed species without
were the result of improper
phytotoxic effects on tomato Technical Report
application or inadequate soil
when an interval of 21 days was
incorporation, as performance
allowed before planting and
Methyl Bromide Alterna- has been acceptable in most of
adequate soil moisture was
tives and Their Current the large-scale trials conducted
maintained between application
Limitations in Florida on grower farms. Tomato
and planting.
growers are fortunate in this
James P. Gilreath, University of regard for they have an effec-
In contrast, in Nelson’s 2001 Florida, Gulf Coast Research
tive herbicide; however, there
California tomato trials mortal-
and Education Center, are many crops where herbicide
ity of annual bluegrass and
Bradenton, Florida options are few, including
common purslane buried 6
pepper, eggplant, and cucurbits
inches deep prior to application
While there are many limita-
like watermelon.
of Plantpro 45 was significantly tions to the adoption of methyl
lower, relative to the methyl
bromide alternatives in Florida, Ornamental growers, such as
bromide/chloropicrin standard,
those limitations are much
producers of caladiums and cut
and not statistically different
different from the principal ones
flowers, have seen little re-
from that of the untreated
in California in that they are not
search on their crops and thus
control. Further, mixed results
State regulatory driven, at least
are much farther behind tomato
8
U.S. Department of Agriculture