BeIle Glade EREC Resc c Eort EV-1984-10
I r" A .<- . A
SEVENTH ANNUAL RICE FIELD DAY
UNIVERSITY OF FLORIDA
EVERGLADES AGRICULTURAL RESEARCH AND EDUCATION CENTER
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
COOPERATIVE EXTENSION SERVICE
BELLE GLADE, FLORIDA
JULY 18, 1984
RICE FIELD DAY
EVERGLADES RESEARCH AND EDUCATION CENTER
BELLE GLADE, FLORIDA
JULY 18 1984
William C. Donovan, Presiding
State Extension Specialist, Sugarcane and Rice
W. C. Donovan
Rice Fertility Studies 1983 1
G. H. Snyder and D. B. Jones
Rice Diseases in the Everglades: 1984 Update 6
D. F. Myers and D. B. Jones
Weed Management Systems for Rice. in Florida 9
J. A. Dusky
1983 Stink Bug Studies 17
Activities of the Rice Council for Market
Charles Wilson, Rice Council Representative
EREC Rice Field Tour
Dutch Treat Lunch (Catered)
Tour of Glades Area Rice Fields
Rice Fertility Studies 1983
G.H. Snyder and D.B. Jones
Two studies were conducted at the Everglades Research and Education
Center in 1983 to determine the optimum time for applying N to rice drill seeded
in organic soil. The rice (Lebonnet) was drill seeded in mid-March and mid-April
for the two studies, respectively, and flooded approximately one month later.
The flood was maintained without interruption until harvest. Nitrogen from urea
was applied at 60 kg/ha at one of the following stages: a) emergence, b)
flooding, c) one week prior to panicle initiation, d) panicle initiation, and e)
fully extended flag leaf prior to heading. Averaging across both studies, only c
and d, above, resulted in yield increases over the check (no N) treatment, and
the greatest yield was obtained for application at panicle initiation. This
experiment, combined with studies conducted in previous years, has led to the
following suggestions for N fertilization of drill seeded Lebonnet rice grown on
organic soils. When drill seeded rice is flooded 3 to 6 weeks after emergence,
use no N at planting. Apply N from urea or ammonium sulfate at panicle
initiation at 60 kg/ha (approximately 50 lb/acre). In our studies, N
fertilization in this manner has consistently resulted in increases in rough
rice dry (12%) weight yield of 15 to 20%. However, growers should apply this
information with caution. The effects of N fertilization on such production
problems as lodging, blast and other diseases, insect infestations, and
sterility, have not been adequately investigated. It is suggested that growers
first try applying N to a few fields to evaluate the use of this practice in
their operation, and then proceed accordingly.
For several years significant yield increases have been obtained by
applying calcium silicate slag at rates of approximately 10 to 20 metric tons/ha
(4.5 to 9 english tons/acre) to soils in the eastern Everglades prior to
planting rice. Ratoon yields also have been increased consistently. In 1983,
slag applications of 5 and 20 tons/ha prior to planting Lebonnet rice increased
plant crop yields by 43 and 58%, respectively. Ratoon crop yields were increased
by 33.6 and 53.2% for the 5 and 20 tons/ha rates, respectively. Total yield for
the two crops at the higher slag rate was 11,295 kg/ha (10,052 lb/ha).
Nevertheless, there is some question as to whether even these yield increases
can be justified in view of the delivered cost of slag. For those growers
following rice with sugarcane, slag applied for rice may also benefit sugarcane
production, thereby allowing the cost of slag application to be spread over
several crops. This point is being investigated in one test initiated in 1983
and two trials begun in 1984.
An evaluation of the responsiveness of various soils in the Everglades
Agricultural Area (EAA) to calcium silicate slag was conducted in a pot
experiment in 1983, using Lebonnet rice. Of the seven soils collected, in only
two did application of calcium silicate slag appear not to increase rice
production (grain yield and total plant biomass). These were soils collected
from a field near the lake west of Pahokee, and a soil collected west of the
Gulf and Western sugar mill. Calcium silicate slag significantly increased grain
yield and/or total plant biomass when added to soils collected from the
following locations: Seminole sugar southeast of Sem-Chi rice mill, Seminole
Sugar Brida Ranch, Seminole Sugar M&M Ranch, Gulf and Western east of Route 27,
Shelton Land and Cattle in the southern EAA east of Route 27. Field studies
conducted on the first two Seminole Sugar locations listed above produced
significant increases in rice production as a result of calcium slag
applications, which is in agreement with the results of this pot study. It
appears that slag may produce rice yield increases in a number of EAA locations.
When rice is planted on certain low-iron soils of the EAA a problem
termed seedling chlorosis develops. One to 3 weeks after emergence the seedlings
become chlorotic and nearly cease growth. This condition generally persists
until several weeks after flooding. Although flooding appears to correct the
condition, many seedlings are to small or weak to survive the drastic changes
imposed by flooding. Applying iron sulfate with the seed has been shown to
alleviate this condition.
Three factors related to the use of iron sulfate (FeSO4) for
reducing seedling chlorosis were studied in 1983. Factors investigated were a)
iron sulfate sources, b) iron sulfate rates, and c) varieties.
Iron sulfate sources and rates Three iron sulfate sources were compared for
their effectiveness in alleviating seedling chlorosis of Lebonnet rice:
a)"heptahydrate" iron sulfate (FeSO .7H20), b) a granular "monohydrate"
iron sulfate (FeSO4.H20), and Iron-Sul, a product that contains
FeSO4 and some free sulfuric acid. As a separate treatment, zinc was applied
at 10 kg/ha. All products were drilled with the rice seed at equivalent iron
rates. Visual ratings were made approximately one month later, using a scale of
1 to 10, where 10 indicated the best possible green color and 1 indicated
extremely chlorotic plants. Grain yields were measured at harvest. The results
of these evaluations are presented in Table 1.
Table 1. Seedling color ratings and
sources and rates.
grain yields as affected by iron sulfate
All sources appeared to improve seedling color and yield. Highest
color ratings were obtained with the highest rate of each source, whereas
highest yields were obtained at either the 20 or 30 kg Fe/ha rate. Highest
yield for the heptahydrate source was obtained at 30 kg Fe/ha. Since this
source contained 20% Fe, the product rate was 150 kg/ha (134 Ib/A). For
Iron-Sul, the highest yield was obtained at 20 kg Fe/ha. This source
contained 16% Fe, so the product rate was 125 kg/ha (111 Ib/A). The small
differences observed among sources probably are not significant. Factors
such as cost, availability, and ease of application may be as important or
more important than efficacy differences among sources in deciding which
source to use for reducing seedling chlorosis. The zinc treatment resulted
in a color rating of 5.3 and a yield of 4912 kg/ha, which were not
substantially different from the check treatment.
Differences among varieties in susceptability to seedling
- - -- - - -- - - - -- - - - - - - -- - - - -
- - -- - - - -
--- --- ---
chlorosis have been noticed in past years. These differences were
quantified for the first time in 1983. Iron sulfate from the heptahydrate
source was drilled with the seed at the rate of 20 kg Fe/ha. Color ratings
and yields were taken as described above. The results are presented in
Table 2. Response of various rice varieties to iron sulfate on a low-iron soil
in the EAA.
----------------------------------------- ----- ------- -
Variety 0 20 0 20
--------- ------- --- ------ ------------ ----- -------------
- kg/ha - -
Labelle 5.3 ** 7.1 4123 NS 3751
Lebonnet 4.8 ** 6.4 4851 NS 5238
L-201 6.8 ** 7.8 4467 NS 4499
Mars 5.6 ** 8.1 4672 ** 5144
Leah 2.4 ** 7.2 2733 ** 4706
** between two values indicate the values are significantly different at
P < 0.01. NS indicates no statistical difference at P < 0.10.
Although the color rating of all varieties was imporved by
application of iron sulfate, L-201 clearly was least affected by seedling
chlorosis and Leah was most affected by it. The grain yield of Leah was
increased 72% when iron sulfate was drilled with the seed.
Rice Diseases in the Everglades: 1984 Update
D. F. Myers & D. B. Jones
Rice diseases have occurred sporadically in the Everglades Agricultural Area
(EAA) from 1982 1984. Brown leaf spot ("HO"), caused by Helminthosporium
oryzae, has been a persistent problem, yet there is no evidence that this
disease has caused economic losses. Some plant pathologists believe that HO is
mainly a disease of a physiologically stressed rice plant and can be corrected
with proper nutrition. We have observed this phenomenon in the EAA. When basic
nutritional problems in Florida rice fields have been corrected, the incidence
of HO should decrease.
Rice blast, caused by Pyricularia oryzae, occurred extensively in 1982.
Frequent rains, which keep relative humidity high and prolong periods of leaf
wetness, are important in the epidemiology of blast and increase the rate and
amount of disease development. While rainfall totals for 1983 were record -
setting, the rain was not as frequent as it had been 1982 particularly during
the rice growing season.
In contrast, sheath blight, caused by the soil-borne fungus Rhizoctonia
solani, has been an increasingly important problem. Once a field has a history
of the disease, it is likely that it will be of increasing importance in
subsequent years. We have observed what appears to be an increasing incidence
of the disease in one field at EREC, Belle Glade in three successive crops.
Two species of Rhizoctonia, R. solani and R. oryzae-sativae, cause disease
in rice. We have not determined which species is present in south Florida. R.
solani is prevalent throughout the south. While this species is thought to
occur in the EAA, its presence has not been confirmed here. Currently, we are
comparing isolates from Florida rice to descriptions of R. solani and to R.
oryzae-sativae, the cause of aggregate sheath spot of rice in California.
Generally, these pathogens can be distinguished by symptomatology by a trained
observer and genetic make-up. We have a preliminary indication that R. solani
is the pathogen in the EAA. We are planning to type our isolates for
anastamosis group for a more complete identification.
Crop Rotation Studies: The possibility that Rhizoctonia sheath blight could
become a major rice disease in the EAA has alarmed some vegetable growers.
Rhizoctonia is involved in many major root and stalk rots of vegetables in the
EAA. Any rotation that would result in an increase in the population of R.
solani in soils where vegetables are grown could theoretically hurt vegetable
production. Nonetheless, there is no evidence that this has actually happened.
We are currently involved in a long-term rotation study with rice and lettuce on
the EAA. Thus far, the incidence of Rhizoctonia in the field has been low and
no conclusions can be made. Our objective in the 1984 rice crop is to increase
the incidence of sheath blight in the field to build populations of Rhizoctonia
solani, to study the epidemiology of the disease in the field, and to map sites
of severe disease closely. This would allow us to compare disease development
in the subsequent lettuce crop next fall with the occurrence of the disease in
future rice crops.
Disease Control: A high level resistance to the sheath blight organism has not
been found. Screening new varieties for disease resistance, however, should
continue under Florida conditions. Crop rotation has not provided much help in
other rice-growing regions of the south, because many of the crops grown in
rotation with rice are also susceptible to Rhizoctonia solani. Fungicides have
been evaluated in other southern rice-growing areas of the U. S. Currently
Benlate and Merfect 340-F are the only registered materials in Florida for
foliar application on rice. Other materials including Tilt & Duter have proven
more effective than Benlate, the current fungicide of choice, in chemical tests
in production states outside of Florida.
Chemical control for HO is not thought to be necessary and we have no
experience yet with blast control .
Duter has been withdrawn from testing because of residue problems. Tilt
could be considered for an exemption under Section 18 of FIFRA, but the chemical
is costly. Further evaluation of fungicides under Florida conditions is needed.
The choice of chemical, doseage, and timing are particularly crucial for good
sheath blight control. Apparently, striking losses can occur after only a
single application of a generally effective fungicide, or at lower application
rates, or because of poorly timed spray applications.
Weed Management Systems for Rice in Florida
J. A. Dusky
The organic soils in the Everglades Agricultural Area is presently devoted
to sugarcane and vegetable production. Rice is an economically feasible
rotational crop during the summer months when these lands are fallow. Sugarcane
land that is followed has a somewhat different weed spectrum than fallow
vegetable land. A rotation of rice following sugarcane has as its major weed
problems, spiny amaranth (Amaranthus spinosus), the panicums, particularly fall
panicum (Panicum dichotomiflorum,) and bloadleaf panium (Panicum adspersum),
sedges (Cyperus sp.) and crabgrass (Digitaria sp.). The major weed infestations
in fallow vegetable land are goosegrass (Eleusine indica), pigweeds (Amaranthus
sp.) and barnyard grass (Echinochloa sp.).
An effort has been made during the past four years to evaluate potential
herbicides that may be utilized in rice production. These herbicides have been
evaluated for their crop safety and weed control efficacy. Earlier testing has
been discussed in previous field day publications. Results from 1983 trials
will be discussed in this paper.
Materials and Methods
Rice, variety LeBonnet, was planted on May 27, 1983 at the rate of 100 lbs
per acre. Plots were 4 ft by 13 ft. Applications were made at two different
times. Preemergence herbicide applications were made on June 4, 1983 and early
postemergence treatments were made on June 21, 1983 when weeds were 2 to 4
inches tall. The major weed infestations in this trial were dayflower
(Commelina diffusa) and an annual sedge (Cyperus sp.).
Herbicide applications were made using a tractor mounted sprayer operated
at 30 psi and 3 mph to deliver 30 gpa. Flat fan nozzles (1104) were used.
Compressed air was used as the propellant. Herbicides evaluated were propanil,
thiobencarb, pendimenthalin, bifenox, butachlor, and molinate alone and in
combination at various rates. Weed ratings and crop vigor ratings were made 2,
4 and 6 weeks after treatment.
Another experiment was conducted to determine the effects of gallonage of
the water carrier used in the application of propanil and the time of treatment
upon rice crop vigor. Rice was planted in the same manner as above. Propanil
was applied at the 2-, 4- or 6-leaf stage, at 1.5 or 3.0 lb ai/A, using 10, 20,
30 or 40 gallons of water per acre. The tractor mounted sprayer was used and
pressure, speed and nozzles were altered to deliver the appropriate gallonage.
Crop vigor evaluations were made 1 week after application.
Results and Discussion
Results of the preemergence herbicide applications are presented in Table
1. Thiobencarb (3.0 6.0 lb ai/A), bifenox (3.0 Ib ai/A), butachlor (4.0 lb
ai/A) and molinate (3.0 6.0 Ib ai/A) provided acceptable control (>70%) of
dayflower for 4 weeks. This percent control did not continue for the season and
by six weeks after treatment control for the most part was no longer acceptable.
Bifenox, butachlor and molinate provided greater than 80% control of the annual
sedge. This control did last during the entire season. None of the treatments
resulted in a loss of crop vigor.
Early postemergence treatments of thiobencarb (4.0 Ib ai/A) and bifenox
(3.0 lb ai/A) did provide adequate control of dayflower and annual sedge four
weeks after treatment (Table 2). This other herbicide treatments did not result
in adequate control. Little or no loss in crop vigor resulted.
When these same compounds were combined with propanil as an early
postemergence treatment, weed control efficacy was enhanced. All the treatments
resulted in excellent control of annual sedge four weeks after treatment (Table
3). Thiobencarb, pendimethalin, bifenox, molinate or butachlor when combined
with propanil provided excellent control of dayflower as well four weeks after
treatment. Residual herbicide control was also greater in that regrowth of the
dayflower did not start until 8 weeks after treatment. There was little or no
loss in crop vigor.
The plots were not harvested in 1983 due to a serious sheath blight
Results for experiments to determine the effects of gallonage, rate, and
time of application of propanil on rice injury are presented in Table 4.
Propanil injury was iost severe when it was applied in 10 gallons of water to
the acre. Injury was significantly reduced when the amount of water used in
application was increased from 10 to 20 GPA at the 2-leaf stage. Increasing the
gallonage at the 4- and 6-leaf stage in the application of propanil did not
significantly reduce injury although the trend for increased tolerance was
Considerable research is still needed, however, it appears that the use of
compounds that provide residual control such as thiobencarb, pendimethalin,
butachlor and molinate in combination with propanil as in an early postemergence
treatment would provide adequate initial weed control and residual in rice
culture. It also appears that increasing the amount of water used in the
application of propanil will reduce the severity of rice injury.
Table 1. Influence of preemergence herbicides upon weed control and crop
vigor 6 weeks after treatment during the 1983 season. Average
of 4 replications.
Rate (lb ai/A)
Table 2. Influence of early postemergence herbicides upon weed control
and crop vigor 4 weeks after treatment during the 1983 season.
Average of 4 replications.
Rate (Ib ai/A)
Table 3. Influence of combination postemergence herbicides treatment
upon weed control and crop vigor 4 weeks after treatment
during the 1983 season. Average of 4 replications.
Rate (lb ai/A)
Table 4. Influence of gallonage, rate and time of application on
propanil rice injury. Average of 4 replications.
Rate (lb ai/A)
Time of Application
1983 Stink Bug Studies
D. B. Jones and R. H. Cherry
Since rice is a relatively new crop to the Everglades Agricultural Area
(EAA) of south Florida, little is known about insect pests attacking the crop.
Although many different insect pests can be found in rice fields in the EAA,
stink bugs are currently the most important pest. Therefore, the objectives of
this study were to: 1) determine the relative abundance of various species of
stink bugs in rice fields, 2) determine the abundance of stink bugs with respect
to plant phenology and calendar date, and 3) develop insecticidal control
Eight rice fields, approximately forty acres per field in size, were
sampled with fifteen inch diameter sweep nets throughout the growing season.
Planting dates for fields sampled ranged from March 1 through May 12, 1983.
Each field was sampled weekly, each sample consisting of 100 sweeps (1800).
Growers sprayed fields for stink bugs when they felt it was appropriate.
Monitoring began three weeks after planting and continued through harvest. Four
fields were monitored through harvest of the ratoon crop.
Samples showed that 88% of the adult stink bugs captured were rice stink
bugs, Oebalus pugnax (Fabricus). Stink bugs began appearing in the fields as
the rice began to head, regardless of the calendar date of heading. Data
indicate that chemical control recommendations developed in other southern rice
growing areas should be applicable to the EAA.
The individual farms (2 fields/farm) will be discussed on the following
pages. This discussion is not meant to be critical of the management programs,
rather it is intended to illustrate how research information can be utilized to
improve stink bug management in the future.
U 120 -
8 t \ TOTAI
/ / ADULT
-20 -10 0 10 20 30
DATS FROM HERDING
planted: April 26
headed: July 1
sprayed: July 11
harvested: August 7
Stink bugs began appearing in the rice shortly after heading (approximately
July 1). The insecticide was applied on July 11 since the last application of
fungicide was scheduled at that time. Stink bug numbers were well below the
suggested treatment level (5 stink bugs/10 sweeps from heading to soft dough
stage) at that time. But, shortly after the spray was applied, stink bug nymphs
began to rapidly appear. Since the nymphs cannot fly it can be assumed they
arose from the hatching of eggs already present in fields. Approximately two
weeks after the insecticide was applied, the stink bug population reached
treatable levels (at this stage, soft dough to harvest, treatment is recommended
when 10 stink bugs/10 sweeps are found). This situation illustrates the fact
that incorrectly timed spraying will not necessarily control stink bugs until
harvest, and fields should be monitored throughout the grain filling period.
-50 -40 -30 -20 -10 0 10 20 30
DRTS FROM HERDING
planted: May 12
headed: August 1
sprayed: August 9, August 24
harvested: September 2
Stink bugs began appearing in the rice field in significant numbers at
heading. This rapid buildup and the fact that the majority of the population
consisted of adults indicates there was a large population of stink bugs nearby.
This was in fact the case. A nearby rice field was being harvested the same
time this field was heading and the adult stink bugs probably were immigrating
into the newly headed field. In this case, the grower observed the stinkbugs
and sprayed at the appropriate time effectively eliminating the stink bugs.
However, he sprayed again, unnecessarily, two weeks later when very few stink
bugs were present. Again, fields should be monitored throughout grain filling
to determine whether spraying is justified.
0 6 1 S I 1 1 I -
-60 -40 -20 0 20 40 60 80 10I
DO TS FROM HEADING
planted: March 30
plant crop: July 16
ratoon crop: September 16
sprayed: July 6, July 19
plant crop: August 3
ratoon crop: November 3
Stink bugs began appearing in small numbers prior to heading. Insecticide
was applied with both applications of fungicide when stink bug populations were
well below recommended treatment levels. Stink bugs began to build up after the
last spraying, but the crop was harvested before they reached treatment levels.
Stink bugs reappeared when the ratoon crop began heading and did reach treatable
levels in the ratoon crop. Even though grain filling of the ratoon crop
occurred during September and October, stink bugs were present. This indicates
ratoon crops, as well as plant crops, should be monitored for stink bugs.
C 4 0 SPRAY HEADED
-40 -20 0 20 40 60 80 100 120 140
DRTS FROM HERDING
planted: March 1
plant crop: June 15
ratoon crop: September 19
sprayed: August 2
plant crop: August 6
ratoon crop: October 21
Stink bugs did not appear in this field until late grain filling and never
quite reached treatment level although the grower did apply an insecticide
shortly before harvest. In the ratoon crop this field had a fairly high
population of grassy weeds which probably supported stink bugs before the ratoon
crop headed. Stink bugs were present throughout grain filling of the ratoon
crop and remained just below recommended treatment levels.
Pesticides Approved for Use on Rice in Florida
K. D. Shuler -
Most of the pesticides listed below have federal labels which do not
restrict their application to any specific area of rice production and are
therefore approved for use on rice grown in Florida. Several pesticides still
only have registrations for the traditional production areas of California and
the Mississippi Delta states. Some of the herbicides listed below which may be
used in Florida are approved for use on weeds and/or soil types which are not
common to Florida. Therefore, this is a list of pesticides which may be used in
Florida, but are not necessarily recommended for Florida conditions. Mention of
trademarks does not constitute a recommendation or endorsement of the product.
Read all labels carefully.
Follow label instructions for proper use of product.
Follow safety guidelines when using chemicals.
Material Company Use
Rohm and Haas
BASF, Mobay, DuPont
blast, stem rot
blast, stem rot
2-4 oz/100 lbs
3-4 oz/100 Ibs
2.25 oz/100 lbs
4 oz/100 lbs
4-8 oz/100 lbs
1.5 oz/100 lbs
SPalm Beach County Extension Agent, Florida Cooperative Extension
Service, located in Belle Glade, FL
/ Preharvest Interval
Material Company Rate PHI 2 /
American Cyanamid stink bug,
chinch bug, fall
chinch bug, fall
1 lb/1,000 sq ft
1 pt/1,000 bu
NOTE: Several fumigants are available for use in gas tight storage bins.
Bolero 8 EC
Rohm and Haas
annual grass &
D. Harvest Aid
Sodium chlorate Helena
bulrush, & sedge
The label reads 3-6 qts/A, but on organic soils we recommend 1-3 qts/A
to prevent the excessive phytotoxicity to rice that occurs when higher
rates are used.
Rate PHI 11