Title: Annual report to the Florida Department of Natural Resources on the project
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Title: Annual report to the Florida Department of Natural Resources on the project
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Creator: Sutton, David L.
Publisher: Agricultural Research Center, University of Florida
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76~9


UME LIBRARY

Fort Lauderdale ARC Research Report FL74-1 ,-p 291q


Annual Report to the Florida Department of Natural Resources
l.F.A.S. Univ. of FRon
on the Project: Growth Retardants

For Aquatic Weed Control


Cooperator: University of Florida, Agricultural Research Center
a/b/
at Fort Lauderdale-a-



Period Covering: January, 1973 to December, 1973



Report Prepared by:

David L. Sutton
University of Florida
Agricultural Research Center
3205 S. W. 70 Avenue
Fort Lauderdale, Florida 33314



Copy Number


In cooperation with the Agricultural Research Service, Southern

Region, Florida Area, U. S. Department of Agriculture; U. S.

Army Corps of Engineers; and the Central and Southern Florida

Flood Control District.

SNo portion of this report is to be reproduced in any manner

without the written consent of the University of Florida.









I. Introduction

This report covers the second year of a 3-year study designed to

investigate the potential of growth retardants as a means for aquatic

vegetation management. The primary purpose of such a control measure

would be to retard the growth of the problem plant so that the problems

it causes are eliminated, or to reduce the growth rate of the problem

species to the extent that other desirable vegetation may effectively

compete against it.

The objectives of this study are:

1. To develop herbicides which will retard the growth of aquatic

vegetation, primarily hydrilla (Hydrilla verticillata Royle).

2. To measure the concentration of the growth regulators in the

plants and in the ambient solution.

3. To determine the effect of these herbicides on the physiology

of hydrilla and desirable native aquatic plants.

4. To ascertain the influence of these herbicides on water quality.

5. To evaluate the effect of growth inhibiting herbicides on fish

and other microorganisms in the aquatic environment.

The major emphasis during this second year of study has been

placed on the first objective, and on calibration of instruments to be

used in the study. For the evaluation study hydrilla was cultured as
c/
previously described,- unless otherwise described.


- Sutton, D. L. 1973. Annual report to the Florida Department of

Natural Resources on the Project: Growth Retardants for Aquatic Weed

Control. Fort Lauderdale ARC Research Report FL73-1. 26 typed pages.









II. Growth Retardant Evaluation

Results from evaluations for the growth retarding potential of

various compounds are presented in Tables I to 6.

A copper complex, MW-I, was not as effective as copper sulfate

at equivalent concentrations of copper (Table I).

Copper sulfate did not increase the effectiveness of BAS-3517-H

as compared to the effect of this organic compound alone (Table 2). A

12.3, 24.3, and 31.5% decrease in dry weight occurred after hydrilla

plants were exposed to 0.1, 1.0, and 5.0 ppmw, respectively, of

BAS-3517-H for 4 weeks. Also, these concentrations did not result in

any visual damage occurring to the plants.

Of the TD series of compounds, only TD-6628 at a concentration of

1.0 ppmw reduced the dry weight of hydrilla as compared to the control

(Tables 3 and 4). Dry weight of plants exposed to this compound was

20.8% less as compared to the control plants. Plants exposed to the

TD-6628 for 4 weeks were visually damaged, indicating that this com-

pound was exhibiting more of a herbicidal than growth retarding effect.

Compounds numbered DPX 2535 and DPX 3674 exhibited both growth

retarding and herbicidal effects on hydrilla depending on the concentra-
d/
tion (Tables 5 and 6). Compound number DPX 3674- at a concentration


- Compound DPX 3674 has been recently cleared for use on non-crop

areas for control of annual grasses and broadleaf plants under the trade
name of Velpar. This compound will be marketed by E. I. du Pont de
Nemours & Company, Wilmington, Delaware 19898. Velpar is a 90% water

soluble powder of the triazine type of compound. Mention of a trademark
name or a proprietary product does not constitute a guarantee or warranty

by the University of Florida, and does not imply its approval to the
exclusion of other products that may also be suitable.









of 0.05 ppmw reduced the dry weight of hydrilla at the end of the

4-week treatment period by 50% as compared to the control, while

hydrilla in the 5.0 ppmw concentration had almost completely disin-

tegrated by the end of the treatment period. The other compounds in

the DPX series were generally not as effective as the DPX 3674, with

the exception of DPX 2535 which exhibited phytotoxic properties similar

to the DPX 3674.

Diuron at a concentration of 0.2 ppmw was as effective as the

5.0 ppmw concentration on hydrilla (Table 6).


III. Herbicide Residue Evaluation

An evaluation for the residual effects of DPX 2535, DPX 3674, and

diuron indicated varying residual effects depending on the concentration

and particular compound (Table 7). In this particular evaluation the

herbicides were added to the glass jar containing hydrilla. After 4

weeks all plant material was removed, and the results for that portion

of the experiment are presented in Table 6. New hydrilla cuttings

were then placed in the jars and allowed to grow for an additional 4

weeks. The plants were visually evaluated after I, 2, and 4 weeks, and

plant dry weight determined at the end of this time. Plants in the jars

initially containing 0.05 ppmw of DPX 2535 and DPX 3674 were 26.8 and

41.0% lower in dry weight than the control at the end of the 4-week

period. Growth of the plants during this second 4-week period was some-

what lower than during the first 4 weeks. Fertilization of the jars at

the beginning of the second 4-week period may have improved growth

during this time.









IV. Effect of Calcium on Growth of Hydrilla

Calcium (Ca) as calcium nitrate up to 1,500 mg Ca/l in 0.1-strength

Hoaglands nutrient solution did not increase growth of hydrilla as

determined by dry weight measurement after I and 2 weeks (Table 8).

Dry weight of plants after 2 weeks was greater than after I week

indicating an adequate supply of nutrients for growth.


V. Calibration of Instruments

The second and third objective of this study will be evaluated

in part by the use of carbon-14 labeled compounds. The use of a

liquid scintillation spectrometer greatly facilitates the tracer

studies with carbon-14 because, theoretically, 41t-geometry is obtained

for detection of the weak beta particles produced by this nuclide.

However, one problem encountered in using liquid scintillation is the

reduction in efficiency caused by quenching; a process which results

in a decrease in the intensity of flashes of light produced by the

beta particles from the carbon-14 in the liquid scintillation. Different

types of quenching can occur such as thermal or chemical quenching when

the solvent absorbs beta energy, or color quenching if the solvent

absorbs the light emitted by the liquid scintillator.

The most convenient method to correct for quenching is to use the

"external gamma reference" method. This method also termed "automatic
e/
external standard" (AES) ratio provides for a sealed gamma source-

to be moved by a special mechanism from a shielded storage well to a

position adjacent to the sample. A ratio is then obtained which is used


e/ The source used in this study is radium-226.









to determine the loss of efficiency due to the quench in the sample.

By counting a series of samples ranging in the amount of quench they

contain, a curve can be constructed to correct for efficiency in

similar samples.

A. Quench due to nutrient solution

In order to determine the amount of radioactivity in the ambient

solution for plants treated with various carbon-14 labeled compounds, a

correction for quench due to the volume of nutrient solution was deter-

mined by adding various amounts of 0.1-strength Hoaglands nutrient

solution to vials containing known amounts of radioactivity. The results

of this test are presented in Table 9. Regression analysis of the data

produced a second degree equation with a correlation coefficient value

of 0.9052 which is significant at the 95% level (Figure I). The regression

equation Y = -935.9310 + 2,600.3095(x) 1,630.7499(x2), where x = the AES

ratio and Y = efficiency, can now be used to correct for nutrient solution

volumes up to 1.25 ml. An additional multiplication factor of 1.13528

must be used to convert counts per minute to disintegrations per minute.

B. Quench due to plant material

A number of methods are available for determining carbon-14 in

plant material, but most of these methods are fairly complex and involve

an elaborate set-up to oxidize the plant material and collect the 14C02

that is given off. The AES ratio provides for a rather simple method to

detect carbon-14 in plant material, providing the plant material is

fairly homogeneous. The method described below is therefore limited to

homogeneous plant material.

Various amounts of fresh hydrilla collected from a nearby canal were

ground in 0.25 ml of 95% ethanol in a tissue grinder. The tissue grinding









center was rinsed with 0.25 ml of alcohol and 0.50 ml of the 95%

ethanol used to rinse the grinding tube. Ground hydrilla samples

which had been blotted dry ranging in weight from 6.5 to 60.0 mg fresh

weight were placed in vials containing known amounts of radioactivity.

The vials were counted again, and produced the results presented in

Table 10. A correlation was calculated using the AES ratio as the

independent variable (x) with efficiency the dependent variable (Y).

Regression analysis produced a second degree equation where Y = -4.8881

+ 270.3975(x) 181.5740(x2) with a coefficient of correlation value

of 0.9971 which is significant at the 95% level (Figure 2). Hydrilla

samples similar to the ones used to construct this quench correction

can now be exposed to carbon-14 labeled compounds and then the amount

of radioactivity in these samples determined.

VI. Plans for the Coming Year

New compounds as they become available will be evaluated for their

growth retarding potential on hydrilla. Additional studies are planned

to evaluate the phytotoxic effect of DPX 3674 on other aquatic plants

and microorganisms,and to follow its fate after application. Studies

involving the use of carbon-14 labeled herbicides and other compounds

will be expanded.


_ _I ~I










Table I. Effect of MW-I and copper sulfate on growth of

3.785-liter glass containers.


hydri lla in


a/ b/
Chemical Concentration- Visual evaluation- Plant dry
(ppmw) weight (g)/
(ppmw) 2 weeks 4 weeks


MW-I 0.1 0 3 0.3822 b

MW-I 1.0 0 I 0.3684 b

MW-I 5.0 4 20 0.1018 a

Copper sulfate 1.0 0 2 0.3641 b

Copper sulfate 5.0 17 28 0.0783 a

Copper sulfate 10.0 65 86 0.0670 a

Control 0 0 0.3939 b


a/ Concentration based on the percentage of copper of each compound.

0 = No effect; 100 = Complete kill.

c Values followed by the same letter are not significantly different

at the 5% level as determined by Duncan's Multiple Range Test.

Each value is the mean of four replications.


----~

















Table 2.


Effect of

growth of


combinations of BAS-3517-H plus copper sulfate on

hydrilla in 3.785-liter glass containers.


Chemil Concentration Visual evaluation Plant dry
Chemical b/
(ppmw) weight (g)/
C(ippmw) 2 weeks 4 weeks weight (g)


Control 0 0 .4039 e

BAS-3517-H 0.1 0 0 .3542 cd

BAS-3517-H 1.0 0 0 .3056 ab

BAS-3517-H 5.0 0 0 .2765 a

BAS-3517-H 10.0 0 0 .2642 a

Copper sulfate 1.0 0 0 .3952 de

Copper sulfate plus
BAS-3517-H 1.0 plus 1.0 0 0 .3233 bc


a/ 0 = No effect; 100 = Complete kill.

SValues followed by the same letter are not significantly different at

the 5% level as determined by Duncan's Multiple Range Test. Each

value is the mean of four replications.


---~














Table 3. Effect of various compounds on hydrilla grown in

3.7-liter glass containers under controlled conditions

during a 4-week period.


Plant dry weight
Compound Concentration after 4 weeks
(ppmw) (g)a/


Control .568 bc

TD-6824 1.0 .590 c

TD-6824 0.1 .589 c

TD-6825 1.0 .548 abc

TD-6825 0.1 .547 abc

TD-6826 1.0 .514 ab

TD-6826 0.1 .549 abc

TD-6827 1.0 .591 c

TD-6827 0.1 .550 abc

TD-15713 1.0 .591 c

TD-15713 0.1 .573 bc

TD-6628 1.0 .481 a

TD-6628 0.5 .507 ab


a/ Values followed by the same letter are not significantly

different at the 5% level as determined by Duncan's Multiple

Range Test. Each value is the mean of four replications.









Table 4.


Effect of various compounds on hydrilla grown in 3.7-liter
glass containers under controlled conditions during a
4-week period.


SVisual evaluationa/ Plant dry
Compound Concentration weight after
(ppmw) After 2 weeks After 4 weeks 4 weeks (g)-/


Control 0 0 0.562 bc

TD-1123 0.1 0 0 0.543 bc

TD-1123 1.0 0 0 0.532 bc

TD-1796 0.1 0 0 0.538 bc

TD-1796 1.0 0 0 0.541 bc

TD-6628 0.1 0 0 0.611 c

TD-6628 1.0 12 21 0.414 a

TD-6732 0.1 0 0 0.554 bc

TD-6732 1.0 0 0 0.584 bc

TD-6733 0.1 0 0 0.532 bc

TD-6733 1.0 0 0 0.526 b

TD-6817 0.1 0 0 0.607 c

TD-6817 1.0 0 0 0.581 bc


a/ 0 no effect; 100 plants killed.

- Values followed by the same letter are not significantly different

at the 5% level as determined by Duncan's Multiple Range Test. Each

value is the mean of four replications.












Table 5.


Effect of four organic compounds on hydrilla grown in

3.7-1iter glass containers under controlled conditions

during a 4-week period.


Compound Concentration Visual evaluationa Dry weight b
2 weeks 4 weeks (g)


Control 0.9 5.0 0.3676 b

DPX 2535 0.2 0.5 99.5 0.0622 a

DPX 2535 1.0 1.5 97.5 0.0204 a

DPX 2535 5.0 0 98.8 0.0164 a

DPX 2801 1.0 3.5 3.0 0.3842 b

DPX 2801 5.0 0 1.5 0.4086 b

DPX 3316 1.0 0.5 0.5 0.4232 b

DPX 3316 5.0 0 0 0.4131 b

DPX 3674 0.2 1.3 95.8 0.0403 a

DPX 3674 1.0 28.8 99.8 0.0123 a

DPX 3674 5.0 100.0 100.0 0.0037 a


a/ 0 no effect; 100 plants killed.

b/
-- Values followed by the same letter are not significantly different

at the 5% level as determined by Duncan's Multiple Range Test.

Each value is the mean of four replications except for the control

which is composed of 12 replications.










Table 6. Effect of three organic compounds on hydrilla grown in

3.7-liter glass containers under controlled conditions

during a 4-week period.


Compound Concentration Visual evaluation- Dry weight-/
(ppmw) 2 weeks 4 weeks (g)


Control 0 0 .5692 d

DPX 2535 0.05 0 0 .3727 c

DPX 3674 0.05 0 3 .2844 c

Diuron 5.00 4 93 .1244 ab

DPX 2535 0.10 0 35 .1630 b

DPX 3674 0.10 0 78 .0817 ab

Diuron 1.00 9 78 .0364 a

DPX 2535 0.20 0 58 .0823 ab

DPX 3674 0.20 2 84 .0410 a

Diuron 0.20 2 22 .1052 ab


a/ 0 no effect; 100 plants killed.

b/ Values followed by the same letter are not significantly different

at the 5% level as determined by Duncan's Multiple Range Test.

Each value is the mean of four replications.










Table 7. Evaluation for residue of three organic compounds in 3.7-liter

glass containers. Hydrilla was in contact with these chemicals

for 4 weeks (results in Table I), after which they were removed,

and new plants added for an additional 4 weeks.


Compound Concentration Visual evaluation-- Plant dry wtb
(ppmw) I week 2 weeks 4 weeks (g)


Control 0 0 5 .3253 d

DPX 2535 0.05 0 0 18 .2380 c

DPX 3674 0.05 0 0 28 .1919 c

Diuron 5.00 60 85 100 -c

DPX 2535 0.10 I I 88 .0299 a

DPX 3674 0.10 3 10 86 .0482 a

Diuron 1.00 30 39 100 .0046 a

DPX 2535 0.20 3 5 93 .0734 ab

DPX 3674 0.20 1 4 97 .0255 a

Diuron 0.20 0 1 34 .1198 b
a/
- 0 no effect; 100 plants killed.

b/ Values followed by the same letter are not significantly different at

the 5% level as determined by Duncan's Multiple Range Test. Each

value is the mean of four replications.

c/ Plants completely disintegrated by the end of 4 weeks.












Table 8. Effect of various levels of calcium on growth of hydrilla.


Levels of calcium
(mg Ca/1)


Plant dry weight (g)a/
After I week After 2 weeks


100 0.279 a 0.353 b

500 0.257 a 0.369 b

1,000 0.276 a 0.364 b

1,500 0.293 a 0.343 b


a/ Values followed by the same letter are not significantly different

at the 5% level as determined by Duncan's Multiple Range Test.

Each value is the mean of eight replications.












Table 9.


Quench correction using automatic external standard ratio

for 0.1-strength Hoaglands nutrient solution.


Nutrient solution Counts per Efficiency Automatic external
(ml).a minute (%) standard ratio


0 47,216 t 319 100.00 .8387 .0015

0.10 46,497 + 789 98.47 .8239 t .0014

0.25 46,391 t 103 98.25 .8012 .0003

0.50 46,083 + 152 97.60 .7596 t .0062

0.75 44,748 t 134 94.77 .7203 .0009

1.00 41,706 137 88.33 .7077 t .0013

1.25 37,186 t 2,506 78.75 .6884 1 .0056

a/
- Nutrient solution counted in 15 ml of scintillation fluid consisting

of: 7.0 g of PPO; 0.3 g methyl POPOP; 100 g napthalene; and suf-

ficient 1,4-dioxane to make 1000 ml.













Table 10. Quench correction using automatic external standard ratio
for fresh hydrilla tissue.


Sample Tissue fresh Counts per1 Automatic external Efficiency
number weight (mg) minute- standard ratio (%)


I 16.5 15,930 54 .3685 70.42
2 10.5 18,570 45 .4719 82.08
3 21.5 13,128 79 .2895 58.03
4 32.1 10,295 42 .2276 45.51
5 42.5 8,280 79 .1860 36.60
6 55.0 6,065 365 .1341 26.81
7 6.5 18,786 51 .4915 83.04
8 15.6 16,078 47 .3776 71.07
9 32.7 16,955 113 .4168 74.95
10 21.1 17,827 51 .4320 78.80
II 15.6 12,253 95 .2662 54.16
12 21.3 14,621 72 .3275 64.63
13 18.9 15,255 64 .3419 67.43
14 22.4 14,137 1 127 .3069 62.48
15 22.5 16,762 172 .4009 74.91
16 10.0 18,675 98 .4873 83.64
17 11.8 19,422 62 .5217 86.98
18 16.5 16,537 227 .3987 74.06
19 20.0 17,031 220 .4226 76.28
20 30.8 14,878 137 .3288 66.64
21 44.0 12,668 76 .2768 56.74
22 51.5 5,421 534 .1207 27.28
23 60.0 3,271 92 .0689 14.65
24 52.0 4,294 275 .0878 19.23
25 46.8 6,677 t 71 .1477 29.91


a/ Hydrilla samples counted in Insta-gel


emulsifier, a compounded blend


of solvent, scintillator, and non-ionic surfactant prepared by Packard

Instrument Company, Inc., Downers Grove, Illinois 60515.




T17


100






90


Sr =0.9052


S= 935.9310 + 2,600.3095 (x) +-1,630.7499(x2)
.60








.65 .70 75 .80 .85

AUTOMATIC EXTERNAL STANDARD RATIO


- ." .- .


Figure 1,. Quench correction for 0. 1 to 1.25 ml of 0.1-strength Hoaglands

:.. ...- ..: nutrient solution -using the automatic external .standardratio

S. '. method,


0


80







70


0






0




LL.
LL
IL.


LUJ


.. I ` _- I.- ." _.- .'._-'


-- --~~--;;


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i ;


"` :-,c- : ; j

:


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?


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c'


10 i


30


L ..

-.


UW4
0 :


w_
rU
-,; ; .


30






i0






0


::: I


3 .5 .6

S*. .AUTOMATIC EXTERNAL STANDARD RATIO
.- ..- .. '. .. .. ,


Figure 2. Quench correction for hydril la samples (up to .60 mg fre.-

weight) using the automatic external standard ratio -method.":,".




7 -
.- .. ; .









'- ~ ." i "'i


i ~18.
4, -:
K'
.....................................................


-,
-r
: ~~~-
:
r- -


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:
... :
..- i;


Y= -4.8881 270.3975(x)- 181.5740(x2)


r = 0.9971








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VII. Distribution List

Copy No.

I Dr. Alva P. Burkhalter
Aquatic Plant Research & Control Coordinator
Florida Department of Natural Resources
Room 595, Larson Building
Tallahassee, Florida 32304

2 Dr. Bryson L. James
Director & Professor (Orn. Hort.)
University of Florida IFAS
Agricultural Research Center
3205 S. W. 70.Avenue
Fort Lauderdale, Florida 33314

3 Dr. John F. Gerber
Assistant Dean
1022 McCarty Hall
University of Florida -IFAS
Gainesville, Florida 32611

4 Mr. Robert D. Blackburn
Location Leader
USDA, ARS, SRAO
Florida Area Fort Lauderdale Location
3205 S. W. 70 Avenue
Fort Lauderdale, Florida 33314

5 Dr. Edward O. Gangstad, Chief
Aquatic Plant Control Planning Division
Department of the Army
Office of the Chief of Engineers
Washington, D. C. 20314

6 Mr. Zeb C. Grant, Director
Maintenance & Operations
Central & Southern Florida Flood Control District
P. O. Box 1671
West Palm Beach, Florida 33408

7 Dr. William B. Ennis
USDA, ARS
Office of Director
Plant Industry Station
Beltsville, Maryland 20705

8 Dr. Peter A. Frank, Plant Physiologist
USDA, ARS
Room 212, Building 56, Denver Federal Center
Denver, Colorado 80225


_ __ ~1_ ~~_~_




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