Herbicides and cut foliage

Material Information

Herbicides and cut foliage
Series Title:
ARC-A research report
Stamps, R. H
Mathur, D. D
Poole, R. T ( Richard Turk )
Central Florida Research and Education Center--Apopka
Place of Publication:
Apopka FL
University of Florida, IFAS, Agricultural Research Center-Apopka
Publication Date:
Physical Description:
7 p. : ; 28 cm.


Subjects / Keywords:
Foliage plants -- Diseases and pests -- Control -- Florida ( lcsh )
Weeds -- Control -- Florida ( lcsh )
Herbicides -- Testing -- Florida ( lcsh )
Plants -- Effect of herbicides on -- Florida ( lcsh )
Herbicides ( jstor )
Weeds ( jstor )
Ferns ( jstor )
government publication (state, provincial, terriorial, dependent) ( marcgt )
bibliography ( marcgt )
non-fiction ( marcgt )


Includes bibliographical references (p. 7).
General Note:
Caption title.
Florida Historical Agriculture and Rural Life
Statement of Responsibility:
R.H. Stamps, D.D. Mathur, and R.T. Poole.

Record Information

Source Institution:
Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location:
Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management:
All rights reserved, Board of Trustees of the University of Florida
Resource Identifier:
70785474 ( OCLC )


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not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
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site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida



R. H. Stamps, D. D. Mathur and R. T. Poole '-
University of Florida
IFAS Agricultural Research Center Apopka
ARC-A Research Report RH-82-19

Three crops, pittosporum (Pittosporum tobira), plumosus fern (Asparagus

setaceus), and podocarpus (Podocarpus macrophylla), account for 10% or

more of Florida interstate cut foliage shipments (8). Good weed control

is an important factor in producing high quality cut foliage. Weeds inter-

fere with harvesting (7), compete with crop plants for water, light, and

nutrients (2) and may harbor insect and disease organisms that attack crop

plants (3).

Herbicides may help reduce weed competition with cut foliage crops

but these chemicals must be selected thoughtfully and used with care. Due

to the ornamental use of cut greens the acceptable visible damage (phyto-

toxicity) thresholds are very low. The high value of these crops makes

yield reductions, whether due to weed competition or herbicides, unaccep-

table. Herbicides must be selected not only with the above crop considera-

tions, but also with weed considerations in mind. Herbicides should be

chosen that are effective against the weeds actually present; this means

proper weed identification is imperative. There is some concern that

specific weeds may develop resistance to herbicides but there is probably

greater concern regarding ecological shifts to weed populations that are

resistant to control by herbicides (6). Use of a series of herbicides

and herbicide mixtures that differ in their effectiveness in controlling

Mention of a herbicide does not constitute a recommendation by the authors
and does not imply its approval to the exclusion of other products.

various weed spectrums reduces the chance of a species that is tolerant

to a specific herbicide from becoming dominant and also reduces the

chance of an accumulation of herbicide residues in the soil (6). Table

1 lists herbicides presently labeled for use on the above cut foliage


Table 1. Herbicides registered for use on plumosus

and podocarpus.1

fern, pittosporum,




Common name



Trade name





Diamond Shamrock
Chevron, Thompson-

diphenamid Enide Tuco
napropamide Devrinol Stauffer
trifluralin Treflan Elanco
oryzalin Surflan Elanco
oxadiazon Progrow Ornamental Scotts/
Herbicide I/
Ronstar Rhone-Poulenc
oxyfluorfen + Progrow Ornamental
pendimethalin Herbicide II Scotts

podocarpus DCPA Dacthal Diamond Shamrock
EPTC Eptam Stauffer
napropamide Devrinol Stauffer
oryzalin Surflan Elanco
oxadiazon Progrow Ornamental Scotts/
Herbicide I/
Ronstar Rhone-Poulenc
trifluralin Treflan Elanco

Check labels for current registration including rates, formulations, appli-
cation intervals, instructions and restrictions.
Napropamide and oxadiazon are registered for use on closely related Aspara-
gus densiflorum 'Sprengeri'.


~_ __

Experiments were conducted to determine the effects of repeated

applications of herbicides to green and variegated pittosporum and

podocarpus. Additional preliminary experiments were carried out to

determine if selected herbicides, not presently registered for use on

plumosus fern, could be used safely and also, if they would suppress

yellow nutsedge (Cyperus esculentus).

Study 1. Effects of selected herbicides on yield of cut foliage.

Herbicides (Table 2) were applied to 5 year old green and variegated

pittosporum and podocarpus on 7/80, 11/80, 3/81, 7/81, 11/81, and 2/82.

Granular formulations were hand broadcast on 1.8 m x 2.4 m plots located

at the Agricultural Research Center Apopka, FL. Plants, 2 per plot, were

grown in Blanton fine sand, fertilized bimonthly with an 8:8:8 plus minors

granular fertilizer (annual N rate 224 kg/ha). Treatments were replicated

3 times under each of 3 shade levels (30, 47, and 63%). Shade was supplied

from polypropylene shade fabric. Plots were irrigated as necessary using

permanent overhead sprinklers. Commercial cutters harvested pittosporum

11/80, 4/81, 10/81, and podocarpus 12/80 and 11/81.

Herbicides had no effect on yield of any of the crops (Table 2). Low

weed pressure, hand weeding 2 times a year, and large, well established

stock plants account for the lack of increased yield due to herbicide usage.

Highest yields were from variegated pittosporum plots. Previous research

also showed that variegated pittosporum out-yielded green pittosporum (1).

Producers should be aware that Florida F.O.B. prices for variegated

pittosporum are consistently higher (18-30%) than for green (4,5,8).

Table 2. Effects of herbicide treatments on yield of green and variegated

pittosporum and podocarpus.

Herbicide Rate in2 Fresh weight in kilograms
(formulation) kg ai/ha green pitt. var. pitt. podocarpus

none -- 13.5 a3 17.8 a 10.1 a

dichlobenil (4G) 6.7 14.0 a 18.8 a 10.3 a

napropamide (10G) 4.5 12.1 a 16.9 a 8.6 a

oxadiazon (2G) 2.2 13.2 a 17.7 a 8.1 a

average 13.2 17.8 9.3

Applied quarterly from 7/80-2/82.
2Kilograms active ingredient per hectare. Divide by 1.12 to determine pounds

3Mean separation within columns by Duncan's multiple range test, 5% level.
Means followed by the same letter not significantly different.

Study 2. Effects of selected herbicides on plumosus fern.

Granular herbicides (Table 4) were hand broadcast to a commercial

plumosus shed in Yalaha, FL on 3/10 and 11/81. Soil type was Astatula

sand with a pH of 5.8. The test area was covered with 63% shade polypro-

pylene fabric and irrigated by rainfall. Plots were 4.6 m x 4.6 m and

treatments were replicated 4 times in this complete block design experiment.

Plots had been treated by the grower with diuron at 2.7 kg ai/ha 1 month

prior to the initiation of this study.

No phytotoxicity was detected and yields were not affected by the

first herbicide application (Table 4). Plumosus was not harvested after

the second herbicide application due to cold damage in December but no

phytotoxicity was detected in November. All plots were heavily infested

with well established lantana (Lantana camera and L. sp.), which were

not controlled by the herbicides used, so none of the treatments gave

good weed control. In plantings not containing such perennials these

herbicides would be expected to be of some benefit.

Table 4. Effects of herbicide treatments applied 3/81 on yield of

plumosus fern harvested 4/81.

Herbicide Rate in Yield
(formulation) kg ai/ha # of bunches


none -- 10.7 a

alachlor3 (15G) 4.5 10.3 a

napropamide (10G) 6.7 12.1 a

oxadiazon (4G) 4.5 9.5 a

simazine4 (4G) 3.4 11.1 a

Kilograms active ingredient per hectare. Divide by 1.12 to deter
pounds ai/acre.

Mean separation by Duncan's multiple range test, 5% level. Means
followed by the same letter not significantly different.

3Alachlor is sold as Lasso by Monsanto.

4Simazine is sold as Princep by Ciba Geigy.


Study 3. Effect of herbicides on yellow nutsedge growing in plumosus fern.

Herbicides (Table 5) were applied to unreplicated 3 m x 3,7 m plots

heavily infested with yellow nutsedge in a commercial plumosus shed in

Pierson, FL. Soil type was Deland fine sand and herbicides other than

paraquat were applied 5/2/80. Paraquat, a nonselective contact herbicide,

was applied to certain plots (Table 5) on 5/7/80 to kill nutsedge top

growth. The plumosus had been mowed about 5 weeks prior to treatment.

Watering was supplied by rainfall and shade was supplied by oak trees.

Two months after treatment only the alachlor plot had acceptable

nutsedge control. Bentazon treated plots showed no sign of phytotoxicity

but atrazine damaged the fern. The other treatments were not phytotoxic

except for the initial burn from the paraquat. Bentazon treatments were

reapplied 7/80 and did damage the nutsedge but did not control it. Nut-

sedge was still suppressed in the alachlor plot 3 months after treatment.

A combination treatment of alachlor and bentazon might control nutsedge

without the initial burn associated with the use of paraquat.

Table 5. Treatments assessed for control

plumosus fern.

of yellow nutsedge growing in

Herbicide Rate in
(formulation) kg ai/ha Trade name Manufacturer

none----- ------

none/* ------ -----

alachlor (15G)/* 4.5 Lasso II Monsanto

butylate (6.7EC)/* 6.7 Sutan Stauffer

EPTC (2.3G)/* 6.7 Eptam Stauffer

metolachlor (15G)/* 3.4 Dual Ciba Geigy

propachlor (65W)/* 6.7 Ramrod/Bexton Monsanto/Dow

atrazine (4EC) 2.2 Purge Science

bentazon (4EC) 1.1 Basagran BASF

bentazon (4EC) 2.2 Basagran BASF

*Plots treated with paraquat (Paraquat CL, Chevron) at 0.6 kg ai/100 gal
5 days after other herbicides applied.

Kilograms active ingredient per hectare. Divide by 1.12 to determine
pounds ai/acre.


Literature Cited

1. Conover, C. A. and R. T. Poole. 1980. Effects of light and

fertilizer levels on cut foliage production. Proc. Fla. State Hort.

Soc. 93:210-212.

2. Crafts, A. S. 1975. Modern weed control. University of California

Press. Berkeley. 440 pp.

3. Klingman, G. C., F. M. Ashton, and L. J. Noordhoff. 1975. Weed

Science: principles and practices. John Wiley and Sons, New York.

431 pp.

4. Lobman, S. and E. F. Scarborough. 1979. Marketing Florida Ornamental

Crops, Fresh Flowers and Fern. Summary 1978-79 Season. Federal -

State Market News Service. 34 pp.

5. Peacock, S. and E. F. Scarborough. 1980. Marketing Florida Ornamental

Crops, Fresh Flowers and Ferns. Summary 1979-80 Season. Federal -

State Market News Service. 38 pp.

6. Shaw, W. C. 1982. Integrated weed management systems technology for

pest management. Weed Science 30 (Supplement):2-12.

7. Stamps, R. H. and D. D. Mathur. 1982. Herbicides for weed control

in leatherleaf fern. HortScience 17:201-203.

8. Sun, E. and E. F. Scarborough. 1981. Marketing Florida Ornamental

Crops, Fresh Flowers and Ferns. Summary 1980-81 Season, Federal -

State Market News Service. 35 pp.