Group Title: AREC-A research report - Agricultural Research and Education Center-Apopka ; RH-80-2
Title: Weed control in foliage nurseries
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Permanent Link: http://ufdc.ufl.edu/UF00065940/00001
 Material Information
Title: Weed control in foliage nurseries
Series Title: ARC-A research report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Poole, R. T ( Richard Turk )
Agricultural Research Center (Apopka, Fla.)
Publisher: Agricultural Research Center-Apopka
Place of Publication: Apopka Fla
Publication Date: 1980
 Subjects
Subject: Weeds -- Control -- Florida   ( lcsh )
Foliage plants -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Richard T. Poole.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065940
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70915446

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D EEW CONTROL IN FOLIAGE S


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BY HU LIBEEf Y
j Richard T. Poole
Agricultural Research Center Apopka Li'
ARC-A Research Report RH-80-2
F..S. Univ. of Florida
Weeds increase production costs and compete with desired plants for aval'labFTe1

water, light, carbon dioxide and nutrients. Weeds also harbor insects, diseases

and nematodes which may attack desired plants. Because foliage plants are used

primarily for their aesthetic value, weeds infesting containers must be removed

to preserve plant beauty, quality, and marketability.

Weed control is often obtained as the by-product of certain practices utilized

in the production of vigorous, uniform, disease and pest-free plants under climate-

controlled conditions. Proper fertilization and irrigation, disease and insect

control are important tools for controlling weeds. Nevertheless, the use of

materials to suppress weed growth in and around the nursery has a place in modern

production practices, and even more so in open field conditions found in semi-

tropical and tropical nursery growing areas where environmental controls cannot

be rigidly maintained.

CLASSIFICATION OF HERBICIDES BY ACTION

Soil or Industrial Sterilants. Certain materials are used to "sterilize"

the soil for extended periods and usually remain in the treated-soil for a

considerable length of time. For example, such treatment is frequently used in

areas along railroad or highway rights-of-way, around utility substations or

power poles or along fence rows. Possible uses of these materials in a nursery

would be limited to "root free" loading areas, perimeter fence rows or in or

adjacent to roadways, provided that the effects of these materials would be

limited to the immediate area of placement.

Fumigants. Fumigants are highly volatile materials or gases (sodium azide,

calcium cyanimid, paradichlorobenzene, formalin, chloropicrin, methylbromide)




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which are toxic to vegetative portions of plants and most seeds as well as to

many other forms of life in the soil. They generally do not persist in the soil

for more than 1 to 2 weeks. They are applied to moist, well-mixed, loose soil

as granules, drenches, or gases.

Preemergence Herbicides. This group of herbicides consists of materials

which are applied to the soil surface and usually incorporated into the upper

few centimeters of soil before the weeds germinate. These herbicides must be

applied before the weeds emerge, as they have little or no effect on weeds already

present. They are usually non-toxic to the crop for which they are registered,

although safety of a material on corn, cotton or peanuts does not guarantee safety

on philodendrons or dracaenas!

Postemergence Herbicides. Other materials, when applied to growing plants,

kill the plant quickly (within several hours) or slowly (several days to weeks).

Postemergence herbicides are applied to weeds already present in contrast to the

preemergence herbicides. Postemergence herbicides may be divided into two

categories depending on whether or not they kill only the contacted portions of

the plant ("contact herbicides") or are absorbed into the vascular system and

translocated through the shoot or root system, eventually killing one or the

other or both ("systemic herbicides"). To achieve good kill with a contact

herbicide, cover as much of the foliage of the target plants as possible. If

the crop is coexistent with the weeds, the use of a directed spray to keep the

herbicide off the foliage of the crop plant is sometimes necessary.

HERBICIDE FORMULATIONS

Herbicides are applied either as sprays or granules; dusts are not used

because of the hazard of drift. Sprays may be prepared with a completely water
soluble crystalline or powdered material (SP), an emulsifiable concentrate (EC),

or a wettable powder (WP) suspension. Wettable powders remain suspended in water

for a certain amount of time, but eventually most or all of the powder will settle.




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Constant agitation is necessary when using wettable powders to prevent settling

and uneven application rates. Granular (G) formulations contain a small amount

of active ingredient impregnated on a large volume of an inert carrier such as

clay, ground corn cobs, sand or vermiculite. Coverage with granules may not be

as good as with liquid application, but costly spray equipment is not required

and granules tend to fall off foliage without injuring the crop plant. However,

the use of granules on palms, dracaenas, sansevierias, dieffenbachias, and other

plants forming cups, whorls, or rosettes of leaves carries with it the risk of

funneling granules into the center of the plants and damaging them.

Two methods of describing rate of application of herbicides are: 1) pounds

per acre of formulated material; or 2) pounds per acre of active ingredients

(active ingredients being the specific-chemical(s) responsible for the herbicidal

effects). For example, a herbicide can be formulated as 5G or 50WP. If 5 pounds

per acre active ingredient is required to control weeds, 100 pounds of the 5G would

be used but only 'O pounds of 50WP material would be used. One hundred pounds of

5G contains 5 pounds active ingredient, but 10 pounds of 50WP contains 5 pounds

active ingredient.
HERBICIDES LABELED FOR ORNAMENTAL USE

CASORON EPTAM ROUNDUP
DACTHAL LASSO SURFLAN
DEVRINOL PRINCEP. TOK
DIQUAT RONSTAR VEGEDEX

WEED CONTROL IN THE GREENHOUSE AND IN STOCK BEDS

To the author's knowledge Diquat is the only herbicide registered for use

under greenhouse benches. Other contact herbicides have been used to kill

existing weeds but they are not now labeled for use in the greenhouse and their

use is therefore illegal. Preemergent herbicides, also not labeled, have been

used in the greenhouse -- sometimes with satisfactory results, sometimes with
disastrous results. For good weed control in the greenhouse, a preventive program

should be followed and any germinating weeds removed on a regular basis.




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SAFETY OF HERBICIDES IN ENCLOSED STRUCTURES
Herbicide Safety Herbicide Safety

Karmex S Pramitol-P ?
Hyvar-X S Treflan ?
Diquat S Pramitol-L U
Princep ? 2,4-D U


The eradication of established weeds in a stock foliage bed is difficult and

must be accomplished by hand. There are presently no known herbicides that will

selectively kill weeds present and not damage the foliage plants. Prevention

and early eradication of young weeds is the best procedure to follow. When stock

beds are growing vigorously and a dense canopy is formed over the bed, few, if any,

seeds will germinate. When vines or cuttings are taken from the stock beds for

propagating material, areas in the bed-are then exposed to light and seed germination

will occur. The easiest and best time to pull weeds is also after harvesting for

propagation material. The weeds should be removed and a registered herbicide for

the crop applied as soon as possible after harvest. CAUTION: Repeated applications

of a herbicide can cause a toxic amount of the material to accumulate in the soil.

DO NOT apply the herbicide more frequently than the time interval specified on

the label.

PRECAUTIONARY NOTE

A word of warning is in order regarding where some of these materials might

be used in a nursery. The use of any herbicide in glasshouses or solid structures

which restrict air circulation and exchange with the outside air should be avoided.

Fumes arising from soil-applied herbicides, even to soil under benches, have caused,

damage in greenhouse crops. Unless certain that the material and formulation are

safe to use in such an area, the best recommendation is to avoid use. A CARDINAL

RULE WITH ANY PESTICIDE WHOSE PERFORMANCE IS UNFAMILIAR TO THE GROWER IS TO TRY

IT ON A LIMITED NUMBER OF PLANTS IN A SITUATION SIMILAR TO THAT UNDER WHICH THE

MATERIAL IS PROPOSED FOR USE.




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