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Group Title: ARC-A research report - Agricultural Research and Education Center - RH-83-7
Title: Don't drench plants with pesticides meant to be used as foliar sprays
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Permanent Link: http://ufdc.ufl.edu/UF00066520/00001
 Material Information
Title: Don't drench plants with pesticides meant to be used as foliar sprays
Series Title: ARC-A research report
Physical Description: 2 p. : ; 28 cm.
Language: English
Creator: Osborne, L. S
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research Center-Apopka
Place of Publication: Apopka FL
Publication Date: 1983
 Subjects
Subject: Pesticides -- Application -- Florida   ( lcsh )
Agricultural chemicals -- Foliar application -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: L.S. Osborne.
General Note: Caption title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066520
Volume ID: VID00001
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: oclc - 71262113

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r-____ ___-_DD~_fJ)RENCH PLANTS WITH PESTICIDES
hLUI E LIBf YTO' BE USED AS FOLIAR SPRAYS
r -i L. S. Osborne
F -i j 1 83 University of Florida, IFAS
Agricultural Research Center-Apopka
.F.S. Univ. of ~SiRdesearch Report, RH-83-7

Research has shown that materials which are safe when used as foliar sprays
can cause moderate to severe phytotoxicity when applied to the soil. Acephate
(Orthene), a commonly used pesticide in the foliage industry, was applied as a
soil drench to Brassaia actinophylla Endl. in 4-inch plastic containers. Three
applications of a solution containing 1 lb. ai/100 gal acephate were applied as
a soil drench (53 ml/pot) at weekly intervals. Plants were rated for phytotoxi-
city 2 weeks after the last drench using the following rating system:
1 = no observable damage
2 = slight cupping and/or yellowing of leaves; no necrosis
3 = necrosis present (slight)
4 = significant necrosis oh leaves
A significant amount of damage was observed in the pesticide treatment with a
mean rating of 2.4 compared to the mean rating of 1.6 for the controls.
In a second trial, phytotoxicity was also observed when bendiocarb (Dycarb)
was misapplied as a soil drench. Thirty Epipremnum aureum (pothos) (Linden &
Andre) Bunt. were obtained from a local grower in 3-inch pots. Drench applica-
tions of bendiocarb (100 ml/pot) were applied to 10 plants at the 30 oz/100 gal
rate. The application of this volume of material to a 3-inch pot was performed
to exaggerate what would normally occur with excessive spray applications
(30-50 ml/pot) and to repeat what actually occurred in one nursery. A second
group of plants was sprayed with the same rate of bendiocarb, but care was taken
not to apply any more than needed to cover the foliage, i.e., runoff was minimal.
Ten control plants were drenched (100 ml/pot) and sprayed (to runoff) with water.
Phytotoxicity was observed only on plants drenched with bendiocarb approximately
12 days after being treated (Table 1). The symptoms observed were necrotic
spots varying in size from 1/32 to 1/2-inch in diameter. Older leaves were the
most severely affected with some having as many as 68 spots. No spots were found
on new growth. These symptoms were distinct and matched sypmtoms observed on
plants in a commercial operation where bendiocarb was applied at the rate of
15 oz/100 gal with 200 gal of material used to treat plants in a 6000 sq ft
greenhouse. The use of this amount of gallonage probably resulted in excessive







amounts of pesticide reaching the soil and thus causing phytotoxicity. This
pesticide has caused similar damage to at least 2 other plants when misused
as a soil drench.
One of the most common statements made concerning pesticide applications
is that pesticides should be applied according to label directions. Many labels
state that plants should be sprayed to runoff or with sufficient gallonage to
obtain thorough coverage. However, growers should be careful because applica-
tions of excessive amounts of material can result in plants receiving the
equivalent of a drenching of the pesticide. Although this doesn't appear to be
a violation of the labeled directions, it is an obvious waste of material and
can result in phytotoxicity. The major point of this report is that pesticides
meant to be applied as foliage sprays can cause damage if they reach the root
system. All pesticides should be applied according to the labeled directions.
If the pesticide is not recommended for use as a drench, then care should be
taken not to spray excessive amounts and thus get runoff into the soil.



Table 1. Effect of bendiocarb on Epipremnum aureum when applied as a foliar
spray or as a soil drench.

MEAN NO. SPOTS/LEAF
PLANT CONTROL SPRAY DRENCH
1 0 0 12.3
2 0 0 19.7
3 0 0 24.0
4 0 0 17.8
5 0 0 18.5
6 0 0 16.7
7 0 0.2 29.3
8 0 0 9.7
9 0 0 13.9
10 0 0 23.4




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