| Material Information
||Why should you test pesticides on your plants?
||ARC-A research report
||4 p. : ; 28 cm.
||Chase, A. R ( Ann Renee )
Armstrong, T. J
Osborne, L. S
Agricultural Research Center (Apopka, Fla.)
||University of Florida, IFAS, Agricultural Research Center-Apopka
||Place of Publication:
||Plants -- Effect of pesticides on -- Florida ( lcsh )
Pesticides -- Testing -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||A.R. Chase, T.J. Armstrong, and L.S. Osborne.
| Record Information
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 70921776
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Copyright 2005, Board of Trustees, University
i.-i/ -Why should you test pesticides on your plants?- .
A. R. Chase, T. J. Armstrong, and L. S. Osborne
University of Florida, IFAS i i
Agricultural Research Center Apopka
ARC-A Research Report RH-81-6 -
Pesticides are routinely used by most nurserymen and are generally- --.
efficaceous and nonphytotoxic. However, when new pesticides become avail-
able or new plants are grown it is wise to test the new combination of
pesticide and plant. Even pesticides with broad spectrum labels for all
ornamentals should be tested since some plants can be damaged under certain
growing conditions. Thus, testing the specific pesticide-plant-growing
condition combination is very important in producing high quality plants.
Growers are advised to anticipate potential pest problems and test
recommended pesticides prior to broad scale usage. The following test
illustrates this potential problem.
Red marantas were grown in steam sterilized potting medium for two
months. They were then treated with a soil drench of Pesticide A at the
labeled rate and retreated at the recommended interval. Another set of
plants was treated with water only. Four months after initial treatment
plants were rated for chlorosis which was apparent on most pesticide
treated plants, while plants which received water only were a healthy green
color. Plants were rated on a 1 (severe chlorosis) through 4 (no chlorosis
or healthy) scale. The average rating for plants receiving water was 3.3
while that for pesticide treated plants was 2.2. There was no obvious
reduction in growth and the leaves did not show any other symptoms of phyto-
toxicity. It is probable that had the entire planting been treated with
Assistant Professor of Plant Pathology, Agricultural Technician II, and
Assistant Professor of Entomology, Agricultural Research Center Apopka.
pesticide, the chlorotic state of the plants would have been attributed to
other causes. Previous to this test we had seen no evidence that this
pesticide caused chlorosis on red maranta and would not have expected this to
occur. Damage such as this can occur if a phytotoxicity test does not pre-
cede broad scale use of a new or previously untried pesticide. An example
of the procedure used to perform a phytotoxicity test is included below.
The initial test need only consist of two treatments. The first is a
set of control plants which will be sprayed with water only and serve as a
comparison for pesticide treated plants. The second set of plants will be
sprayed with the pesticide at the rate recommended on the label. Each set
of plants should include at least ten healthy, representative plants from the
group you wish to treat with the pesticide. If you want to use the pesticide
on ten different foliage plants you should include ten of each species in the
phytotoxicity test. When the plants are sprayed be sure to handle both sets
of plants the same. If the pesticide is accompanied by a spreader-sticker
then the control water treatment also should include the spreader-sticker.
Apply the pesticide to the plants according to labeled instructions and re-
peat the treatment on the interval suggested. Some pesticides are safely
used at the labeled frequencies while they are phytotoxic when usedmore
frequently. At the research center we apply pesticides at least four times
before concluding the experiment. However, since time and the pressure to
treat may be important you may choose to shorten the experiment. There are
many ways that phytotoxicity can appear on your plants including leaf tip or
marginal burn, stunting, chlorosis, complete collapse of leaves, leaf drop,
and distortion. Any abnormalities found only in pesticide treated plants
indicates a potential hazard and the pesticide should be handled accordingly.
The following points should be mentioned with respect to conducting pesticide
1. Stressed plants (those plants which are wilted or have received
excessive amounts of either fertilizer, water or light), are
more susceptible to phytotoxicity damage than healthy plants.
2. All treatments should be made during the time of day which best
fits the normal production operation. Plants are more susceptible
to damage when chemicals are applied to them during the heat of the
day and these periods should be avoided. During winter, wait until
the water and air warm before spraying plants.
3. Do not confuse fertilizer burn or a disease with phytotoxicity
caused by pesticides. If a symptom is found on the pesticide
treated plants as well as on the control plants, then you can
assume that the symptom is indicative of another problem.
4. If abnormalities are seen on your treated plants which are absent
on your control plants you should conduct the test a second time
or refrain from large scale use until the abnormalities can be
5. It is important to realize that the results obtained are only
true for the conditions existing during the experiment. It is
usually impossible to determine the safety of a pesticide used
under varying conditions in a single test. Be sure to design
your phytotoxicity test to conform to the actual spraying environ-
TEST PESTICIDES BEFORE BROAD SCALE USAGE. Don't wait until all of your
plants are infected or infested to try a new combination and don't perform
phytotoxicity tests by spraying entire plantings. The financial risks run
by eliminating a small preliminary test are very great and should be avoided
whenever possible. Creating a working procedure for conducting phytotoxicity
tests in your nursery can save you time and money.