of Caffeine" reprinted from Crops Magazine, 20 July, 2002 (copyright
Reed Business Information, used with permission).
Control and Management of Quarantine Pests on Ornamental
Problem: Ornamental crops are permitted for export
only if they are free of all quarantine pests (for example, certain species
of thrips, aphids, scales, mites, snails, slugs and nematodes). If pests
are found by quarantine inspectors, a shipment may be rejected, and the
grower may lose permission to export. Due to the risks associated with
quarantine pests, growers use pesticides intensively prior to harvest.
Even with intensive insecticide use, growers of orchids and anthuriums
have trouble controlling thrips, mites and whiteflies. Many growers decide
when to apply pesticides based on the calendar, instead of scouting for
pests. This approach accelerates the development of pesticide resistance.
The use of post-harvest treatments (such as pesticide dips and hot water)
allows growers to reduce pre-harvest use of pesticides. However, effective
post-harvest treatments are not available for all flower crops. Some commodities
(such as gardenia flowers) are prohibited from export due to potential
pest problems. For these commodities, approved quarantine treatments,
or a change in the current quarantine law, is required.
Goals and Approaches:
To address these problems, we are developing
better sampling methods for detecting thrips in orchids, researching the
effects of calendar-based pesticide spray programs on populations of pests
and natural enemies in anthuriums, and testing non-toxic dip ingredients
for their potential in removing surface insects from flower and foliage
crops. In addition, we are developing new quarantine treatments for control
of green scale on gardenia.
Preliminary indications are that thrips are randomly
distributed within orchid plantings. Distributions of thrips were not
heavily influenced by orchid variety. These findings will be used to develop
optimal sampling methods for thrips detection. Although natural enemies
of thrips were present, they did not provide effective control. On anthuriums,
it was found that natural enemies did not bring thrips under biological
control despite continuous presence of the pest for one year. Results
also indicated that thrips may be resistant to an insecticide commonly
used against this pest by anthurium growers. A combination of fluvalinate
and insecticidal soap was found to be the most suitable post-harvest dip
for control of coffee green scale on gardenia. This treatment, in combination
with field control of coffee green scale, is the basis for a proposed
systems quarantine approach under which the export of gardenia flowers
from Hawaii to the continental USA would be permitted. APHIS is in the
process of revising the Code of Federal Regulations (CFR) relative to
the export of gardenia flowers. Meanwhile, the export of gardenia flowers
from Hawaii to California is permitted under special conditions set out
by APHIS, based on our proposed quarantine approach.