Group Title: ARC-A research report - Agricultural Research Center-Apopka ; RH-75-5
Title: Detection and control of common insect and mite pests of tropical foliage plants
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Permanent Link: http://ufdc.ufl.edu/UF00065971/00001
 Material Information
Title: Detection and control of common insect and mite pests of tropical foliage plants
Series Title: ARC-Apopka research report
Physical Description: 6, 4 p. : ; 28 cm.
Language: English
Creator: Hamlen, R. A ( Ronald Alan ), 1940-
Short, D. E ( Donald Eugene ), 1935-
Henley, Richard W
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research Center
Place of Publication: Apopka FL
Publication Date: 1975
 Subjects
Subject: Foliage plants -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: R.A. Hamlen, D.E. Short and R.W. Henley.
General Note: Caption title.
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Bibliographic ID: UF00065971
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70954195

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HISTORIC NOTE


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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
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






) '

rj5.


DETECTION AND CONTROL OF COMMON INSECT AND MITE PESTS
OF TROPICAL FOLIAGE PLANTS

R. A. Hamlen, D. E. Short and R. W. Henley
IFAS, University of Florida
Apopka, Florida -..
ARC-Apopka Research Report RH-75-51 fi-lkJV E LIB 3F A

Insects and mites are a major cause of tropical floliage4~A~ r 1 9s s to
growers and retailers and their presence on plants often constitutes uisan e
to the consumer. Control of these pests is difficult during production and
after sale during utilization. Establishment of cont ipf gryms. requires
basic knowledge of the life cycle of these pests. It i "4mpa 't E Cn2)
it was introduced into the greenhouse or retail shop, how it spreadsa, n -d-+ts'
relative rate of multiplication. Since pesticides so often are required, it
is necessary to decide on the most effective chemical to use, what formulation
is best, the correct dosage rate, and the proper method, as well as the time
and frequency of application. Major emphasis must be given to select pesti-
cides safe both to the crop and the people who may come in contact with these
plants.

This article describes the most important insect and mite pests of
tropical foliage plants and discusses their development and control.

APPLICATION OF INSECTICIDES AND MITICIDES

Before discussing the specific pests themselves, a comment on the types
of pesticides may aid in understanding why specific pesticides (Table 1) are
selected for controlling particular pests. A major consideration is that both
cultural conditions and types of plants grown in the foliage plant industry are
so varied that no single pest control program can be suggested. One possible
program is the application of maintenance or preventative sprays at 1- to 3-
week intervals, depending upon the pest, crop and the length of pesticide
residue. Such a program should kill most of the initial pest invaders and
prevent pest populations from further development. It is far easier to maintain
relatively pest-free stock, propagation and production areas than to eradicate
pests once they become well established in high populations. Where a preventa-
tive program is not followed, it is essential to inspect plants closely at
weekly intervals to detect initial pest populations and once found, to apply
effective control measures before pests reach damaging levels. Systemic
pesticides like Meta-Systox-R or dimethoate, usually provide the most effective
control of pests that feed by sucking plant sap (aphids, mealybugs, scales and
whiteflies). Systemic pesticides applied as sprays enter the plant and are
transported to the leaves and stems. Thus, when an insect punctures and feeds
on sap of a plant treated with a systemic, it receives a lethal dose of the
chemical. Systemics are of particular advantage when pests are covered by
foliage and are therefore inaccessible to pesticides that kill only on contact.
In the application of any insecticide or miticide both leaf surfaces, especially
the lower side must be reached by the spray. Systemic activity of the pesticide
is noq excuse to justify poor spraying techniques. A spreader-sticker such as
PlyaY' should be added to the spray solution to insure proper coverage and

Allied Chemical Co., Atlanta, Georgia. Usually added at concentration of 2-4
oz in 100 gal (7-14 drops in 1 gal).





-2-

retention of the pesticide on the foliage. This is especially important if
plants are watered overhead, a technique which quickly washes pesticides off
the foliage if a sticker is lacking. Where mites are troublesome, miticides '
(chemicals with activity specifically against mites) should be used. These
will be discussed later.

Some systemic emulsifiable concentrates (Meta-Systox-R or dimethoate) are
effective when applied as soil drenches. Never apply these chemicals as soil
drenches to plants under water stress as plant injury is likely to result. A
granular, systemic insecticide, miticide and nematicide called Temik 10G, has
been highly effective against sucking insects and mites. To correctly apply
Temik the recommended weight of granules (Table 2) must be distributed over
specific soil surface areas of containers, benches or beds. One-quarter to
1/2 inch of water should follow to flush the chemical off the granules and
into the root zone where it can be absorbed and translocated to the upper
plant parts. Temik usually will provide effective control for 1- to 3-months,
but it is available for use only in commercial nurseries, it is extremely
poisonous, and treated plants must be held for 4 weeks prior to sale. Addi-
tional suggestions on the use of Temik are contained in the Florida Foliage
Grower, Volume 11, No. 3, 1974.

PHYTOTOXICITY

Phytotox.icity is a term used to define plant injury often caused by
pesticides. It frequently appears as damage to foliage such as marginal burn,
chlorosis, spotting and distorted or abnormal growth. Although any portion of
the plant may be affected, the new growth is most likely to show damage. In
the use of soil drench applications, root tissue may be injured causing stunting
or slow plant decline.

To minimize phytotoxicity, pesticides should be applied during the cooler
parts of the day. Application should be made in the early morning in order
that the foliage will be dry before temperatures reach 85 to 90F. Generally
wettable powders are considered less phytotoxic than emulsifiable concentrate
sprays; however, wettable powders often leave objectionable residues on the
foliage. Table 3 contains information on the safety of routinely used insect-
icides and miticides for tropical foliage plants. Since some plants are more
easily injured by certain insecticides, it is advisable to make 3 or 4 prelimi-
nary sprays at weekly intervals to a few plants under each growing environment,
before proceeding to treat an entire crop. If combinations of chemicals are to
be used in a single spray, for instance Pentac plus Meta-Systox-R for mite and
scale control, be especially careful to make preliminary treatments. Since
there may be several formulations of a chemical compound labeled for market
with different concentrations of the active ingredient; recommendations on the
manufacturers label should be followed explicitly.

SPECIFIC PESTS

APHIDS Aphids are small, soft-bodied insects which feed on young developing
leaves and stems, causing distorted or stunted plant growth. Their body color
is quite variable, most commonly including green, yellow or black forms. An
alert plantsman can often detect their white skins shed on older leaves which
are frequently the first indication of an aphid infestation. Multiplication
rate of aphids when uncontrolled, is enormous; When aphid populations become





-3-


overcrowded, winged forms may be produced and disperse to begin new infesta-
tions. Many growers first notice an infestation on plants adjacent to green-
house vents or evaporative cooling pads because these are the locations where
aphids frequently gain entry. Winged forms caught in air currents may be
rapidly spread throughout a greenhouse. The initial source of these aphids
may be partially eliminated by strict sanitation and weed control both outside
and inside the greenhouse. Aphids excrete a sticky honeydew which coats the
infested foliage. This honeydew is ideal for growth of the black sooty-mold
fungus rendering the affected plant unsightly and unsalable. Good aphid hosts
are: Aphelandra, Brassaia, Gynura, Hoya, and Dieffenbachia. Control is
usually achieved by a single, properly applied spray, drench or granular
treatment (Table 1). Occasionally, reinfestations occur and a second spray
application may be necessary after 4- to 6-weeks.

CATERPILLARS Caterpillars are immature forms (larvae) of moths and are
commonly referred to as armyworms, loopers or cutworms. These insects actively
feed'on and damage a wide range of foliage plants. Infestations often occur
when adult moths fly into greenhouses from outdoor areas and deposit eggs on
foliage. Initial infestations are difficult to detect because larvae often
feed only at night and only after larvae grow to good size do they actually
feed on the whole leaf. When small, the feeding larvae remove the undersurface
layers of leaf tissue and produce a "window" effect on the leaf surface, a
condition commonly observed with Brassaia seedlings. Caterpillars are chewing
insects and are susceptible to contact or stomach poison insecticides and are
unaffected by systemics like Temik. Exclusive use of Temik often allows larvae
populations to increase to the point where severe losses occur. It is much
easier to suppress infestations if controls are applied when caterpillars are
small (Table 1). A relatively new biological control material which is very
safe to humans is a bacterium which causes a fatal disease of caterpillars.
The bacterium, Bacillus thuringiensis (commonly referred to as Bt) is commerci-
ally available as Biotrol, Dipel or Thuricide. To be effective, caterpillars
must actually eat plant parts containing Bt residues. Many growers have tried
Bt and have had little success. Upon investigation we have found that they had
failed to use a spreader-sticker with the Bt to improve coverage and retention
on the foliage. Once Bt is ingested, affected larvae cease to feed and die in
2- to 3-days. Repeated applications at 7- to 14-days may be needed to maintain
residues on rapidly growing foliage.

FUNGUS GNATS Foliage growers frequently become concerned about tiny
"black flies" which can become abundant under greenhouse conditions. These
flies often are fungus gnats and represent a potential threat. The 1/8 inch
long adult fly is most visible near or on the soil surface or under leaves.
The immature legless form, the black-headed larvae is less than 1/4 inch long
and lives in the soil. These larvae have been associated with feeding on and
decay of plant roots and lower stem tissues. Highly organic soils appear to
promote infestations, especially in the presence of decaying plant tissue.
Feeding may be particularly injurious to seedlings, rooted cuttings or young
plants. Controls are usually directed against the larval stages by applications
of chemical drenches to infested soils (Table 1).







MEALYBUGS These are soft-bodied insects possessing a covering of
fuzzy, white, waxy, threads. Although there are various types that attack
foliage, the longtailed, solanum and citrus mealybugs are most troublesome.
As with aphid infestations, affected foliage most often is coated with honey-
dew. Adults and nymphs (young) tend to clump on affected foliage making it
difficult for insecticides to penetrate the waxy deposits that surroundsthem.
For this reason, systemic chemicals are often more effective than contact
insecticides. Reproduction is continuous in greenhouses, consequently it is
important to make several insecticide applications at intervals of approximately
14 days. Systemic drench and granular (Temik) insecticides are also effective.
Frequent hosts are: Aphelandra, Ardisia, Dieffenbachia, Gynura, Scindapsus,
Asparagus, Dracaena, Maranta and Dizygotheca.

In addition to foliar mealybugs, several mealybug species live below the
soil surface and feed on root tissue. This small, below ground pest is often
overlooked until infestations are severe and widespread. In the retail shop,
how frequently are plants removed from containers to inspect their roots? If
root mealybugs are present, a careful examination may reveal white, cottony-
like masses which contain eggs and females. Root mealybug nymphs are active
and may crawl from pot to pot via drainage holes or be spread in irrigation
water. Populations may become established in soils beneath infested plants,
forming a source of reinfestation to following crops. To eradicate this pest,
be sure to sterilize all soil, pots, tools and destroy any infested plants
which have not'responded to previous insecticide applications. Clean bench
and potting areas, apply effective insecticide drench treatments to stock
plants (Table 1) and practice strict sanitation in the future. Temik is also
effective when care is given to uniformly apply the proper amount over the soil
surface before watering in. Common host plants are: Collinia, Peperomia,
Dieffenbachia, Philodendron, Syngonium, Scindapsus, Ficus, Dizygotheca,
Chlorophytum and bromeliads.

MITES The two-spotted spider mite is the most common and destructive
mite on tropical foliage plants. This mite is small, may be brown, greenish
or orange-red, is 8-legged and hardly visible even when full grown. You will
need a 10X or greater magnifying glass to readily see them and populations
often become quite large before they are detected. Most plantsmen readily
recognize this pest when it produces webs over the foliage, especially on the
new leaves. Mites feeding on the underside of leaves produce a greyish or
yellowish speckling which is especially prominent when viewing the upper leaf
surface. In severe infestations and leaf injury, affected leaves become dry and
drop off. A point of importance in understanding this pest in the greenhouse
is its dispersal mechanism. When numbers and subsequent competition for food
increase, mites congregate in an orangish mass at the apex of the plant,
typically at the tip of the apical leaf. Individual mites then drop on silken
threads, forming a 'rope' of living mites. Spread to new plants can then occur
by air movement, on clothes or by cultural operations. Once this dispersal
phase begins, severe and irreversible damage has usually occurred resulting
in an unsalable crop. Miticides (Table 1) should be applied a minimum of two
times at a 5- to 7-day interval to allow for egg hatch between applications so
that both adults and individuals that hatch from eggs are killed. If a miticide
is properly applied and is not providing control, shift to another because mite
populations easily develop resistance to most miticides. Kelthane, Omite,





-5-


Pentac and Temik each belong to a different class of chemicals and may be used
alternately every few months to avoid development of resistant mites. Growers
must learn from experience which chemicals, when correctly applied, fail to
give satisfactory control, and to then try other non-chemically related products.
Often, a severe mite problem occurs on plants in the retail shop because a few
mite eggs or nymphs survived even the best and most conscientiously followed
control program during production. It is imperative therefore, that a miticide
be applied to major mite host plants as close to the date of shipment as possible.
The retailer might also consider applying a miticide to major mite host plants
prior to placement into retail operations. Major hosts of this pest are:
Brassaia, Codiaeum, Collinia, Cordyline, Dieffenbachia and Maranta.

Other than the spider mite, several microscopic, injurious mites also have
been repeatedly detected on foliage plants. The most important of these appear
to be the broad and cyclamen mites. These mites are transluscent and so small
that their presence is usually first detected by the plant injury symptoms
rather than by visual observation. Affected leaves are curled or cupped,
smaller than usual and frequently newly produced leaves will not mature (Hedera)
or developing leaves will have serrated margins (Aphelandra). Heavy infesta-
tions often cause death of the shoot apex.

The false spider or flat mite, another microscopic mite, is reddish in
color and heavy infestations produce a bronze or reddish discoloration on basal
areas of affected leaves. Damage by this pest has been especially serious on
Aphelandra, Columnea and ornamental cacti.

These proceeding small mites are readily moved about on infested plants,
equipment or nursery personnel. Injury caused by these tiny pests is often
mistaken by growers, florists, consumers and researchers for spray injury or
cultural mismanagement and, therefore, effective controls are not applied.
As with the spider mite, repeated applications of an effective miticide on a 5-
to 7-day interval is advised (Table 1).

SCALES Scales are usually small and inconspicuous and by the time an
infestation is noted, the population of scales is usually so great that the
plant is unsalable. Once again the enormous amounts of honeydew excreted by
feeding scales allows the prolific growth of sooty mold. Eggs, produced
beneath a relatively hard female shell hatch into translucent crawlers, the
only stage usually not covered by a relatively hard covering. Crawlers move
over new foliage to locate feeding sites, usually on or near veins on the
underside of leaves. This stage is practically invisible to the unaided eye
making it nearly impossible to detect new infestations on cuttings or other
propagation material. This practically invisible nature of the crawler stage
allows introduction of scales into production areas. This is why it is
imperative to maintain stock areas "scale-free". It is wise to quarantine
newly acquired plants and if careful examination shows living scales present,
apply effective insecticides (Table 1) until the infestation is eliminated. To
check for living scales, lift the female scale shell using the point of a knife.
If it is firmly attached to the plant or if the top cover pops off revealing a
yellow-orangish, plump mass attached to the leaf surface, consider the scale
alive. However, apparently dead female scales may contain living eggs that will






-6-


produce crawlers. Use at least a 10X hand lens to look for the miniature
"jelly bean-like" eggs beneath the empty female shell. Chemical control is
difficult because of the shell-like body of the females which protects both
feeding scales and eggs from the toxic chemicals. Sprays or drenches of
systemic insecticides such as Meta-Systox-R or dimethoate, are effective when
correctly applied (Table 1). Sprays may need to be repeated at 2- to 3-week
intervals. Continue to check for living scales, especially on new foliage,
keeping in mind that scale populations are slow to respond to treatment and they
breed constantly in the greenhouse. Therefore, persistence in treatment and
careful observation of results will be required to bring success.

THRIPS These small, slender, gregarious, fleet-footed insects feed by
rasping or shredding plant tissue surfaces with their mouth parts. Tissue
around feeding punctures dries out giving a silver or yellow flecked appearance
to wounded areas. Larvae are frequently pale yellowish and highly active.
Adults are often darkly colored and are able to jump when disturbed. Thrips
feed primarily on young tissue in the bud or shoot apexes where new leaves are
expanding. Once again a keen eye and the frequent use of a good hand lens may
avoid expensive losses. Repeated sprays at 7- to 10-days with Meta-Systox-R
have been effective (Table 1). Primary hosts are Brassaia, Ficus, Phildoendron,
Sansevieria and Syngonium.

WHITEFLIES This pest is most noticable when infested plants are moved.
The winged adults which collect in vast numbers on the upper or young foliage
take to the air producing a miniature 'snowstorm'. Whiteflies also produce
enormous amounts of honeydew. Greenhouse infestations more than often occur
through the introduction of infested plants or by migration of winged adults
from infested areas outside of the greenhouse. Again, inspect newly received
plants and remove all extraneous plant material from in and around your
operation. In controlling this pest the adults are easily killed, but the
remaining stages usually continue to develop and produce more adults. It is,
therefore, advisable to apply an insecticide repeatedly at a 7- to 10-day
interval for 3- to 4-weeks (Table 1). Temik when applied properly may control
whitefly for periods up to 2 months.









* le 1.


Insecticides and miticides effective for control of insect and mite pests of
tropical foliage plants.


Dosage

Insect Pesticide and Formulation 1 Gal 100 Gal


Diazinon 4E
Diazinon 50% V
Dimethoate 2E*
Dimethoate 2E
Malathion 57%
Malathion 25%
Meta-Systox-R
Meta-Systox-R
Temik 10% G**


(soil drench)*
EC
WP
25% EC*
25% EC (soil drench)*


Caterpillars:
armyworms,
loopers, cut-
worms


Bracillus thuringiensis
(Biotrol, Dipel, Thuricide)
Sevin'50% WP
Sevin 80% S


1/2-1 Tbsp
2 Tbsp
1 1/4 Tbsp


rgus gnats Diazinon 4E (soil drench) 1/2 Tsp 1/2 Pt
arvae) Diazinon 50% WP (soil drench) 1/2 Tbsp 1/2 Lb
------------------ ----------------------------------------------c


Foliar mealy-
bugs, soft and
armored scales


Root mealy-
bugs


Diazinon 25% EC (scales)
Diazinon 4E
Diazinon 50% WP
Dimethoate 2E*
Dimethoate 2E (soil dren
Malathion 57% EC
Malathion 25% WP
Meta-Systox-R 25% EC*
(soil drench for mealybi
Temik 10% G**


ch)*



ugs)*


Diazinon 4E (soil drench)
Dimethoate 2E (soil drench)*
Sevin 50% WP (soil drench)
Temik 10G**


2 Tsp
1 Tsp
1 Tbsp
1 1/2 Tsp
1 Tsp
2-3 Tsp
4-6 Tbsp
1 1/2-2 Tsp
1 Tsp
Table 2

1/2-2 Tsp
3/4-1 1/2 Tsp
1 Tbsp
Table 2


2 Pts
1 Pt
1 Lb
1 1/2 Pts
1 Pt
2-3 Pts
4-6 Lbs
1 1/2-2 Pts
1 Pt


1/2-2 Pts
3/4-1 1/2 Pts
1 Lb


continued next page


Aphids


Tsp
Tbsp
1/2 Tsp
Tsp
1/2 Tsp
1/2 Tbsp
1/2-2 Tsp
Tsp
Table 2


Pt
Lb
1/2 Pts
Pt
1/2 Pts
1/2 Lbs
1/2-2 Pts
Pt


1/2-1 Lb
2 Lbs
1 1/4 Lbs


2-------------------------------------- ---------------------------








Continued ...


Table 1. Insecticides and miticides effective for control of insect and mite pests of
tropical foliage plants.

Dosage

Insect Pesticide and Formulation 1 Gal 100 Gal


Mites: Broad,
Cyclamen,
False Spider,
and Spider


Thrips


Whiteflies


Kelthane 18.5% EC
Kelthane 35% WP
Omite 30% WP (spi
Pentac 50% WP (br
Temik 10%G**


der mite)
oad and spider mite)


Dimethoate 2E*
Malathion 57% EC
Malathion 25% WP
Meta-Systox-R 25% EC*
Temik 10%G**

Diazinon 25% EC
Diazinon 4E
Diazinon 50% WP
Dimethoate 2E*
Malathion 57% EC
Malathion 25% WP
Meta-Systox-R 25% EC*
Temik 10%G**


1-2 Tsp
1 Tbsp
4 1/2 Tsp
1 1/2 Tsp
Table 2

1 1/2 Tsp
2 Tsp
5 Tbsp
1 1/2-2 Tsp
Table 2

2 Tsp
1 Tsp
1 Tbsp
1 1/2 Tsp
1 1/2 Tsp
2 1/2 Tbsp
1 1/2-2 Tsp
Table 2


1-2 Pts
1 Lb.
1 1/2 Lb
1/2 Lb


1 1/2 Pts
2 Pts
5 Lbs
1 1/2-2 Pts


2 Pts
1 Pt
1 Lb
1 1/2 Pts
1 1/2 Pts
2 1/2 Lbs
1 1/2-2 Pts


Abbreviations:


Tsp Teaspoons; Tbsp = Tablespoons; Pt = Pint; Lb = Pounds; EC = Emulsifiable
Concentrate; WP = Wettable Powder; G = Granular.


*Systemic Pesticides

**Temik is also a systemic pesticide but for use only in commercial nurseries. Do not apply
Temik for at least 4 weeks before plants go to retail shops.




1


Table 2. Amount of Temik O1G to be applied to beds, benches, row stock,
grouped or individual pots and containers.

Pounds per Acre (Broadcast Equivalent)

50 75 100

Ounces per 1000 ft of row* 60 90 120
Ounces per 1000 sq ft 20 30 40
Ounces per 100 sq yd 16 24 32
Grams per sq meter 5.0 7.5 10
Grams per sq ft 0.5 0.75 1.0


Container
diameter (inches)


Level teaspoons
Temik O1G per pot**


Grams
Temik O1G per pot**


3 ---- 0.05
4 --- 0.1
5 1/16 0.15
6 1/8 0.2
8 1/4 0.4
10 1/3 0.6
12 1/2 1.0

Based on 40-inch row spacings.
** Equivalent to 40 ounces per 1000 sq ft or 100 Ibs per acre.




Q


Table 3. Safety of insecticides and miticides for selected foliage plants.





Botanical Name dN / _

Aphelandra squarrosa ? S S S S
Araucaria excelsa S S S S S S
Ardisia sp. S S S S S S S
Brassaia actinophylla S U S U U ? ? S U .S
Collinia elegans U U U U ? S S
Dieffenbachia amoena S S S S S S
Dieffenbachia exotica S ? S S U S ? S S S
Dracaena godseffiana S S S S S S S
Dracaena sanderiana U S S S S S
Ficus benjamin S
Hoya carnosa U S S S S
Maranta erythroneura U S S S S S S
Monstera deliciosa S S S S S
Nephrolepis exaltata ? U U S U ?
Peperomia obtusifolia ? ? S ? U S S
Philodendron oxycardium S S S S S S S
Philodendron panduraeforme S S S S S S
Pilea cadierii ? U S S S
Sansevieria spp. S S S S S S
Scindapsus aureus S S ? S U S S
Syngonium spp. S S U S ? S S


S = safe at recommended rates; U = unsafe and ? = an inconsistent reaction following
spray applications.




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