Title: TropicLine
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Permanent Link: http://ufdc.ufl.edu/UF00089450/00014
 Material Information
Title: TropicLine
Series Title: TropicLine
Physical Description: Serial
Language: English
Creator: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Fort Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Ft. Lauderdale, Fla.
Publication Date: April/June 1998
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Volume ID: VID00014
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Horticulture Newsletter of the University of Florida Fort Lauderdale Research & Education

Volume 10, Number 2 April-June, 1998
Editor: Alan W. leerow Christine T. Waddill, Dean, Cooperative Extension

Nitrogen Source Affects Growth and Quality of Bougainvillea

Timothy K. Broschat

Bougainvillea is a popular flowering landscape and container plant in mild climates, but can be difficult to grow in containers. Iron
deficiency chlorosis is a common disorder in container-grown plants, and may have multiple causes. High soil pH, root rots, soluble
salt injury, or poor soil aeration are usually associated with Fe deficiency symptoms in bougainvillea (Broschat, unpubl. data).
Fertilizer N form can also affect Fe deficiency in some plants (Colgrave and Roberts, 1956; Conover and Poole, 1982; Nelson and
Selby, 1974; Sideris and Young, 1956). The purpose of this study was to determine the effects of N source on the growth, quality,
and flowering of container-grown bougainvillea.

Materials and methods

Experiment 1. Liners of Bougainvillea 'Brasiliensis' were planted into three-liter plastic pots containing a 5 pine bark: 4 sedge peat:
1 sand substrate (by volume) amended with 4.9 kg dolomite and 880 g m-3 of Micromax micronutrient blend (Scotts Co.,
Marysville, OH). Plants were fertilized every 2 weeks with 30, 60, or 90 ml/container of a solution containing P at 0.38 mg ml1, K at
1.66 mg ml-1, and Mg at 0.55 mg ml-1 from monosodium phosphate, potassium sulfate, and magnesium sulfate, plus N at 1.70
mg ml-1 from either ammonium sulfate, sodium nitrate, or half ammonium sulfate and half sodium nitrate. This resulted in N
application rates of 50, 100, and 150 mg N/ pot. This experiment was set up on 28 June 1995. Twenty replicate plants were
assigned to each fertilizer rate X N-source treatment and were arranged in a completely randomized design in an open-sided
greenhouse (max. photosynthetic photon flux=1890 mE m-2 sec-1 ). Plants were irrigated daily with about 1.5 cm of water from
overhead irrigation. Temperature in this greenhouse ranged from a min of 15C to a max of 37C.

Plants were rated subjectively for chlorosis severity on 4 Jan. 1996. A rating scale of 0 to 5 was used (0=dark green, no chlorosis,
3=moderate chlorosis, 5=dead from severe chlorosis). Plant dry mass, number of flowers, and substrate pH were also determined
on that date. Fertilizer source effects were determined by analysis of variance. Fertilizer rate effects were determined by regression

Experiment 2. Liners of Bougainvillea "Brasiliensis' were potted on 13 Nov. 1996 using the same substrate and containers as in
Experiment 1. Phosphorus and K were provided by 3.9 g of superphosphate (0N-8.7P-0K) and 6.9 g of sulfur-coated potassium
sulfate (Lesco, Inc., Rocky River, OH) per container every 3 months. Fertilizer treatments consisted of biweekly per pot applications
of 50 ml of a solution containing N at 6.3 mg ml-1 from urea, ammonium sulfate, diammonium phosphate, ammonium chloride,
ammonium nitrate, sodium nitrate, potassium nitrate, or calcium nitrate. Four other materials, sulfur-coated urea (Lesco, Inc.), two
resin-coated ureas (Osmocote 38N-0P-0K, Scotts Co., Marysville, OH and Polycoated urea, Lesco, Inc.), and resin-coated
potassium nitrate (Haifa Chemicals, Haifa, Israel) were applied once at rates of 3.8 g N/pot. The total amounts of N applied over a
6-month period by liquid and controlled-release fertilizer were equivalent. Ten replicate containers per treatment were arranged in a
completely randomized design as in Experiment 1.

Chlorosis ratings, plant dry mass, and number of flowers were recorded after 3 months, as in Experiment 1. Leaf samples
consisting of the youngest fully-expanded leaves were collected from all plants and analyzed for total Fe and N content.
Pour-through substrate solution samples were collected 5 days after a liquid fertilizer application during the final week of the
experiment. These leachate samples were analyzed for ammonium-N, nitrate-N, Fe, EC, and pH. Since small (1-2 mm) necrotic
lesions appeared on the older leaves of some plants shortly after the initial treatment, the number of leaves with lesions per plant
were counted on 6 Dec. 1996. Data were analyzed by regression analysis or by analysis of variance, with mean separations by the
Waller-Duncan k-ratio method.

Results and discussion

In the first experiment Bougainvillea 'Brasiliensis' fertilized with only sodium nitrate as a N source exhibited more severe chlorosis
symptoms than those receiving only ammonium sulfate (Table 1). Plants receiving ammonium sulfate plus sodium nitrate had
intermediate chlorosis ratings. Bougainvilleas fertilized with ammonium sulfate had an average of 47.9 flowers/plant vs. 4.4 for
those receiving sodium nitrate (Table 1). Plant dry mass was also much larger for bougainvilleas fertilized only with ammonium

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The fertilizer source by rate interaction was highly significant for plant dry mass, but was not significant for chlorosis severity and
number of flowers (Table 1). When fertilization rate effects were analyzed within each N source treatment, the following trends
were evident: Increasing fertilization rate within the ammonium sulfate treatments had no effect on chlorosis severity, but increased
the number of flowers and plant dry mass (Table 1). Increasing fertilization rate within the sodium nitrate treatments increased
chlorosis severity, but had no effect on number of flowers or dry mass. Increasing the overall fertilization rate (data from both
fertilizer sources combined) slightly increased plant chlorosis severity, but also significantly increased flower number and plant dry
mass (data not shown).

The first experiment suggests that bougainvilleas respond positively in terms of growth (as measured by dry mass) and flowering to
increasing amounts of ammonium sulfate, but ammonium sulfate had little or no effect on chlorosis severity. On the other hand,
chlorosis increased with increasing amounts of sodium nitrate, but increasing sodium nitrate had no effect on flowering or growth.
Although flower production was much greater for plants fertilized with ammonium sulfate than with sodium nitrate, the number of
flowers appeared to be related to plant size and vigor. Still, ammonium sulfate-fertilized plants averaged about 5 flowers,
ammonium sulfate plus sodium nitrate about 4, and sodium nitrate about 3 flowers per g of dry mass. Both plant size and vigor
were greatly reduced in chlorotic plants.

Fertilization with only nitrate-N fertilizer has been associated with Fe deficiency and reduced growth in Calathea (Conover and
Poole, 1982), conifers (Nelson and Selby, 1974), azaleas (Colgrave and Roberts, 1956) and pineapple (Sideris and Young, 1956).
Nitrate fertilizers are known to increase soil and plant tissue pH, whereas ammonium fertilizers have the opposite effect (Kirkby and
Mengel, 1967). Container substrate pH in the first experiment averaged 6.43 for the ammonium sulfate-treated plants, 6.46 for
ammonium sulfate plus sodium nitrate, and 6.82 for sodium nitrate. Although flower number and plant dry mass had significant
negative correlations with substrate pH (r=0.60, P=0.019 and r=0.58, P=0.022, respectively), the negative correlation of chlorosis
rating with substrate pH was only marginally significant (r=0.47, P=0.076).

The positive effects of ammonium sulfate fertilization are believed to be due to the NH4+ ion, rather than SO4=, since all plants
received adequate amounts of SO4= in the form of K2S04. Although the increased chlorosis severity associated with sodium
nitrate fertilization could be due to the Na+ ion, there is no support in the literature for such an interaction. The second experiment
was set up to eliminate the possibility of Na+ or SO4 = affecting these results.

In the second experiment, where bougainvilleas were grown with a variety of ammonium or nitrate sources, the largest plants were
those receiving controlled-release ureas (Table 2). Plant size was intermediate for the soluble urea and ammonium sources and
smallest for nitrate-fertilized plants. Number of flowers was highest for plants receiving controlled-release ureas, but all soluble
ammonium and nitrate salts produced equally low numbers of flowers. Chlorosis severity also was lowest for plants receiving
controlled-release ureas, intermediate for most of the soluble urea and ammonium sources, and highest for nitrate-fertilized plants.
The number of leaves with small necrotic lesions was highest for sodium, potassium, and calcium nitrate-fertilized plants and
lowest for those receiving urea or ammonium salts, or controlled-release potassium nitrate. Thus, plant quality, as measured by
these four variables, was generally poorest for plants receiving nitrate-N, best for those receiving controlled-release urea, and
intermediate for those receiving soluble urea or ammonium fertilizers.

The physiological basis for this association of chlorosis and leafspotting with nitrate fertilization is less clear. The chlorosis
symptoms observed appeared to be classical Fe deficiency symptoms, with sharply delimited green veins on otherwise yellow or
whitish new leaves. New leaf size was also greatly reduced in more severe cases. Leaf Fe concentrations were not correlated with
fertilizer treatments, chlorosis severity, or with any of the other plant quality variables (data not shown). However, the role of Fe
deficiency in this disorder cannot be completely ruled out since leaf Fe concentrations often are not correlated with plant quality or
chlorosis severity (Mills and Jones, 1996).

Nitrate fertilizers increased substrate pH to a greater extent in Experiment 2 (x = 7.21 for nitrate versus 6.28 for ammonium) than in
Experiment 1. Although the lowest substrate pH values were those from ammonium chloride and diammonium phosphate
treatments, these treatments did not result in the best quality plants. Substrate nitrate concentrations were equivalent for containers
fertilized with soluble ammonium and nitrate fertilizers, suggesting that nitrification of ammonium was occurring during this study.
The very low substrate nitrate and ammonium levels for S-coated urea can be attributed to its having released most of its N during
the 3-month study. On the other hand, Osmocote 38N-0P-0K is claimed to have a 12 to 14 month life at 21C. It apparently released
N at a very slow rate due to its heavy coating.

There were no significant correlations of any plant quality variables with substrate EC. Leafspot severity was negatively correlated
only with substrate ammonium-N levels (r = -0.25, P=0.006). Substrate pH was strongly affected by N form (P < 0.0001) in
Experiment 2, but was less strongly correlated with plant dry mass (r = -0.20, P = 0.025) and with chlorosis severity (r = 0.23, P =
0.011). Leafspot severity was significantly affected by N form (P< 0.0001) and was positively correlated with substrate pH (r = 0.39,
P < 0.0001). Leafspot severity was only marginally related to substrate nitrate-N concentrations (r = 0.16, P = 0.076). Although
pH-induced Fe deficiency associated with nitrate fertilization appears to be the primary cause of the chlorosis in bougainvillea, it is
possible that factors other than substrate pH, nitrate-N, ammonium-N, or EC may also be involved in this problem. The leafspotting
disorder appears to be a phytotoxic response associated more with a lack of ammonium-N than the presence of nitrate-N.


These studies showed that N source strongly affects the growth and quality of bougainvillea. Although the physiological reasons
are unclear, plants fertilized with controlled-release ureas were the largest, had the most flowers, and the least chlorosis and
leafspotting. Those receiving only nitrate N were severely stunted, extremely chlorotic, had a high incidence of leafspotting and
leafdrop, and produced few flowers. Water-soluble urea and ammonium salts produced plants of intermediate quality. Thus,
bougainvillea growers should use controlled-release urea fertilizers and avoid the use of nitrate fertilizers for optimum plant growth

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and quality .

Literature cited

Colgrave, M.S. and A.N. Roberts. 1956. Growth of the azalea as influenced by ammonium and nitrate nitrogen. Proc. Am. Soc.
Hort. Sci. 68:522-538.

Conover, C.A. and R.T. Poole. 1982. Influence of nitrogen source on growth and tissue nutrient content of three foliage plants.
Proc. Fla. St. Hort. Soc. 95:151-153.

Kirkby, E.A. and K. Mengel. 1967. Ionic balance in different tissues of the tomato plant in relation to nitrate, urea, or ammonium
nutrition. Plant Physiol. 42:6-14.

Mills, H.A. and J.B. Jones, Jr. 1996. Plant analysis handbook II. MicroMacro Publishing, Inc., Athens, Ga.

Nelson, L.E. and R. Selby. 1974. The effect of nitrogen sources and iron levels on the growth and composition of Sitka spruce and
Scots pine. Plant Soil 41:523-588.

Sideris, C.P. and H.J. Young. 1956. Pineapple chlorosis in relation to iron and nitrogen. Plant Physiol. 31:211-222.

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Tabtle 1 F er-,:.nse of E:Bo-'gain Jrea 'Brasilins.s' 1: fert li er ;j.jur, e and ra.e EH Feriment 1

S' ilir,: e SI eel ly hr i:rs i:-s r,1:, f f:loiers Dry mass
fterril:?er rate ra tin (,.)
(mr ,I lipcl)

Amm-onium iulfate 5' II 25 2 4 '

'1 II i : 6 3 ; 11I ;-;

15) I 1 "% 12.

Mean I 4 9 9 3

Ferilizer rate H -.

Amminiur nitrate

n'ldium nitrate f5. 1 2 ? 2
l 1I : 2I- I c. ::

\: I3 M:1 72F
1 51:., 4 2,. II 7 2

M.ean I 21:1 2 5 4

Fertilizer rate "

Sodium nitrate 51:1 I j 3 6 I 5

III 2 1 16 3 1

'I 51:I 2 9 3 3 1 3

Mhl3n ar 44 1 15

Feiiliz er rate r5S [1 J

C'.veall effe:t;

ri S,-ur,:e '.

r. Fare (L)

ri Face (,j) riB ,5 J'.

N. '--,i.Ir ,: Fate (L) [-. -."

i'idarkl green no i:hlcrosis :.=m-.lderatr' rhlnor':sis 5=d-ead frrnm severe Chlor.:r-=,i

and Nr:S i. n.:atesiqnifian,:e- t n5 Ci1. 1,' 1 ani nr.-n-signific:anr resprec-'ctiel

Table 2. Effects of N source on dry mass, number of flowers, chlorosis severity, and number of leaves with necrotic lesions in
Bougainvillea 'Brasiliensis'.

N Source Dry mass (g) Number of Chlorosis No. leaves Leaf Fe (ag Substrate pH Substrate Substrate EC (dS

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flowers severity

S-coated urea



n' iu.mnian'e

''.:.'un'r nlir3i-


Calcium nitrate

r O ,,nr,."

12.1 abv
13.6 a

S0 -:,
11 ?. 3 :...

.S .. :,3

7.0 de

?. I

2.8 f

4 ,ef

41.9 b

54.6 a

?. .,

0.9 d

3.3 d.

3.3 d

R R. ,

0.8 c

1.1 c

1 C.
1 1: '.

2.1 b

1 8 a.

2.8 a


with lesions

1.4 c

0.3 c




0.3 c

0 1a

6.0 ab

1 4."

217 b

158 cd

4 ?.0 :

1 i ,3

144 cd

1 d :"

14 ?. ,.,


1-'.-:. ,.:.3

6.89 cd

6.70 de

i:. ?.5 l

5.76 h

6.. c5

7 ?.1 St,

: :-0 C.

6.93 c


N03-N (tgg NH4-N (pg
ml-1) ml-1)
3.3c 0.1 c

7.8 c 0.3 c

11 3j -

1 10 0 at. .
110031 .

11- ?.t, ?.1 -t

129.9 a 39.4 a

1 38.6 a s0. ". .

1.4 1 3 00 .:

1'j0 3 0 1 .:

138.6 a 0.1 c

-?. 1 t.." 0 1,

z0 = dark green, no chlorosis, 3 = moderate chlorosis, 5 = dead from severe chlorosis

YOsmocote 38N-OP-OK

XLesco Poly-coated urea

WHaifa Multicote

VMean separation by the Waller-Duncan k-ratio method, k = 100

**indicates significance at P<.001

Control of Royal Palm Bug with Imidacloprid

F. W. Howard and Alan Stopek

(adapted from Principes 42: 80-84 (1998)

The royal palm bug, Xylastodoris luteolus Barber (Hemiptera: Thaumastocoridae), feeds exclusively on royal palms
(Roystonea regia (H. B. K.) O.F.Cook. It has been reported from Cuba and Florida. Extremely small piercing-sucking
insects, the adults ofX. luteolus are elongate, 2-2.5 mm long and of a pale yellow-green (luteous) color (Baranowski,

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The bugs begin to attack fresh leaves as they are unfolding. This results in small, yellow spots
scattered on the lower frond surfaces. As the bug populations increase and more bugs feed,
fronds become necrotic, turning brown and desiccated. Damaged fronds eventually become
tattered due to wind action, and sunlight bleaches them to a lighter grey color. As each new
leaf is produced about monthly, the bugs attack them so by the end of the summer a large
portion of the crown may be damaged (Baranowski, 1958). Most observers would agree that
the bugs do more damage to royal palms during some years than others.

Reinert (op. cit.) identified three species of spiders that preyed on royal palm bugs, and
suggested that they, along with heavy rains, were major factors in the natural control of the
species. However, we have observed dense populations of the bugs on palm fronds during
very rainy periods, and whether populations of these prolific bugs are regulated by spiders and
rain alone is still open to question. Other natural enemies or abiotic factors that may regulate royal palm bug populations
in Florida have not been identified.

When royal palm bugs reach damaging populations, chemical control is the only known method of controlling them. But
chemical control ofX. luteolus is difficult because of the tall heights of the palms: Baranowski (op. cit.) reported that X
luteolus seldom attacks palms of less than 4 m in height. Reinert (1975) found that foliar applications of oxamyl,
monocrotophos, and carbofuran reduced royal palm bug populations from more than 68 to less than 3 bugs per 3 leaflets.
Unfortunately, because of chemical drift, none of these highly toxic chemicals would be suitable for foliar applications
to tall palms, especially in cities.

Root drenches of oxamyl and monocrotophos reduced numbers of bugs per 3 leaflets after 2 weeks, but after 4 weeks the
populations were well into recovery (Reinert, 1975). Again, these chemicals were applied in a research study; they may
not be suitable for widespread use as root drenches, especially under the edaphic and hydrological conditions of southern
Florida (chemicals travel fast in the sandy soil and the water table is relatively high). Dimethoate shares some of the
undesirable characteristics of other synthetic pesticides, but used as a drench was probably the safest of the methods
tested. This treatment reduced the bug populations from 113.2 to 32.8 bugs per 3 leaflets after four weeks (Reinert op.
cit.). Because about 1/3 of the population remained, it would have rebounded quickly. In summary, a practical method of
controlling royal palm bug has not been available for years.

A relatively new insecticide, imidacloprid, seemed promising for this use. It can be applied without a special use permit.
This chemical was discovered and developed as an insecticide by Bayer. It is the active ingredient in several of Bayer's
products, including Admire or Gaucho in different countries for use on various food crops, Marathon for use on
ornamentals in greenhouses and Merit for use on ornamentals and turf grass out-of-doors. Imidacloprid is considered to
be a pesticide of unusually low mammalian toxicity. Animal toxicity data from the Material Safety Data Sheet for this
product lists oral LD50 rates as 1858-2591 mg/kg and the dermal LD50 rate as >2000. When applied as a root drench, it
remains for long periods in the soil and is taken up slowly. For this reason, there is typically a delay of a few weeks to a
few months, depending partly on the size of the plant, before the chemical becomes active against the target pest. Once
active, it may remain so for an extended period as long as the plant continues to take up the chemical. These
characteristics make it potentially very useful for controlling royal palm bug. The present report communicates results of
a test of imidacloprid for effectiveness in controlling royal palm bug.


The experiment was conducted in the town of Palm Beach, on sandy soil. Field evaluations were conducted at two sites where royal palm bug
damage had been severe in previous years. Site #1 was adjacent to Lake Worth. Site #2 was about 1.5 km inland on the island from Lake Worth.

Four palms were treated on each site with 56.7 g (2 oz.) of Merit 75 WP mixed in 9.5 1 (2.5 gal) of water, the equivalent of 42.5 g of imidacloprid
per palm. Half of this rate was applied to one palm at one of the sites. This mixture was poured from a bucket very slowly into the soil
immediately surrounding each palm. Mulch layers, if present, were scraped back, then returned after the drench treatment. At both sites, every
other palm was treated, leaving alternate palms as controls. The treatments were applied on 21 January 1997.

Damage assessment was conducted 51 days later (March 13) and 108 days later (May 8). The first and second youngest leaves of treated and
control palms were observed from the ground for evidence of royal palm bug damage. Because we couldn't reach the fronds of all the palms, we
didn't obtain statistically analyzable data to compare populations on treated palms and controls. However, we examined many fronds closely to
confirm the association between bugs and their damage, and counted the numbers of bugs per leaflet on several fronds as an indication of the
severity of the infestations at the study sites.

Results and Discussion

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Damage assessment. Prior to application of treatments on 21 January, at site #1 there was only minor damage due to
royal palm bugs, but some fronds had necrotic areas that we attributed to wind damage of a storm in November. At Site
#2, there were brown necrotic streaks typical of royal palm bug damage on some younger fronds of some palms. Royal
palm bug damage had been especially severe at this site in past years (Richard Home, Parks Foreman, Palm Beach
Public Works Department, Personal Communication).

When the palms at both sites were examined 51 days after application of treatments, bug damage had progressed since
January on some of the untreated palms, but there was no conclusive difference between treatment and controls.

When the palms were examined 108 days after application of treatments, the fronds of the seven palms treated with 56.7
g of imidacloprid were virtually free of royal palm bug damage, except for damage on older fronds which may have been
caused by either bugs, wind or cold spells prior to the treatment. The single palm treated with 28.35 g of imidacloprid
was similarly free of damage. In contrast, the first and second fronds of the eight untreated palms previously selected as
controls had extensive damage typical of royal palm bugs. The tissue of these leaves was mostly brown with some small
green areas remaining. The damage was very conspicuous from the ground.

As a further observation, a total of 15 royal palms in a row at Site #1, including the 4 treated palms and 11 untreated
palms, were examined 108 days after treatment. The 4 undamaged (treated) palms contrasted dramatically with the 11
untreated palms, which were all severely damaged by royal palm bug.

Observations on royal palm bugs. On 21 January, we counted a mean of 3.0 (range: 2-5) royal palm bugs per leaflet on
10 leaflets randomly selected from palms at Site #1. At Site #2, where there was typical royal palm bug damage on
younger fronds of some palms, a mean of 59.1 (range: 8-17) royal palm bugs per leaflet were counted on 7 leaflets from
one of these palms.

When examined 108 days after treatments, there were abundant royal palm bugs on young damaged fronds of three of
the untreated palms that we could reach. On a leaflet that we selected as harboring a typical infestation, we determined
that there were about 300 of the bugs, including adults and nymphs. There were only about 15 bugs per leaflet on the
fourth untreated palm that we examined. Bug damage was as severe on this palm as on the other untreated palms,
suggesting that the population had been higher and was now declining. On the treated palms, 0-5 royal palm bugs per
leaflet were observed.

We observed no evidence of important natural enemies of royal palm bugs on any of the palms.

These preliminary data on bug populations show that royal palm bugs occurred at levels of up to 300 bugs per leaflet in
association with severe damage. More frequent observations on a larger number of palms would be required for
conclusive data on population dynamics of this bug. However, the results of damage assessment clearly showed that the
treatments prevented damage by royal palm bugs.

The delayed period before imidacloprid treatments become effective and the period during which they remain effective
in controlling royal palm bug remains unknown. Since it protected the youngest two leaves, and in royal palm a new leaf
is produced about monthly (Baranowski, 1958), it was apparently effective for at least 2 months.

A disadvantage of this product for this use is its cost. At current prices the cost of treatment at the lowest rate used in
this evaluation (28.4 g ) is $19 per palm. However, it may be applicable to limited areas, e. g. around tourist hotels.
Imidacloprid has been applied to royal palms on Fisher Island, an affluent development in Miami, for control of royal
palm bugs (Eric Messersmith, Pest Control Specialist, Montgomery Foundation, Miami, FL, Personal communications).

Literature Cited

Baranowski, R. M. (1958). Notes on the biology of the royal palm bug,Xylastodoris luteolus Barber (Hemiptera: Thaumastocoridae).
Annals of the Entomological Society of America 51, 547-551.

Mathen, K., Rajan, P., Radharkrishnan Nair, C. P., Sasikala, M., Gunasekharan, M., Govindankutty, M. P., and Solomon, J. J. (1990).
Transmission of root (wilt) disease to coconut seedlings through Stephanitis typical (Distant) (Heteroptera: Tingidae). Tropical Agriculture
(Trinidad) 67, 69-73.

Reinert, J. A. (1975). Royal palm bug,Xylastodoris luteolus, damage and control on royal palms in Florida. Proceedings of the Florida
State Horticultural Society 88, 591-593.

Slater, J. A., and Schuh, R. T. (1990). A remarkably large new species ofDiscoris from Colombia (Heteroptera: Thaumastocoridae).
Journal of the New York Entomological Society 98, 402-405.

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