Aphid control on Burley and Flue

Aphid control on tobacco
Sannino et al
25
Aphid control on Burley and Flue-cured tobacco with foliar
insecticides1
Luigi Sannino, Felice Porrone, Cristina Biondani, Gioacchino Salerno
Abstract
Application of insecticides to tobacco cultures of
Burley (cv. 531) and Bright (cv. BTMS21) in field
tests reduced aphid incidence in 1998. Trials were
conducted at two locations: Scafati (Southern Italy)
and Bovolone (Nor thern Italy); treatments,
consisting of eight products, were applied three
times starting on the transplant date. Instead, the
bifenthrin+oil treatment was repeated every four
days for the first fifty days after transplanting.
Bifenthrin+oil, imidacloprid, pymetrozine,
bifenthrin, acetamiprid and pirimicarb showed a
good efficacy, reducing infestation in the range
80% - 99% at Scafati and 95-99% at Bovolone.
Verticillium lecanii was clearly inferior to others
insecticides, reducing the infestation level only by
49%. Tega-bion was not at all effective. Oil caused
no phytotoxicity based on visual examination of
treated plants.
Riassunto. Lotta agli afidi del tabacco Burley
e Virginia bright con insetticidi ad applicazione fogliare
Contro gli afidi del tabacco sono state condotte
nel 1998 prove di lotta a Scafati (SA) e Bovolone
(VR) rispettivamente su colture di tabacco Burley
(cv. 531) e Bright (cv. BTMS21). Complessivamente sono stati confrontati otto trattamenti, applicati
tre volte a partire dalla data del trapianto ad eccezione del trattamento bifenthrin+olio in cui l’olio è
stato ripetuto ogni 4 giorni. Bifenthrin+olio,
imidacloprid, pymetrozine, bifenthrin, acetamiprid
e pirimicarb hanno mostrato un alto livello di controllo, con riduzioni dell’infestazione tra 80 e 99%
a Scafati e tra 95 e 99% a Bovolone. Verticillium
lecanii è risultato sensibilmente inferiore, riducendo l’infestazione soltanto del 49%. Del tutto inadeguato al controllo degli afidi si è dimostrato tegabion, che necessita probabilmente di modalità di
applicazione diverse. L’olio non ha causato sintomi visivi di fitotossicità.
Key words: Nicotiana tabacum, Myzus persicae (Sulz.), control
Introduction
One of the most serious problems of the
worldwide tobacco culture concerns the green
peach aphid, Myzus persicae (Sulzer) (vector of
numerous viral syndromes and, due to this,
strongly contrasted), that developed resistance in
different parts of the world to carbamates,
1
This paper is an extract of the report presented at the
annual meeting of the project “Management of insect pests
and viruses of tobacco using ecologically compatible
technologies” held at the Rothamsted Experimental Station,
Harpenden (England), in 1998.
Luigi Sannino, Felice Porrone, Cristina Biondani, Istituto
Sperimentale per il Tabacco, Scafati (SA)
Gioacchino Salerno, Associazione POMA, Battipaglia (SA)
organophosphates and pyrethroids compounds
(Cravedi & Cervato, 1991; Denholm & Rowland,
1992; Cervato & Cravedi, 1995).
Aphids also damage tobacco by removing
plant juices and contaminating leaves with cast
skins and honeydew.
Chemical control measures are the most
reliable means currently available to control the
tobacco aphids.
Producers are undertaken in a continuous
effort to discover new and avant-garde
insecticides; despite this, there have been
instances in which aphids developed resistance
shortly after their availablility on the market. To
limit these phenomena there is need to experiment
new products and, more generally, take on control
strategies which allow reducing to minimum the
Il Tabacco, 8, 2000: 25-31
afididef.p65
25
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26
Il Tabacco,
insecticide selection pressure, so as to preserve
its effectiveness.
The aim of this experiment was to test some
insecticides, already registered or in course of
registration, for the tobacco aphids control. Field
trials were conducted in Campania and Veneto,
two typical tobacco growing regions in Italy, in
a more-year project sphere (Tab-Res-Info 96/T/
18, co-funded by the E.U. Tobacco Research
Fund and the Italian Ministry of Agriculture)
dealing with management of insect pests and
viruses of tobacco using ecologically compatible
technologies.
In this note are reported results achieved in
1998.
Material and methods
Trials were carried out at the Tobacco Research
Institute (TRI) farms at Scafati (Salerno,
Southern Italy) and Bovolone (Verona, Northern
Italy), using tobacco cultures of Burley (cv. 531)
and Virginia Bright (cv. BTMS21), respectively,
both aphid-susceptible.
The following products were compared:
qAcetamiprid, a new broad spectrum systemic
insecticide, belonging to the family of
chloronicotinyls (neonicotinoids) presently in
course of registration for use on several crops
among which tobacco; it shows high activity
against Hemiptera, especially aphids, and also
Thysanoptera and Lepidoptera (Takahashi et al.,
1992; Domenichini & Roffeni Tiraferri, 1998);
qImidacloprid, of the same group of acetamiprid,
an insecticide active both by contact and
ingestion against insects with sucking feeding
apparatus (Tomlin, 1994; Angelini et al., 1997);
q Pymetrozine, belonging to the pyridine
azomethine group, represents a novel type of
insecticide characterised by high selectivity for
plant sucking insects such as aphids, white flies
and other similar pests, in which it causes the
feeding blockage;
qBifenthrin, active pyrethroid by contact and
ingestion at rather low use rates against a large
number of insects including aphids, Lepidoptera
afididef.p65
26
8
and Coleoptera (Domenichini & Pacini, 1994).
Against tobacco aphids it has shown fair results
(Sannino, 1997; Sannino & Piro, 1998);
qPirimicarb, one of the most used aphicide in
Italy;
qBiolid, a “narrow-ranged” oil that, unlike
traditional ones, is characterised by a prevailing
presence of paraffin molecules which present a
reduced content of aromatic hydrocarbons
giving the product a lower phytotoxicity;
qVerticillium lecanii (VL1), entomopathogen
fungus, isolated at TRI in 1997 from dead
aphids found on tobacco and kept at 4 °C on
potato-dextrose-agar (PDA);
qTega bion, a new compound, presently in course
of registration, for protection of crops against
diseases caused by fungi and viruses thanks to
the mechanical action of the film deposited on
leaves (Cole, 1996).
In both experiments a randomised complete
blocks design in four replications was used.
Treatments, consisting of several applications of
commercial products (except for VL1) at the rates
suggested by firms, were eight (insecticides +
untreated control). Treatment application was
performed by means of a high volume sprayer,
utilising 1000 l/ha of water, with a spray adjuvant
added at the rate of 40 ml/hl. Regarding the VL1,
mycelial plugs from cultures on PDA were
inoculated in darkness at 25 °C for a period of 12 weeks. On the day of treatment application, the
cultures were filtered and the conidia count was
performed in the resulting suspension, which was
diluted with distilled water until reaching the 106
conidia/ml concentration. Treatment was
performed during evenings to avoid the
deleterious effects of the direct sun radiation.
Treatment application was started on the
transplanting date and repeated until mid July
according to the treatment time interval reported
in the spray schedules (Table 1). Oil was repeated
every four days for fifty days after transplanting.
At Scafati, the experimental plot (24 m2
surface) consisted of five rows of twenty plants
each spaced 0.35m on the row and 0.90m between
rows corresponding to about 32500 plants per
hectare. At Bovolone the experimental plot (100
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Aphid control on tobacco
Sannino et al
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Table 1. Treatments and application time interval.
Tab. 1. Trattamenti e intervallo di applicazione.
Ins e cticide
Bifenthrin + oil
Imidacloprid
Acetamiprid
Bifenthrin
Pirimicarb
Pymetrozine
Vert icillium
lecanii
Metalazil +
Metalaxyl- M
Comme rcial product Application rate Application rate
(% a. i.)
(g/ha a. i.)
(g/ha c. p.)
Brigata Flo +
Biolid(2.0)
Confidor 200 SL (20)
Exp.60707A (20)
Brigata Flo (2.0)
Pirimor (17.5)
(Plenum) (25)
Isolate Vl1
Tega bion
20 + 5000
1000 + 5000
Oil: every 4 days
Bifentrin: every 12 days
100
50
20
350
200
106 conidia/ml
water
500
250
10 0 0
2000
800
20 days
20 days
12 days
12 days
20 days
2 lt/plot
10 days
250
12 days
110
m2) was composed of 8 rows of 35 plants each,
spaced 0.35m on the row and 1m between rows,
corresponding to about 27700 plants per hectare.
The efficacy evaluation was done considering
either the number of live individuals or the aphid
infestation remarks on the five apical leaves of
15 plants of the central rows of each plot. In the
latter case the following scale (in six classes) was
used: 0 = absence of aphids; 1 = 1-6 aphids/leaf; 2
= 7-15 aphids/leaf; 3 = 16-30 aphids/leaf; 4 = 3160 aphids/leaf; 5 = > 60 aphids/leaf. As infestation
index was used the weighted mean of scores:
INFI = Σ(ni*pi)/Σni
where ni is the i-th assessed plant and pi its score.
At Scafati, transplanting was done 22 May and
observations on the following dates: 9 June, 24
June, 16 July and 4 August, at 18, 33, 55 and 74
days from the transplanting.
At Bovolone, transplanting was done 20 May
and observations on the following dates: 29 June,
8 July, 15 July, 22 July, 29 July, 5 August and 12
August, at 38, 47, 54, 61, 68, 75 and 82 days
from the transplanting.
Cultural practices were those usually used for
the type of tobacco. In field, no further insecticide
applications were performed besides those of the
experimental treatments.
afididef.p65
27
Inte rval be twe e n
s prays
Results and discussion
In both locations, plant establishment was nearly
100% and the very few misses were immediately
replaced.
At Scafati the first aphids arrived on tobacco
plants at the beginning of June, but the parasite
population density remained very low until the
end of the month, increasing appreciably only
towards mid-July (Figure 1).
Bifenthrin+oil, imidacloprid, pymetrozine,
bifenthrin, acetamiprid and pirimicarb showed
in the order a good efficacy, reducing infestation
in the range 80% - 99%. Verticillium showed
some control, but clearly inferior to other
insecticides (Table 2). Among the more effective
products, bifenthrin+oil was the best, even if the
differences with respect to imidacloprid,
pymetrozine bifenthrin, acetamiprid and
pyrimicarb did not reach the conventional level
of statistical significance.
At Bovolone, in the observation period which
lasted about 40 days, infestation recorded on the
control showed a trend similar to Scafati’s, being
quite low till the end of June and then gradually
increasing in July and August (Figure 2).
Bifenthrin+oil, pymetrozine, imidacloprid,
acetamiprid, bifenthrin and pirimicarb were in
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Il Tabacco,
8
Table 2. Effect of products on aphid infestation at Scafati in 1998: average and trend (daily
variation) of infestation score (No. aphids on the upper five leaves) and percentage of control.
Tab. 2. Effetto dei prodotti sull’infestazione afidica a Scafati nel 1998: media e andamento (variazione giornaliera) dell’infestazione (n. afidi sulle cinque foglie apicali) e percentuale di controllo rispetto al testimone.
Products
Avg aphids /5 le ave s
Tre nd (*100)
% control
Bifenthrin+oil (bif+o)
Imidacloprid (imi)
Pymetrozine (pym)
Bifenthrin (bif)
Acetamiprid (ace)
Pirimicarb (pir)
Vert icillium lecanii
Control
0.4
0.7
0.7
0.8
2.0
2.1
5.7
10.2
0.9
0.4
0.6
1. 7
10.2
9.8
18.0
40.3
99
99
99
99
80
80
49
Contras ts (Prob. |t|)
Vert icillium vs others
Pirimicarb vs others
[bif, bif+o] vs [imi, pym, ace]
[bif] vs [bif+o]
[imi, ace] vs [pym]
[imi] vs [ace]
0.003
0.411
0.650
0 . 8 17
0.680
0.465
0.065
0.350
0.696
0.937
0.575
0.313
0 . 0 15
the order quite effective, reducing the infestation
level in the range 95% - 99% (Table 3). Tega
bion was not at all effective, showing in some
cases infestations higher than control.
Summarising, bifenthrin+oil confirmed the
good efficacy shown in the 1997 trials, slightly
superior to the other insecticides.
Imidacloprid, considered in the comparison
because now largely used in tobacco crops
(Cristianini, 1997; Sannino & Piro, 1998), has also
given confirmation of its high aphid control
capability.
Pymetrozine, recently registered for use on
tobacco and other fruit and vegetable crops in
Italy, showed an effectiveness comparable to that
of imidacloprid. As a consequence of the fast
inhibition of the probing behaviour, aphids are
effectively inhibited to transmit predominantly
persistent plant viruses (Harrewjin & Piron,
1994). Due to its mode of action the product can
afididef.p65
28
be used where conventional insecticides have
become ineffective (Bolsinger et al., 1993).
Among other insecticides tested, Acetameprid
was as effective as Bifenthrin, while Pirimicarb
was barely inferior probably due to development
of parasite resistance.
At Scafati, while the majority of the tested spray
schedules reduced substantially aphid infestation
on tobacco, they were quite ineffective for virus
control, except in the instance of bifenthrin+oil,
which showed a high degree of control. At
Bovolone, the extremely low frequency of infected
plants does not allow any comments.
No phytotoxicity occurred on plants treated with
oil, as well on the others, based on visual symptoms.
Acknowledgements
Thanks are due to dr. Rosario Nicoletti (Tobacco
Research Institute)for providing Veticillium
lecanii cultures
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Aphid control on tobacco
Sannino et al
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Fig. 1. Effect of products on the infestation (No. aphids on the upper five leaves) in the observation
period at Scafati.
Fig.1. Effetto dei prodotti sull’infestazione (n. afidi sulle cinque foglie apicali) nel periodo di osservazione a Scafati.
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30
Il Tabacco,
Fig. 2. Effect of products on aphid infestation (0-5 scale) in the observation period at Bovolone.
Fig.2. Effetto dei prodotti sull’infestazione afidica (scala 0-5) nel periodo di osservazione a
Bovolone.
afididef.p65
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Aphid control on tobacco
Sannino et al
31
Table 3. Effect of products on aphid infestation at Bovolone in 1998: average and trend (daily
variation) of infestation score (0-5 scale) and percentage of control.
Tab. 3. Effetto dei prodotti sull’infestazione afidica a Bovolone nel 1998: media e andamento (variazione giornaliera) dell’infestazione (scala 0-5) e percentuale di controllo rispetto al testimone.
Products
Bifenthrin+oil (bif+o)
Pymetrozine (pym)
Imidacloprid (imi)
Acetamiprid (ace)
Bifenthrin (bif)
Pirimicarb (pir)
Tega- bion
Control
Contras ts (Prob. |t|)
Tega- bion vs others
Pirimicarb vs others
[bif, bif+o] vs [imi, pym, ace]
[bif] vs [bif+o]
[imi, ace] vs [pym]
[imi] vs [ace]
Avg aphids /5 le ave s
Tre nd (*100)
% control
0.1
0.1
0.2
0.2
0.3
0.6
2.1
2.3
0.6
0.0
0.5
0.2
0.6
2.2
5.9
6.7
99
99
98
98
98
95
2
<0.001
0.174
0.984
0.732
0.835
0.991
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