Plant Health Brief
A Publication of the Agri-Food & Veterinary Authority of Singapore -
Diamond Back Moth infestation on Vegetables
Number of Thrips/Trap
90
80
70
60
50
2014
40
2015
30
20
10
0
Number of Diamond Back Moths/Trap
Thrips infestation on Orchids
August 2015
70
60
50
40
2014
2015
30
20
10
0
Comments:. The overall average thrips population for
Comments: The overall average Diamondback moth
August 2015 was 11 thrips/trap while in July 15 it was
around 6 thrips/trap. High incidence of thrips was
observed in two farms as against only in one farm in July
15 , with an average of 30 and 21thrips/trap in both the
locations while it was 35 thrips/trap at one location only
last month. Comparing results from last year, there was
a moderate decrease in the overall average thrips
population from around 14- thrips/trap (Aug 14) to 11
thrips/trap (Aug 15).
(DBM) population for this month was a moderate increase
from 30 moths/trap in July 15 to 35 moths/trap in Aug 15. In
July 2015, high incidence of DBM was observed in one farm
in Lim Chu Kang area (135 moths/trap) while in Sungei
Tengah area it was 66 moths/trap as compared to 60
moths/trap and 132 moths/trap respectively of the same
sites for this month . Comparing results from last year, there
is a significant decrease in the overall DBM population from
48 moths/trap (Aug14) to 35 moths/trap (Aug 15).
PUCCINIA PAULLULA- RUST PATHOGEN ON
MONSTERA DELICIOSA
Monstera deliciosa (Araceae) is a popular indoor
evergreen foliage plant. This species is related to
Philodendrons, and have similar glossy, leathery
evergreen leaves that are divided. They need rich
soil, good draining containers, occasional
fertilization and require leaves free of dust. They
prefer good light and high humidity. This species
is devoid of any serious pests but rust disease is
common and can cause economic loss if the
leaves are affected by the rust disease. The
common name “rust” refers to reddish or orange
or yellow blister like swellings also known as
“pustules” that are produced on infected leaves
and stems of host plants. The fungi that cause
rust diseases are called “obligate parasites” which
means that they need living plants to survive.
Rust disease seldom kills plants but overall plant
health is reduced. In severe cases, leaf blighting and
premature leaf fall may occur. Rust fungi may
require one host or two different hosts to complete
its life cycle. Symptoms of rust disease often start
as chlorotic lesion on the upper surface of the
leaves. These develop into blister like swelling or
pustules (Fig 1 & 2) on the lower surface that
produce powdery mass of spores. Spores are easily
spread by splashing of water and need wet surface
to germinate and cause infection. The causal agent
of the rust disease in Monstera deliciosa is Puccinia
paullula. Generally there are two types of spores
viz., urediniospores and teliospores in a rust
disease. Urediniospores of this rust pathogen (Fig
3) is known to be present throughout the year but
with little or no germination except during the cooler
months. Teliospores are produced only during the
warmer months. Teliospores germinated without
dormancy and 28 deg C was the average optimum
PEST INTERCEPTIONS FOR AUGUST 2015
temperature
for
teliospore
production.
Management of the rust disease starts with There was no pest interception for the month of
careful inspection of all incoming plants for August 2015.
symptoms such as chlorotic lesions and rust
PESTICIDE INFORMATION
pustules. Once rust disease is detected, it is
advised to remove all infected leaves or severely COMMON
Malathion
infected plants, as rust spores can spread NAME
through air and water splashes. Reducing leaf TRADE NAME
Maladion 57, Maladion 84,
wetness will help to prevent rust disease
Malanon 57EC, Malanon 84.3
development. Distance spacing of plants can also
EC, Malanon 50EC, Trinon,
help in reducing the spread. Fungicide spraying
Trinon
84.3EC,
Wendellwith
propiconazole
or triadimefon
or
Malathion, Malathion 50% W/V,
azoxystrobin may help in controlling the rust
Thiodat 57 EC, Malathion
disease.
57%,Agthion 50EC
TYPE
CHEMICAL
NATURE
FORMULATION
PROPERTIES
USES
Fig 1. Rust pustules on M. deliciosa
TOXICOLGY
DOSAGE
Insecticide
Organophosphate
Emulsifiable Concentrate
Non-systemic insecticide with
contact,
respiratory
and
stomach action
For the control of
many leaf
eating and sucking insects. Also
effective
against
arthropod
disease vectors in public health
programme .
Acute oral LD50 for rats: Around
5000 mg/kg. Irritant to skin and
eyes. Harmful to honey bees .
1 to 2 ml/lit
WITH-HOLDING Around 1-2- weeks
PERIOD
Fig 2. Close up of rust pustules on M. deliciosa
Fig 3. Urediniospores of Puccinia paullula on M. deliciosa
CONTACT US
Please report any unusual occurrence of plant pests
(new or severe occurrence) to Plant Health Laboratory,
AVA. It would help to protect our plant industry and the
garden city from new invasive pests. Please provide the
location, plant hosts attacked and suspected pests or
diseases to our officers to follow-up and confirm the
situation if required. You can report your observations
through:
Email: [email protected]
Telephone: 63165168 or 63165188 or Fax: 63161090
Visit us at: http://www.ava.gov.sg