Báo cáo nghiên cứu khoa học " Benefits and difficulties of using petroleum spray oil " pot

Presentation Overview• Spray oil defined • Emulsifiers • How spray oil works • PSO vs conventional pesticide • Phytotoxicity limiting factor for spray oil use • Spray oil as pest contro

Benefits and difficulties of using petroleum spray oil

Oleg Nicetic and Debbie J Rae

Centre for Horticulture and Plant Sciences,

University of Western Sydney, Hawkesbury Campus, Richmond, NSW, Australia

Presentation Overview

• Spray oil defined

• Emulsifiers

• How spray oil works

• PSO vs conventional pesticide

• Phytotoxicity limiting factor for spray oil use

• Spray oil as pest control agent on its own

• Spray oil as an adjuvant

• Use of spray oil for spray drift reduction

Spray oil defined

Spray oil nomenclature

• White oil

• Petroleum Spray Oil (PSO)

• Mineral Spray Oil (MSO)

• Agricultural Mineral Oil (AMO)

• Horticultural Mineral Oil (HMO)

• Narrow range vs broad range

• Winter oil vs Summer Oil

• PSOs are derived from lubricating oils.

Three main types of molecules make up a spray oil:

– Isoparaffins: provide most of the efficacy.

– Naphthenes: less effective than isoparaffin – Aromatics: a cause of plant damage.

Median

n-paraffin

carbon number

Viscosity 50% distillation temperature

ASTM D 2887 Saybolt universal

seconds (SUS) at 37.8ºC

ASTM D 445

1.33 kPa (10 mm Hg) ASTM D 1160

101.33 kPa (760 mm Hg) ASTM D 447

• Oils can be light or heavy as measured by nCy

(carbon number)

– Generally range from nC21 (light) – nC25 (heavy)– Carbon number is related to the temperature

20 196 344

10%

Values

24.3

243.5 394.5

D 445 Viscosity: Kinematic at 40°C

at 100°C

71.1

D 2161 Viscosity: Saybolt at 37.8°C

340

D 2502

Mean molecular weight

Emulsifier

OIL EMULSIFIER WATER

Oil + Emulsifier = Spray oil

Typically PSOs contain from 0.35 to 2%

emulsifiers However as PSO paraffinicity and

unsulfonated residue (= hydrogen saturation)

increase, it becomes more difficult to form oil-water emulsion thus the content of emulsifiers can

increase to 6%

Modern oils form quick breaking emulsions that ideally should break on contact with the target-the oil thinly coating the target, the water running off.

Quick-break oil in

water emulsions

Practical implication for using oils in field

 Proper and constant agitation of the water-oil emulsion in the tank Temperature of the mixture in the tank or in the hose should never exceed 420 C

 Adding oil to the adequate (sufficient) quantity of water and providing agitation while mixing

 Be careful when making tank mix of oil and other

pesticide specially when WP are added Tank should be nearly full with oil emulsion and then pre-mixed WP

should be added As general rule it should not be more than 0.1kg of insoluble powder per 100 L of oil-water

emulsion

Stability of emulsion

 Depending on quantity and type of emulsifier, emulsion

of PSO and water can be stable from few minutes to few hours Generally current PSOs have emulsion stability from 20 minutes to 2 hours

 In the tank, emulsion should never been left without

agitation for more than 20 minutes

 After emulsion was sprayed to the plant deposit should dry within 2 hours, preferably within 30 minutes

PSO vs conventional pesticide

Advantages over conventional pesticide

• They have very low toxicity to vertebrate

animals and humans

• They may be handled with minimum

Disadvantages over conventional

pesticide

• Higher risk to cause phytotoxicity that limits

PSO’s use when plants are stressed and when temperature and relative humidity is high

• To be effective PSO has to be sprayed at higher volume then most conventional pesticides which increases labour costs, increases time of

spraying and requires availability of lot of water

• Overall in the short term PSO based IPM

program is more expensive than conventional program but in the longer term they could have economic benefits.

Phytotoxicity is major limitation for use of oil as an insecticide, a deterrent or as an

adjuvant.

Why PSO is phytotoxic

 Every mineral oil interferes with plant physiological

functions including transpiration and movement of

phytohormones

 In the last 10 years progressively higher mean carbon number oils are being used and these oils more strongly affect plant physiological functions

 Recommendations for spraying oil need to be more

cautious and should never exceed recommended label dose and cumulative yearly dose

 Recommended label dose and cumulative yearly dose vary from species to species but usually tangerines and mandarins are most susceptible, pomelos and navel

oranges are intermediate, sweet oranges, lemons and grapefruit are less susceptible

Major causes of phytotoxicity

– Presence of aromatics and impurities in oil – Amount of oil deposited on plant

– High temperatures (particularly over 35°C) – Presence of moisture or heat stress

– Plant type and growth stage

– Poor agitation

– Incompatible mixing

Acute phytotoxicity

Oil soaking

Oil soaking precursor to phytotoxicity

 A particularly high risk for the use of oil is temperatures over

300 and relative humidity over 80%; conditions that are often present in the tropics

 Oil viscosity decreases with increased temperature and it takes a long time for oil to dry so penetration into plant is

very high and soaking can be observed after a single low

concentration spray

 When oil soaking is detected, oil sprays should be

discontinued until oily spots disappear Unfortunately under humid tropical conditions it takes a long time for oily spots todiffuse from the fruits

Leaf drop

20 sprays at 0.2% PSO

12 sprays at 0.4% PSO

SK 99 0.1% + pesticide

SK 99 0.2% + pesticide

Pesticide only

Leaf drop

Mekong delta production practice

 In Delta farmers time the fruit production for Tet by inducing

water stress First they cut the water inducing dry condition and then they use heavy watering to induce flowering If PSO

sprayed at that time leaf can drop

 More frequent sprays even at low concentration cause more leaf and fruit damage than single higher concentration spray

 Generally PSO should not be sprayed during flowering under any condition

Sunburn

Colouring

c

Colouring

Mekong delta production practice colouring

 For varieties that develop orange colour PSO should not be sprayed 3-4 weeks before harvest

 However if PSO is cumulated in fruit skin due to consistent

soaking then colour can be affected even when spray is

discontinued several months before harvest

 When oil soaking was not present low concentration of 0.2% did not cause any colour deterioration even when oil was spray till the harvest

Safe limits for use of PSO

When PSO is used till the point of run-off (3000 L/ha for fully

grown trees) than:

 For susceptible varieties such as tangerine, no more than 2.5% oil per year should be sprayed while for more resilient varieties

up to 4% can be sprayed each year

 For susceptible varieties no more that 0.2% should be applied per spray if the interval between sprays is less than 14 days

and for more resilient varieties not more than 0.4% However

no more than 2 consecutive sprays at interval less than 14 days should be sprayed

 If single sprays are applied for scales then for susceptible

varieties not more than 0.5% should be applied and 1% for

more resilient varieties

Cost of oil application

0 200000

SOFRI 1998

Fruit yield andy quality

Could benefits of PSO overpower its

disadvantages???

How spray oil works

How Spray Oils Works

• Insecticidal mode of action is anoxia/suffocation

– Focused on scales and mites

Beneficial arthropods are minimally

affected

Tamarixia radiata

Diaphorencyrtus aligarhensis

Beneficial arthropods are minimally affected

Green ants minimally affected

– Prevention of bacterial diseases e.g huanglongbing in

citrus transmitted by citrus psylla, Diaphorina citri.

Droplet size and spray volume

4000 10.0

4.00

3600 9.0

3.50

2800 7.0

3.00

1700 4.5

2.50

600 1.5

2.00

380 0.6

1.50

L/ha for drive-past sprayer

Spray oil as pest control agent

on its own

0 2 4 6 8

0. 5%

L ov is

0. 5%

D -C -T ro

n N R

ab ab

c

Effect of oil on survival of adult D citri (Trial 1)

Rae et al 2005 In press

a

Effect of oil on survival of adult D citri (Trial 2)

Rae et al 2005 In press

Adult psyllid mortality increases with both oil concentration and the volume of spray mix applied when psyllids are contained

Adult psyllid numbers were significantly reduced by 1.0% oil sprays in an outdoor situation, but this may have been due to avoidance of sprayed surfaces rather than through mortality

Mineral oil deposits reduce citrus leafminer oviposition

Concentrations much lower (0.125%) than those used to drown scales and mites (1-2%) have dramatic effects on numbers of eggs laid by citrus

leafminer (Beattie et al 1995)

Effects increase with increasing median

nCy values (Liu et al 2001)

Mineral oil deposits reduce citrus leafminer oviposition

15/12 29/12 12/1 7/2 21/2 14/3 27/3 12/4 30/4 16/5

1994 - 1995

0 1 2 3 4 5 6 7 8

Liu et al.

(unpublished data)

Impact of 4 pre-egg peak 0.5% nC23

PSO sprays in coastal New South Wales

Citrus leafminer — Phyllocnistis citri

Eggs are laid on immature leaves < 4 cm long

Control should be based on prevention (prophylatic control) and focus on flush phenology — not levels of infestation

Spray immature flushes thoroughly with 40-50 mL PSO per 10L water Begin

spraying when buds open and continue spray every 5-14 days until most leaves are 30 mm long.

Remove unwonted flushes.

Mite infestations on citrus are usually induced by disruptive pesticides

When they do occur they can

be controlled with spray oils.

Infestations are unlikely to

occur when multiple low

concentration oil sprays are

used to control citrus leafminer

C21

2 x 1%

C21

3 x 1%

C21

4 x 1% C21

U U U U

U

F U

U

U

Multiple low and high-concentration sprays also have significant impacts on other pests, for example, citrus red mite populations on orange fruit in southern China

Soft scales and mealybugs

Most soft scales (eg Coccus

sp.,Saissetia sp.,Ceroplastes sp.) and

mealybugs (Planococcus citri,

Pseudococus sp.) are more difficult to

control than armoured scales

can be control by thorough spraying of infested surfaces Mealybugs generally can only be partially control.

Wax scales such as white wax scale

(Ceroplastes destructor), pink wax scale (Ceroplastes rubens) and hard wax scale (Ceroplastes sinensis) are the easiest soft

scales to control

Oil alone applied at 1% concentration at

very high volume could be as effective as

most synthetic pesticides and mixtures of

oil and synthetic pesticides

Armoured scales (Hard scales)

Armoured scales such as red

scale (Aonidiella aurantii ) and purple scale (Lepidosaphes

beckii) are easily controlled with

spray oils.

0.5 to 1% sprays should be

applied thoroughly to all above ground surfaces.

Infestations warranting sprays

are unlikely to occur when

multiple low concentration

sprays are used for control of

citrus leafminer.

Rotational use of primicarb and

other IPM compatible synthetic

pesticides should be used to control aphids when infestations warrant spraying

Resistance is minimised by the

rotational use of the pesticides

Products should be used at the

lowest registered rates

Spray oils will reduce aphid

population but they are less

effective against some species of aphids (e.g black citrus aphid) than others

Aphids

Spray oil as an adjuvant

The compatibility of spray oil with other

pesticides

• When spray oil is used together with other

pesticides, it has synergistic effects on most

chemicals under most circumstances.

• However, it can cause significant

phytotoxicity when mixed with some

incompatible chemicals.

• It can also increase the impact of some

potential phytotoxic chemicals.

The potential benefits of mixing spray oil

with other pesticides

• protect them from breakdown

• increase their efficacy (pick-up)

• enhance cuticular penetration

• increase persistence (residual activity)

• prevent evaporation and drift

• increase adherence and effect of spreading

• reduce surface tension and increasing coverage

• increase canopy penetration

The negative effects of mixing spray oil with

incompatible pesticides

• Leaf drop

• Leaf burn

• Black spot on leaves

• Tip burn on leaves

• Deformation of flowers

• Oily spots on leaves and fruits

• Less growth

• Dieback

Synthetic pesticides compatible with oil in tank mix

copper oxychloride diflubenzunon

mancozeb demeton-S-methyl

permethrin cartap

methomyl abamectin

methidathion chlorpyrifos

fenvalerate dimethoate

endosulfan malathion

Synthetic pesticides not compatible with oil in tank mix

carbaryl on deciduous trees

highly ionised foliar

fertilizers chlorothalnil

surfactants sulfur in any form

spreaders butatin oxide

captan propargite

Pesticides enhanced by mixing with oil

pyrethroids BT

chlorfenapyr diflubenzuron

imidacloprid chlorpyrifos

spinosad abamectin

Use of spray oil for spray drift

reduction

Drift measure 2 m downwind for Hardi ceramic hollow cone nozzles

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