Đề tài Benefits and difficulties of using petroleum spray oil

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 °C °F °C °F nC19 331 628 nC20 344 651 nC21 ‘60’ 212 415 356 673 nC23 ‘70’ 224 435 380 716 nC24 ‘80’ 235 455 391 736 nC25 ‘100’ 247 476 401 754 nC27 421 790 • 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 50% 90% 27.4D 2887Equivalent n-paraffin carbon number (nCy) 265.5D 1160at 1.33 kPa 426D 2887Distillation temperatures (C) at 101.33 kPa ASTM MethodKey properties of SK base oil Other Values CP 74, CN 26, CA 0D 2140Molecular types (%) 0.8299D 1298Density at 15 °C  99.8D 483Unsulfonated residue (% UR: minimum) - 24D 97Pour point (°C: maximum) 12.43 3.12 D 445Viscosity: Kinematic at 40°C at 100°C 71.1D 2161Viscosity: Saybolt at 37.8°C 340D 2502Mean molecular weight Emulsifier OIL EMULSIFIER WATER Oil + Emulsifier = Spray oil OIL WATER 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. Water Oil Water runs off Oil remains on leaf surface or moves into leaf 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 protective clothing • They are less harmful to beneficial insects and mites • Pests cannot develop resistance 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 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 to diffuse from the fruits. Leaf drop 20 sprays at 0.2% PSO12 sprays at 0.4% PSO Leaf drop 0 5 10 15 20 25 30 35 40 SK 99 0.2% SK 99 0.4% SK 99 0.1% + pesticide SK 99 0.2% + pesticide Pesticide only m ea n nu m be r o f l ea vs + - S E a a b ab b 0 10 20 30 40 50 60 70 SK 99 0.2% SK 99 0.4% SK 99 0.1% + pesticide SK 99 0.2% + pesticide Pesticide only m ea n nu m be r of le av es + - S E a a a a a Tangerine variety Kiew Wan Tangerine variety Honey 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 Sunburn 0 5 10 15 20 25 30 SK 99 0.2% + pesticide Pesticide only nu m be r o f s un bu rn ed fr ui t + - S E Colouring Colouring 0 2 4 6 8 10 12 14 0.2% PSO 0.4% PSO 0.1% PSO + Pesticide 0.2% PSO + Pesticide Pesticide treatment co lo ur in de x a bb a c Colouring 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.2% PSO + Pesticide Pesticide treatment co lo ur in de x aa 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 400000 600000 800000 1000000 1200000 1400000 PSO pesticide IPM pesticide control strategy VN D Pesticide cost Labour cost Total SOFRI 1998 Fruit yield andy quality SOFRI 1998 0 20 40 60 80 100 120 140 160 Weight (g) Sugar (%) Yield (kg) PSO pesticide IPM pesticide 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. Behaviour Modification • Key behaviours being influenced are: – Feeding – Oviposition: egg laying • Pests influenced by oil include • Spider mites • Thrips • Whiteflies • Aphids • Psyllids • Bugs • Agromyzid leafminers • Fruit flies • Gracillariid leafminers • Budworms/bollworms • Weevils Beneficial arthropods are minimally affected Tamarixia radiata Diaphorencyrtus aligarhensis Olla v-nigrum Harmonia axyridis Beneficial arthropods are minimally affected Green ants minimally affected 0 1 2 3 4 5 6 7 8 PSO pesticide IPM pesticide treatment N um be r of g re en a nt s co lo ni es SOFRI 1998 Control of deseases: – Fungicide: powdery mildew on variety of crops and sigatoka on bananas – Prevention of virus infestation: viruses transferred by aphids and whitefly – Prevention of bacterial diseases e.g. huanglongbing in citrus transmitted by citrus psylla, Diaphorina citri. Droplet size and spray volume 400010.04.00 36009.03.50 28007.03.00 17004.52.50 6001.52.00 3800.61.50 L/ha for drive-past sprayer L/tree hand spray Tree height (m) Calculation per hectare for 400 citrus trees at 3.5x7 m Spray oil as pest control agent on its own 02 4 6 8 Co ntr ol Om eth oa te Di flu be nz ur on 0.5 % Lo vis 0.5 % D- C- Tr on NR 0.5 % Gu an gd on g 0 0.4 0.8 1.2 Larvae Eggs A ve ra ge nu m be r p er flu sh Rae et al. 1997. International Journal of Pest Management 43, 71-75 010 20 30 40 50 60 70 80 90 100 w ater 0.25% PSO 0.50% PSO 0.75% PSO 1% PSO 1.25% PSO Treatment Pe rc en ta ge m or ta lit y a bc bc ab ab c R2=0.42 Effect of oil on survival of adult D. citri (Trial 1) Rae et al. 2005. In press 00.2 0.4 0.6 0.8 1 1.2 w ater 2x0.25% PSO 0.5% PSO 2x0.5% PSO 0.75% PSO 2x0.75% PSO Treatment Pr op or tio n of d ea d ps yl lid s bc d bc c b a Effect of oil on survival of adult D. citri (Trial 2) Rae et al. 2005. In press 05 10 15 20 25 30 w ater PSO Treatm ent N um be r o f a du lts (+ SE ) a b Precount Precount Effect of oil on survival of adult D. citri (outdoor) Conclusions Eggs are not very effectively controlled by oil once laid on the host plant, but egg laying can be effectively deterred by oil deposits Immature stages, especially 1st and 2nd instars are effectively controlled (>90% mortality) with oil concentrations of 0.5% and above 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 M in es p er l ea f 0 0.2 0.4 0.6 0.8 1.0 nC21 HMO concentration (% v/v) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 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 M in es p er le af Unsprayed Sprayed 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. Mites 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 Un spr ay ed 1 x 1% C2 1 1 x 2% C2 1 2 x 1% C2 1 3 x 1% C2 1 4 x 1% C2 1 4 x 0. 5% C2 1 6 x 0. 5% C2 1 4 x 0. 25 % + 4 x 0.5 % C2 1 6 x 0. 5% C2 3 4 x 0. 25 % + 4 x 0.5 % C2 3 6 x 0. 5% C2 7 4 x 0. 25 % + 4 x 0.5 % C2 7 Fa rm er 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 N um be r of r ed m ite F U U U U UU 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 Only young 1st and 2nd instars larvae 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 • Cause acute phytotoxicity • Leaf drop • Leaf burn • Black spot on leaves • Tip burn on leaves • Deformation of flowers • Oily spots on leaves and fruits • Cause chronic phytotoxicity • Less growth • Dieback Synthetic pesticides compatible with oil in tank mix copper oxychloridediflubenzunon mancozebdemeton-S-methyl permethrincartap methomylabamectin methidathionchlorpyrifos fenvaleratedimethoate endosulfanmalathion Synthetic pesticides not compatible with oil in tank mix carbaryl on deciduous trees highly ionised foliar fertilizerschlorothalnil surfactantssulfur in any form spreadersbutatin oxide captanpropargite Pesticides enhanced by mixing with oil pyrethroidsBT chlorfenapyrdiflubenzuron imidaclopridchlorpyrifos spinosadabamectin Use of spray oil for spray drift reduction Drift measure 2 m downwind for Hardi ceramic hollow cone nozzles at 500 kPa 0 50 100 150 200 250 300 350 400 5 cm 15 cm 25 cm 30 cm 5 cm 15 cm 25 cm 30 cm 1299-12 1299-20 co lo ur in te ns ity o f t ra ce r water 2% oil babababa aa ba baba