Citrus Section UPDATE ON PETROLEUM SPRAY OIL FOR CITRUS RUST MITE CONTROL

Transcription

1 Citrus Section Proc. Fla. State Hort. Soc. 114: UPDATE ON PETROLEUM SPRAY OIL FOR CITRUS RUST MITE CONTROL J. L. Knapp, H. N. Nigg, and H. E. Anderson University of Florida, IFAS Citrus Research and Education Center 700 Experiment Station Road Lake Alfred, FL Additional index words. rates, split applications, water spray volume. Abstract. The evaluation of ExxonMobil, Helena Chemical Com pany, PetroCanada, and Sun Company petroleum spray oils for control of citrus rust mite is reported. In an experiment with PetroCanada oil, 20 gallons of oil plus gallons of water per acre applied in April, July, and October did not pro duce leaf or fruit damage, but did control citrus rust mites for 8 months. One or gallons per acre application of Petro Canada oil compared favorably with Sun Company oil at the same rates. In general, higher rates of oil provided better and/or longer citrus rust mite control. plus gal lons of water per acre provided better residual citrus rust mite control compared to the same oil and rate applied in 30 and 50 gallons of water per acre. A 2 gallon rate of Helena Chemical Company oil provided rust mite control for approximately 40 days in two trials. ExxonMobil oil compared favorably with Sun Company oil at gallons per acre with one appli cation in July. Split applications in June and August of gal lons of ExxonMobil and Sun Company oils in gallons of water per acre provided 111 days (late June-Octo ber) of citrus rust mite control. Overall, petroleum oils from ExxonMobil, Helena Chemical Company, PetroCanada, and Sun Company performed well in these tests. The citrus rust mite (CRM), Phyllocoptruta oleivora (Ashmead) is found on the twigs, leaves, and fruit of all citrus vari eties in humid citrus-growing regions of the world (McCoy et al., 1988; Yothers and Mason, 1930). In Florida, the CRM is a pest of fruit destined for the fresh and processed market. Cit rus rust mite populations reach high and injurious levels quickly (McCoy and Albrigo, 1975) and under environmental conditions favoring the increase of mite populations (McCoy et al., 1988; Pratt, 1957), mite injury from cellular feeding can affect fruit growth (Allen, 1979), fruit drop (Allen, 1978), in ternal fruit quality (McCoy et al., 1976), and external fruit quality (McCoy and Albrigo, 1975; McCoy et al., 1988). The CRM infests new fruit and new foliage each year in Florida in March-April (McCoy, 1979). Populations may reach injurious population densities from June to November (Allen and McCoy, 1979; McCoy et al., 1988; Pratt, 1957), and some growers apply up to four acaricidal sprays within a grow ing season. This research was supported by the Florida Agricultural Experiment Sta tion, and approved for publication as Journal Series No. N Petroleum spray oils (also termed horticultural, mineral, white, or narrow range spray oils) have been used on a variety of pests and crops (Johnson, 1985; Riehl, 1981; Simanton and Trammel, 1966). Petroleum spray oil (PSO) evaluations made in the 1980s and 1990s led to the publication of the specifications designated FC -88 (Knapp, 1990). Petro leum spray oils meeting this specification have been used commercially in Florida since that time. Petroleum spray oil use on citrus in the fall has been somewhat restricted by recommendations based on reported phytotoxic responses including reduced soluble solids (Furness, 1981; Riehl et al., 1956; Riehl et al., 1957; Sinclair et al., 1941; Thompson and Sites, 1945), reduced yield (Beattie et al., 1989; Bodenheimer, 1951; Furness and Maelzer, 1981), and reduced cold hardiness (Knapp et al., 1992; Trammel and Simanton, 1966). Among the factors reported to increase the phytotoxicity of horticultural spray oils on citrus are re peated applications (Dean and Hoelscher, 1971; Dean et al., 1978) and application timing (Lee and Knapp, 1994). Phytotoxic effects of petroleum spray oils have proven difficult to reproduce (Lee and Knapp, 1992, 1994). The main purpose of these experiments was to investigate the efficacy of petroleum spray oils for CRM control. Specific objectives were: 1) evaluate petroleum spray oil phytotoxicity, 2) compare application water volumes, 3) compare 435,, and mid-boiling point oils at different gal per acre (gpa) rates, and 4) evaluate split and single oil applications. Materials and Methods specifications and sources are in Table 1. applica tions were made with winds of less than 5 mph and rainfall of less than 0.1 in within 48 h after the spray had dried. Experiment 1. (1998). The purpose of this experimentwas to compare rates of PetroCanada Biocover MLT (435), LS (), and SS () oils with Sun Company oil for con trol of CRM. Three applications were made: postbloom - 23 Apr, summer - 21 July, and fall - 20 Oct., at and 20 gal plus gal of water per acre with a Durand Wayland PTO driven air blast sprayer (Durand Wayland, Inc., LaGrange, Ga.). Bio cover oils were emulsified with 1 % AO2 emulsifier (PetroCan ada). The Sun Spray oil was emulsified with 1% T-Mulz- FCO (Harcross Chemicals, Inc., Kansas City, Kan.). This ex periment was conducted near Lake Alfred, Fla. in a 9-year-old Hamlin (Citrus sinensis L. Osbeck) grove with ft between trees and 20 ft between rows. This grove was irrigated by over head sprinklers and was herbicided trunk to trunk (Table 2). Experiment 2. (1999). The purpose of this experiment was to compare the rate per acre of a single application of Bio cover LS and SS oils emulsified with 1.2 and 1.6% emulsifier compared to a single application of Sun Company FC - 88 oil for control of CRM. One application was made on - 16 Jul of and gpa gal of water with the same equip- 46 Proc. Fla. State Hort. Soc. 114: 2001.

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3 Table 3. Experiment Petroleum Spray Test (citrus rust mite/cm2) on Hamlin Oranges (application -16 July) Date weight Rate gpa* 7/12 7/21 7/27 8/09 8/17 8/23 8/31 9/14 0) 1) BiocoverLS (1.2%)w 2) BiocoverLS (1.2%) 3) BiocoverLS (1.6%) 4) BiocoverLS (1.6%) 5) BiocoverSS (1.2%) 6) BiocoverSS (1.2%) 7) BiocoverSS (1.6%) 8) BiocoverSS (1.6%) 9) Sun Spray 9 Nv ) Sun Spray 9 Nv b> 35.8 a 13.4 c 19.5 b 19.3 b 39.3 a 9.6 c 6.7 d 19.4 b 16.3 b 17.9 b a* 0.1 fg 0.6 efg 0.5 def 1.1 cd 1.3 c 0.3 fg 0.5 cde 0.4 efg 2.1b 0.0 g a 0.0 e 0.1 de 0.1 de 0.2 de 0.6 b d 0.2 de 0.0 e 0.7 be 0.0 e a 0.1b 0.2 b 0.3 b a 0.1 cd 0.3 be ed ed 0.1 cd 0.4 b a 1.1b 0.1c 0.1c 0.9 b a 0.1 ef 0.3 ef 0.0 f 0.1 ef 2.2 b 0.2 ef 1.0 d 0.3 e 2.0 c 0.1 ef be 0.2 e 0.3 e 0.2 e 0.1 e 4.3 e 0.5 e 2.2 c 1.4 d 2.8 b 0.1 e Z gal of water per acre, tractor speed 1.66 mph. >Means in each column not sharing a common letter are significandy different at the 5% level (DMRT). Data transformed to LOG (x + 1) for analysis Non- transformed data presented for comparison. "Bolded numbers are equal to or higher than 1.0 mite/cm2. "Biocover oils are PetroCanada oils. VFC -88 oil was used as the standard. The source of this oil was Sun Company. Emulsified with 1% T-Mulz emulsifier. Means in each column followed by the same letter are not significantly different by the GLM procedure and Tukey's HSD test, a = 0.05 n = 160. Table 2) provided about 49 d of CRM control. The 20 gpa rate of Biocover MLT provided about 73 d of control (Table 2). The 20 gpa rate of Biocover LS (), Biocover SS (), and Sun Spray 9N oils provided season long control (Table 2). The gpa rate of all oils provided from d of CRM control with the exception of Biocover SS which provided sea son long control (Table 2). Experiment 2. (Table 3). For experiment 2, oils were ap plied once at or gpa in gal of water. The application was made and 16 July and CRM evaluations were conduct ed until 14 Sept. Mite populations increased first in the gpa rate plots: Biocover SS (1.2% emulsifier) at + 37 d, Bio cover SS (1.6% emulsifier) and Sun Spray 9N at + 45 d. The gpa oil rate provided CRM control for 59 d as did Biocover LS () oil. From these data it appears that a gpa single application of Biocover oils provided about 45 d of CRM con trol and the gpa rate of the same oils provided about 60 d of CRM control. This performance was as good or better than Sun Spray 9N ( oil) at and gpa. These results but tress the results of experiment 1 in that higher oil rates pro vided better CRM control. Experiment 3. (Table 4). Experiment 3 compared 5.0, and.0 gpa of Sun Spray 9N () oil applied on 29 June in 30 and gpa of water. The initial control of CRM was the same for all rates and gallonages; residual control was signifi cantly shorter as gallons of oil per acre and gallons of water per acre were reduced. For example, the gpa rate of Sun Spray 9E at gal of water per acre provided better CRM control after day 35 than gpa of Sun Spray 9E with 30 gal of water per acre. In gal of water per acre, the gpa of Sun Spray 9E was better than 5 gpa of Sun Spray 9E in gal of water per acre after day 35. These data confirm the data of experiments 1 and 2 (Tables 2 and 3) that higher oil rates provide better residual control of CRM; approximately 50 d for the gpa rate applied in gpa of water (Table 4). Experiment 4. (Table 5). Experiment 4 compared Sun Spray 9E ( oil) with Mite-E- from Helena Chemical Com pany. Sun Spray 9E provided CRM control for approximately Table 4. Experiment Curtec Application Petroleum Spray Test (citrus rust mite/cm2) on Hamlin Oranges (application 29 June). weight Rate /AC Rate H2O/AC 6/22 7/07 7/19 8/04 Date 8/11 8/19 8/25 9/7 0) 1) Sun Spray 9 N> 2) Sun Spray 9 N> 3) Sun Spray 9 N> 4) Sun Spray 9 N> 5) Sun Spray9 N? 6) Sun Spray 9 N> 5.0 gal gal gal 5.0 gal gal gal gal gal gal 30 gal 30 gal 30 gal a' 1.6 abc 1.6 abc 1.4 c 1.9 abc 1.4 c 2.1 ab a 0.2 b 0.2 b a 0.2 c 0.5 be 0.7 b 0.6 b a 0.8 d 0.4 de 0.1 e 3.7 b 2.6 c 0.8 d a 2.1 d 1.5 d 0.3 e 5.6 b 4.3 c 1.2 d a 1.5 cd 2.3 c 0.4 e 4.2 b 4.8 b 1.2 de b 2.2 c 2.0 c 1.5 d 9.0 a 6.9 b 2.3 c d 9.0 b 5.1c 4.9 c 12.4 a 13.4 a 3.6 d 'Bolded numbers are equal to higher than 1.0 mite/cm-. >FC -88 oil was used for all treatments. The source of this oil was Sun Company. Emulsified with 1% T-Mulz emulsifier, tractor speed 1.66 mph. Means in each column followed by the same letter are not significantly different by the GLM procedure and Tukey's HSD test, a = 0.05 n = Proc. Fla. State Hort. Soc. 114: 2001.

4 Table 5. Experiment Petroleum Spray Test (citrus rust mite/cm2) on Hamlin Oranges (application on 29June). Date weight Rate gpa 6/22 7/07 7/19 8/04 8/11 8/19 8/25 9/ ) 2.1 a' 1.3 a 3.0 a.3 a 6.9 a.7 a 5.3 b 2.5 c 1) Mite-E- 2 gal 3.6 a 0.2 c 0.4 c 1.2 c 12.3 a.8 a 14.5 a 2) Mite-E- 3 gal 1.0 b 0.3 b 1.2 b 6.2 b b 1.0 b 3.9 c 4.6 b 3) Sun Spray 9E> gal 1.4 b 0.1 c 0.3 d 0.4 c 1.5 d 4.9 b 'Bolded numbers are equal to or higher than 1.0 mite/cm-. >FC -88 oil was used as the standard. The source of this oil was Sun Company. Applications were made in gal of water per acre, tractor speed 1.66 mph. Means in each column followed by the same letter are not significantly different by the GLM procedure and Tukey's HSD test, a = 0.05 n = d with one gpa application. The 2 gpa rate of Mite-E- provided CRM control for approximately 42 d. The 3 gpa rate of Mite-E- provided CRM control for 20 d. We have no explanation for this difference between rates of Mite-E-. Experiment 5. (Table 6). Experiment 5 compared single applications and 20 gpa rates of Biocover oils to gpa of Sun Spray 7E (435) and and 20 gpa Sun Spray 9E () oils. These single application rates were compared to gpa rates of Biocover MLT oil and Biocover LS oil applied on 3 July and Aug. For the period of this experiment, the 20 gpa rate of Biocover SS () oil provided the best control of the single application treatments and equaled the control provid ed by the split gpa applications of Biocover LS () oil. As in experiment 1 (Table 2) the 20 gpa rate provided better residual control of CRM than the gpa rate (Table 6). For the gpa split applications of Biocover MLT (435) oil CRM control was adequate for about 20 d for the first application and for 60 d for the second application. The Biocover LS () oil applied at gpa in 2 applications provided better CRM control than the other oils except for Biocover SS () oil at a 20 gpa rate. These data confirm our previous data that a high weight oil, a higher rate of oil, and more frequent ap plications provided better CRM control. Experiment 6. (Table 7). A single gpa application of Sun Spray 9E in gal of water provided 50 d of CRM con trol. A single gpa application of Orchex 892 (ExxonMobil ) oil provided CRM control for about 60 d for both the 50 gal and gal of water applications. A single 2 gpa applica tion of Mite-E- provided about 49 d of control, comparable to the single gpa application of Sun Spray 9E oil. It should be noted that the CRM pressure was only 0.5 CRM/cm2 prior to the application. A single 2 gpa application of Sun Spray oil emulsified with HM 9326 emulsifier (Helena Chemical Company) provided 14 d of control. The split applications of gpa Orchex 892 at 50 and gal of water per acre provided CRM control for 59 d for the first application. The second application of Orchex 892 in 50 gpa of water was at 1.2 CRM/cm2 after 28 d or 88 d of CRM control for both applications. In gal of water per acre, gpa of Orchex 892 () oil provided a total of 111 d of CRM Table 6. Experiment Petroleum Spray Test (citrus rust mite/cm2) on Hamlin Oranges. weight gal/acre' 29June * 11 July 1 Aug. 8 Aug. 23 Aug. 8 Sept. 20 Sept. Oct. Single application 5 July ± 36.7 d> 47.0 ±49.8 a 9.9 ±14.2 a 4.0 ± 6.2 a 4.7 ±6.3 a 2.8 ± 5.8 be 1 ±21.3 a 0.7 ± 2.2 e Biocover MLT ± 98.6 a* 0.5 ± 2.4 b 0.2 ± 1.5 b 0.0 ± 0.2 ± 0.6 b 1.0±2.7cd 6.03 ±.5 c 12.0 ±12.8 a Biocover LS 57.0 ± 35.6 b 0.5 ± 3.0 b 0.0 ± 0.3 b 0.0 ± 0.8 ± 2.8 d 5.09 ± 8.11c 7.3 ±.6 be Biocover LS ± 38.1b 0.5 ± 3.0 b 0.0 ± 0.0 ±0.1 c 0.2 ± 1.2 d 2.36 ± 5.2 cd 3.7 ± 7.7 de Biocover SS 36.7 ± 39.0 cd 0.2 ± 1.2 b 0.0 ± 0.0 ± 0.2 c 0.4 ± 2.4 b 1.1 ±4.4 cd 4.61 ± 9.0 c 8.1 ±11.9 be Biocover SS ± 54.0 b 0.3 ± 1.3 b 0.0 ± 0.2 b 0.0 ± 0.2 c 0.0 ± 0.3 d 0.06 ± 0.4 d 0.8 ± 2.5 e Sun Spray 7 E ± 37.9 be 0.0 ± 0.4 b 0.1 ±0.6b 0.2 ± 1.7 c 0.7 ± 2.2 b 8.5 ±11.1 a ± 18.6 a.5 ± 11.8 ab Sun Spray 9 E 23.6 ±32.1 d 0.1 ±0.6 b 0.0 ± 0.1b 0.2 ± 1.3 c 0.2 ± 1.4 b 4.3 ± 6.6 b.38 ± 12.5 b 6.3 ± 12.0 cd 2 applications 3 July and Aug ** *** ± 36.7 d 47.0 ±49.8 a 9.93 ± 14.2 a 4.0 ±6.2 a 4.7 ±6.3 a 2.8 ± 5.8 be 1 ±21.3 a 0.7 ± 2.2 e Biocover MLT ± 38.2 d 0.6 ± 2.7 b 1.0 ± 3.4 b 3.0 ±7.1 a 0.1 ±0.5b 0.0 ±0.1 d 0.1 ±1.1 d 3.1±6.3de Biocover LS b 0.8 ± 2.7 b 0.7 ± 2.4 b 1.7 ± 5.6 b 0.0 ± 0.0±0.1d 0.2 ± 1.6 d 0.9 ± 2.9 e Z gal of water per acre, tractor speed 1.5 mph. >'Bolded numbers are equal to or higher than 1.0 mite/cm-. "Means in each column followed by the same letter are not significantly different by the GLM procedure and Tukey's HSD Test, a = n = *Single application 5 July **First of two applications (3 July 2000). ***Second of two applications ( Aug. 2000) Proc. Fla. State Hort. Soc. 114:

5 CJT o Table 7. Experiment Petroleum Spray Test (citrus rust mite/cm2) on Hamlin Oranges. gal/ Water weight acre gal/acre' 20June 26June lojuly 26 July 2 Aug. 11 Aug. 18 Aug. 6 Sept. 19 Sept. 27 Sept. 13 Oct. Single application on 19 July ± 8.4 bv 3.9±8.4bx 3.6 ± 8.4 ab 2.3 ±6.0 a 1.6 ±4.0 a 1.7 ±4.3 a 2.1±4.6abc 13.7 ±21.3 a 9.1 ± 14.7 b 13.9 ±3.0 a 3.4 ± 6.4 be Sun Spray 9NW 11.6±31.4a 4.2 ±8.7 a 0.0 ± 0.2 ± 0.9 b 1.5 ± 5.3 b 3.3 ± 8.7 b 3.1 ± be 5.6 ± 9.7 ab Sun Spray 9E 3.4 ± 6.5 ab 2.8 ± 6.4 ab 0.0 ± 0.0 ± 0.1 ± 0.8 c 0.3 ± 1.7 d 1.3 ±4.0 c 3.3±8.2cd 3.2 ± 8.0 b 3.9 ± 7.2 b Mite-E ± 2.0 c 0.5 ± 1.8 b 0.3 ± 1.6 b 0.1 ±0.6 be 0.9 ±2.5 be 0.7±2.2cd 6.1 ± 11.2 b 6.4 ±.3 be 12.1 ±12.5 a 11.0 ±.7 a Orchex 892W ±26.0 a 3.86 ± 6.6 ab 0.1 ±0.2 b 0.2 ±1.2 be 0.1 ±0.2 b 0.6 ±2.1 b 0.9 ± 3.1b 2.6 ±6.0 be 2.0 ± 5.3 be 3.7 ± 8.5 b Orchex 892* 3.0 ± 1.7 b 7.0±2.4cd 0.0 ± 0.1 ±0.1 c 0.2 ± 1.1b 0.2 ± 1.2 b 1.0 ±3.4 bed 2.4 ± 5.5 be 6.2 ±.1 a Sun Spray 9NV 2 gal + HM 9326 lpt ± 2.0 c 7.0 ± 2.6 b 0.8 ± 3.5 ab 1.1 ±3.8 ab 1.9±5.7ab i 2.7 ± 5.8 abc 6.1 ± 11.5 b 20.1 ±20.1 a 11.4 ±13.2 a 11.5 ±.7 a 2 applications 21 June and 22 Aug ** *** Sun Spray 9 Nw Sun Spray 9 E Orchex 892* Orchex 892W Mite-E ± 8.4 b 0.8 ± 2.5 c 9.2 ± 14.6 a 2.2 ±7.0 be 0.9 ± 2.5 c 9.6 ± 16.4 a 3.9 ± 8.4 b 0.1 ± 0.4 b 0.6 ± 2.7 c 0.0 ± 1.8 ±4.9 be 3.6 ± 8.4 b 0.1 ± 0.3 d 0.1 ± 0.6 d 0.3 ± 1.6 d 0.8 ± 2.7 b 2.3 ±6.0 a 0.0 ± 0.4 ± 2.4 b 0.1 ± 0.5 b 0.1 ± 0.5 b 0.4 ± 2.2 b 1.6 ±4.0 a 0.1 ±0.7 be 0.9±4.7abc 0.1 ± 0.4 c 0.1 ±0.9 be 1.2 ±2.6 a 1.7 ±4.3 a 0.2 ± 0.9 b 0.5 ± 2.5 c 0.2 ± 1.6 b 2.4 ±4.6 a 2.1 ±4.6 be 0.1 ±0.8 b 2.5±5.3ab 0.8 ± 2.3 b 0.3 ± 1.2 b 3.9 ± 8.8 a 13.7 ±21.3 a 0.1 ± 1.2 b 0.2 ± 1.3 c 0.4 ± 2.2 b 0.0 ± 2.5 ± 5.4 be 9.1 ± 14.7 b 0.1 ± 0.4 d 0.3 ± 1.7 d 1.2 ±4.0 bed 0.1 ±0.8 d 2.0 ± 4.8 d 13.9 ±3.0 a 0.3 ± 1.0 c 0.4 ± 3.0 b 1.2 ±3.9 be 0.4 ± 2.0 c 1.8 ± 4.1b 3.4 ± 6.4 be 0.8 ± 3.5 c 0.6 ± 4.1c 3.4 ± b 0.8 ± 3.2 c 2.1 ±4.5 be 'Tractor speed 1.5 mph. >Bolded numbers are equal to or higher than 1.0 mite/cm2. "Means followed by the same letter are not significandy different by the GLM procedure and Tukey's HSD Test, a = n = 160. WFC -88 emulsified with 1% T-Mulz-Ao2 emulsifier. VHM 9326 was the emulsifier and was provided by Helena Chemical Company. *Single application 19 July **First of two applications (21 June 2000). ***Second of two applications (22 Aug. 2000). K5 O o

6 control. The Sun Spray 9E () oil gpa split applications in gpa of water also provided CRM control for 111 d. Mite-E- at 2 gpa in gpa of water provided CRM control for approximately 43 d. The second application of Mite-E- did not provide control comparable to the first application (Table 7). By mid-october, all single application treatments had higher CRM counts than the untreated controls while the split application treatments generally had lower CRM/cm2 than the untreated controls. After approximately 30 d after treatment, all single application treatments showed higher CRM counts than the split application treatments (Table 7). Citrus rust mite control appeared to be related to gpa of water applied, with best control achieved at gpa. Sun Spray (Sun Company), Orchex (ExxonMobil) and Biocover (PetroCanada) oils performed well in these ex periments. In general, oil outperformed 435 oil. Multiple applications of any particular oil were better than a single ap plication of the same oil except at the highest oil rate of 20 gpa. Mite-E- (Helena Chemical Company) performed equal to other oils in one experiment, but not as well in an other experiment. Mite-E- is emulsified differently than other oils and introduces a new concept into the use of petro leum spray oils. More work will be needed before the Mite-E- concept is proven, but the current data are encouraging. Also introduced here was a oil. This heavier oil gener ally provided longer CRM control than 435 and oils. Be fore this oil can be recommended, however, degreening, color break and pounds solids effects must be investigated as they have been for the other weight oils. The future for petroleum spray oil use in citrus appears bright. These materials provided excellent control of CRM, appear to be environmentally friendly, and are cost effective. Literature Cited Allen, J. C The effect of citrus rust mite damage on citrus fruit drop. J. Econ. Entomol. 71: Allen, J. C Effect of citrus rust mite damage on citrus fruit growth. J. Econ. Entomol. 72: Allen, J. C. and C. W. McCoy The thermal environment of the citrus rust mite. Agr. Meteorol. 20: Beattie, G. A. C, E. A. Roberts, L. E. Rippon, and C. L. Vanhoff Phytotoxicity of petroleum spray oils to Valencia orange, Citrus sinensis (L.) Osbeck, in New South Wales. Austral. J. Exp. Agr. 29: Bodenheimer, F. S Citrus entomology in the middle east. Uitgeverij Dr. W. Junk. 'S-Gravenhage, The Netherlands. Dean, H. A. and C. E. Hoelscher Juice quality of Valencia oranges as affected by petroleum oil applied during the post-bloom and summer pe riod. J. Econ. Entomol. 64: Dean, H. A., H. Tannahill, and J. R. Bush Effects of postbloom and summer oils on yield, fruit size and growth of four varieties of oranges, J. Econ. Entomol. 71: Furness, G. O The phytotoxicity of narrow distillation range petro leum spraying oils to Valencia orange trees in South Australia. Part II: The influence of distillation temperature and spray timing on fruit quality. Pestic. Sci. 12: Furness, G. O. and D. A. Maelzer The phytotoxicity of narrow distilla tion range petroleum spraying oils to Valencia orange trees in South Aus tralia. Part I. The influence of distillation temperature and spray timing on yield and alternate cropping. Pestic. Sci. 12: Johnson, W. T Horticultural oils. J. Environ. Hort. 3: Knapp, J. L Effect of different petroleum oils on defoliation, fruit qual ity, and pest control of Florida citrus. Proc. Fla. State Hort. Soc. 3:1-4. Knapp, J. L., Bullock, R. C, P. A. Stansly, C. C. Childers, and C. W. McCoy Table 2. Citrus rust mitetreatment guide for control on Florida Citrus, p In: J. L. Knapp (Ed.) Florida Citrus Spray Guide. Fla. Coop. Ext. Serv. Publ. SP 43. Lee, L. W. and J. L. Knapp Horticultural spray oil has little effect on citrus fruit quality, leaf drop and leaf freeze hardiness. Proc. Fla. State Hort. Soc. 5:-13. Lee, L. W. andj. L. Knapp Effects of timing and multiple applications of horticultural oil sprays on citrus. Proc. Fla. State Hort. Soc. 7: McCoy, C. W Migration and development of citrus rust mite on the spring flush of Valencia orange. Proc. Fla. State Hort. Soc. 92: McCoy, C. W. and L. G. Albrigo Feeding injury to the orange caused by the citrus rust mite, Phyllocoptruta oleivora. Ann. Entomol. Soc. Amer. 68: McCoy, C. W., L. G. Albrigo, andj. C. Allen The biology of the citrus rust mite and its effect on fruit quality. Citrus Ind. 69:44-49, McCoy, C. W., P. L. Davis, and K. A. Monroe Effect of late season fruit injury by the citrus rust mite, Phyllocoptruta oleivora, on the internal quality of Valencia orange. Fla. Entomol. 59: Pratt, R. M Relation between moisture conditions and citrus rust mite infestations. Proc. Fla. State Hort. Soc. 70: Riehl, L. A Fundamental consideration and current development in the production and use of petroleum oils. Proc. Intern. Soc. Citricult. 1: Riehl, L. A., R. T. Wedding andj. L. Rodriguez Effect of oil spray ap plication timing on juice quality, yield and size of Valencia oranges in a southern California orchard. J. Econ. Entomol. 49: Riehl, L. A., R. T. Wedding,J. L. Rodriguez andj. P. La Due Effects of oil spray and of variation in certain spray ingredients on juice quality of cit rus fruits in California orchards, J. Econ. Entomol. 50: Simanton, W. A. and K. Trammel Recommended specifications for cit rus spray oils in Florida. Proc. Fla. State Hort. Soc. 79: Sinclair, W. B., E. T. Bartholomew and W. Ebeling Comparative effects of oil spray and hydrocyanic acid fumigation on the composition of or ange fruits. J. Econ. Entomol. 34: Thompson, W. L. andj. W. Sites Relationship of solids and ratio to the timing of oil sprays on citrus. Proc. Fla. State Hort. Soc. 58: Trammel, K. and W. A. Simanton Properties of spray oils in relation to effect on citrus trees in Florida. Proc. Fla. State Hort. Soc. 79: Yothers, W. W. and A. C. Mason The citrus rust mite and its control. USDATech. Bull Proc. Fla. State Hort. Soc. 114: