L-2325
B. Cartwright
Former Extension entomologist
The Texas A&M University System
Using a pesticide wisely requires forethought and analysis of a particular pest problem or situation to determine the best choice under those particular conditions. Often, more than one choice exists for a particular pest. Factors that should be considered in selecting one pesticide over another include:
Use of the information contained in the guide. This publication is designed to provide, to the best extent possible, a listing of the insecticides and miticides available for use against selected citrus crop pests. It is written for comparison and educational purposes only and is not intended to provide complete information for applications of a product. The product label attached to the container always must be consulted before use. The pesticide listing for control of citrus pests was compiled from the most recent product labels available at the time this guide was prepared. No guarantee of effectiveness is intended by listing a particular product for use against a particular pest; only that the pest is listed on the label for the product. For selected pests, where a sufficient research base exists, an efficacy rating (ER) is provided to give a performance index of various products for controlling a particular pest. Ratings are based on field tests conducted in Texas and other citrus growing areas. Local conditions and pest pressure may cause actual performance to vary.
Water sources used for pesticide applications in the Lower Rio Grande Valley are alkaline with pH readings typically ranging from 7.8 to 8.2. Use of high pH water, particularly above 8.0, may affect the performance of many pesticides, particularly organophosphates and carbamates. Degradation of certain pesticides is more rapid at higher pH, especially at higher temperatures (>95°F). Little information is available on the degradation rate of specific pesticides in high pH water; some pesticides are relatively unaffected. Generally, it is a good idea to check pH levels with a pH meter on a regular basis and buffer spray water with suitable acid buffer down to a range of 6-7 pH. When tank mixes of more than one pesticide or when fertilizer is combined with a pesticide, the final spray solution should be checked to determine pH.
Adjuvants or spray additives are intended to enhance product performance or coverage. Surfactants or spreading agents lower the spray particle surface tension allowing droplets to spread out on plant surfaces instead of combining to form large droplets subject to run-off. They are especially useful when spraying hard-to-wet surfaces such as waxy citrus leaves, armored scale insects, mite colonies with webbing or hairy-surfaced weeds. Some pesticide products are formulated with surfactant included.
Stickers and extenders function to lengthen pesticide performance life by increasing product tenacity or weathering qualities of materials sprayed on plant surfaces. These frequently are combined with surfactants and are available as "spreader-stickers." Other adjuvants available for special applications include anti-foam agents and suspending agents that improve performance and enhance application of pesticide suspensions. In general, adjuvants properly used increase product performance, reduce waste and help minimize non-target contamination.
The key to using pesticides safely is to be aware of potential hazards and take adequate precautions before and during use to prevent any unwanted effects. Before using any pesticide, read the label. Besides application instructions, the label provides information on re-entry intervals, hazards to the environment and non-target organisms, a statement of practical treatment or first-aid in case of exposure, storage and disposal procedures for containers, pre-harvest intervals to avoid excessive residues and the symptoms of poisoning. Users also should consult Texas Pesticide Laws and Regulations for state provisions that affect the application of pesticides to citrus.
With the exception of some tangerines and tangelos, most citrus cultivars do not require honeybee pollination. However, blooming citrus is highly attractive to honeybees as a food source and may provide a good nectar source for a high quality honey sought by beekeepers. Although insecticides are not routinely applied during bloom, it is important to recognize that many pesticides applied to citrus are toxic to honeybees. The insecticides may cause significant bee death while they are foraging in sprayed orchards or through contamination of water or pollen brought back to the hive. The grower and beekeeper should cooperate closely to minimize bee losses. The following guidelines will reduce bee losses:
Table 1. Effectivenes of selected pesticides against major citrus pests.
| Pesticide | Formulated rate/acre | Days to harvest (PHI) | Re-entry interval (days)3 | Signal word1 | Honey- bee hazard2 | Toxicity to beneficials4 | Mites | Armored scales | Brown soft scale | Mealy bugs | |||||
| Mites | Insects | Citrus rust | Texas cius | Citrus red | |||||||||||
| Acaraben 4E | 4-6 pt | ASTD | W | HT | - | - | 3 | 1 | 1 | N | N | N | |||
| Carzol 92 SP | 5-10 oz | 7 | 1 | D | MT | - | H | 3 | 0 | N | + | + | N | ||
| Comite 6.5 | 2-3 pt | 7 | ASTD | D | RNT | - | L | 1 | 2 | 3 | N | N | N | ||
| Dicofol 4 EC | 3-8 pt | 7 | ASTD | C | RNT | H | L | 3 | 3 | 3 | N | N | N | ||
| Ethion 4E | 4-6 pt | 0 | 1 | D | HT | - | - | 3 | 0 | 2 | 1 | 1 | N | ||
| Guthion 2L | 2.5-3.75 pt | 28** | 7-SL | D | HT | - | H | 1 | 2 | N | 3 | 3 | 2 | ||
| Lorsban 4E | 2-7 pt | 21** | 1 | W | HT | - | - | 2 | 0 | 0 | 2 | 3 | 0 | ||
| Morestan 25 WP | 5 lb | 21 | ASTD | C | RNT | M | L | 2 | 3 | 3 | N | N | N | ||
| Oil | 2.5-3.75 gal | ASTD | C | RNT | M | M | 0 | 0 | 3 | 3 | 3 | 0 | |||
| Sevin 80S | 2.5-3 Ib* | 5 | ASTD | W | HT | L | H | N | + | N | + | 3 | 0 | ||
| Sulfur 6E | 1-11 pt* | ASTD | C | RNT | H | L | 2 | 0 | N | + | N | N | |||
| Supracide 2E | 2.5-5 pt* | 14** | 30 | D | HT | H | H | N | N | + | 3 | 3 | 1 | ||
| Temik 15 G | 33-67 lb | See label | D | HT | - | - | 3 | 3 | 1 | N | 0 | 0 | |||
| Vendex L | 10-20 oz* | 7 | ASTD | D | RNT | L | L | 3 | 3 | 3 | N | N | N | ||
| Vydate L | .625-2.5 pts* | 7 | ASTD | D | HT | - | - | 3 | N | N | N | N | N | ||
|
* Amount per acre derived by multiplying amount per 100 gal x 2.5; 250 gallons per acre is the assumed volume. ** PHI depends on rate, method of application, the number of applications or particular citrus crop; consult label.
1 Signal words: D = danger (most hazardous), W = warning, C = caution (least hazardous). Key to efficacy ratings:
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Many pesticides have special precautions listed on the label that should be considered prior to their use. Failure to completely follow label guidelines may result in excessive residues at harvest, plant injury, poor pest control or undue hazards to non-target organisms including the applicator. The following are some of the major precautions for some of the most commonly used citrus pesticides:
Petroleum oil sprays. When applied properly, oils provide a very useful tool for controlling some citrus pests without damage to beneficial organisms but the sprays require careful use to avoid plant injury. Soil moisture, humidity, temperatures, growth stage of leaves and fruit and the type of oil used can influence whether or not tree injury occurs. Spray oils should not be applied when soil moisture is low or when relative humidity is below 30 percent and daytime temperatures are likely to exceed 95° F. Effective use of oils for pest control requires that the oil persist on the tree long enough to kill the pest but not long enough to cause tree injury. Persistence of oil film on foliage beyond the tree's tolerance can interfere with photosynthesis and transpiration. Such damage can result in twig dieback, leaf drop, reduced yield and the reduction in amount of fruit sugars (soluble solids).
Tangerines and tangelos tend to be more sensitive to oil damage than grapefruit and oranges. Late summer or fall applications of oil sprays may delay maturity, which will interfere with proper coloring of early harvested fruit and may cause increased cold susceptibility. Persistence of oils on leaf surfaces increases with higher oil dosages or through the use of oil with higher distillation temperatures such as a narrow range 440-type oil. When choosing the type or rate of oils, keep in mind that oil dissipates more quickly under higher temperatures.
In situations where damage is likely from a regular oil spray because of hot, dry conditionsn oil can be added at a low percentage to certain insecticide sprays to improve coverage. Before combining oil with any pesticide, read the label carefully to make sure the risk of phytotoxicity is not excessive. Do not combine oil sprays with sulfur or follow an application of sulfur within at least 50 days or plant injury may occur. When combining pesticides with oil, use of emulsifiable concentrates or other liquid formulations is preferred over wettable or soluble powders.
Comite. Complete coverage is essential. Leaf distortion and/or fruit spotting may occur when used in the spring or it may occur if Comite is tank mixed with oil or applied within 2 weeks of an oil application. Do not use in a spray solution above pH 10 or mix with alkaline materials (such as lime) .
Ethion. Do not apply within 90 days of a previous application.
Guthion. With one applicatlon per season, a 7-day preharvest interval should be observed; if two applications are required, PHI = 28 days.
Lorsban 4E.Do not apply when temperatures exceed 95° F. Do not apply when trees are stressed by drought or high temperature. Lorsban 4E should not be used in combination with Difolatan 80. For orchard floor application, do not tank mix with Roundup or Paraquat herbicides.
Morestan. One application per season.
Sulfur. Do not make sulfur applications during hot weather. Applications are restricted to November through May. Do not apply within 30 days of an oil application.
Supracide. Make no more than two applications per growing season, with at least 45 days berween applications. Do not apply within 14 days of harvest. If applied with oil, the preharvest interval is G0 days.
Vendex. Do not apply more than four times in 12 months or within 7 days of harvest.
The information and suggestions included in this publication reflect the opinions of Extension entomologists and pathologists based on field tests or use experience. The management suggestions are a product of research and are believed to be reliable. However, it is impossible to eliminate all risks. Conditions or circumstances that are unforeseen or unexpected may result in less than satisfactory results even when these suggestions are used. The Texas Agricultural Extension Service will not assume responsibility for such risks. Such responsibility shall be assumed by the user of this publication.
Suggested pesticides must be registered and labeled for use by the Environmental Protection Agency and the Texas Department of Agriculture. The status of pesticide label clearances is subject to change and may have changed since this publication was printed. County Extension agents and appropriate specialists are advised of changes as they occur.
The user is always responsible for the effects of
pesticide residues on his livestock and crops, as well as problems
that could arise from drift or movement of the pesticide from
his property to that of others. Always read and follow carefully
the instructions on the container label.
Table 2. Additional products labeled for use on citrus.
| Product 2 | Labeled use | Rate per acre1 | Signal word | Days to harvest |
|---|---|---|---|---|
| Cygon 400 | Mealybugs, mites | 4-8pt | W | 4 |
| Cythion 57% | Scales | 1 -1 .5 pt | W | 7 |
| Diazinon AG500 | Aphids, soft scale | 0.5-1 pt | W | 21 |
| Dibrom 8E | Aphids, mites, brown soft scale | 2.5 pt* | D | 7 |
| Dipel 2X | Orangedog | 0.3-0.6 lb | C | 0 |
| Imidan 50 WP (oranges only) | Scales | 2.5 Ib* | D | 7 |
| Lannate L | Beet armyworm | 2-4 pt | D | 1 |
| Lorsban 15 G | Ants | 6.70 | C | 28 |
| Metasystox-R | Aphids, Texas citrus mite | 2.5-3.75 pt* | C | 7 |
| Parathion 4E | Scales, mealybugs | 1.6 pt* | D | 14 |
| Thiodan 3E | Aphids | 1.5-3.5 qt | W | Non bearing |
| Zolone 3EC | Orangedog, whiteflies | 4-8 pt | W | 14 |
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1* = Amount per acre derived by multiplying amount per 100 gallons x 2.5; 250 gallons per acre is the assumed volume. 2 Phytotoxicity may occur on young leaves and fruit; see label for precautions. | ||||
The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.
Educational programs conducted by the Texas Agricultural Extension Service are open to all people without regard to race, color, sex, disability, religion, age or national origin.
Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Zerle L. Carpenter, Director, Texas Agricultural Extension Service, The Texas A&M University System.
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