TEXAS GUIDE FOR CONTROLLING INSECTS
ON COMMERCIAL VEGETABLE CROPS

Alton N. Sparks, Jr.
Extension Entomologist
The Texas A&M University System

TABLE OF CONTENTS

SELECTING A PESTICIDE

USING THIS GUIDE

pH EFFECTS OF SPRAY WATER

BIOLOGICAL CONTROL

MICROBIAL INSECTICIDES

CULTURAL CONTROL

INSECTICIDE RESISTANCE MANAGEMENT

PROTECTING BEES FROM INSECTICIDES

PESTICIDE SAFETY

ENDANGEED SPECIES REGULATIONS

POLICY STATEMENT FO MAKING PEST MANAGEMENT SUGGESTIONS

SYMBOLS AND ABBREVIATIONS USED IN TABLE 2

TABLE 1. PRODUCT INFORMATION

TABLE 2. PRODUCTS FO INSECT AND MITE CONTROL (LISTED BY CROP)

• Beans (Dry and Snap)
• Beets (Table)
• Carrots
• Celery
• Cantaloupes, Honeydews, Cucumbers and Watermelons
• Cole Crops (Broccoli, Cauliflower and Cabbage)
• Eggplant
• Kale and Collards
• Lettuce (Head)
• Mustard and Turnips (Greens and Roots)
• Okra
• Onions
• Peas (Dry and Green)
• Peppers
• Potatoes (Irish)
• Pumpkins and Other Winter Squash
• Radishes
• Spinach
• Squash (Summer)
• Sweet Corn
• Sweet Potatoes
• Tomatoes

TABLE 4. PRE-HARVEST INTERVALS

The commercial vegetable market has low tolerances for insect and mite damage on edible foods. Such damage can reduce the yield and quality of produce. Sometimes a crop is rejected at market because of even small amounts of damage, cosmetic blemishes or the presence of insect parts. Another reason to control insect pests is that some of them are vectors of plant diseases, particularly viruses.

To meet stringent market requirements for vegetables, it is sometimes necessary to control insects before the crop is actually damaged. Therefore, pests must be detected early, as they enter a field. Vegetable crops should be inspected for insect pests two or three times per week to determine when to begin insecticide treatment and to properly time subsequent applications. Insecticide applications made too early may not provide the protection needed, while those made too late will not prevent crop damage. When pest problems are predictable because they occur every year, applying systemic insecticides, or spraying at susceptible crop stages, may be justified as a preventive measure.

SELECTING A PESTICIDE

A pesticide should be chosen with knowledge of the specific pest problems and crop conditions. There is often more than one pesticide that will control a particular pest. In selecting a pesticide, consider:

• Product efficacy or effectiveness against the target pest, as well as impact on other pests in the field;

• Chemical class or mode of action; rotating among pesticide classes with different modes of action may help delay insecticide resistance in the pest;

• Target specificity and hazard to beneficials and other non-target organisms; broad spectrum insecticides generally provide only temporary protection and generally are more apt to harm non-target organisms;

• Application frequency needed or amount of residual control provided; broad spectrum insecticides that kill beneficial organisms can cause the resurgence of primary and secondary pests and make frequent insecticide application necessary;

• Cost per acre, factoring in the number of applications required to achieve control as well as the potential for pest resurgence and associated costs;

• Potential hazards to the applicator, mixer, farm workers and the environment; signal words on product labels indicate the hazards to humans; the label also describes environmental hazards;

• Use restrictions, including re-entry intervals, pre-harvest intervals, number of allowable applications, time required between applications, and restrictions on mixing with other products.

USING THIS GUIDE

This publication lists the insecticides and acaricides registered for control of selected pests of commercial, field-grown vegetable crops (home vegetable gardeners should refer to B-1300, "Managing Insect and Mite Pests in Vegetable Gardens"). It is written for comparison and educational purposes only, and is not intended to be a complete pest control manual. This list of insecticides was compiled from the most recent product labels available at the time of publication. The inclusion of an insecticide in this listing does not guarantee its effectiveness against a particular pest; it simply signifies that the pest is listed on the product's label. The registered rate(s) for pesticides in multiple crop listings (e.g., cole crops) and multiple pest listings (e.g., cutworms), or with more than one formulation, may vary with the specific crop-pest-formulation combination. Furthermore, the crops included on the label can vary with formulation and/or trade names. Therefore, THE PRODUCT LABEL MUST BE CONSULTED BEFORE USE.

Also, when using products with a special local need (24C) registration or specific exemption (Section 18 - not listed in this publication), a copy of the label must be in the possession of the user at the time of application.

Where there is sufficient research, products that have proved efficacious against selected pests are indicated by an asterisk following the rates labeled for that pest. These ratings are based on field tests conducted by Texas A&M University research and Extension faculty. Local conditions, pest pressure and pest species (for multiple pest listings - e.g., aphids) may cause actual performance to vary. It is always important to monitor the performance of any pesticide. The lack of a rating in this guide does not imply that a product is not efficacious, but that there is no experimental data on the particular pest or crop.

pH EFFECTS OF SPRAY WATER

Water throughout much of Texas is alkaline, with pH readings ranging from 7.8 to 8.2. Use of high pH water (particularly above 8.0) for pesticide applications may affect the performance of many pesticides, particularly organophosphates and carbamates. Certain pesticides degrade more rapidly at higher pH, especially at temperatures higher than 95 degrees F. Little information is available on the degradation rate of specific pesticides in high pH water; some pesticides are relatively unaffected. It is a good idea to check pH levels regularly with a pH meter, and add a suitable acid buffer to spray water when needed.

When tank mixes of more than one pesticide are used, or when fertilizer is combined with a pesticide, the final spray solution should be checked to determine pH. Alkaline sprays should be buffered to a pH of approximately 7.0. However, even in a properly buffered solution, sprays should be applied as soon as possible to reduce possible chemical degradation.

BIOLOGICAL CONTROL

Insect and mite infestations are often held below damaging levels by weather, inadequate food, and natural enemies such as predators, parasites and pathogens. It is important to recognize the impact of these natural control factors and, where possible, to encourage them. Biological control is the use of living organisms (parasites, predators and pathogens) to control pests. This approach does not present the human health and environmental concerns associated with some chemical pesticides. Important natural enemies of insect and mite pests attacking vegetables include lady beetles, green lacewings, syrphid fly larvae, spiders, several insect pathogens and a variety of tiny wasps that parasitize the eggs, larvae and pupae of many vegetable pests.

Biological control generally is most effective when used with other compatible control practices in an integrated pest management (IPM) program. These practices include cultural controls, planting resistant host plants, monitoring pests, and selectively using insecticides. The Texas A&M University System is committed to developing and encouraging the use of pest management practices which use biological control.

Biological control practices include the importation, ' conservation and augmentation of natural enemies.

Classical biological control is the importation of natural enemies into areas where they do not occur. Importation has been most effective where an exotic pest has entered Texas without the natural enemies that control it in its native range. Conservation of natural enemies is generally achieved by avoiding the use of insecticides until they are needed to prevent the development of economically damaging pest infestations. The impact of insecticides also can be minimized by using products that are more toxic to the target pest than to natural enemies.

Augmentation usually involves the purchase and release of natural enemies that do not naturally occur in sufficient numbers to provide pest control. Natural enemies sold for pest control in vegetables include predators (green lacewings and lady beetles) and parasites (primarily nematodes and wasp parasites of caterpillars and eggs). Suggestions for the proper use rates, timing and methods of release to obtain cost-effective control with any of these predators or parasites have yet to be developed by researchers, but may be available from companies selling and supporting the use of their products.

MICROBIAL INSECTICIDES

There are a number of microbial products containing pathogens such as bacteria, fungi or viruses available for controlling pests. Most commercially available products are targeted at caterpillars and contain preparations of the bacterium Bacillus thuringiensis (B.t.). These vary in their spectrum of activity. There is one B.t product for controlling beetles. Other microbials containing fungi or viruses are listed in Table 3.

In general, microbials control a single species or small group of related pests and do not destroy beneficial arthropods (predators and parasites), a characteristic that sets them apart from most conventional insecticides. An exception is the fungal pathogen Beauvaria bassiana, which controls more pests than most microbial insecticides, and also kills beneficial organisms. Even so, it protects beneficials better than most broad spectrum insecticides. In addition to their selectivity, most microbial products are exempt from residue tolerances, which allows greater flexibility in re-entry and pre-harvest intervals than with most insecticides. They are cleared for use on nearly all vegetable crops.

Microbial insecticides can be extremely effective against several pest species, but they must be applied correctly to be successful. Most perform much better when applied before the pests become too numerous or too large. Therefore, monitoring pest populations and developmental stages is essential to the proper timing of applications. Also, most microbial insecticides must be ingested by or come in direct contact with pests, and perform much better with thorough coverage of the crop. Many of their labels specify the use of higher spray volumes. Because even similar microbial insecticides (e.g., B.t products) differ in use rates, target pests, activity ranges and application requirements, the product's label must be consulted before use.

CULTURAL CONTROLS

Cultural controls reduce insect pest problems by making conditions less favorable to pests. Common cultural practices that can affect pest problems include variety selection, planting date, crop sequencing, crop residue destruction and sanitation. Crop damage often can be prevented or reduced by planting resistant varieties or planting on a date that will allow the crop to escape peak pest populations. Removing a pest's alternate hosts before a crop is planted, and avoiding sequential plantings of crops susceptible to the same pests, can delay or reduce pest infestations. Also, crop residues and culls should be destroyed to eliminate potential breeding sites for pests.

INSECTICIDE RESISTANCE MANAGEMENT

Insecticides can be grouped into classes according to their modes of action. Experience has shown that relying on a single group of insecticides may cause pests to develop resistance to the entire group. To prevent this, and to achieve better overall insect control, rotate the insecticide groups used, taking advantage of different modes of action. Ideally, rotations should be timed to expose each generation of a pest to only one insecticide class or mode of action. Consult Table 1 to determine the class to which a particular insecticide belongs.

Nerve-active insecticides with similar chemical structures affect insects in similar ways. For example, pyrethroids (esfenvalerate, permethrin, etc.) all act on an insect's nervous system in the same way. Organophosphates (methyl parathion, azinphos-methyl) and carbamates (carbaryl) also affect the insect's nervous system, but in a different way than the pyrethroids. Because organophosphates and carbamates have similar modes of action, these insecticides should be rotated with other insecticide classes rather than with each other. Thus, the idea is to rotate modes of action rather than just insecticide classes. Insect growth regulators and other non-nerve active insecticides also can be used in an insecticide rotation as alternatives to using nerve-active products alone.

PROTECTING BEES FROM INSECTICIDES

Pollination by honeybees is extremely important in the production of vegetables and vegetable seed crops, especially squash, cucumber, pumpkin, watermelon, cantaloupe and muskmelon, and seed crops of asparagus, broccoli, onion and radish. Where bees are required for flower fertilization, the producer, insecticide applicator and beekeeper should cooperater closely to minimize bee losses and maximize pollination.

The following guidelines should reduce bee losses:

1. Apply insecticides, if practical, before bees are moved into fields or adjacent crops for pollination. When bees are in the vicinity, evening applications after bees have left the field are less hazardous than early morning applications.

2. Where insecticides are needed, consider their toxicity and time applications to minimize contact with foraging bees. Bees do not forage at night. "Highly toxic" insecticides should be applied only in late evening to delay possible co ntact with bees until the next morning. "Moderately toxic" or "Relatively non-toxic" insecticides should be applied in late evening or early morning to prevent direct spraying of foraging bees. For more information on the hazards of in secticides to honey bees, refer to Table 1.

3. To prevent heavy losses of bees, don't spray any insecticide directly on colonies or allow it to drift to colonies. Bees often cluster on the fronts of their hives on hot evenings. Pesticide drift or direct spray at this time generally kills many bees .

PESTICIDE SAFETY

The key to using pesticides safely is to be aware of potential hazards and take adequate precautions before, during and after use. Before using any pesticide, READ THE LABEL. In addition to application instructions, the label provides information on re-entry intervals, posting requirements, hazards to the environment and non-target organisms, endangered species restrictions, restrictions on application methods, worker protection requirements, practical first-aid treatment in case of exposure, storage and disposal procedures for containers, pre-harvest application intervals to prevent excessive residues, and the symptoms of poisoning. Users also should consult Texas Pesticides Laws and Regulations for state provisions that affect the application of pesticides to vegetables and which, in some cases, are more restrictive than federal laws.

ENDANGERED SPECIES REGULATIONS

The Endangered Species Act is designed to protect and recover animals and plants that are in danger of becoming extinct. Under the provisions of this Act, the U.S. Fish and Wildlife Service assists the Environmental Protection Agency and the Food and Drug Administration in implementing pesticide programs by conducting biological analysis of the effects of pesticides on threatened and endangered species. Many pesticide labels now carry restrictions on the use of products or application methods in areas designated as biologically sensitive. These restrictions continue to change. Refer to product labels and/or call your county Extension agent or U.S. Fish and Wildlife Service personnel to determine what restrictions apply to your area. Regardless of the law, pesticide users can be good neighbors by being aware of how their actions may affect people and the environment.

POLICY STATEMENT FOR MAKING PEST MANAGEMENT DECISIONS

The management suggestions included in this publication reflect the opinions of Extension entomologists based on field tests or use experience, 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 pesticide label.

For additional information, contact your county Extension staff or write the Extension Entomologists, Department of Entomology, Texas A&M University, College Station, TX 77843, (409) 845-7026.

SYMBOLS AND ABBREVIATIONS USED IN TABLE 2

Table 1. Product Information.

¹ All are registred trade names, ^®.
² OP = organophosphate; CAR = carbamate; OC = organochlorine; OT = organotin; SP = synthetic pyrethroid; NP = natural pyrethrin; SBM = substituted melamine; BIO = biological
³ D = Danger (Toxicity Category I); W = Warning (Toxicity Category II); C = Caution (Toxicity Category III).
⁴ ASTD = Allow spray to dry. MC = After application is completed. Texas Pesticide Laws and Regulations should be consulted for specific information on re-entry intervals. Intervals may vary with formulation.
⁵ HT = highly toxic; MT = moderately toxic; RNT = relatively non-toxic.
⁶ Consists of pottasium salts of fatty acids
⁷ Oils include petroleum distillate and botanical oils.

Table 2. Products for Insect and Mite Control (listed by crop).

^a Except cucumbers.
^b Also available in bait formulation.
^c Suggested rates vary among labels.
^d Cucumber rates lower.
^e Watermelon rates lower.
^f Except watermelons.

^a Also available in bait formulation
^b Collards only
^c Rates vary among labels
^d Rates lower for Kale
^e Collards - fresh market only
^f Rates lower for collards

^a Also available in bait formulation.
^b Rates vary among labels.

^a Also available in bait formulation
^b Mustard only
^c Turnips only
^d Rate higher for mustard greens
^e Not labelled on roots
^f Rates lower for turnips

^a Bulb onions only
^b Efficacious against onion thrips
^c Efficacious against western flower thrips

^a Bell pepper only ^b Labeled for use against green peach aphid
^c Also available in bait formulation
^d Rates vary among labels
^e 24C registration for non-bell type peppers, bell peppers on federal label

^a Labeled for soil and foliar application; soil application rates higher

^a Also available in bait formulation
^b Rates vary among labels
^c Pumpkins only

^a Including wireworms, rootworm larvae and seedcorn maggot
^b Also available in bait formulation
^c Fresh market only
^d Do not place in direct contact with the seed
^e Also available in granular formulation
^f Note potential interactions with herbicides listed on label

^a Also labeled as preplant dip for cuttings

^a Also known as corn earworm
^b Also available in bait formulation
^c Fresh market only
^d Not labelled for cherry tomatoes


Table 3. Products with general vegetable labels. Before using, examine labels closely for variations in registered crops, pests, rates, use restrictions or other information.

Insecticide	PHIa	Registered Cropsb	Pests on labelc
Azadirachtin	0	All except sweet corn	Whitefly, aphids, leafminers, armyworms, leafhoppers
Bacillus thuringiensis - var. kurstaki and/or aizawai - var. san diego	0	All	Lepidopterous larvaed
	0	Potato, tomato, eggplant	Colorado Potato Beetle
Beauveria bassiana	0	All	Whiteflies, aphids, thrips
Insecticidal soap	0	All except sweet corn	Soft-boiled insects including aphids, caterpillars, leafhoppers, leafminers, psyllids, mites, thrips, whitefliese
Insecticidal viruses	0	Beans, beets, cole crops, celery, cucumber, lettuce, onions, peas, peppers, sweet corn, tomatoes	Varies with product: Spod-X - only beet armyworm GemStar - Corn earwormf, tobacco budw orm
Oils	0	All - varies with product	Varies with product - includes aphids, mites, beetle larvae, leafminers, whiteflies, psyllids, thrips, some caterpillars
Pyrethrins	0	All	All except mites and soil pests
Sulfur	0	All	Mites

^a Pre-harvest interval in days.
^b Of crops included in this guide (Table 2).
^c Of pests included in this guide (Table 2).
^d Activity on selected larvae varies among strains.
^e Tank mix with a labeled companion insecticide is required for some pests
^f Also listed as Tomato fruitworm.

Table 4. Pre-harvest intervals (days) for insecticides on vegetable crops. *

^* Pre-harvest intervals for Lindane and Cryolite are based on plant growth stage or vary among labels (see label).
^a PHI depends on rate, formulation or number of applications; see label for details; longest interval listed.
^b Do not apply after fruit set
^c PHI shorter when only roots are harvested
AP = At planting application only
SL = See label PHI variable
AC = At cultivation application

Table 4. Pre-harvest intervals (days) for insecticides on vegetable crops (continued).

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.

2M-6-97, Revised

ENT, HORT 6

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Last modified: October 9, 1997 by Edgar Cross