Beyond the label: maximizing pesticide performance
by Jim Willmott, extension specialist, Rutgers University Cooperative Extension, Clementon, New Jersey
GrowerTalks, November 1997

Everything you need to know to get the best results from 25 widely used insecticides, miticides and fungicides

Pesticides are essential pest management tools. Effective results, however, require proper use. Too often, failures are attributed to products, while application mistakes actually caused the problem.

Here are some general ideas for improving pesticide performance, along with specific tips for success with 25 fungicides, insecticides and miticides which were reported in a recent survey (Hudson, et al., 1996, Jones, et al., 1996) as the products most frequently used by the U.S. greenhouse and nursery industry (imidacloprid not included in the survey, was added to our list due to its widespread use.) Pesticides are listed in alphabetical order by their common names-not in order of reported use.

Before you spray

The key to pesticide success is to keep in mind that chemicals should always be used as part of an integrated pest management (IPM) program. Neglecting the essentials -pest monitoring, exclusion, sanitation, biological control and good cultural practices- reduces pesticide results and increases the probability of pest resistance. With that said, here are 9 more factors that are critical to effective pest control.

1. Make the correct diagnosis. Don't jump to conclusions! Misidentification often results in further crop damage. For example, you might assume mites are damaging ivy geraniums, when they actually have edema, a physiological problem. Miticides won't solve the cultural and environmental problems that cause edema. If you're not sure, get help.
2. Detect the problem early. This requires formalized monitoring and knowledge of key crops and pests. Early detection reduces crop damage and pesticide use.
3. Select the best pesticide. This depends on many factors, but each pesticide has strengths and weaknesses. Performance varies with factors such as environmental conditions and stage of pest or crop development. Marathon, for example, is an excellent systemic whitefly insecticide, but it's not the best choice for young poinsettia cuttings with limited root development because it's absorbed by roots. Remember: Don't rely on one product. Rotate between chemical classes to reduce risk of pest resistance. For insects and mites, rotate after two or more applications of the same product. And rotate your fungicides, too. While it's not stressed as often as for insecticides, it's equally important.
4. Read the product label thoroughly. Many grower mistakes could be avoided by following the label instructions. For example, a 1996 survey of greenhouse pesticide use indicated that 20% of growers applied Subdue as a foliar spray. Yet, with the exception of azaleas, Subdue is labeled exclusively for media drenches for soil-borne pathogens on greenhouse crops. Another common and potentially serious mistake is treating vegetable transplants and herbs with pesticides that haven't been tested or approved for them.
5. Select the appropriate application equipment. Effective equipment results in good coverage of plant parts infested or infected by the target pest. Hydraulic sprayers, mist blowers, electrostatic sprayers, injectors, foggers, aerosol cans and smokes each have their place and are effective for the right pest at the right time.
6. When possible, start small. Avoid treating large areas all at once -especially when using new products and tank mixes, or when treating new and unfamiliar crops.
7. Understand your water. Most growers recognize that water quality is important to crop nutrition, but few are aware that it sometimes relates to pesticide efficacy. High water pH and alkalinity, or hardness from calcium, magnesium or other ions, can result in reduced pesticide efficacy. For example, insecticidal soaps precipitate when mixed in water with high calcium and magnesium. Also, some pesticides, including Dycarb, are quickly hydrolyzed in alkaline water. Check your water and adjust pH and alkalinity with appropriate adjuvants. Always mix and apply pesticide solutions promptly to reduce the chance of breakdown.
8. Purchase appropriate quantities and store them in a cool, dry, well-ventilated area. Most pesticides have a shelf life of several years. However, improper storage conditions and long time periods increase the potential for failure because of mixing problems or breakdown of active ingredients. Be sure to read and follow label directions for proper storage, and don't buy more than you need for one year.
9. Keep accurate records of applications and results. Record all information including pesticide rates, application equipment, crops, environmental conditions, time of day, etc. Don't forget to evaluate application results. Document results along with application information. Good records are essential for planning future pest management strategies.

Inclusion or omission of products is based on the results of the survey and does not constitute endorsement by Rutgers University Cooperative Extension. Pesticide applicators are responsible for ensuring that use complies with regulations and the product label.

Tips for specific products: insecticides and miticides

Abamectin

• Trade name: Avid 0.15 EC
• Pesticide class: macrocyclic lactone
• Key pests: spider mites and leafminers
• Label crops: most greenhouse and field-grown ornamentals
• REI: 12 hours

When applied to upper leaf surfaces, Avid penetrates into tissue and kills mites that inhabit and feed on lower leaf surfaces. While it's chemically unrelated to other miticides and insecticides, resistance to Avid has been reported. To reduce the rusk, Dr. David Smitley, Michigan State University, recommends rotating miticides so that each one is used for four weeks before switching to a new one. Use three or more products in the rotation. Possibilities include: Kelthane, Pentac, Sanmite, M-Pede (soap), Sunspray (horticultural oil), Attain, Talstar and Mavrik. Don't apply Avid to ferns and Shasta daisies.

Acephate

• Trade names: Orthene 75SP, PT 1300, Orthene, PT 1300 DS, Orthene and Pinpoint 15G
• Chemical class: organophosphate
• Key pests: whiteflies, thrips, aphids, scales, mealybugs and leafminers
• Labeled crops: varies with formulation (see labels)
• REI: 24 hours

Acephate is a systemic insecticide that penetrates plant tissue and moves upward and outward in plants. Good activity is reported on many sucking pests including aphids and whiteflies. University and industry research has demonstrated enhanced activity against aphids, whiteflies and thrips when acephate is tank mixed with various pyrethroid insecticides. Orthene SP and Tame are labeled for tank mixing. The combination is synergistic, giving increased control over either product used alone. Orthene activity is also enhanced when combined with insecticidal soap, but the risk of plant injury increases. Aerosol formulations, for use only in greenhouses, can also be "space mixed" -released into the greenhouse at the same time. PT 1300 Orthene can be space mixed with PT 1800 Attain or PT 1200 Resmethrin. Regardless of application technique, good coverage ensures optimal results. When using aerosol formulations use fans to create horizontal air circulation.

Bacillus thuringiensis (Bt)

• Trade names: Gnatrol
• Chemical class: microbial/biological
• Key pests: fungus gnat larvae
• Labeled crops: most greenhouse ornamentals
• REI: 12 hours

Gnatrol is commonly used to control fungus gnat larvae. It contains a highly effective spore-forming strain of Bt that produces toxic crystals that are lethal when consumed by fungus gnat larvae. Populations are difficult to control once larvae penetrate into roots and crowns since they are less likely to ingest the Bt. Bt doesn't control adults. This product should be applied as a drench toward the end of an irrigation period to avoid dilution or leaching. Avoid applications in combination with fertilizers or fungicides containing copper or chlorine since they may neutralize the active ingredient. Applications must be repeated every few days until infestations are controlled.

Bifenthrin

• Trade names: Talstar T&O 10 WP and F, PT 1800 Attain
• Chemical class: pyrethroid
• Key pests: aphids, mealybugs, whiteflies, fungus gnats (adults only), scales, caterpillars and spider mites
• Labeled crops: many greenhouse and outdoor ornamentals
• REI: 12 hours

Bifenthrin is a pyrethroid insecticide with miticidal properties. Since it's not systemic, good spray coverage is key to successful pest control with Talstar. Applications must be directed to cover lower leaf surfaces for whiteflies and mites. Talstar activity may be increased by tank mixing with organophosphates. Many growers tank mix with Azatin, an insect growth regulator IGR for control of both adult and larval stages of fungus gnats. PT 1800 is an aerosol formulation of bifenthrin. Apply it to dry leaf surfaces when temperatures are between 65F and 80F. It may be applied alone or in combination, as a space mix, with PT 1300 Orthene or PT 1200 Resmethrin.

Chlorpyrifos

• Trade names: PT 1325 ME DuraGuard
• Chemical class: organophosphate
• Key pests: aphids, caterpillars, fungus gnat larvae, leafminers, mealybugs, scales, thrips, whiteflies
• Labeled crops: many greenhouse and field-grown ornamentals
• REI: 12 hours

DuraGuard is a relatively new formulation of chlorpyrifos that is microencapsulated to improve residual activity and plant safety. As a contact insecticide, good coverage is necessary. Be sure to shake the container prior to adding concentrate to the spray tank. Maintain agitation of spray solution to prevent settling in tank and uneven application. DuraGuard provides excellent control of fungus gnat larvae.

Cyfluthrin

• Trade name and formulation: Decathlon 20 WP
• Chemical class: pyrethroid
• Key pests controlled: aphids, caterpillars, fungus gnat adults, mealybugs, thrips
• Label crops: many greenhouse and field-grown ornamentals
• REI: 12 hours

Decathlon is a pyrethroid insecticide with contact activity, so complete spray coverage is necessary. Maintain agitation in spray tank. Tank mixed combinations with organophosphates such as Orthene may improve control of some pests, including silver leaf whitefly. Very low use rate of 1 to 2 oz. per 100 gal. requires careful measuring.

Diazinon

• Trade names: Knox Out 2FM, Knox Out PT1500R
• Chemical class: organophosphate
• Key pests: aphids, caterpillars fungus gnat larvae, leafminers, mealybugs, scales, spidermites, thrips, whiteflies
• Labeled crops: many greenhouse and field-grown ornamentals (see label)
• REI: 12 hours

Diazinon is a contact insecticide with no systemic properties. Thorough spray coverage is necessary. Be sure to cover lower leaf surfaces. Microencapsulated formulation gives Knox Out improved residual activity and plant safety.

Dienochlor

• Trade name: Pentac Aquaflow 4F, Pentac 50 WP
• Pesticide class: chlorinated hydrocarbon
• Key pests controlled: mites, whiteflies
• Label crops: many greenhouse ornamentals
• REI: 24 hours

Pentac is a contact miticide that also has activity against whitefly eggs and nymphs. As a miticide, its results are slower than for other products. Thorough spray coverage is essential. Ensure adequate mixing and agitation in spray tank to prevent settling and uneven application. For high populations under warm conditions, repeat application should be made in seven days. Combination with a pyrethroid with miticidal activity will improve knock-down and reduce the risk of resistant mites. Many growers tank mix Pentac with Mavrik.

Endosulfan

• Trade name: Thiodan 50 WP & 33 EC, Fluex Thiodan Smoke
• Pesticide class: chlorinated hydrocarbon
• Key pests controlled: aphids, cyclamen mites, whiteflies
• Label crops: many greenhouse and field-grown ornamentals and tomatoes (smoke formulation for greenhouse only)
• REI: 24 hours

Thiodan is one of the few remaining chlorinated hydrocarbon pesticides. As such, it's useful in insecticide rotations that often contain organophosphates and pyrethroids. While not indicated on the label, some growers report successful thrips control. All endosulfan formulations are highly toxic: Follow all labeled safety precautions when mixing and applying. Sprayable formulations require good coverage. Applications may injure open blooms. Thiodan is also available as a smoke formulation in Fluex Thiodan. It produces extremely small particles that disperse uniformly throughout enclosed greenhouses before settling on plant surfaces. Be sure that temperatures are above 70F and below 90F during application. Also, leaf surfaces must be dry. While some smokes require only that EPA ventilation criteria be met, Thiodan smoke has a 24 hour REI.

Fenpropathrin

• Trade name: Tame 2.4 EC
• Pesticide class: pyrethroid
• Key pests controlled: aphids, whiteflies, mealybugs, spider mites
• Label crops: anthurium, chamomile, bedding plants, chrysanthemum, columbine, foliage plants, geranium, gladiolus, impatiens, lily, marigold, poinsettia and snapdragon grown in greenhouses, lathe houses and shade houses only
• REI: 24 hours

Tame is a contact insecticide. It's labeled for tank mixing with Orthene. Follow label precautions to avoid phytoxicity. Rotate with pesticides in other classes after several applications to avoid resistance. For easier measuring of small quantities, convert ounces to milliliters, and measure with a graduated cylinder. One oz. equals 29.6 ml.

Fluvalinate

• Trade name: Mavrik Aquaflow 2F
• Pesticide class: pyrethroid
• Key pests controlled: aphids, caterpillars, mealybugs, spider mites, thrips, whiteflies
• Label crops: most greenhouse and field-grown ornamentals, vegetables and herbs (see label)
• REI: 12 hours

Mavrik is a contact insecticide/miticide requiring good coverage especially for whiteflies and spider mites that inhabit lower leaf surfaces. Adjust spray water pH to between 5 and 7. Mavrik may be tank mixed. Many growers combine with Pentac, for improved mite control, and Enstar II for improved control of immature aphids, fungus gnats, whiteflies and scales.

Horticultural Oil

• Trade name: Sunspray Ultrafine
• Pesticide class: horticultural oil
• Key pests controlled: aphids, fugus gnat adults, leafminers, mealybugs, scales, spider mites, thrips, whiteflies
• Label crops: many greenhouse and field-grown ornamentals, vegetables and herbs (see label
• REI: 12 hours

Spray must completely cover target pests. Avoid applications during periods of high temperature and humidity. Don't mix with fungicides or any sulfur-containing pesticide. Agitation of spray solution must be maintained. Since there is no residual control, repeat treatments weekly until pest populations are under control. Tank mixes with insecticides often increase effectiveness, but potential for plant injury also increases.

Imidacloprid

• Trade name: Marathon 1G & 60 WP
• Pesticide class: cloronicotinyl
• Key pests controlled: aphids, mealybugs, scales, thrips, whiteflies
• Label crops: many greenhouse and field-grown ornamentals
• REI: 12 hours

Over the last few growing seasons, Marathon has established itself as a reliable systemic insecticide for controlling a wide range of greenhouse insect pests. The product is absorbed through roots and translocates to foliage. Marathon formulations are labeled for soil treatment only: Do not apply WP formulation to foliage! Successful application requires well developed, healthy root systems. Applications prior to rooting are prone to leaching. Marathon is long lasting, but relatively slow to act. Apply early in the crop cycle to young plants under conditions that favor water uptake. Avoid excessive irrigation and leaching for 10 days following application. When applying WP formulation through irrigation systems, be sure to thoroughly mix product in stock tank and maintain agitation. Also, ensure that systems are calibrated and provide uniform distribution to crops.

Insect growth regulators (IGRs)

• Trade names: Adept 25 WP, Azatin 3 EC, Citation 75 WP, Dimilin 25 WP, Enstar II, Neemazad 4.5 EC, Precision 25 WP, PT 2100 Preclude

Survey results indicated that IGRs were used frequently by growers, but didn't specify products. IGRs are effective in controlling the immature stages of several key pests, including thrips, whiteflies, aphids, fungus gnats, shore flies and leafminers. Most are labeled exclusively for ornamental greenhouse crops, but the neem-based products, Azatin and Neemazad, may be used on many vegetables. Check labels for specific pests and crops and application techniques for each product.

Insecticidal soap

• Trade name: M-Pede, Olympic Insecticidal Soap
• Pesticide class: potassium salts of fatty acids
• Key pests controlled: aphids, caterpillars, fungus gnat adults, mealybugs, scales, thrips, whiteflies
• Label crops: many greenhouse and field-grown ornamentals, vegetables and herbs (see label)
• REI: 12 hours

Soaps work by contact -they have no residual activity, so be sure spray coverage is thorough. Water containing high levels of calcium, magnesium, iron and other metallic ions that are associated with hard water will reduce effectiveness. Conditioning adjuvants can be added if needed. Applications are most effective when made during conditions that favor slow drying. Evening, early morning and cloudy periods are ideal. Applications under high light, temperature and humidity increase the chances for crop injury. Tank mixes with other insecticides often increase activity, but the risk of crop injury also increases.

Fungicides

Chlorothalonil

• Trade name: Daconil 2787 75 WP & 4F, Exotherm Termil 20% Smoke
• Pesticide class: carbamate
• Key diseases or pathogens controlled: botrytis, black spot of rose, leaf spots including alternaria and septoria, powdery mildews, rusts (see label for complete list)
• Labeled crops: many greenhouse and field-grown ornamentals (see label). Exotherm Termil is for greenhouse use only
• REI: 48 hours

Chlorothalonil is a protectant, contact fungicide that requires complete coverage of plant tissue. Maintain protection of new growth by applying at the recommended label intervals. Wet sprays with hydraulic sprayers work best with Daconil formulations. Mix well and maintain agitation. Exotherm Termil is a smoke formulation. Apply to dry plants when temperatures are between 70F and 90F. Before igniting be sure all vents are closed, cans are spaced properly and are set on fireproof surfaces. Start igniting cans at the point farthest from the door.

Copper sulfate pentahydrate

• Trade name: Phyton-27 5.5 EC
• Pesticide class: fixed copper
• Key diseases or pathogens controlled: alternaria, black spot of rose, botrytis, powdery mildew, leaf spots caused by pseudomonas, xanthomonas
• Labeled crops: many greenhouse and field-grown ornamentals (see label)
• REI: 24 hours

Phyton-27 may be applied as a spray, fog or drench. It has good plant safety and is used on tender plant tissue, including cuttings and flowers. Use of low-volume equipment is effective on botrytis, but not powdery mildew or xanthomonas.

Etridiazole

• Trade name: Terrazole 35WP, Truban 30W, 25EC, 5G
• Pesticide class: triadiazole
• Key diseases or pathogens controlled: root and crown and foliage diseases caused by phytophthora and pythium
• Labeled crops: many greenhouse and field-grown ornamentals (see label)
• REI: 12 hours

Fungicide must be drenched into media to protect roots and crowns. For bedding plants in flats, mix recommended rate into 100 gal. of water and apply to 800 sq. ft. (approximately one qt. per flat). For potted plants, 100 gal. should cover about 400 sq. ft. (8 oz. per 6-in. pot). Water after application with about 50% of drench volume. Etridiazole and thiophanatemethyl are combined in Banrot for broad spectrum control of root and crown rots. However, the highest label rates for Banrot contain less etridiazole than the suggested curative rate on Terrazole or Truban labels. If you have active pythium or phytopthora, the higher rate is necessary. Keep in mind, strict sanitary practices combined with judicious irrigation will go a long way in minimizing root rot problems. Don't rely exclusively on fungicides!

Fosetyl-al

• Trade name: Aliette 80WP & 80WDG
• Pesticide class: organic phosphate
• Key diseases or pathogens controlled: pythium and phytophthora rots, downy mildew of rose
• Labeled crops: many greenhouse and field-grown ornamentals (see label)
• REI: 12 hours

Aliette is a systemic fungicide that, unlike most others, moves downward as well as upward in plants. Drench application is labeled for many crops. Foliar applications are specifically labeled for bedding plants. May be combined with Chipco 26019 for broader spectrum pathogen control. Aliette WDG isn't compatible with Daconil 2787. To avoid copper phytoxicity, don't apply Aliette and copper-based products at less than seven-day intervals. Also, don't mix with any sticking spreading or wetting agent. Minimize root rot problems with good sanitation and watering practices.

Iprodione

• Trade name: Chipco 26019 50WP
• Pesticide class: dicarboximide
• Key diseases or pathogens controlled: alternaria, botrytis, rhizoctonia
• Labeled crops: many greenhouse and outdoor ornamentals including bedding and foliage plants (see label)
• REI: 12 hours

Contact fungicide with localized systemic activity. Apply as a spray, drench or dip. Labeled for application through high-volume equipment. Foliar sprays give excellent control of botrytis, but rotate fungicide classes to avoid resistance. Don't use exclusively in rotation with Ornalin or Curalan since active ingredients are in the same chemical class. Drench applications are effective on rhizoctonia, but don't treat impatiens or pothos. Growers who apply through injectors and drip irrigation must be careful to maintain agitation of stock solution and ensure uniform distribution to crops.

Mancozeb

• Trade name: Protect T/O 80 WP, Ditaane T/O 75DF, Dithane T/O 4F, Fore 80WP
• Pesticide class: carbamate
• Key diseases or pathogens controlled: alternaria, black spot of rose, botrytis, downy mildews, flower blights, many leaf spots and rusts
• Labeled crops: many greenhouse and outdoor flowering pot crops, bedding plants, foliage plants and perennials. Crops vary with product (see label)
• REI: 24 hours

Contact, protectant fungicide with no systemic activity. Ensure complete coverage of plant tissue. During conditions conducive to disease, maintain applications at seven to 10-day intervals to ensure adequate protection of new growth. Use a spreader sticker for hard-to-wet foliage. Maintain agitation of solutions to prevent settling and uneven applications.

Metalaxyl/mefanoxam

• Trade name: Subdue Maxx, 2E & 2G
• Pesticide class: acylalanine
• Key diseases or pathogens controlled: pythium, phytophthora, azalea petal blight
• Labeled crops: many greenhouse and field grown ornamentals including bedding, foliage, and flowering pot crops
• REI: 12 hours, except for Subaction, so application intervals are relatively long.

Depending on the crop, apply every one to two months. To minimize the chances of phytotoxicity, measure carefully and don't exceed recommended rates or application intervals. Subdue Maxx has lower application rates than Subdue 2E.

PCNB

• Trade name: Terraclor 75WP, Terraclor 4F, PCNB 75WP
• Pesticide class: chlorinated hydrocarbon
• Key diseases or pathogens controlled: rhizoctonia, sclerotinia, sclerotium rolfsii, pellicularia
• Labeled crops: many foliage, bedding and flowering pot crops, including bulbs
• REI: 12 hours

PCNB is a contact fungicide with relatively long residual activity. Apply as a soil drench at seeding or transplanting. It shouldn't be applied through irrigation systems. Maintain agitation spray solution to prevent settling and uneven application. Proper pathogen identification is essential if PCNB is used alone. Control spectrum does not include pythium and phytopthora. Most growers tank mix with a water-mold fungicide. Some bulbs may be dipped for control of rhizoctonia and other rots. See label for specifics.

Thiophanate methyl

• Trade name: Domain 4.5F & 50WP, Cleary's 3336 50WP 4.5F & 2G, Scotts Fungo WP and Fungo Flo
• Pesticide class: benzimidazole
• Key diseases or pathogens controlled: black spot of rose, botrytis, fusarium, phomopsis, powdery mildews, septoria, rhizoctonia, sclerotinia, thielaviopsis
• Labeled crops: most greenhouse and field-grown ornamentals
• REI: 12 hours

Broad spectrum, systemic fungicide for foliar, drench and dip applications. Flowable and AWP formulations require thorough mixing and agitation. Apply with hydraulic sprayers. A recent study by Penn State University revealed that many Pennsylvania greenhouses had thiophanate methyl-resistant strains of botrytis. Tank mixes with contact fungicides such as Protect T/O, Daconil 2787 or Chipco 26019 are helpful in reducing the chances of resistance and improving control if resistant strains are present. Numerous premixed combination products are available for foliar diseases including Benefit, Duosan, Consyst and Zyban. For all diseases, practice rotation with different classes of fungicides. For broad spectrum root and crown rot prevention, tank mix with pythium/phytophthora selective fungicides. Banrot is a combination product containing thiophanate methyl and etridiazole. If rhizoctonia is active, however, it's better to apply thiophanate products alone as they're labeled for higher (curative) application rates than Banrot. Don't tank mix with copper-containing products or highly alkaline pesticides such as lime sulfur or Bordeaux mixture.

Vinclozolin

• Trade name: Ornalin 50WP & 4L, Curalan 50DF & 4L
• Pesticide class: dicarboximide
• Key diseases or pathogens controlled: botrytis, sclerotinia
• Labeled crops: many greenhouse and field grown ornamentals (see label)
• REI: 12 hours

A contact fungicide with localized systemic activity. Excellent control of botrytis, but exclusive use promotes resistant strains. Practice rotation and/or apply in tank mixes with fungicides in different chemical classes. Don't use exclusively in rotation with Chipco 26019 since the active ingredients are in the same chemical class. Apply as a spray or through thermal foggers. Maintain agitation of spray solution -even when using foggers. Not labeled for drench applications. Don't spray seedlings until they've formed three true leaves.

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