This guide lists recommendations for insect, mite and disease control in walnut orchards. The chemicals, formulations and application rates listed here are based on label directions, research and orchard experience.
Pest management depends on producers and their knowledge of the orchard and its characteristics. Producers must weigh several factors: cultivar, tree size, tree density, canopy characteristics, pest complex and pest history. Consider all these factors when choosing which chemicals to apply and at what rates. Other variables include the amount of water used per acre and the method of application.
Trade name products are mentioned as examples only. Occasionally, manufacturers register different formulations of a product that contain a different concentration of active ingredient. This does not mean that OSU Extension either endorses these products or intends to discriminate against products not mentioned. Consult product labels to determine whether their use confers advantages over the products listed in this guide.
Always refer to the pesticide label for use instructions. It is the legal document.
Producers ask two common questions about the chemical control of insects and diseases:
The schedule below suggests an amount of formulated product to use per acre, and not the amount of active ingredient. This amount is based on a typical orchard of middle age and average tree density, with moderate pest pressure. Less product may be needed in 1- to 4-year-old orchards. Conversely, more chemical (within label limits) may be required for large, mature trees experiencing heavy pressure from multiple pests.
Many insecticide labels today list the minimum amount of water needed per acre in concentrate sprays of insecticides. Labels also tell users how to calculate the amount of chemical needed per acre in a concentrate sprayer. CHECK THE LABEL BEFORE SPRAYING! Some label directions indicate dilute applications only, such as the dimethoate labels for cherry fruit fly control. Also:
Important: Blackline of walnuts is a serious disease that can’t be controlled by use of pesticides. For more information, see Growing Walnuts in Oregon, EM 8907, catalog.extension.oregonstate.edu/em8907.
Use only one material except where a combination is indicated. Follow label precautions when tank-mixing oils, fungicides, and insecticides. Materials are not listed in order of preference.
Early prebloom: Late March to early April, when catkins begin to enlarge |
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Pest or disease/ |
Amount of product/acre |
Comments/reentry interval |
Blight and downy leaf spot |
||
Badge X2 |
3.5–11 lb |
48-hour reentry. |
Bordeaux 4-2-100 |
— |
The low-lime formula reduces the possibility of bordeaux foliage injury. See footnote 2. |
C-O-C-S WDG |
4–7.7 lb |
48-hour reentry. |
Copper-Count-N |
8–12 qt |
48-hour reentry. |
Cuprofix Ultra 40 Dis-perss |
5–10 lb |
48-hour reentry. |
Dithane F45 |
1.8 qt |
Group M3 fungicide. See footnote 4. Label indicates you must tank-mix with a fixed copper product. 24-hour reentry. 75-day PHI. |
Kocide 3000 |
3.5–7 lb |
48-hour reentry. |
Manzate Pro-Stick |
2.4 lb |
Group M3 fungicide. See footnote 4. Label indicates you must tank-mix with a fixed copper product. 24-hour reentry. 75-day PHI. |
MasterCop |
3-6 pt |
48-hour reentry. |
Nordox 75 WG |
5–8 lb |
12-hour reentry |
Nu-Cop 50DF |
4–8 lb |
48-hour reentry. |
Phyton 27 AG |
30–50 fl oz/100 gal water |
48-hour reentry. |
Previsto |
2–4 qt |
48-hour reentry. |
Regalia |
1–4 qt |
Use with a surfactant and on 7-day intervals. 4-hour reentry. |
Late prebloom: Early to mid-May, when shoots begin to expand |
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Pest or disease/ |
Amount of product/acre |
Comments/reentry interval/preharvest interval |
Anthracnose Many of these chemicals have received registration for the nut crop group, may be efficacious, and are legal to use on walnut; however, most have not been tested for efficacy against anthracnose. Tank mix or alternate chemicals to prevent fungi from developing resistance. Limit the use of any one group during crop production. |
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Abound |
12 fl oz |
Group 11 fungicide. See footnote 6. 4-hour reentry. 45-day PHI. |
Aframe Plus |
14–21 fl oz |
Group 3+11 fungicide. See footnote 6. 12-hour reentry. 60-day PHI. |
Aproach |
6-12 fl oz |
Do not use more than 3 applications or on trees less than 2 years old. Group 11 fungicide. 12-hour reentry. 7-day PHI. |
Flint Extra |
3–3.8 oz |
12-hour reentry. |
Luna Experience |
8.8–17 fl oz |
Group 3 + 7 fungicide. 12-hour reentry. 35-day PHI. |
Luna Sensation |
7.6 fl oz |
Group 7 + 11 fungicide. 12-hour reentry. 60-day PHI. |
Merivon |
5–6.5 fl oz |
Group 7 + 11 fungicide. Do not use with EC or oil-based prod-ucts. 12-hour reentry. |
Pristine |
10.5–14.5 oz |
Group 7 + 11 fungicide. 12-hour reentry. 14-day PHI. |
Quadris Top |
12–14 fl oz |
Group 3 + 11 fungicide. See footnote 6. 12-hour reentry. 45-day PHI. |
Quash |
3.5 oz |
Group 3 fungicide. 12-hour reentry. 25-day PHI. |
Quilt Xcel |
14–21 oz |
Group 3 + 11 fungicide. See footnote 6. 12-hour reentry. 60-day PHI. |
Syllit FL |
3 pt |
48-hour reentry. 7-day PHI. |
Tilt |
4–8 fl oz |
12-hour reentry. 60-day PHI. |
Topguard EQ |
5–8 fl oz |
Do not use with silicone surfactants. Group 3 + 11 fungicide. 12-hr reentry. 45-day PHI. |
Willowood Azoxy 2SC |
12 fl oz |
Group 11 fungicide. See footnote 6. 4-hour reentry. 45-day PHI. |
Blight See materials listed for Early prebloom stage. |
Blight See materials listed for Early prebloom stage. |
June–July |
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Pest or disease/ |
Active ingredient |
Amount of product/acre |
Comments/reentry interval/preharvest interval |
Aphids Note: When possible, rely on biological control from the aphid parasitoid Trioxys pallidus or reduced-risk materials. |
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Admire Pro |
Imidacloprid |
1.2–2.4 oz |
Group 4A insecticide. Can be applied as soil application through chemigation system, rates and restrictions differ for this application, see label. Generic labels available. 12-hour reentry. 7-day PHI. |
Asana XL |
Esfenvalerate |
9.6–19.2 oz |
Group 3A insecticide. Do not apply a second spray within 3 weeks of the first. Do not apply more than 0.2 lb ai/A per season. Do not graze livestock in treated orchards. 24-hour reentry. 21-day PHI. |
Belay |
Clothianadin |
3-6 oz |
Group 4A insecticide. Thorough coverage necessary. 12-hour reentry. 21-day PHI. |
Beleaf 60 SG |
Flonicamid |
2.0-2.8 |
Group 29 insecticide. Thorough coverage required. Aphids will cease feeding but may remain on plant for a short period after exposure. 12-hour reentry. 40-day PHI. |
Brigade WSB |
Bifenthrin |
8–32 oz |
Group 3A insecticide. Highly toxic to bees and toxic to fish and aquatic invertebrates. 12-hour reentry. 7-day PHI. |
Cobalt |
Chlorpyrifos + lambda cyhalothrin |
22–57 oz |
Group 1B + 3A insecticide. Premix product, see label as both AIs have cumulative limits/season. 24-hour reentry. 14-day PHI. |
Esteem 35WP |
Pyriproxyfen |
4-5 oz |
Group 7A insecticide, Do not exceed 2 applications or 10 oz per season. Generics are available. 12-hour reentry. 21-day PHI. |
Insecticidal soap (M-Pede) |
Potassium slats of fatty acids |
2% by volume |
OMRI listed for organic use. 0-day PHI. |
Malathion 5 EC |
Malathion |
See labels. (1.5-4 pt) |
See footnote 1. Group 1B insecticide. 24-hour reentry. 7-day PHI. |
Movento |
Spirotetramat |
6–9 oz |
Group 23 insecticide. Toxic to aquatic organisms. Minimum interval between treatments is 14 days. Limited to 21.5 oz per year. 24-hour reentry. 7-day PHI. |
Supracide 2E |
Methidathion |
1–2 pt as dilute spray, 4–8 pt as concentrate spray |
See footnote 1. Group 1B insecticide. Restricted use. Apply as a cover spray when aphids appear. Do not graze orchard floors. 48-hour reentry, depending on rate. 7-day PHI. |
Transform WG |
Sulfoxaflor |
0.75-1.5 oz |
Group 4C insecticide. No more than 2 consecutive applications or applications less than 7 days apart. Avoid drift to flowering ground cover to protect pollinators. 24-hour reentry. 7-day PHI. |
Warrior II |
Lambda-cyhalothrin |
1.28–2.56 oz |
Group 3A insecticide. Generics available. Do not apply more than 0.12 lb (7.68 fl oz or 0.48 pt of product)/acre post bloom. 24-hour reentry. 12-day PHI. |
Aphids, codling moth Note: Monitor codling moth with pheromone traps beginning in June. See footnote 3. |
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Scales (apply when crawlers appear; chemical control of scales usually is not necessary) |
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Delegate WG |
Spinetoram |
4.5–7 oz |
Group 5 insecticide. Target codling moth larvae at the onset of egg hatch. No more than 4 applications per season. Minimum 7-day interval between applications. (Suppression of codling moth only.) 4-hour reentry. 1-day PHI. |
Esteem 35 WP |
Pyriproxyfen |
16 fl. oz |
Group 7C insecticide. Thorough coverage required. This material can be effective on codling moth and scale. Target codling moth larvae at the onset of egg hatch. Do not exceed 2 applications per season. 12-hour reentry. 21-day PHI. |
Entrust SC |
Spinosad |
4-10 |
Group 5 insecticide. OMRI approved for organic use. Activity for codling moth only. 4-hour reentry. 1-day PHI. |
Intrepid 2F |
Methoxyfenozide |
12–24 oz |
Group 18 insecticide. Target codling moth larvae at the onset of egg hatch or slightly earlier, some ovicidal activity. 4-hour reentry. 14-day PHI. |
Intrepid Edge |
Methoxyfenozide + |
10–18 oz |
Group 18 + Group 5 insecticide. Target codling moth larvae at the onset of egg hatch or slightly earlier, some ovicidal activity. No more than 18 oz or 4 applications per season. 4-hour reentry, 7-day PHI. |
Movento |
Spirotetramat |
6–9 oz |
Group 23 insecticide. 14-day minimum application interval, no more than 21.5 oz/A per year. Targets scale and aphids only. 24-hour reentry. 7-day PHI. |
Supracide 2E |
Methidathion |
1–2 pt as dilute spray, 4–8 pt as concentrate spray |
See footnote 1. Group 1B insecticide. Apply as a cover spray when aphids appear. Do not graze orchard floors. 48-hour reentry, depending on rate. 7-day PHI. |
July–August |
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Pest or disease/ |
Active ingredient |
Amount of product/acre |
Comments/reentry interval/preharvest interval |
Walnut husk fly Treatments may not be required every year; monitor with yellow sticky cards or other trap. See footnote 5. Note: Baits can be combined with insecticides to enhance control and reduce reliance on coverage. Commercial baits include Brandt Insect Bait and NU-Lure Bait. Follow labels for mixing directions and rates. |
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Ambush 25W |
Permethrin |
12.8–25.6 oz |
Group 3A insecticide. Do not graze treated orchards. Extremely toxic to fish and aquatic habitat. Do not apply more than 1.6 lb ai/A per season. 24-hour reentry. 14-day PHI. |
Asana XL |
Esfenvalerate |
9.6–19.2 oz |
Group 3A insecticide. Do not apply a second spray within 3 weeks of the first. Do not apply more than 0.2 lb ai/A per season. Do not graze livestock in treated orchards. 24-hour reentry. 21-day PHI. |
Assail 70WP |
Acetamiprid |
1.1–4.1 oz |
Group 4A insecticide. Apply when egg-laying females are present. No more than 4 applications per season. 12-hour reentry. 14-day PHI. |
Baythroid XL |
Beta-cyfluthrin |
2–2.4 oz |
Group 3 insecticide. 12-hour reentry. 14-day PHI. |
Belay |
Clothianadin |
3–6 oz |
Group 4A insecticide. Thorough coverage necessary. 12-hour reentry. 21-day PHI. |
Brigade WSB |
Bifenthrin |
8–32 oz |
Group 3A insecticide. Do not graze livestock on treated cover crops. Highly toxic to bees. Toxic to fish and aquatic invertebrates. 12-hour reentry. 7-day PHI. |
Cobalt |
Chlorpyrifos + lambda cyhalothrin |
22–57 oz |
Group 1B + 3A insecticide. Premix product; see label as both AIs have cumulative limits/season. 24-hour reentry. 14-day PHI. |
Delegate WG |
Spinetoram |
4.5–7 oz |
Group 5 insecticide. Do not apply more than 3 consecutive treatments of group 5 materials. 4-hour reentry. 1-day PHI. |
Entrust SC |
Spinosad |
4–10 |
Group 5 insecticide. OMRI approved for organic use. 1-day PHI. |
GF-120 NF |
Spinosad + bait com-pounds |
10–20 oz or 1–3 oz/tree (spot treat-ment) |
Group 5 insecticide. OMRI approved for organic use. Attracticide (bait-spray) applied as coarse droplet spray; thorough coverage is not necessary. Apply at first emergence of adult flies. |
Imidan 70W |
Phosmet |
2–8.5 lb |
Group 1B insecticide. Water soluble bags. Do not apply after hull split. Mechanically harvested nuts only. 7-day reentry. 28-day PHI. |
Malathion 5 EC |
Malathion |
See labels. (1.5-4 pt) |
See footnote 1. Group 1B insecticide. Note multiple formulations. 24-hour reentry. 7-day PHI. |
Success Naturalyte Insect Control |
Spinosad |
4–10 oz |
Group 5 insecticide. Entrust is the organic formula-tion. 24-hour reentry. 14-day PHI. |
Warrior II |
Lambda-cyhalothrin |
0.02–0.04 lb ai/A (1.28–2.56 fl oz) |
Group 3A insecticide. Apply no more than 7.68 oz after bloom. 24-hour reentry. 14-day PHI. |
Fall webworm Insecticides labeled for walnut husk fly and Bacillus thuringiensis will control this pest. Only spot treatments are necessary. Completely drench the infested branch. Applications made when the larvae are small are most effective. |
Ingredient common name (herbicide mode of action) and product name example |
Chestnuts |
Hazelnuts |
Walnut |
Apple |
Pear |
Apricot |
Cherry |
Nectarine |
Peach |
Plums |
Prunes |
Rate |
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Applications that are soil active |
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dichlobenil (20) Casoron |
x |
x |
x |
x |
4 to 6 lb ai/a (100 to 150 lb/a Casoron); apply in cold, wet weather. |
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diuron (7) Karmex |
x |
x |
x |
x |
x |
1.6 to 3.2 lb ai/a (2 to 4 lb/a Karmex 80DF) |
||||||||
isoxaben (21) Trellis SC |
x |
x |
x |
x |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
0.5 to 1 lb ai/a |
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indaziflam (29) Alion |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.046 to 0.085 lb ai/a |
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mesotrione (27) Callisto, Broadworks |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.093 to 0.187 lb ai/a (3 to 6 fl oz/a product) |
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napropamide (3) Devrinol |
x |
4 lb ai/a (8 lb/a) |
||||||||||||
norflurazon (12) Solicam |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
1.95 to 3.98 lb ai/a |
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oryzalin (3) Surflan |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
2 to 6 lb ai/a |
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pendimethalin(3) Prowl |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
Prowl H2O: 1.9 to 6 lb ai/a |
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pronamide (3) Kerb |
x |
x |
x |
x |
x |
x |
x |
x |
1 to 4 lb ai/a (2 to 8 lb/a) depending on species present and soil texture. |
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simazine (5) Princep |
x |
x |
x |
x |
x |
x |
x |
x |
See product label for rates. Princep Caliber 90 is a Special Local Needs label (OR-080038) for sweet cherries only. |
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sulfentrazone (14) Zeus XC/Sulfentrazone 4SC |
x |
x |
x |
x |
0.125 to 0.375 lb ai/a |
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terbacil (5) Sinbar WDG |
x |
NB |
NB |
x |
x |
x |
x |
0.4 to 0.8 lb ai/a (0.5 to 1 lb/a), newly established; 2 to 4 lb/a Sinbar, bearing, depending on soil type. |
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trifluralin (3) Treflan 4L/EC |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.5 to 1 lb ai/a (1 to 2 pints/a Treflan 4L) |
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trifluralin (3)+ isoxaben (21)+ oxyfluorfen (14) Showcase |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
2.5 to 5 lb ai/a |
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Applications that are soil and foliar active |
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flazasulfuron (2) Mission |
x |
x |
0.033 to 0.045 lb ai/a (2.14 to 2.85 oz/a) |
|||||||||||
flumioxazin (14) Chateau SW |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.188 to 0.38 lb ai/a |
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oxyfluorfen (14) Goal 2XL |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
1.25 to 2 lb ai/a |
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oxyfluorfen (14) + penoxsulam (2) Pindar GT |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
1.47 lb ai/a oxyfluorfen + 0.015 lbs ai/a penoxsulam (1.5 to 3 pints/a) |
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rimsulfuron (2) Matrix |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.063 lb ai/a |
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saflufenacil (14) Treevix |
x |
x |
x |
x |
0.045 lb ai/a (1 oz/a) |
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Postemergence contact and translocated herbicides |
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2,4-D (4) Saber |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
Green sucker control in hazelnuts: 0.7 to 0.95 lb ai/a |
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ammonium nonanoate Axxe |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
6 to 15% v/v OMRI certified |
||
Final-San-O |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
14 to 26 fl oz/gal. Apply prior to planting or non-cropped areas. |
||
caprylic acid + capric acid Suppress |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
6 to 9% v/v . OMRI listed. |
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carfentrazone (14) Aim EC |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
Green sucker control in hazelnuts: |
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clethodim (1) |
NB |
NB |
NB |
NB |
NB |
NB |
x |
NB |
NB |
NB |
0.06 to 0.125 lb ai/a |
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clopyralid (4) Stinger |
x |
x |
x |
x |
x |
x |
x |
Apples: 0.094 to 0.25 lb ae/a Others: 0.12 to 0.25 lb ae/a |
||||||
diquat (22) Reglone |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
NB |
0.375 to 0.5 lb ai/a |
|||
fluazifop (1) Fusilade DX |
NB |
NB |
NB |
NB |
x |
x |
x |
x |
x |
x |
0.25 to 0.375 lb ai/a |
|||
glufosinate (10) Rely 280 |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.88 to 1.5 lb ai/a |
|||
glyphosate (9) Roundup |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
General weed control and grass suppression in row middles; read label carefully for crops listed and geographic location. |
|||
halosulfuron (2) Sandea |
x |
x |
x |
x |
x |
Pome Fruit: 0.035 to 0.094 lb ai/a (0.75 to 2 oz/a); Nut crops: 0.031 to 0.063 lb ai/a (2/3 to 1 1/3 oz/a) |
||||||||
paraquat (22) Gramoxone SL 2.0 |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
Green sucker control in hazelnuts: 0.625 to 1 lb cation/a (2.5 to 4 pints/a Gramoxone 2.0 SL; 1.7 to 2.7 pints/a Firestorm) |
|||
pyraflufen (14 Venue) |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
0.001 to 0.005 lb ai/a |
||
sethoxydim (1) Poast |
x |
x |
x |
x |
x |
x |
x |
x |
x |
x |
NB |
Grass suppression in row middles: |
Information on plant protection is available from several sources at Oregon State University:
The single most important approach to pesticide safety is to read the pesticide label before each use and then follow the directions. If still in doubt after reading the label, contact a person qualified to help evaluate the hazard of the chemical and its use. Qualified people include Extension specialists, county educators, pesticide product representatives, and retailers.
Pesticides are toxic and should be handled with care — but they can be used safely if you follow recommended precautions. Follow all label requirements, and strongly consider any recommendations for additional personal protective clothing and equipment. In addition to reading and following the label, other major factors in the safe and effective use of pesticides are the pesticide applicator’s qualifications, common sense, and positive attitude. Always take all safety precautions when using pesticides.
In case of accidents involving pesticides, see your doctor at once. It will help your doctor to know exactly which pesticide is involved. The label on the container gives this information. Take to the physician the pesticide label or information from the label, such as the product name, registration number of the U.S. Environmental Protection Agency, common name and percentage of active ingredient, and first aid instructions. If the label cannot be removed, take along the pesticide container (if not contaminated), but do not take it into the hospital or doctor’s office.