Wildlife is an important part of a healthy rural environment. This fact sheet is one of a series that describes how pesticides can be managed to minimize harm to wildlife on our farms, in our waters, and in our forests.
Wildlife is a valuable natural resource. Most farmers enjoy seeing wildlife on their farm, and many benefit economically by leasing hunting and fishing rights to sportsmen. In North Carolina, more than $1.1 billion is spent annually by hunters and fishermen alone.
Cotton fields provide both food and cover for wildlife. For example, quail and other birds nest in grassy strips alongside cotton fields. Farm wildlife such as these are often called "edge species" because they live in noncrop areas such as hedgerows or along the edges of fields. Wildlife that live in these areas find food and grit in the adjacent crop fields. Pesticides applied to these fields are therefore likely to affect wildlife. For example, researchers tested quail that had been killed by hunters and found that 60 percent of the quail had insecticides in their bodies.
Wildlife that are directly exposed to toxic pesticides can become sick or die. In a 1978 study of quail living near cotton fields that had been sprayed with methyl parathion, 35 percent had enough insecticide in their bodies to cause sickness or death. Birds that are made sick by insecticides may neglect their young, abandon their nests, and become more susceptible to predators or disease.
While direct poisoning from toxic pesticides is a concern, many pesticides that are not highly toxic can still be harmful to wildlife by reducing the food and cover that wildlife need in order to survive. Insecticides reduce insect foods, and herbicides decrease plant cover. Herbicide use can reduce gamebird populations on farms by destroying habitats that chicks use to find insects and other foods. Similarly, pesticides can decrease the number of aquatic foods necessary to the survival of ducklings.
Careful selection and use of pesticides, however, can lessen their impact upon wildlife. This publication (1) describes how pesticides used on cotton fields can harm wildlife and (2) describes how farmers can minimize adverse effects of pesticides on wildlife.
Reducing pesticide use is one of the best ways to protect fish and wildlife resources. Using sound cultural practices reduces pest problems and, therefore, results in lower pesticide use. Cultural practices that decrease the need for pesticides include rotating crops, selecting resistant varieties (when possible), planting and harvesting at the proper time, and using integrated pest management (IPM)techniques. IPM is a farming approach that employs alternative methods of pest control, rather than relying solely on agrichemicals. With IPM, pesticides are used only when the cost of applying a pesticide is outweighed by the cost of pest damage to the crop. This 'threshold" must be reached before chemical pest control is economically justified. In this way, IPM practices help to reduce pesticide use and protect wildlife and the environment. For more information on alternatives to pesticide use, contact your county Extension Service agent.
Insecticides
Wildlife are exposed to insecticides when they eat granules or chemical residues on plants and in insects. For instance, quail chicks feed on dead and dying insects following applications of insecticides. Wildlife entering cotton fields during or soon an insecticide has been sprayed may be exposed when the pesticide contacts their skin and eyes or when they inhale the vapor.
Tables 1 and 2 list insecticides recommended in the North Carolina Agricultural Chemicals Manual for use on cotton. Table 1 rates insecticides according to their toxicities to birds, mammals, and fish. The effects of insecticides on wildlife and fish can be minimized by using the least toxic alternative. Insecticides in Table 2 are rated low, moderate, or high based on the hazard their use presents to wildlife (birds and mammals). The hazard of an insecticide is based on its toxicity to wildlife, the way it is used, and other characteristics, such as its persistence in the environment. For example, methomyl (Lannate) is acutely toxic to birds and mammals (Table 1). However, because methomyl does not persist in the field, careful use of this chemical presents only a moderate hazard to wildlife (Table 2). Wildlife exposed to insecticides rated high may die or become sick. Insecticides rated moderate may also cause death or sickness, although death is unlikely. Insecticides rated low are unlikely to harm wildlife directly.
Atplanting Soil Insecticides
Several granular atplanting soil insecticides used in cotton production are toxic to wildlife and have caused wildlife dieoffs; these include aldicarb (Temik), phorate (Thimet), and disulfoton (DiSyston). Granular insecticides are a serious hazard to birds. Birds eat granules exposed on the soil surface, mistaking them for food and grit. Ingesting just a few granules of a toxic insecticide can kill a small bird.
To reduce the hazardous effects of granular insecticides on wildlife:
Spilled granules at row ends are particularly hazardous since birds often search field edges for food and grit. Full incorporation, including disking under spilled granules at row ends, reduces wildlife poisonings caused by granular soil insecticides.
Liquid Insecticides
Several foliar insecticides used on cotton are extremely toxic to wildlife; these include phosphamidon (Dimecron), dicrotophos (Bidrin), and dimethoate (Cygon). When foliar sprays are necessary, the risk to wildlife can be minimized by choosing the least toxic alternative.
When multiple sprays are necessary to control a pest, the hazard to wildlife is increased. Birds that survive a single exposure to an insecticide are more likely to die if they are exposed again. Recovery from exposure to an organophosphate insecticide, such as dicrotophos (Bidrin), can take 30 days. Therefore, it is even more important to use the least toxic material to wildlife when several sprays are needed.
To reduce hazard to wildlife from liquid formulations:
Several studies of aerial applications of pesticides have reported significant drift of material into nearby wildlife habitats. If it is necessary to use highly toxic insecticides, apply them with ground equipment; this will help to minimize drift and reduce the hazard to wildlife. Ground application may also allow wildlife more time to leave the area during the spraying operation.
Spray drift can be minimized by using application equipment with low drift characteristics, replacing inappropriate or worn nozzles, using appropriate pressure and volume for the chosen nozzle, and adding a drift control agent. Ultralowvolume sprays are more likely to cause drift than lowpressure sprays. Of course, avoid spraying when the wind is blowing faster than 8 mph.
Fungicides
Most fungicides are only slightly toxic and do not present a hazard to birds and mammals; they include PCNb (Terraclor), ETMT (SuperX), Metalaxyl (Ridomil PC), and captan. Some fungicides are highly toxic to fish; these include captan and PCNB.
Fungicide use can be reduced by controlling seedling diseases with cultural practices such as proper rotation, timely planting, and proper seed selection.
Nematicides
Nematicides used on cotton include dichloropropene (Tel one II), fenamiphos (Nemacur), and aldicarb (Temik). Nemacur and Temik are more hazardous to wildlife than Telone II because they stay active in the environment longer and have been reported to cause wildlife mortality. Although Telone II is toxic to wildlife, its use has not been reported to cause wildlife poisonings. This is probably because it does not stay active for long and its application procedures are different.
The hazard to wildlife from nematicides can be reduced by rotating crops, applying chemicals only when economic thresholds are reached, and using the least toxic alternative. Danger to wildlife from granular nematicides is reduced when granules are fully incorporated into the soil. Disking spilled granules into the soil significantly reduces danger to wildlife.
Table 1. Toxicity of Pesticides Used on Cotton to Birds, Mammals,and Fish
| Pesticide (Brand Name) | Birdsa | Mammals | Fishb |
| acephate (Orthene) | M | L | L |
| aldicarb (Temik) | HC | H | H |
| bifenthrin (Capture) | L | L | EH |
| cyfluthrin (Baythroid) | L | L | EH |
| chlorpyrifos (Lorsban) | H | L | EH |
| cypermethrin (Cymbush) | L | M | EH |
| dicofol (Kethane) | H | L | H |
| dicrotophos (Dimecron) | HC | H | M |
| dimethoate (Cygon) | HC | M | M |
| disulfoton (DiSyston) | HC | H | H |
| esfenvalerate (Asana XL) | L | L | EH |
| fenamiphos (Nemacur) | HC | H | EH |
| lambda cyhaiophrin (Karate) | L | L | EH |
| methidathion (Supracide) | H | M | EH |
| methomyl (Lannate) | H | H | H |
| methyl parathion (PenncapM) | Hc | H | M |
| oxydementonmethyl
(MetasystoxR) |
H | M | M |
| permethrin (Ambush, Pounce) L | L | EH | |
| phorate (Thimet) | HC | H | EH |
| phosphamidon (Dimecron) | HC | H | M |
| propargite (Comite) | L | L | H |
| profenofos (Curacron) | | L | EH |
| sulprofos (Bolster) | H | L | H |
| thiodicarb (Larvin) | M | H | H |
| tralomethrin (Scout Xtra) | L | L | EH |
(a) Wildlite hazard is based on the following toxicities:
(b) fish 96 hour LC50 toxicities are as follows:
To convert fish toxicities
to pounds per active ingredient per acrefoot of water, multiply by 2.7.
c Active ingredient (not necessarily a specific product) has caused wildlife deaths.
Table 2. Hazards of Insecticides Sprays Used on Cotton to Wildlife
| Insect | Insecticide(Brand Name) | Wildlife hazarda | Wildlife Killsb | Comments |
| Aphids | bifenthrin
(Capture) dimethoate (Cygon) phosphorothioate (MetasystoxR) methyl parathion (PenncapM) phosphamidon (Dimecron,Swat) dicrotophos (Bidrin) |
low high moderate moderate high high |
no yes no yes yes yes |
Aphid
control with insecticides should be attempted only as a last resort, especially early in the season. Dimecron and Bidrin may be cancelled |
| Beet
and fall armyworms |
chlorpyrifos
(Lorsban) sulprofos (Bolster) profenofos (Curacon) thiodicarb (Larvin) methomyl (Lannate) |
moderate low moderate moderate |
no no no no |
See
comment on Lannate under bollwomm. |
| Bollworm | bifenthrin
(Capture) cyfluthrin (Baythroid) cypermethrin (Ammo) esfenvalerate (Asana XL) lambda cyhalothrin (Karate) tralomethrin (Scout Xtra) sulprofos (Bolster) profenofos (Curacon) thiodicarb (Larvin) methomyl (Lannate) |
low low low low low low moderate low moderate moderate |
no no no no no no no no no no |
Lannate
is very toxic to birds end mammals. Residues disappear quickly. Hazard is greatest when wildlife enter fields soon after spraying or are sprayed directly. See Table 1 for information on toxicity to fish |
| Cabbage
and soybean loopers |
acephate (Orthene) | low | no | Treatment
is generally not recommended. |
| European corn borer) | bifenthrin
(Capture lambda cyhalothrin (Karate) cyfluthrin (Baythroid) |
low low low1 |
no no no |
|
| Spider mites | methidathion
(Supracide) propargite (Comite) dicofol (Kelthane) |
moderate low moderate |
no no no |
|
| Stink bugs | methyl
parathion (PenncapM) |
moderate | yes | Known
mortality occurred with liquid, not encapsulated, formulation |
| Thrips | .
acephate (Orthene) dimethoate (Cygon) dicrotophos (Bidrin) phosphamidon (Dimecron,Swat) |
low high high high |
no yes yes yes |
Bidrin
and Dimecron are extremely toxic to wildlife. |
(a) Wildlife hazards:
(b) Kills
Herbicides
Most herbicides used on cotton are only slightly toxic to birds and mammals. One exception is paraquat (Gramoxone). Paraquat is toxic to birds and bird embryos. Some herbicides are highly toxic to fish; these include fluazifop (Fulsiade 2000), fluometuron (Cotoran), oxyfluorfen (Goal), pendimethalin (Prowl), and trifluralin (Treflan).
However, herbicides can destroy wildlife habitats and reduce the food and cover available to wildlife. When habitats are reduced on a farm, there is a tremendous effect on the wildlife populations there. Wildlife populations decline when herbicides or mechanical methods are used to maintain "clean" fencerows, ditch banks, and field borders. These "strip habitats" provide wildlife valuable cover for nesting, brood rearing, and escaping from predators.
Many species of wildlife, including quail and rabbits, benefit from strip habitats. Where possible, consider maintaining these areas in wildlife cover. Protect these areas from herbicides and mow less frequently. Consider mowing filter strips and ditch banks only once per year, preferably during early spring. If possible, mow on a twoyear rotation. For example, mow one side of a ditchbank in the first year and the other side in the second year. This method provides yearround habitats for wildlife. Disking filter strips and field borders, rather than mowing, encourages growth of important wildlife food plants and improves the structure of the habitat for wildlife.
Remember These Tips To Protect Fish and Wildlife Resources