FRUIT TREES

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 orchardists 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.

Orchards attract wildlife by providing food, cover, and nesting areas. Birds such as bobwhite quail nest in grassy understories, while songbirds and mourning doves nest in fruit trees.

Pesticides used in orchard management may harm wildlife directly or indirectly. Wildlife can be affected directly (can become sick or die) when they are exposed to highly toxic agrichemicals. Wildlife are exposed to pesticides when they eat the residues on plants and in insects. Eggs and young birds in nests may be exposed during spraying operations. Wildlife made sick by pesticides may neglect their young, abandon their nests, and become more susceptible to predation and disease.

Pesticides indirectly affect wildlife when the quantity or quality of their habitats is reduced. For instance, insecticides that drift into a stream can kill aquatic invertebrates and reduce food supplies for ducks or fish. When herbicides are sprayed on wildlife habitats, valuable vegetative cover is reduced.

Careful selection and use of pesticides, however, can lessen their impact upon wildlife. This publication (1) describes how pesticides used in fruit production can harm wildlife and (2) describes how farmers can minimize adverse effects of pesticides on wildlife.

Ways to Reduce Pesticide Use

Reducing pesticide use is one of the best ways to protect wildlife resources on your farm. Using sound cultural practices reduces pest problems and results in lower pesticide use. Following integrated pest management (IPM) guidelines can also lead to reduced pesticide use. 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 further information on alternatives to pesticide use, see your county Extension Service agent.

Insecticides

Species that live in or around orchards are exposed to insecticides when they eat chemical residues on plants or in insects. Wildlife that are in fields or that enter fields soon after an insecticide is sprayed are exposed when they inhale vapor or when the insecticide contacts their skin or eyes.

Tables 1, 2, and 3 list insecticides recommended in the North Carolina Agricultural Chemicals Manual for use on fruit crops. 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 alternatives. Insecticides in Tables 2 and 3 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.

Liquid Insecticides

Insecticides currently used in orchards that have been found to cause wildlife deaths include dimethoate (Cygon) and diazinon. Many other insecticides and miticides used in orchards have not been reported to cause wildlife deaths but are highly toxic to wildlife; these include formetanate (Carzol), methomyl (Lannate), chlorpyrifos (Lorsban), oxamyl (Vydate), and methidathion (Supracide). The toxicity of these insecticides to wildlife is similar to insecticides that are known to cause wildlife deaths. Therefore, care should be taken to avoid exposing wildlife.

Applying insecticides more than once every 10 to 14 days increases the risk to wildlife, even when moderately toxic pesticides are used. Wildlife that have not fully recovered from a previous exposure to an insecticide are more likely to die if they are exposed again. Therefore, when multiple sprays are needed, it is very important to use the least toxic pesticide available.

To reduce danger to wildlife from liquid insecticides:

• spray only when IPM thresholds are met
• use the least toxic insecticide that will control the insect pest
• minimize drift of insecticides into fish and wildlife habitats.

Drift can be minimized by using application equipment with low drift characteristics, replacing inappropriate or worn nozzles, using the appropriate pressure and volume for the chosen nozzle, and adding a drift control agent. Also, avoid spraying when the wind is blowing faster than 8 mph.

Pesticides applied with lowpressure sprayers are less likely to drift off target than those applied using high-pressure, air-blast sprayers or ultra-low-volume (ULV) sprayers. Ultra-lowvolume formulations are more hazardous to fish and wildlife than conventional sprays because they often approach 100 percent active ingredient and have a high potential to drift.

Nematicides

Nematicide options include fumigants and liquid formulations. Fumigants include Telone (dichloropropene), Vorlex (methyl isocyanate), and Brom-O-Gas (methyl bromide with chloropicrin).

Although fumigants are highly toxic, their activity is of short duration and they have not been reported to cause wildlife poisonings. Nemacur (fenamiphos) may present a Rreater hazard to wildlife since it is highly toxic and remains active longer. Nemacur has been reported to cause wildlife deaths. When possible, use Telone (dichloropropene) to minimize the hazard to wildlife.

Fungicides and Bactericides

Fungicides and bactericides that are used for disease control are only slightly toxic to birds and mammals and are not a hazard at the rate applied to apples, peaches, and nectarines. However, several fungicides are extremely toxic to fish, including captan (Orthocide), chlorothalonil (Termil or Daconil), copper sulfate, and benomyl (Benlate). Benlate does not tend to leach or runoff. Termil and Daconil have moderate mobility in sandy soils. Therefore, use care when applying these fungicides to avoid contamination of streams and ponds.

Benlate, thiophanate-methyl (Topsin-M), and copper sulfate are extremely toxic to earthworms and other soil invertebrates. In some orchards, most soil animal life (including large earthworms) has been eliminated by the extensive use of coppercontainingfungicides. Therefore, these fungicides can reduce food supplies for some mammals and birds.

Herbicides

Herbicides recommended for use in orchards are only slightly toxic to birds and mammals. One exception is paraquat (Gramoxone), which is moderately toxic to birds and highly toxic to embryos when applied directly to eggs. Paraquat, pendimethalin (Prowl), oryzalin (Surflan), and sethoxydim (Poast) have moderate to high toxicities for fish.

Overall, however, herbicides used in orchards do not present a direct hazard to wildlife. Herbicides can adversely affect wildlife when their use destroys the habitat surrounding orchards. Care should be taken to avoid spraying herbicides into wildlife habitat.

Rodenticides

There are two rodenticides registered for orchard use in North Carolina. One of these, zinc phosphide (Zinc Phosphide Mouse Bait, Ridall-Z, and ZP Rodent Bait), is acutely toxic to mammals and birds, and it is a hazard to nontarget wildlife in orchards. The other compound, chlorophacinone (Rozol Ground Spray, Rozol Ready-To-Use Pine Vole Bait, Rozol Paraffinized Pellets, and Parapel Paraffinized Pellets), is highly toxic to rodents but much less toxic to other mammals and birds. Because ground spray application may expose nontarget animals, the use of pelleted bait is preferred. Exposure to nontarget animals can be reduced by applying rodenticides only to sections of orchards where pine voles are causing damage. Concentrations of pine voles can be mapped using the "apple sign test" as outlined in Extension Service publication AG302, Animal Damage in Apple Orrhards

Table 1. Toxicities of Insecticides and Miticides Used on Fn~it crops to Birds, Mammals, and Fish

^aWildlife hazard is based on the following toxicities:
H (Highly toxic) = LD50 less than 30 mg/kg and LC50 less than 500 ppm.
M (Moderately toxic) = LD50 greater than 30 and less than 100 mg/kg and/or LC50 greater than 500 and less than 1,000 ppm.
L (Low toxicity) = LD50 greater than 100 mg/kg and LC50
NT (not toxic)

^bFish 96 hour LC50 toxicities are as follows:
EH (Extremely toxic) less than 0.1 ppm
H (Highly toxic) 0.1 to 1.0 ppm
M (Moderately toxic) 1 to 10 ppm
L (Low toxicity) greater than 10 ppm
To convert fish toxicities to pounds of active ingredient per acre foot of water, multiply by 2.7.

^CActive ingredient (not necessarily a specific product) has caused wildlife deaths.

Table 2. Hazard of Insecticides Used on Apples to Wildlife

^aWildlife hazzards:
high indicates possible wildlife sickness, deaths less likely;
moderate indicates possible wildlife sickness, deaths less likely;
low indicates sickness unlikely.

^bKilIs:
yes indicates wildlife deaths due to use of the insecticides (active ingredient) have been reported.

no indicates wildlife deaths have not been reported when pesticide is used according to label.

Table 3. Hazard of Insecticides Used on Nectarines and Peaches to Wildlife

^aWildlife hazards:
high indicates possible wildlife deaths;
moderate indicates possible wildlife sickness, deaths less likely;
low indicates sickness unlikely

^bKills:
yes indicates wildlife deaths due to use of the insecticide (active ingredient) have been reported.
no indicates wildlife deaths have not been reported when pesticide is used according to label.

Farmers can reduce exposure of nontarget wildlife to pelleted baits by placing the baits in active runways. The best location for rodent baits is where two or more runways intersect. Hand placing baits requires half the amount of rodent bait per acre of orchard and has the same efficacy as broadcast distribution but costs more over large areas.

Remember These Tips To Protect Fish and Wildlife Resources

• Incorporate IPM practices into your fruit production.
• Use proper cultural practices that help to reduce pesticide use.
• Use the pesticide least toxic to fish and wildlife to get the job done
• Protect field borders and other noncrop habitats from herbicides and insecticides.
• Never spray leftover pesticides into wildlife habitats.
• Minimize drift when applying chemicals around fish and wildlife habitats by using low-pressure sprays and selecting nozles that produce large droplets.
• Protect fish ponds and wetlands by avoiding spraying over ponds or drainage ditches.
• Never wash equipment or containers where rinse water could enter ponds or streams.
• Read and follow the instructions on the pesticide label.

 

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