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copper compounds EPA Rule--Water Quality Standard

NAPIAP Briefing Paper

Water Quality Standard and Copper Pesticides
____________________________________________

On December 1, 1992, EPA issued a rule setting water quality
standards for priority toxic pollutants that applies to States
identified as not complying with the Clean Water Act. While the
rule applies to 12 States and 2 Territories, all other States and
Territories had previously set standards that comply with the
Clean Water Act. Under this rule, copper is a priority toxic
pollutant.

Copper compounds are used as fungicides and bactericides in 
agricultural prodcticn, as algicides and for control of fungal
rot, mildew, and decay of numerous materials. Strategies to meet
the clean water standards could restrict the use of pesticides
containing copper.

Standards for Copper
____________________

The rule sets standards for copper in fresh water at a 4-day
average continuous concentration of 12 micrograms per liter
and a 1-hour average maximum concentration of 18 micrograms
per liter. Fresh water is defined as having a salinity of 1
part per thousand or less, 95 percent of the time. For more
saline water, the standard for copper is 2.9 micrograms per
liter.

The rule allows States to modify the standards for metals,
including copper, with a water-effect ratio that can make the
standards less stringent. The ratio accounts for the effects
of other materials in receiving water on the bioavailability
and toxicity of a metal. For example, organic material, such
as algae, can complex with copper to reduce its
bioavailability and toxicity.

The ratios are to be computed with sandard toxicity testing
protocols, and EPA will provide guidance to the States in
determining the ratios.

Fungicidal Properties and Uses of Copper Compounds
__________________________________________________

The fungicidal properties of copper have been recognized for
many years. Copper sulfate was used as a seed treatment for
bunt control of wheat as early as 1761, and later (1885)
Bordeau Mixture (copper sulfate plus lime) was used for
control of downy mildew of grape.

Since 1920, a number of inorganic and organic copper
fungicides have been developed and include copper carbonate,
copper ammonium carbonate, copper hydroxide, copper
naphthenate, copper oleate, copper oxide, copper oxychloride,
copper oxychloride sulfate, copper 8-quinolinolate, copper
sulfate, copper salts of fatty and rosin acids, copper sodium
sulfate, phosphate complex, and copper-zinc sulfate complex.

Copper compounds are registered as foliar sprays for control
of numerous fungal and bacterial diseases of plants. Their
use is recommended by states on many crops including citrus,
rice, almonds, walnuts, tomatoes, peaches, peanuts, peppers,
and beans for control of brown rot, greasy spot, melanose,
blast, brown leaf spot, sheath blight, shothole, anthracnose,
bacterial canker, speck and spot, early and late blight, leaf
curl, Cercospora leaf spot, rust, bacterial leaf spot, frogeye
Spot, common blight, halo blight, walnut blight, and downy and powdery mildew.

Coppers are particularly effective for controlling bacterial
plant diseases and are often used in combination with other
fungicides (chlorothalonil, streptomycin, maneb, mancozeb, or
sulfur) to enhance control.

The possibility of plant injury under certain weather
conditions is a major limitation to the use of copper
compounds on some crops.

Copper compounds are registered for control of algae in
impounded waters, lakes, ponds, reservoirs, irrigation and
drainage conveyance systems, and for fungal/bacterial slimes
in sewer pumps, force mains, pulp and paper mills, cooling
towers and spray ponds.

Copper compounds are registered for controlling fungal rot,
decay and mildew on cordage, textiles, lumber, wooden crates,
boxes, pallets, etc., paint, sealers, varnishes, paper, waxes,
tree wounds, and surfaces (brick, composition board, masonry,
plaster, etc.).

There are approximately 2,000 registered products which
contain copper compounds as active ingredients.

Amount of Copper Funqicide Used in Aqriculture
_______________________________________________

The Resources for the Future pesticide data base estimates
that 9.9 million pounds active ingredient are used on 51 crops
(Gianessi and Puffer, 1992).

The top 5 uses of copper are citrus, rice, almonds, walnuts
and tomatoes which account for 70 percent of the quantity of
and 60 percent of the acreage treated with copper compounds.
The top 15 uses account for 93 percent of total copper use.

Copper is intensively used on many fruit, nut, and vegetable
crops, which account for almost 80 percent of copper use in
agricultural fungicides.

Crops with more than 50 percent of acres treated with copper
fungicides are all fruit, nuts, or vegetables. They include
nectarines (100), walnuts (81), celery (81), pears (79),
apricots (68), almonds (56), tomatoes (55), carrots (52), and
citrus (50). These 9 crops account for 60 percent of copper
use in agricultural fungicides and include 4 of the top 5
copper fungicide uses.

Copper use is heavily concentrated in the fruit, nut, and
vegetable producing States of California and Florida, which
account for 8.5 million pounds (85 percent) of copper use in
agricultural fungicides. California accounts for 5.7 million
pounds (58 percent) and Florida 2.7 million pounds (28 percent).

Alternatives to Copper  Fungicides
__________________________________

Copper compounds are inexpensive broad-spectrum fungicides.
In cases where effective alternatives are available, they will
generally be more expensive, synthetic organic compounds.

In the NAPIAP Fungicide Benefits Assessment Report (1991), a
number of States listed crops and their diseases for which
copper is used but no effective alternative pesticide was
available. These included: almonds (rust, shothole), citrus
(melanose), pistachios (fruit rot), walnuts (walnut blight),
cherry (bacterial canker), strawberry (leaf blight and crown
rot, leaf spot), beans (bacterial blight), crucifers
(Xanthomonas), peppers (bacterial leaf spot), tomatoes
(bacterial speck, bacterial spot), beets (Cercospora leaf
spot), eggplant (leaf and fruit rots), and spinach (white
rust, blue mold, anthracnose, Cladosporium leaf spot).

The Fungicide Benefit Assessment Report estimated that without
copper, bacterial diseases could frequently cause yield losses
of 5-20% on many fruit, nut, and vegetable crops.

References:

Gianessi, L.P., and C.A. Puffer, Funqicide Use in U.S. Crop
Production, Resources for the Future, August, 1992.

Table 1.  Use of Copper as a Fungicide
_______________________________________

Crops                Acres          Acres        Percent   Rate/     Total
                    Planted         Treated      Treated   Acre    Quantity
______________________________________________________________________________  
                                                             lbs a.i.
                                                             ________

Citrus             1,084,000        547,162        50      4.7    2,554,314
Rice               2,420,000        147,701         6     10.7    1,583,355
Almonds              427,685        239,504        56      4.5    1,077,768
Walnuts              213,200        172,901        81      5.7      981,875
Tomatoes             369,000        202,023        55      4.0      816,567
Peaches              207,000         69,464        34      6.8      468,957
Peanuts            1,412,000        121,728         9      3.0      367,533
Grapes               810,712         95,095        12      2.3      219,607
Apples               571,000         55,054        10      3.9      215,625
Nectarines            29,162         29,162       100      7.2      210,550
Pears                 79,000         62,603        79      3.1      193,357
Avocadoes             86,998          7,671         9     22.1      169,295
Plums                148,614         21,398        14      5.8      124,206
Cherries             128,000         25,045        20      4.7      118,243
Potatoes           1,302,000         71,600         5      1.5      105,517
Olives                33,264         12,308        37      7.4       91,079
Dry beans          1,785,000         46,042         3      1.9       88,418
Apricots              21,027         14,298        68      4.7       66,486
Celery                33,000         26,737        81      1.9       50,191
Watermelons          183,000          9,483         5      4.7       44,417
Carrots               85,000         44,463        52      1.0       42,855
Green beans          332,000         19,003         6      2.1       39,521
Sugarbeets         1,253,007         36,260         3      1.0       36,260
Cranberries           27,000          6,821        25      5.0       34,105
Spinach               32,261         12,666        39      2.5       31,868
Sweet peppers         60,193         12,269        20      2.0       24,548
Onions               112,000         12,995        12      1.7       22,597
Lettuce              244,000         17,749         7      1.2       21,434
Cucumbers            120,000         14,165        12      1.3       18,222
Filberts              28,346          5,102        18      2.7       13,928
Cauliflower           52,716         14,361        27      l.0       13,753
Strawberries          42,930          7,658        18      1.7       12,786
Cabbae                81,000          8,707        11      1.3       11,157
Hops                  30,000          4,601        15      2.0        9,300
Raspberries            9,939          2,643        27      2.7        7,203
Broccoli              52,716         10,345        20      0.7        7,065
Blueberries           48,748          1,074         2      6.0        6,444
Squash                44,767          1,680         4      2.6        4,390
Collards               9,000          4,259        47      1.0        4,259
Blackberries           4,472          1,610        36      2.4        3,896
Green peas           315,185          3,021         1      1.2        3,527
Pumpkins              21,879          2,074         9      1.5        3,010
Pistachios            50,174            502         1      5.1        2,555
Egplant                3,439            570        17      4.3        2,429
Cantaloups           113,000            875         1      2.7        2,362
Beets                 11,377           4033        35      0.4        1,751 
Brussels sprouts       4,197          1,091        26      1.4        1,571
Hot peppers           23,000            244         1      2.9          715
Kiwi                   8,909             89         1      6.9          616
Dry peas             239,000            482         0      1.0          482
Green Onions          12,186            447         4      0.5          210

   Total                          2,228,838                       9,932,179

Source:  Gianessi and Puffer, 1992