Copper products, characteristics, and uses

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Copper is a metal widely used in agrichemical products to control a wide range of fungal, bacterial and other pests. This article provides a general summary of copper compound categories as pertinent to fruit crops. For further information, see the reference section at the end.

Categories and products

Practically speaking there are two broad categories of copper compounds. Copper sulfate (bluestone, copper sulfate snow), a completely soluble copper form, and various “fixed” coppers that are less soluble. Copper is toxic to bacterial and fungal spores when in the dissolved form. Dissolved copper is the greatest risk of phytotoxicity to green plant tissue. Dissolved copper is very prone to rain wash off.

Copper sulfate is generally used in combination of spray lime as Bordeaux, which helps to stick copper to plant surfaces and reduce the amount of dissolved copper. Copper sulfate is compatible with oil and lime. Since copper sulfate is very soluble with water, there is greater potential for phytotoxicity than the fixed coppers.

Fixed coppers are much less soluble than pure copper sulfate. Fixed coppers are compatible with lime. Types of fixed coppers are copper hydroxide, copper oxychloride sulfate (COCS), basic copper sulfate is also known as tribasic copper sulfate (cupric sulfate, tricupric hydroxide, hemihydrate), and mixtures of two or more copper types.

Another type of “fixed” copper is the copper salts of fatty and rosin acid, sold as liquid compounds. These are not compatible with lime.

Fixed copper and lime should not be used with Guthion, Imidan, Sevin, Thiodan, Bayleton, Captan, Carbamate, Syllit, or phosphorus acid fungicides, because of compatibility and hydrolysis concerns.

Bordeaux mixing procedure

A typical rate is 8 lb of copper sulfate, 8 lbs spray lime, and 1-gallon miscible superior oil per 100 gallons of water.

Dissolve copper sulfate in one-half tank water. Once completely dissolved, add the spray lime (make sure it is fresh) with constant agitation as the tank fills. Add the oil last but before completely filling the tank. The mixture must be agitated continuously. Never combine copper sulfate alone with dormant oil.

Properly made Bordeaux mixture should be near neutral pH (7.0) for safe use.

The copper compound table

The table summarizes characteristics of commonly used copper compounds, both dry and liquid products. The metallic copper content is the active ingredient and should be used to compare various compounds. In addition, it is important to note that copper sulfate and CS 2005 are both copper sulfate pentahydrate types. CS 2005 is used in the citrus industry and has been heavily promoted in Michigan.

Table 1. Copper product summary

Product
Copper form
Amount of formulation
Metallic copper equivalent
Unit type
Metallic copper per unit
Copper sulfate = bluestone = blue vitriol
Copper sulfate pentahydrate*
99%
25%
1 lb
0.25 lb
Kocide 101
Copper hydroxide
77.0%
50%
1 lb
0.50 lb
Champ WP
Copper hydroxide
77.0%
50%
1 lb
0.50 lb
Nu-Cop 50DF
Copper hydroxide
77.0%
50%
1 lb
0.50 lb
Kocide 2000
Copper hydroxide
53.8%
35%
1 lb
0.35 lb
Kocide DF
Copper hydroxide
61.4%
40%
1 lb
0.40 lb
Kocide 3000
Copper hydroxide
46.1%
30%
1 lb
0.30 lb
Basic Copper 53
Basic copper sulfate
95%
53%
1 lb
0.53 lb
Cuprofix Ultra 40D
Basic copper sulfate= CuSO4 · 3Cu(OH)2 · H20
71.1%
40%
1 lb
0.40 lb
Basicop
Basic copper sulfate
95%
53%
1 lb
0.53 lb
Cuprofix Disperss
Basic copper sulfate
36.9%
20%
1 lb
0.20 lb
C-O-C-S WDG
Copper oxychloride sulfate
79%
50%
1 lb
0.50 lb
COCS 53%
Copper oxychloride + basic copper sulfate
53%
53%
1 lb
0.53 lb
Champ 2F = Champ liquid copper = Champium Formula 2
Copper hydroxide
37.5%
24.4%
1 gal
3.00 lb
Tenn-Cop 5E
Copper salts of fatty and rosin acids
58.0%
5.14%
1 gal
0.43 lb
Copper-Count-N
Copper ammonium carbonate
31.4%
8%
1 gal
0.784 lb
CS 2005
Copper sulfate pentahydrate*
19.9%
5%
1 gal
0.418 lb

*Note: Check labels for crops listed. Copper sulfate pentahydrate forms are more soluble than other types and thus are more prone to phytotoxicity and washoff. Fatty and rosin acid forms are not compatible with lime.

References

  • Ritchie, David. Copper-containing fungicides/bactericides and their use in management of bacterial spot on peaches. Southeast Regional Newsletter. Vol 4, No. 1, March 2004.
  • Floyd, Robert. 1991. Bordeaux mixture and similar copper fungicides. Department of Agriculture – Western Australia. Farmnote 78.

Related Events

Related Articles

Related Resources