Copper formulations for fruit crops

Here is a guide to copper compounds commonly used in fruit to help manage a wide array of fungal and bacterial diseases.

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 compounds, many of which are used in fruit growing. Copper is toxic when the dissolved form penetrates into plant tissue. In general, growers should avoid the use of spray additives such as foliar nutrients, and any surfactants with penetrating characteristics when applying coppers. Fixed copper and lime should not be used with Guthion, Imidan, Sevin, Thiodan, Bayleton, captan, carbamate (Ferbam), syllit, or phosphorus acid-type compounds (Fosphite, ProPhyt, Phostrol, Agri-Fos, Aliette). Check product labels for further details.

Commercial copper products differ in the copper form, the amount of formulated copper compound in the product, the amount of metallic copper (active ingredient), and whether it is liquid or a dry formulation. Copper compounds can be compared on the basis of how much metallic copper is contained in a gallon or pound of product. More metallic copper means more phytotoxicity potential, but this is not the whole story. Copper forms differ greatly in the availability of free copper ions released on wet plant surfaces, as indicated by the three major groups as follows.

Copper sulfate is highly soluble in water, and compatible with lime and oil if mixed properly. Copper sulfate has a greater potential for phytotoxicity than “fixed” coppers and thus is generally combined with lime to help tie up the copper ions. Compounds labeled as basic copper sulfate and copper sulfate pentahydrate are generally highly soluble forms, although chemical companies may include components such as gypsum that help to tie up copper ions on plant surfaces.

Copper hydroxide, copper oxychloride sulfate (COCS), and tribasic copper sulfate (cupric sulfate, tricupric hydroxide, hemihydrate) are all “fixed” coppers that are less soluble than copper sulfate forms.

Copper salts of fatty and/or rosin acid are not compatible with lime, but have some of the “fixed” copper characteristics of less copper ion burn potential on plant surfaces.

Copper compounds with finely ground copper components are more “active” against pathogens and are potentially more phytotoxic because of the better distribution and greater tendency to go into solution compared to coarser formulations.

Table 1. Copper product summary – check label for allowed use on crop.

Product Copper form Amount of formulation Metallic copper equivalent Unit type metallic copper per unit
Dry formulations
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
Copper oxychloride + basic copper sulfate 53% 53% 1 lb 0.53 lb
Liquid formulations
Champ 2F = Champ liquid copper = Champium Formula 2 Copper hydroxide 37.5% 24.4% 1 gal 3.00 lb
Cueva Fungicide Concentrate** Copper octanoate (copper salt of fatty acid) 10% 1.8% 1 gal 0.15 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 formulations are generally more soluble than other types and thus are more prone to phytotoxicity and washoff unless combined with lime as a safening agent. *Cuprofix Disperss, a copper sulfate formulation, also contains gypsum, a calcium containing compound which provides some safening of the copper, much like the lime in Bordeaux. ** Fatty and rosin acid forms are not compatible with lime.

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