One of the most common complaints from growers about traditional copper fungicides is the thick, bluish coating left on plants after a field treatment. According to University experts, this blue-colored film can be more than just an annoyance. It can actually impact yield potential.

“Growers really dislike this physical characteristic, which we call the ‘blue hue’,” said Sarah Hornsby, president of Agricultural Crop Consulting, Inc., in Parrish, Fla. But this heavy bluish discoloration is more than a physical irritant, she notes. “Copper hydroxide coating seems to draw moisture out of the plant. It also appears to slow down photosynthesis while temporarily halting growth.” 

After spraying higher rates of copper hydroxides, Hornsby describes plants as “tightening and curling up.” And although the plants do recover in a day or two, Hornsby believes the “blue hue” coating actually stresses plants after each application.

Another unintended side effect of coppers’ blue film is reduced performance of reflective mulch, which is widely used for insect control on tomatoes and peppers in Hornsby’s Central Florida region. “Coating on reflective mulch puts a strain on our growers,” she said. “After two or more sprays, the reflective mulch gets covered up, which reduces its value and return on investment.”

A ‘truer, not bluer’ soluble solution

For growers wanting to ‘lose the blue’ without sacrificing well-known disease control from copper, ADAMA has the answer with MasterCop fungicide/bactericide

A copper complex formulation of copper sulfate pentahydrate, MasterCop controls bacterial and fungal diseases on high-value crops, but without heavy residue or bluish coating left on plants.