Making Sense of Biologicals: A Key Tool Against Citrus Canker

Tacy Callies MSOB


Disease management ranks high on the list of every Florida citrus grower’s agenda. Tools are available for producers to combat citrus diseases like greasy spot, melanose, scab, foot rot and citrus canker. But growers can never have enough tools, especially when disease resistance is a real possibility in the future.

“To grow citrus trees and produce quality fruit has increasingly been more challenging in Florida,” says Mike Allan, North America vice president for Certis Biologicals. “There are several diseases that citrus growers have to combat every day in the field. They need the necessary tools that are broad-spectrum enough for them to be able to reduce disease incidences to harvest a viable crop.”

Growers can always use extra tools in the toolbox when it comes to maximizing yields and remaining sustainable. Biologicals are one of these tools.

“There’s a real synergy that can be obtained incorporating a program that rotates with biologicals in a cropping system that over time will increase the longevity and effectiveness of conventional chemistries in the grove,” says Allan. “Biologicals provide that synergy and the ability to have tools that are effective in an integrated pest management program.”

Citrus canker is an economically damaging disease to Florida’s citrus industry. Fruit that is severely diseased can drop prematurely, which leads to reduced yields. In addition, the marred appearance of diseased fruit makes it unmarketable.

“I doubt there’s any Florida grower that’s not familiar with citrus canker,” said Michael Harowitz, consultant for Certis Biologicals. “It’s a disease that, at one time, the state attempted to eradicate but was unable to successfully do that. Once it was determined that it was going to be impossible to eradicate the disease, it then became the challenge for the industry to determine how to manage it and live with it.”

For now, copper fungicides are the grower’s best line of defense against citrus canker along with other fungicides and bactericides. But what will happen if one day the disease develops resistance? Resistance occurs when there’s repeated exposure of a certain chemistry to a specific disease. Over time, a bacteria or fungus becomes immune to a specific chemistry and renders it ineffective.

The answer to this potential problem may lie in biologicals.

Biologicals encompass a group of products derived from living organisms. Growers apply these products in conjunction with appropriate chemical applications to provide added protection against certain pests, diseases and weeds. Conventional fungicides can be used less frequently if biologicals are used as a supplement.

Biologicals could be a game-changer for the citrus industry because of their effectiveness against citrus canker.

Certis Biologicals provides biological pesticides for commercial agricultural use. One of the company’s leading products against citrus canker is the bactericide AgriPhageTM. It attacks and kills the bacteria responsible for citrus canker. The product can be used in an existing program as a resistance management tool in all citrus types.

“As per EPA-approved product labels, copper fungicides and bactericides have a maximum amount of metallic copper that can be applied in a season,” says Allan. “While copper is foundational to disease control in citrus, it is important to have alternatives applied in rotation, such as AgriphageTM for citrus canker.”

Certis Biologicals also offers Double Nickel 55® and Double Nickel LC®, broad-spectrum biofungicides that control or suppress fungal and bacterial plant diseases. Kocide 2000-O® and Kocide 3000-O® are low-load copper fungicides approved for use and control of many citrus diseases. LifeGard® is also labeled for citrus canker control.

“Growers need alternatives, and at Certis we work hard to provide them with choices. For every situation in the field, there’s no one decision that is exclusive. Every choice has an outcome that is designed to support growers’ efforts in delivering maximum quality and yields,” concludes Allan.

Visit for more information on Certis Biologicals.

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About the Author

Clint Thompson