By Ramdas Kanissery
Young citrus trees are highly sensitive to herbicides. Even small amounts of drift onto green bark or foliage can significantly impact tree growth (Figure 1). Taking a few practical precautions during herbicide applications can help protect young trees and keep them growing strong during their early establishment years.
AVOID HERBICIDE CONTACT WITH GREEN BARK
The greatest risk is herbicide contact with the green, tender bark of young trees. Systemic herbicides, such as glyphosate or 2,4-D, can be absorbed through young bark and may cause yellowing, leaf drop or a general setback in tree growth. Until the bark thickens and matures, avoid spraying close to the trunk.
Trunk guards or tree wraps remain one of the most dependable ways to protect young trees. Be sure to inspect them regularly and replace any that are cracked, damaged or loose.
MANAGE SPRAY DRIFT IN TREE ROWS
When spraying weeds in the tree rows, set the sprayer to lower pressure and use larger droplets to reduce drift. Avoid applications during breezy conditions. Remember that heat coming off bare soil can carry fine droplets up into the canopy. Early morning applications, when conditions are cooler and air movement is minimal, are usually the safest option.
PREVENT HERBICIDE MOVEMENT INTO IPCS
Loose or poorly fitted individual protective covers (IPCs) can actually allow herbicide spray to collect inside the cover. When this happens, the spray can contact the tender trunk directly and cause injury. Make sure IPCs fit snugly at the base and are well secured so they do not open or flap in the wind. Always check covers before spraying and tighten, repair or replace any that have gaps, cracks or tears.
USE RESIDUAL HERBICIDES SAFELY
Soil-active residual or pre-emergent herbicides can be effective tools, but they need to be used carefully around young trees with shallow, developing root systems. Always read the label for any restrictions related to tree age or stage of establishment. Some products can only be applied a certain number of months or years after planting, while others require more mature bark. These requirements vary from product to product. When in doubt, stay at the lower end of the labeled rate.
For additional details, consult the quick herbicide reference guides for postemergence and preemergence herbicides in citrus, which outline tree age requirements and other product-specific restrictions.
INTEGRATE NON-CHEMICAL METHODS
Timely mowing in the row middles is an effective way to reduce overall weed pressure in the grove. Keeping row middles clean limits seed production and movement into the tree rows, which can reduce the need for frequent herbicide applications near young trees.
FINAL THOUGHTS
A bit of extra care during a tree’s first few years pays off. Protecting young trunks and roots from herbicide exposure keeps trees healthy and helps them enter production strong and vigorous.Top of Form
Ramdas Kanissery is an associate professor at the University of Florida Institute of Food and Agricultural Sciences Southwest Florida Research and Education Center in Immokalee.
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