Weeds can reduce citrus growth and production, especially in young trees. A management program should be put in place to control weeds in tree rows to minimize competition with citrus, but it is also important to control weeds in row middles to reduce soil erosion.
Weed management can be achieved by utilizing a combination of control practices including but not limited to cultural, preventive, mechanical, chemical or biological methods.
Ramdas Kanissery, assistant professor at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Southwest Florida Research and Education Center discussed weed control during the annual Florida Citrus Growers’ Institute hosted by UF/IFAS.
TREE-ROW WEED CONTROL
To control weeds in tree rows, Kanissery advised applying glufosinate-ammonium for post-emergent weed control. To achieve the best results with this active ingredient, apply to emerged, young, actively growing weeds. Warm temperatures, high humidity and bright sunlight improve the performance. Avoid application to weeds under stress.
Putting ammonium sulfate (AMS) in the tank before adding the herbicide increases efficacy on most weed species significantly, according to Kanissery. The suggested AMS rate is 1.5 to 3 pounds per acre.
Avoid contact or spray drift with green bark, stems or foliage, because injury may occur. Young trees with green stems should have a nonporous wrap in place to avoid contact with susceptible tissue.
ROW-MIDDLE WEED CONTROL
When it comes to row middles, some vegetation is desired to reduce soil erosion from rain and wind. But vegetation growth must be suppressed and maintained to prevent encroachment into the clean tree rows. According to Kanissery, chemical mowing allows for the best of both worlds when managing weeds.
Chemical mowing consists of the use of sublethal rates of post-emergent herbicides, such as glyphosate, in conjunction with mechanical mowing. Vegetation must be in an actively growing stage and not under any stress at the time of herbicide application for maximum regrowth suppression.
Cover crops are also gaining popularity as a weed management approach. Research observations show cover crops significantly reduce weed pressure and enrich the soil in treated row middles.
Learn more about row-middle weed management.