When developing a weed management program, there are many things for growers to consider. Application site, the stage of weed growth, herbicide selection, the amount of herbicide used, spray volume and pressure, and herbicide bandwidth are just a few of the factors that contribute to the cost and success of a weed management program.
Ramdas Kanissery, weed scientist at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), shared specific weed-control considerations for citrus growers during a recent UF/IFAS virtual seminar.
According to Kanissery, a successful herbicide program starts with selecting the appropriate herbicide or herbicide mixture. He said selecting the proper herbicide requires an understanding of how herbicides work on plants and how to maximize product results.
To maximize post-emergent herbicides, Kanissery recommended using optimum rates for high weed infestations and weeds in mature growth stages.
Rotating post-emergent herbicides with different modes of action will also help to reduce selection pressure on weed populations and help manage weed tolerance, he advised.
For post-emergent herbicides, there are two general types of adjuvants used for tank-mixing: surfactants and spray utility agents. Selection of the adjuvant should be based on various factors, including the herbicide product requirement, mixing and application condition, cost of the adjuvant and availability.
Kanissery said sprays should be applied when there is ample sunlight, low wind speed and when weeds are non-stressed and actively growing in the early growth stage.
To get the most out of pre-emergent herbicides, Kanissery said to apply residual herbicides to bare soil to ensure maximum soil incorporation, turn on irrigation to activate the residual herbicides in soil and include a compatible post-emergent tank-mix partner if there is minimal weed growth.
He said glufosinate-ammonium, a potential alternative to glyphosate, mixes well with pre-emergent herbicides like indaziflam, flumioxazin and diuron.
Probably the most important piece of advice Kanissery offered is to always remember tree safety when applying any herbicide. To protect trees, avoid foliage and fruit contact and install protective wraps around the trunk of young citrus trees, he advised.
Kanissery also said tree injury can be prevented by not using high herbicide rates in new plantings and to always conduct a soil analysis or bioassay before planting new trees.
Learn more about weed control here.