ASHS 2024 Conference

Citrus in key citrus production states in the U.S. have been heavy hit from insect borne and disease pressures. The bacterial disease Huanglongbing (HLB) has had devastating impacts on the citrus industry in Florida. Despite having this threat to the Texas industry as well, the most recent negative impact to decrease citrus acreage has been due to harsh climatic events. In February 2021, citrus groves in south Texas were hit with icy weather that exposed orchards to prolonged freezing temperatures for several hours. The impacts of this one event reduced citrus orchards in south Texas by approximately 25% (over 2,800 ha or 7,000 acres). Climate variability has increased grower awareness to the potential for more frequent extensive drought and freezing winter periods. To better evaluate how to rehabilitate freeze damaged citrus trees, a two-year field study was created aimed at improving tree root health and soil conditions. Compost amendment (CA) was broadcast applied as well as application underneath the tree canopy of grapefruit trees in combination with varying nitrogen fertilizer rate application. Three fertilizer treatments: T1 (base rate = 112 kg N ha-1), T2=1.5x and T3=2x the T1 base rate were evaluated in a randomized complete block design with (11.2 Mg CA ha-1) and without CA in Rio Red grapefruits. Results indicated that root abundance significantly increased under composted trees compared to non-composted trees. Composted trees led to higher yields within 18 months following the freeze event compared to non-composted trees. The impacts of this research may aid Texas citrus growers and other producers looking to improve in-field management strategies that may assist in preparation for post-freeze weather events and extended seasons of water scarcity.