The Effect of Huanglongbing on Young Citrus Tree Water Use

Abstract

<jats:p>Understanding the role of Huanglongbing (HLB) caused by <jats:italic>Candidatus Liberibacter asiaticus</jats:italic> on citrus (<jats:italic>Citrus</jats:italic> sp.) water use is critical for determining if changes in water management of commercial citrus orchards affected by this disease is necessary. Reference evapotranspiration (ET<jats:sub>o</jats:sub>) is the most used methodology for irrigation scheduling, particularly in light of reports that indicate the lack of water for irrigation will become a major problem in many places around the world including Florida. The objectives of this study were to determine citrus tree water relationship [water use, sap flow, and stem water potential (Ψ)] as affected by ET<jats:sub>o</jats:sub> and HLB. The study was initiated on Jan. 2014 on two sweet orange (<jats:italic>Citrus sinensis</jats:italic>) cultivars included Hamlin and Valencia grown in a fine sandy soil texture (sandy, siliceous, and hyberthermic Arenic Alaquods) in a greenhouse. Twelve weighing lysimeters of each cultivar (six HLB-affected and six nonaffected trees) were used to determine selected water relation parameters. Results indicated a significant reduction in water use, Ψ, and sap flow for affected trees when compared with nonaffected trees. Citrus water use of healthy trees during the 2-year study was 31% and 27% greater than HLB-affected trees for ‘Hamlin’ and ‘Valencia’, respectively. Lower water use of HLB-affected trees resulted in 10% and 15% greater available soil water content than healthy ‘Hamlin’ and ‘Valencia’ trees, respectively. Therefore, reducing the water supply for HLB-affected trees than healthy trees may be a desirable practice that would lead to significant water savings.</jats:p>

Interaction of Huanglongbing and Foliar Applications of Copper on Growth and Nutrient Acquisition of Citrus sinensis cv. Valencia

“…The foliar applications of Cu increased leaf Cu concentrations above the upper limit considered sufficient for citrus (16 mg/kg dry weight) at lower rates of Cu applied for the HLB-affected trees than the non-HLB controls. The impact of HLB on Cu uptake has not been defined clearly in the literature, with some studies indicating suppression (Nwugo et al, 2013a(Nwugo et al, , 2013bSpann and Schumann, 2009), some indicating no effect (Handique et al, 2012;Masaoka et al, 2011;Tian et al, 2014), and, in a recent study, an increase (Hamido et al, 2017), although the Cu foliar analysis in that study was not published (Morgan, personal communication).…”

Effect of Essential Nutrients on Roots Growth and Lifespan of Huanglongbing Affected Citrus Trees

“…1 Factorial effects: T = season of the year, R = Rootstocks, N = nitrogen rate, and S = Secondary macronutrients, reading was taken every month from Jan. to Dec. of 2018 and 2019. 2 NS, *, **, and *** represent non-significant or significant at p ≤ 0.05, < 0.01, and < 0.0001, respectively. 4 NS, *, **, and *** represent non-significant or significant at p ≤ 0.05, < 0.01, and < 0.0001, respectively.…”

“…Huanglongbing (HLB, or citrus greening) is the most destructive endemic disease of Florida citrus production, with no identified cure insight [1,2]. The Asian citrus psyllid (ACP, Diaphorina citri Kuwayama) is a widespread pest throughout Florida is an important pest of citrus as it transmits the phloem-limited bacteria Candidatus Liberibacter asiaticus (Ca.…”

“…<------------------Significance 3 ----------------untreated control (1), full Ca dose (2), full Mg dose (3), and half Ca and half Mg doses (4), (full dose = 45 kg ha −1 ) 2. Means on vertical column followed by different letters are significantly different at p ≤ 0.05, based on the Tukey-Kramer HSD test (n = 36) 3.…”

“…(untreated control), (2) 1× (foliar only), (3) 2× (1× foliar and 1× ground-applied), and (4) 3× (1× foliar and 2× ground-applied), (1× = 9 kg ha −1 of S encapsulated metallic Mn and Zn each and 2.2 kg ha −1 of B) 2. Means on vertical column followed by different letters are significantly different at p < 0.05, based on the Tukey-Kramer HSD test (n = 36).…”