Fe2+ Ions Alleviate the Symptom of Citrus Greening Disease

Abstract

Citrus greening (CG) is among the most devastating citrus diseases worldwide. CG-infected trees exhibit interveinal chlorotic leaves due to iron (Fe) deficiency derived from CG; thus, Fe content is lower in infected leaves than in healthy leaves. In this study, we demonstrated that the foliar application of Fe2+ relieves the symptom of CG infection in citrus trees. We applied Fe2+ and citrate to the leaves of infected rough lemon plants. Following this treatment, a reduction in the number of yellow symptomatic leaves was observed, and their growth was restored. Using chlorophyll content as an index, we screened for effective Fe complexes and found that a high ratio of citrate to Fe2+ in the applied solution led to effects against CG in Shikuwasa trees. A high proportion of Fe2+ to total Fe was another key factor explaining the effectiveness of the solution in CG infection, indicating the importance of Fe2+ absorption into plant cells. We confirmed the proportion of Fe2+ to total Fe through the high correlation of reflectometry data via a triazine reaction and X-ray absorption fine structure analysis. These results demonstrate that the foliar application of a high-Fe2+ citrate solution can restore the growth of CG diseased trees.

Incidence and Molecular Detection of Greening Disease in Two Citrus Cultivars in Sargodha, Pakistan

“…They reviewed the characteristic symptoms like yellowing of leaves, Lopsided fruits, blotchy mottle, aborted seeds, and unripe fruits (Fruit remain green). Similar results have also been reported by (Saifullah et al, 2015;Inoue et al, 2020). Yellowing of leaves, blotchy mottling, upright growth of CGD infected trees, and lopsided fruits were observed during our study which is in accordance with McCollum and Baldwin (2017).…”

Rootstock Influences on Health and Growth Following Candidatus Liberibacter asiaticus Infection in Young Sweet Orange Trees

“…One of the most often described symptoms of CLas infection in field trees, an asymmetrical blotchy mottle, was rarely observed in leaves of our CLas-positive trees. Based on previous reports of significant nutritional deficiencies associated with HLB disease, and the reduction of some HLB symptoms through improved nutritional management [5,6,[26][27][28][29], we hypothesize that the optimal nutritional conditions for tree growth in our greenhouse may have masked some of the manifestations of CLas infection, such as blotchy mottle. It is unclear to what extent nutritional conditions might have similarly affected the expression of leaf yellowing.…”

<strong>Identification of huanglongbing Based on Visual Symptoms: a Grower’s Diagnostic Toolkit</strong>

“…Blotchy mottling patterns on the leaves are asymmetrical using the mid-rib as a central line, which is by far the inevitable diagnostic greening symptom, and it is between said as a severe infection and incidentally similar to the sign of Fe deficiency when leaves turn into discolored yellow (Inoue et al, 2020) (Fig. 1).…”

“…A valid reason of losing the commercial value of fruits affected by HLB along with the yield reduction, falling market price, management of disease and production is very costly, which severely affects the economic condition and also citrus greening highly deteriorate the marketability of fruits in agricultural field (Inoue et al, 2020). When a tree begins to be infected, it is totally a loss project to apply chemical pesticide because it cannot cure completely with pesticides; in addition, young plants are more susceptible to this disease, and it is therefore a very laborious job for farmers to replace the young plants that have been affected so far.…”

“…When a tree begins to be infected, it is totally a loss project to apply chemical pesticide because it cannot cure completely with pesticides; in addition, young plants are more susceptible to this disease, and it is therefore a very laborious job for farmers to replace the young plants that have been affected so far. Recently, no fruitful method has been developed to cure this deadliest disease, except to remove all infected plants from good ones to eliminate the spread of the pathogen (Inoue et al, 2020). One of the most difficult tasks is to identify citrus greening and other disorders due to the likeliness between HLB and other citrus diseases such as Citrus tristeza virus and problems with nutrient deficiency, which are often confusing.…”