The primary host affected by citrus stubborn disease is the sweet orange, but the bacterium can also infect weeds such as periwinkle (Vinca rosea) and London rocket (Sisymbrium irio).
In the wild, shortpod mustard (Hirschfeldia incana) infested by the beet leafhopper, Circulifer tenellus, can prove to be an important reservoir of infection.
S. citri can also be transmitted to China aster (Callistephus chinensis), Shasta daisy (Leucanthemum × superbum), red clover (Trifolium pratense) and radish (Raphanus sativus) by the leafhopper Scaphytopius nitridus.
Small leaves and upright, bunchy growth of branches is common in infected plants, as is dieback and leaf drop.
[8] However, Citrus stubborn does not affect canopy height, width, trunk diameter, and juice quality, regardless of the severity of the infection.
[7] In addition, when it is evident that a tree is diseased, the symptoms are very common and could be attributed to numerous other pathogens or environmental factors.
[11] Temperate regions with limited seasonal rainfall, like in central California, Arizona, and the Mediterranean, are most affected by Citrus Stubborn disease.
[11] Trees severely affected by citrus stubborn disease have been shown to have reduced fruit production by 45-52%, as compared with their undiseased counterparts.
[12] To further increase the effectiveness a chemical component can be added by spraying insecticides on the trap plants, eliminating the insect vector and preventing the bacteria from reaching the citrus crop.
[8] Citrus stubborn disease can be spread through grafting, so it is important to ensure that the mother tree is free of Spiroplasma citri before propagation.