Meyer lemon, also known as Valley lemon, is a hybrid citrus of orange and lemon introduced to the United States from China. It is a key carrier of diseases based on the Tristeza citrus virus (CTV), which is very damaging or even deadly to other citrus fruit. The Meyer lemon is immune. Its role as a pathogen carrier has led Julian W. Sauls, professor and horticulturist at Texas A&M University to call Meyer lemon the "Typhoid Mary" of citrus tree fruits.
Reduction in Vigor & Fruit Harvest
Citrus trees infected with one or more strains of the Tristeza virus will exhibit early symptoms such as slow or halted branch tip growth, diminished budding or blooming, and reduced amounts of fruit that matures and becomes harvest ready.
Tissue & Tree Death
Citrus trees with a particularly virulent strain of Tristeza can decline and die very rapidly. The foliage will noticeably wilt; the branches will die back; any existing buds, fruit and leaves may drop; and the entire tree will die within a few weeks.
Stem pitting affects most common commercially cultivated citrus fruit, including sweet orange, grapefruit and lime. The Meyer lemon Tristeza virus invades the stem tissues, desiccating in spots or partially hollowing out the semi-woody stem tissues, which disrupts or halts the flow of water and nutrients to the developing fruit. This stunts fruit development and can cause premature fruit drop or result in sub-par or inedible fruit.