Development of Molecular Marker to Detect Citrus Melanose Caused by Diaporthe citri from Citrus Melanose-like Symptoms

It is difficult to distinguish melanose and melanoses-like symptoms with the naked eye because they appear similar. To accurately detect melanose symptoms caused by Diaporthe citri from melanose-like symptoms, we developed PCR-based specific primers Dcitri by aligning the internal transcribed spacer (ITS) region of D. citri with the ITS of Diaporthe cytosporella, Diaporthe foeniculina, Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria citri, and Fusarium oxysporum found on citrus peel. PCR results showed that the specific product was amplified in D. citri but not in other isolates including, C. gloeosporioides, B. cinerea, A. citri, F. oxysporum. In addition, specific products were observed in melanose symptoms caused by D. citri but not in melanose-like symptoms, such as copper-injury, sunscald, damages by yellow tea thrips, and pink citrus rust mite. Using the Dcitri primers developed in this study, it is expected that melanose caused by D. citri could be accurately distinguished from melanose-like symptoms.

Citrus Rust Mite Phyllocoptruta oleivora (Ashmead) (Arachnida: Acari: Eriophyidae)

The citrus rust mite, Phyllocoptruta oleivora (Ashmead), also called silver mite, is an important pest of citrus in most humid regions of the world (McCoy and Albrigo 1975, Vacante 2010) (Figure 1). It was first described in 1879 from Florida (Burditt et al. 1963). Phyllocoptruta oleivora is the most important mite pest of Florida citrus due to the cost of control and damage caused to fruits, particularly those for the fresh market (Knapp 1994, Hoy 2011). It coexists with another rust mite called the pink citrus rust mite, Aculops pelekassi (Keifer) (Childers and Achor 1999); however, Phyllocoptruta oleivora is usually the prevalent species.https://edis.ifas.ufl.edu/in1278