Studies on artificial induction of cape saint paul wilt disease using putative vectors

Experiment to transmit Cape Saint Paul wilt disease (CSPWD) of coconut commenced in 1992. Nzinga palmivora, Myndus adiopodoumeensis., and several species of derhidae were considered to be probable vectors of CSPWD of coconut palms. The mouth parts of these leafhopper and planthoppers are highly modified for piercing plant tissues and sucking sap for food. Surveys revealed these insects to be sufficiently widespread and widely distributed on coconut palms in Ghana to be likely vectors. These insects were tested as putative vectors of CSPWD on a variety of susceptible palms. A total of over 100,000 of each group were collected directly from palm foliage at several sites where the CSPWD was active and introduced into cages, which contained test paints. No transmissions were noted. However, three test palms, which received M. adiopodoumeensis introductions in one experiment, expressed characteristic symptoms of CSPWD for 4 months but remission of symptoms was later observed. Subsequent PCR analyses showed no phytoplasma, the pathogen of CSPWD in specimen samples. Possible reasons for the negative results obtained are discussed and future direction of the work is indicated.