Growth Response of Tapinanthus bangwensis (Engl. and Krause, Danser) Seeds in vitro and Artificial Infestation in the Field

The growth response of mistletoe, Tapinanthus bangwensis (Engl. and Krause) Danser to different temperatures and photoperiods on hormone-free culture media in vitro were assessed. Cultural procedure with plant sap extracts and field infestations were used to study the mistletoe interaction with Gliricidia sepium, Mangifera indica, Coffee robusta and Theobroma cacao. In the laboratory, mistletoe responded positively to a temperature range of 25-30 °C and 16-24 hr photoperiod. The seedling stages of germination, holdfast and haustorium development and leaf emergence were achieved optimally on an artificial medium of 1% (w/v) mineral salts and vitamins, 3% (w/v) sucrose, 1% (w/v) glucose, 0.04% (w/v) potassium nitrate (KNO3) and 1% (v/v) amino acid. Generally, growth was faster in field infestation than in vitro culture. Tapinanthus bangwensis did not develop on G. sepium branches and its extracts. This is consistent with field observations where mistletoes were not found on G. sepium. The selective nature of T. bangwensis to develop on different hosts and their extracts reflects differences in biochemical/nutrient contents of hosts sap. However, it was more probable that physical destruction of M. indica cambial cylinder by mistletoe haustorium deprived the parasite of water and nutrients resulting in its death. Based on T. bangwensis growth responses in nature and in culture, T. cacao was found susceptible, C. robusta was moderately susceptible and G. sepium and M. indica was non-hosts.