Hemiparasitic mistletoe, Tapinanthus bangwensis, alters nutrient allocation in cocoa host-parasite systems

Hemiparasitic plants can alter host physiology by diverting water and nutrients, yet their effects on nutrient allocation in perennial tropical crops remain poorly quantified. This study examined whether Tapinanthus bangwensis (Engl. & K. Krause) Danser infestation alters cocoa leaf nutrient composition, whether mistletoe tissues accumulate nutrients relative to host leaves, and whether infestation effects persist after measured farm-level soil nutrients are considered. Fifteen smallholder cocoa farms in Ghana were sampled, with paired infested and uninfested cocoa trees selected on each farm. Cocoa leaves, associated mistletoe leaves and composite 0–20 cm soil samples, were analysed for N, P, K, Ca, Mg, S, Fe, Cu, Zn, and Mn. Paired t-tests compared infested and uninfested cocoa leaves and compared mistletoe leaves with associated host leaves. Nutrient-specific mixed-effects models tested whether infestation remained associated with cocoa leaf nutrients after including measured farm-level soil nutrient covariates. Infested cocoa leaves had lower N, P, K, and Cu than uninfested leaves, but higher Ca and Mg. Mistletoe leaves contained higher P, K, Ca, Mg, S, and Mn than their associated host leaves. Infestation effects persisted for several nutrients after soil covariates were included. These findings suggest that T. bangwensis alters nutrient allocation within cocoa host-parasite systems and complicates interpretation of foliar nutrient status in infested perennial crops.